Processed Cheeses and Analogues

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Processed Cheese and Analogues

The Society of Dairy Technology (SDT) has joined with Wiley-Blackwell to produce a series of technical dairy-related handbooks providing an invaluable resource for all those involved in the dairy industry, from practitioners to technologists, working in both traditional and modern large-scale dairy operations. For information regarding the SDT, please contact Maurice Walton, Executive Director, Society of Dairy Technology, PO Box 12, Appleby in Westmorland, CA16 6YJ, UK. email: [email protected] Other volumes in the Society of Dairy Technology book series: Probiotic Dairy Products (ISBN 978 1 4051 2124 8) Fermented Milks (ISBN 978 0 6320 6458 8) Brined Cheeses (ISBN 978 1 4051 2460 7) Structure of Dairy Products (ISBN 978 1 4051 2975 6) Cleaning-in-Place (ISBN 978 1 4051 5503 8) Milk Processing and Quality Management (ISBN 978 1 4051 4530 5) Dairy Fats and Related Products (ISBN 978 1 4051 5090 3) Dairy Powders and Concentrated Products (ISBN 978 1 4051 5764 3) Technology of Cheesemaking, 2nd edition (ISBN 978 1 4051 8298 0)

Processed Cheese and Analogues

Edited by

A.Y. Tamime Consultant in Dairy Science and Technology Ayr, UK

A John Wiley & Sons, Ltd., Publication

This edition first published 2011 © 2011 by Blackwell Publishing Ltd. Blackwell Publishing was acquired by John Wiley & Sons in February 2007. Blackwell’s publishing program has been merged with Wiley’s global Scientific, Technical and Medical business to form Wiley-Blackwell. Registered office: John Wiley & Sons, Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK Editorial offices: 9600 Garsington Road, Oxford, OX4 2DQ, UK The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK 2121 State Avenue, Ames, Iowa 50014-8300, USA For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at www.wiley.com/wiley-blackwell. The right of the authors to be identified as the authors of this work has been asserted in accordance with the UK Copyright, Designs and Patents Act 1988. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold on the understanding that the publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought. Library of Congress Cataloging-in-Publication Data Processed cheese and analogues / edited by A.Y. Tamime. p. cm. – (Society of Dairy Technology series) Includes bibliographical references and index. ISBN 978-1-4051-8642-1 (hardcover : alk. paper) 1. Processed cheese. I. Tamime, A.Y. SF272.5.P76 2011 637 .358 – dc22 2010052430

A catalogue record for this book is available from the British Library. This book is published in the following electronic formats: ePDF [9781444341829]; Wiley Online Library [9781444341850]; ePub [9781444341836]; Mobi [9781444341843] Set in 10/12.5pt Times by Laserwords Private Limited, Chennai, India 1 2011

Contents

Preface to the Technical Series Preface Contributors 1 Processed Cheese and Analogues: An Overview A.Y. Tamime 1.1 Historical background 1.2 Diversity of products 1.2.1 Terminology and/or nomenclature 1.2.2 Classification 1.3 Patterns of production 1.4 Principles of manufacturing stages 1.4.1 Natural cheeses 1.4.2 Formulation of a balanced mix 1.4.3 Emulsifying salts 1.4.4 Addition of miscellaneous additives 1.4.5 Heat treatment 1.4.6 Homogenisation 1.4.7 Filling machines and packaging materials 1.5 Conclusions References 2 Current Legislation on Processed Cheese and Related Products M. Hickey 2.1 Introduction and background 2.2 Definitions and standards of identity 2.2.1 Background and evolution 2.2.2 Legislation in the European Union (EU) 2.2.3 Legislation in the UK 2.2.4 Legislation in the Republic of Ireland 2.2.5 Legislation in Germany 2.2.6 Legislation in the Netherlands 2.2.7 Legislation in France

xi xiii xv 1 1 2 2 3 3 5 5 5 7 7 12 12 13 14 14 25 25 26 26 27 36 41 42 44 45

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2.2.8 Legislation in Denmark 2.2.9 Legislation in Sweden 2.2.10 Legislation in Spain 2.2.11 Legislation in Italy 2.2.12 Legislation in the Czech Republic 2.2.13 Legislation in Hungary 2.2.14 Legislation in the USA 2.2.15 Legislation in Canada 2.2.16 Legislation in Australia and New Zealand 2.2.17 Legislation in Japan 2.2.18 Legislation in Mercosur/Mercosul 2.2.19 Legislation in Chile 2.2.20 Legislation in some Middle Eastern countries 2.2.21 Codex Alimentarius standards 2.3 Summary and conclusions 2.4 Acknowledgements References 3 Effects of Natural Cheese Characteristics and Processing Conditions on Rheology and Texture: The Functionality of Cheese Components in the Manufacture of Processed Cheese T.P. Guinee 3.1 Definition of processed cheese products: an introduction 3.2 Overview of manufacture 3.2.1 Background 3.2.2 Manufacture 3.3 Microstructure of PCPs 3.4 Principles of processed cheese manufacture 3.4.1 Destabilisation and dehydration of milk during the manufacture of natural cheese 3.4.2 Characteristics of protein in natural cheeses 3.4.3 Effects of heating/shearing cheese (protein) 3.4.4 The interaction of emulsifying salt with cheese protein during processing 3.5 Effects of natural cheese characteristics on PCPs 3.5.1 Calcium content 3.5.2 pH 3.5.3 Degree of maturity and intact casein content 3.6 Effects of processing conditions 3.6.1 Time 3.6.2 Temperature 3.6.3 Shear 3.7 Conclusions References

46 46 47 48 48 50 51 57 59 59 60 62 63 68 73 73 74

81 81 83 83 85 86 87 87 88 90 90 91 92 93 97 101 101 103 104 105 106

Contents

4 Functionality of Ingredients: Emulsifying Salts J.A. Lucey, A. Maurer-Rothmann and S. Kaliappan 4.1 Introduction 4.2 Main types of emulsifying salts 4.2.1 Citrate 4.2.2 Phosphate-based 4.2.3 Other types of emulsifying salts 4.3 Properties and roles of emulsifying salts used in processed cheese 4.3.1 Calcium binding/ion exchange 4.3.2 pH adjustment, buffering and titration behaviour 4.3.3 Casein dispersion, protein hydration and fat emulsification 4.3.4 Creaming and structure formation during cooling and storage 4.3.5 Antimicrobial activity 4.3.6 Crystal formation and other properties of emulsifying salts 4.4 Selection of emulsifying salt 4.5 Conclusion References 5 Flavours and Flavourants, Colours and Pigment G. Osthoff, E. Slabber, W. Kneifel and K. D¨urrschmid 5.1 5.2 5.3 5.4

Introduction Types of processed cheese Raw material Flavour 5.4.1 Natural flavourants 5.4.2 Chemical flavourants 5.4.3 Flavour changes 5.5 Colours 5.5.1 Natural colours 5.5.2 Colour decay and changes 5.5.3 Process colours 5.6 Sensory attributes of processed cheese 5.7 Conclusion References 6 Manufacturing Practices of Processed Cheese M. Nogueira de Oliveira, Z. Ustunol and A.Y. Tamime 6.1 6.2 6.3 6.4

Introduction Some historical background Processed cheese and products Key steps in processing 6.4.1 Selection of ingredients 6.4.2 Emulsifying salts

vii

110 110 111 111 113 115 116 116 118 120 122 124 124 127 129 129 133 133 133 134 135 135 139 140 141 141 142 142 142 143 144 148 148 148 150 153 154 158

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Contents

6.4.3 Preservatives 6.4.4 Formulation of the cheese blend 6.4.5 Grinding/shredding 6.4.6 Heating/cooking 6.4.7 Miscellaneous processing steps 6.4.8 Packaging 6.4.9 Rate of cooling and storage 6.5 Changes in processed cheese during its shelf-life 6.6 Conclusions References 7 Processed Cheese Plants and Equipment: A Practical Overview S. Dixon 7.1 Introduction 7.2 Unit operations 7.2.1 Weighing the ingredients to be processed 7.2.2 Initial size reduction 7.2.3 Grinding 7.2.4 Blending the ingredients to form a standardised cheese mix or blend 7.2.5 Transferring the standardised cheese blend to a cooking system 7.2.6 Direct steam injection into the cooking systems 7.2.7 Filtering the molten cheese 7.3 Processing plant for the manufacture of processed cheese slices 7.4 Conclusions 8 Packaging Materials and Equipment E.M. Buys and J.F. Mostert 8.1 Introduction 8.2 Packaging materials 8.2.1 General specifications 8.2.2 Functions of a package 8.2.3 Types of packaging materials 8.2.4 Hygiene of packaging material 8.2.5 Shelf-life and interactions with packaging materials 8.3 Packaging equipment 8.3.1 Background 8.3.2 Portions/wedges 8.3.3 Blocks 8.3.4 Sausage shape 8.3.5 Metal cans 8.3.6 Tubs, jars, cups and plastic containers 8.3.7 Collapsible tubes

163 167 167 167 170 170 170 171 173 173 179 179 180 180 181 182 184 185 187 194 195 198 199 199 200 200 200 201 201 202 204 204 205 208 210 211 211 213

Contents

8.3.8 Packs with external decoration 8.3.9 Slices 8.4 Conclusion References 9 Production of Analogue Cheeses E.D. O’Riordan, E. Duggan, M. O’Sullivan and N. Noronha 9.1 9.2 9.3 9.4

Introduction Definition and legislation Applications and advantages of analogue cheese products Manufacture of analogue cheese 9.4.1 General principles and manufacturing protocol 9.4.2 Key ingredients used in the production of analogue cheese products 9.4.3 Formulation 9.4.4 Processing equipment 9.5 Factors influencing analogue cheese functionality 9.5.1 Hydration of protein: impact on cheese functionality 9.5.2 Effect of compositional change on analogue cheese functionality 9.6 Developments in analogue cheese 9.6.1 Protein replacement 9.6.2 Fat replacement 9.6.3 Microwave expansion of analogue cheese 9.7 Future of analogue cheese References 10 Quality Control in Processed Cheese Manufacture A.Y. Tamime, D.D. Muir, M. Wszolek, J. Domagala, L. Metzger, W. Kneifel, K. D¨urrschmid, K.J. Domig, A. Hill, A. Smith, T.P. Guinee and M.A.E. Auty 10.1 Introduction 10.2 HACCP 10.2.1 Background 10.2.2 Implementation (theoretical approach) 10.2.3 Implementation (practical approach) 10.2.4 Verification of HACCP 10.2.5 Monitoring the processing plant 10.3 Examination of raw materials 10.3.1 Natural cheeses 10.3.2 Butter and fat of plant origin 10.3.3 Dairy powders 10.3.4 Natural flavouring ingredients 10.3.5 Emulsifying salts

ix

213 214 215 216 219 219 219 220 220 220 223 226 226 228 230 231 236 236 238 238 239 239 245

245 247 247 248 255 259 260 266 266 268 268 268 269

x

Contents

10.4 10.5

10.6

10.7

10.8

10.9 10.10

10.3.6 Miscellaneous additives 10.3.7 Water/steam 10.3.8 Sampling for quality appraisal of the retail product Analysis of chemical composition Microbiological quality and safety of the product 10.5.1 Introduction and microbiological techniques 10.5.2 Microbiological safety of the product 10.5.3 Preliminary treatment of natural cheese milk and effect of certain additives 10.5.4 Hygienic production/facility: HACCP 10.5.5 Bacteriological examination Assessment of physical characteristics 10.6.1 Unmelted characteristics 10.6.2 Melting characteristics Assessment of the microstructure 10.7.1 Background 10.7.2 Some aspects affecting microstructure formation 10.7.3 Cryo-SEM description of processed cheese microstructure 10.7.4 Faults in processed cheese products 10.7.5 Product development 10.7.6 Application of confocal scanning laser microscopy as a quality control tool in processed cheese manufacture Sensory profiling of processed cheese 10.8.1 Elements of sensory assessment 10.8.2 Assessor selection 10.8.3 Acclimatisation and confirmation 10.8.4 Sensory vocabulary 10.8.5 Tasting protocol 10.8.6 Analysis and interpretation of data Conclusions Acknowledgements References Appendix: Example of a product quality information as a result of using a HACCP system

Index A colour plate section appears between pages 302 and 303

269 269 269 270 271 271 271 277 278 279 279 279 281 283 283 283 291 295 297 303 311 311 312 313 314 315 316 319 320 320 339 341

Preface to the Technical Series

For more than 60 years, the Society of Dairy Technology (SDT) has sought to provide education and training in the dairy field, disseminating knowledge and fostering personal development through symposia, conferences, residential courses, publications, and its journal, the International Journal of Dairy Technology (previously published as the Journal of the Society of Dairy Technology). In recent years, there have been significant advances in our understanding of milk systems, probably the most complex natural food available to humans. At the same time, improvements in process technology have been accompanied by massive changes in the scale of many milk processing operations, and the manufacture a wide range of dairy and other related products. The Society has embarked on a project with Wiley-Blackwell to produce a Technical Series of dairy-related books to provide an invaluable source of information for practising dairy scientists and technologists, covering the range from small enterprises to modern large-scale operations. This tenth volume in this series, on Processed Cheese and Analogues, provides a timely and comprehensive update of the principles and practices involved in the production of these products, from raw materials and processing technology to assurance of the quality of the final product. Processed cheese and its analogues have found many uses in both domestic consumption and in the catering and fast food sectors, providing functional properties beyond those that can normally be achieved with traditional cheeses. Andrew Wilbey Chairman of the Publications Committee, SDT

Preface

There is a wide range of processed cheese products, i.e. natural products made from blending different cheeses to form a range of solid and spreadable products, and cheese analogues (made not from cheese, but from dairy and non-dairy ingredients) available to the food market worldwide. Some of these products are extensively used in the fast food/catering chains (e.g. as ‘shredded’ cheeses), and are of increasing economic value in the industrialised and developing countries. The purpose of this book, which is written by a team of international scientists, is to review the latest scientific developments in this field. The authors, who are all specialists in these products, have been chosen from around the world. The scientific aspects reviewed in this publication include (a) the functionality of ingredients, including the natural cheeses, emulsifying salts, stabilisers, flavourings and colourings, (b) the interactions between natural cheese and processing conditions in developing the rheology and final texture of the product, (c) current processing equipment and manufacturing practices, (d) the current statutory regulations (national and international) of these products because an appreciable percentage of the internationally traded ‘natural’ cheese includes processed cheese varieties and (e) quality assurance of processed cheese (in terms of chemical, physical and microbiological properties and sensory profiling) to ensure the safety of the product for the consumer. Some key scientific aspects of processed cheese manufacture can be manipulated to control and maintain the consistency and quality of the final product, and coverage of this topic has produced some overlap with those sections dealing with, for example, the interaction of emulsifying salts with natural cheese components. I have felt justified in allowing this overlap because it emphasises the prime importance of the ingredients used during the preparation of the cheese blend including the effects of processing on the quality and consistency of processed cheese for the end-user. There is no doubt that the book will have an international recognition by dairy technologists, students, researchers and processors, and will become an important component of the Technical Series promoted by the Society of Dairy Technology. A.Y. Tamime

Contributors

Editor Dr A.Y. Tamime 24 Queens Terrace Ayr KA7 1DX UK Tel. +44 (0)1292 265498 Fax +44 (0)1292 265498 Mobile +44 (0)7980 278950 E-mail: [email protected] Contributors Dr M.A.E. Auty Teagasc Food Research Centre Moorepark Fermoy Co. Cork Ireland Tel. +353 25 42442 Fax +353 25 42340 E-mail: [email protected] Professor E.M. Buys Department of Food Science University of Pretoria Lynnwood Road Pretoria 0002 South Africa Tel. +27 12 420 3209 Fax +27 12 420 2839 E-mail: [email protected] Mr S. Dixon 215 Moss Bank Road St Helens

Merseyside WA11 7NS UK Tel. +1 507 775 7070 Fax +1 507 775 7878 Mobile +1 507 254 2338 E-mail: [email protected] and [email protected] Dr J. Domagala University of Agriculture Animal Products Technology Department 30–149 Krakow Balicka 122 Poland Tel. +48 12 662 4803 Fax +48 12 662 4810 E-mail: [email protected] Dr K.J. Domig Department of Food Science and Technology BOKU – University of Natural Resources and Life Sciences Muthgasse 18 A-1190 Vienna Austria Tel. ++0043 (0)1 47654 6750 Fax ++0043 (0)1 47654 6751 E-mail: [email protected] Dr E. Duggan Food and Health Institute UCD Agriculture and Food Science Centre University College Dublin Belfield Dublin 4

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Contributors

Ireland Tel. +353 1 7167675 Fax +353 1 7161147 E-mail: [email protected] Dr K. Durrschmid ¨ Department of Food Science and Technology BOKU – University of Natural Resources and Life Sciences Muthgasse 18 A-1190 Vienna Austria Tel. +43 (0)1 36006 6295 Fax +43 (0)1 36006 6293 E-mail: [email protected] Dr T.P. Guinee Dairy Products Research Centre Teagasc Moorepark Fermoy Co. Cork Ireland Tel. +353 25 42204 Fax +35325 42340 E-mail: [email protected] Dr M. Hickey Derryreigh Creggane Charleville Co. Cork Ireland Tel. +353 (0)63 89392 E-mail: [email protected] Dr A. Hill University of Guelph Department of Food Science Guelph Ontario N1G 2W1 Canada Tel. +1 (0)519 824 4120 extension 53875 Fax +1 (0)519 824 6631 E-mail: [email protected]

Mr S. Kaliappan Frito-Lay R&D 7701 Legacy Drive Plano, TX 75024-4099 USA Tel. +1 (0)972-334-4951 Fax +1 (0)972-334-2329 E-mail: [email protected] Professor W. Kneifel Department of Food Science and Technology BOKU – University of Natural Resources and Life Sciences Muthgasse 18 A-1190 Vienna Austria Tel. +43 (0)1 36006 6290 Fax +43 (0)1 36006 6266 E-mail: [email protected] Professor J.A. Lucey University of Wisconsin-Madison Department of Food Science 1605 Linden Drive Madison, WI 53706-1565 USA Tel. +1 (608) 265 1195 Fax +1 (608) 262 6872 E-mail: [email protected] Dr A. Maurer-Rothmann Management Business Line Dairy Business Unit Food BK Giulini Ladenburg Germany Tel. +49 (0)6203 77 148 Fax +49 (0)6203 77 185 E-mail: [email protected] Dr L. Metzger Alfred Chair in Dairy Education Dairy Science Department South Dakota State University Box 2104 Dairy-Microbiology Building

Contributors

Brookings, SD 57007 USA Tel. +1 (0)605-688-5477 Fax +1 (0)605-688-6276 E-mail: [email protected] Dr J.F. Mostert Food Safety and Human Nutrition ARC-Animal Production Institute Private Bag X2 Irene 0062 South Africa Tel. +27-12-672-9296 Fax +27-12-665-1551 E-mail: [email protected]

xvii

Fax +353 1 7161147 E-mail: [email protected] Professor E.D. O’Riordan UCD Agriculture and Food Science Centre University College Dublin Belfield Dublin 4 Ireland Tel. +353 1 7167016 Fax +353 1 7161147 E-mail: [email protected]

Professor D.D. Muir DD Muir Consultants 26 Pennyvenie Way Girdle Toll Irvine KA11 1QQ UK Tel. +44 (0)1294 213137 E-mail: [email protected]

Professor G. Osthoff Department of Microbial Biochemical and Food Biotechnology University of the Free State PO Box 339 Bloemfontein 9300 South Africa Tel: +27 (0)51 4012216 Fax +27 (0)51 4019335 E-mail: [email protected]

Professor M. Nogueira de Oliveira Universidade de S˜ao Paulo Departamento de Tecnologia Bioquimico-Farmacˆeutica Avenue Prof. Lineu Prestes 580, Bloco 16 Sao Paulo 05508-900 Brazil Tel. +55 (0)11 3091 3690 Fax +55 (0)11 3815 6386 E-mail: [email protected]

Mr M. O’Sullivan Food and Health Institute UCD Agriculture and Food Science Centre University College Dublin Belfield Dublin 4 Ireland Tel. +353 1 7167158 Fax +353 1 7161147 E-mail: [email protected]

Dr N. Noronha Food and Health Institute UCD Agriculture and Food Science Centre University College Dublin Belfield Dublin 4 Ireland Tel. +353 1 7167675

Mr E. Slabber Dairybelle PO Box 744 Bloemfontein 9300 South Africa Tel. +27 (0)51 4114426 Mobile +27 (0)825619092 Fax +27 (0)51 4301450 E-mail: [email protected]

xviii

Contributors

Dr A. Smith University of Guelph Analytical Microscopy Department of Food Science Guelph Ontario N1G 2W1 Canada Tel. +1 (0) 519 824-4120 ext. 52112 Fax +1 (0) 519 824-6631 E-mail: [email protected] Professor Z. Ustunol Michigan State University Department of Food Science and Human Nutrition 2105 S. Anthony Hall

East Lansing, MI 48824 USA Tel +1 517 355 7713 extension 184 Fax +1 517 353 1676 E-mail: [email protected] Dr M. Wszolek University of Agriculture Animal Products Technology Department 30–149 Krakow Balicka 122 Poland Tel. +48 12 662 4788 Fax +48 12 662 4810 E-mail: [email protected]

Plate 1.1 Some illustrations of packaging materials used for processed cheese and analogues sold in the UK market.

Processed Cheese and Analogues, First Edition. Edited by A.Y. Tamime.  2011 Blackwell Publishing Ltd. Published 2011 by Blackwell Publishing Ltd.

(a)

(b)

(c) Plate 4.1 Some properties of processed cheese. (a) Typical process cheese made with emulsifying salts: no oiling-off and a smooth appearance. (b) Processed cheese made without any emulsifying salt: considerable oiling-off occurs. (c) Processed cheese that has been over-creamed: the structure is brittle and crumbly. (Reproduced courtesy of Nobuaki Shirashoji, Morinaga Milk Industry Co. Ltd., 1-835 Higashihara Zama, Kanagawa 288-8583, Japan.)

(b)

(a)

Congealed matrix

Swollen particulates

Free oil & water

(c)

(d)

Cohesive matrix

Milky liquid

Homogeneous cheese mass

Plate 9.1 Illustrations of the four main stages of matrix development during the manufacture of analogue cheese.

(a)

(b)

P

F

F

P

(d)

(c)

F F

P

Plate 9.2 Light microscopy images of the four main stages of matrix development during the manufacture of analogue cheese.

Plate 10.1 Visual marking of the yellow and green hygienic zones in the factory. (Reproduced with courtesy of SEROTP Ltd., Tychy, Poland.)

Plate 10.2 Confocal scanning laser micrograph of processed cheese showing fat droplets (green), continuous protein phase (red) and crystalline inclusions of (a) calcium lactate and (b) calcium phosphate shown by negative contrast. (Source: Moorepark data.)

Plate 10.3 Bright ﬁeld light micrograph of analogue cheese stained with iodine/potassium iodide solution to reveal gelatinised starch inclusions (black). (Source: Moorepark data.)

Plate 10.4 Confocal scanning laser micrograph of analogue cheese showing fat droplets (green), protein phase (red) and presumptive starch inclusions shown by negative contrast. (Source: Moorepark data.)

(a)

(b)

(c)

(d)

Plate 10.5 Microstructure of experimental processed cheese products after heating to 80◦ C and holding for (a) 1, (b) 16, (c) 24 or (d) 32 min; the cheese were formulated from Cheddar cheese, water and emulsifying salts. (Source: Moorepark data.)

(a)

(b)

(c)

(d)

(e)

(f)

Plate 10.6 Microstructure of experimental pasteurised processed cheese products after holding for 4 min at different temperatures (◦ C): (a) 70, (b) 75, (c) 80, (d) 85, (e) 90 or (f) 95.

1 Processed Cheese and Analogues: An Overview A.Y. Tamime

1.1 Historical background The production of processed cheese started in Europe, and could date to the mid-1890s. Natural cheeses have limited shelf-life and, depending on many factors (i.e. level of moisture content, sanitary conditions during the manufacturing stages and storage conditions of the product), this can range from a few weeks to a couple of years. It is possible to suggest that the idea of processed cheese originated from a desire to extend the shelf-life of natural cheese or to develop a new type of cheese which was milder in taste or more stable. Around the same period, commercial developments were made in Germany for the export of short shelf-life soft cheese, e.g. Camembert, Brie and Limburger, which was achieved by heating the cheeses in metal cans. Similar processing methods were also developed for Dutch cheeses, but the process was most successful in Switzerland by using sodium citrate (Berger et al ., 1989). Essential steps in the manufacture of processed cheese is melting and heating blends of natural cheeses (e.g. different types, varying degree of maturity, i.e. fresh/young or matured, and cheese ‘re-work’), the addition of emulsifying salts, agitation to produce a homogeneous mixture, followed by packaging and cooling or vice versa. The application of heat (i.e. indirect or direct steam injection) inactivates the starter culture organisms and other bacteria, including the enzymes present in natural cheeses, and produces a product with extended shelf-life. Although the casein in natural cheeses possesses certain emulsifying characteristics, the stability of processed cheese could not be achieved without the use of emulsifying salts, such as citrates and phosphates. Commercial production of processed cheese started in earnest in Europe and the USA between 1910 and 1920. The production techniques were based on Cheddar and other cheese varieties, and used citrates or phosphates as the emulsifying salts. These early attempts to produce good-quality processed cheese were of limited success, but the process became widespread by the 1930s when the emulsifying salts (e.g. polyphosphates and other types) appeared on the market (Berger et al ., 1989). In addition, other dairy and non-dairy ingredients could be added to the blend before processing, and the use of these ingredients is normally governed by statutory regulation within each country of manufacture. Processed Cheese and Analogues, First Edition. Edited by A.Y. Tamime. © 2011 Blackwell Publishing Ltd. Published 2011 by Blackwell Publishing Ltd.

2

Processed Cheese and Analogues

Over the past few decades, many aspects of the manufacture of processed cheese have been reviewed by many authors (Jackson & Wearmouth, 1959; Price & Bush, 1974a,b; Shimp, 1985; Sachdeva et al ., 1988; Marchesseau et al ., 1997; Schar & Bosset, 2002; Abd El-Salam et al ., 2005; Dimitreli & Thomareis, 2007; Kapoor & Metzger, 2008), and the same subject has been reviewed in different textbooks (Meyer, 1973; Thomas 1977; Guinee, 1987; Berger et al ., 1989; Cari´c, 1991; Merkenich et al ., 1992a,b, 1994; Cari´c & Kal´ab, 1993; Kal´ab, 1995; Cari´c & Milanovi´c, 1997; Kosikowski & Mistry, 1997; Zehren & Nusbaum, 2000; Guinee et al ., 2004; Schrader & Hoffman, 2008; Adhikari et al ., 2009; Bunka et al ., 2009; Johnson et al ., 2009). In addition, Mann (1969, 1970, 1974, 1975, 1978a,b, 1981, 1983a,b, 1986, 1987, 1990, 1993, 1995, 1997, 1999, 2003) has compiled several successively up-to-date international digests on processed cheese. Contrary to the current belief, processed cheese is made from good-quality natural cheeses (blends of fresh/young and matured) rather than degraded stock; however, these latter types of cheeses are only used in very small proportions, including re-work processed cheese. In addition, the processing equipment used during the manufacture of processed cheese is known as cooker or kettle (e.g. vertical or horizontal; see Chapter 6), and continuous or batch processes are also available on the market. Although the latter method of processing is more popular as it provides greater control of product quality and is more suitable for large-scale operations, the batch process may be still be favourable in small- and medium-sized production units or, alternatively, because the batch process was developed first – ‘old habits die hard’. In contrast, ‘imitation’ processed cheese is made from mixtures of dairy and/or non-dairy proteins and fat/oils. Hence, it was suggested by Shaw (1984) that in response to increasing manufacturing costs of processed cheese, imitation products have been developed to meet demand in fast food outlets (e.g. pizza), by the catering trade, ready cooked foods, in formulated foods and in school lunch programmes (see also IDF, 1989; McCarthy, 1990; Mortensen, 1991; Engel, 1992; Lee et al ., 1992; Song et al ., 1992; Bachmann, 2001; Hoyer & Kirkeby, 2007). It is evident that there are many similarities between the manufacture of processed cheese and analogues, and this chapter provides a general background to these products, their properties and the patterns of their consumption in some selected countries.

1.2 Diversity of products 1.2.1 Terminology and/or nomenclature The products of the preservative treatment of natural cheeses by the application of heat came to be known as processed cheese or processed cheese food; in some instances the word ‘process’ is used instead of ‘processed’. This product is manufactured in many countries, and numerous variants of this type of product have appeared on the market over the years with alternative names, such as ‘pasteurised’, ‘emulsified’, pasteurised blended, ‘American’, ‘cooked’ or ‘sterilised’ cheese (Cari´c & Kal´ab, 1993; Guinee et al ., 2004; see also Chapter 2). Developed products, known as ‘imitation’ processed cheese, are widely produced, and are made from mixtures of dairy and/or non-dairy proteins and dairy fat or vegetable oil. These products are variously labelled as ‘analogues’, ‘analogs’ imitation’, ‘substitute’, ‘artificial’, ‘extruded’, ‘synthetic’, ‘Tofu’ and/or ‘filled’ cheese (Shaw, 1984; IDF, 1989;

Processed Cheese and Analogues: An Overview

3

McCarthy, 1990). The following references are recommended for further reading on different aspects on processed cheese analogues (Santos et al ., 1989; Ahmed et al ., 1995; El-Nour et al ., 1996, 1998, 2001a,b; Hetzner & Richarts, 1996; Ennis & Mulvihill, 1997; Abou El-Nour et al ., 1998, 2001; Muir et al ., 1999; Tamime et al ., 1999; Kaminarides & Stachtiaris, 2000; Mleko & Foegeding, 2000, 2001; Bachmann, 2001; Lobato-Calleros et al ., 2001; Pereira et al ., 2001; Abou El-Nour & Buchheim, 2002; Pereira et al ., 2002; El-Nour, 2003; Gustaw Mleko, 2007). These types of product are reviewed in Chapter 9.

1.2.2 Classification At present, there are many types of processed cheese made worldwide. Smith (1990) reported the classification of these products based on the FAO/WHO Food Standards Programme of the Codex Alimentarius Commission, and they are grouped into two different categories based on the physical characteristics of the product: processed cheese and spreadable processed cheese (for further details, refer to Chapter 2). The standard also details the following aspects. • • • • •

Permitted dairy and food additives/ingredients. Minimum processing temperature at 70◦ C for 30 s. The named variety of natural cheese to be used to describe the processed cheese type, and the blend being required to contain at least 70 g 100 g−1 of the cheese mentioned. The chemical composition of the product is expressed as dry matter content and percentage of fat-in-dry matter (FDM). Labelling information.

The main difference between processed cheese and processed cheese spread products proposed by Smith (1990) is the level of moisture content in the product, which affects its rheological properties, the spreadable type being softer. However, the commercial manufacture of processed cheese may also include the ‘block’ and ‘slices’ types, which merit separate subgrouping in the proposed FAO/WHO standards (Smith, 1990). Last but not least, there is no existing standard for processed cheese ‘sauce’ (i.e. natural and/or analogue), which is used sometimes in hamburger outlets. An example of the processing method of cheese sauce was reported by Hine (1995) (see also Duval et al ., 1994a,b). Natural cheeses used as an ingredient during the manufacture of processed cheese products may range from a minimum of 51 g 100 g−1 in the spreadable type to 95 g 100 g−1 in other products (Anonymous, 1986). The standards/legislations for these products in different countries are reviewed in detail in Chapter 2.

1.3 Patterns of production In the mid-1980s, the production figure for processed cheese in the European Union (EU), USA, Norway, Finland, Austria, Switzerland and Australia was ∼1.4 million tonnes (IDF, 1995; Anonymous, 1999), increasing to 1.53 million tonnes in 2004 (IDF, 2005). Detailed production figures for the 30 member countries of the International Dairy Federation (IDF) are shown in Table 1.1. It is possible that the world production of processed cheese will increase in the future, mirrored by the expected growth in the world production of natural

4

Processed Cheese and Analogues

Table 1.1 Production trends (×1000 tonnes) of processed cheese for 30 International Dairy Federation (IDF) member countriesa between 1995 and 2004. Year Country

1995

2000

2004

Argentina

7

10

7

Australia

58

60

47

Belgium

52

55

44

Canada

76

67

71 b

Denmark

17

NA

Estonia

NA

NA

1

Finland

13

16

17

France

128

138

129

Germany

159

171

175

19

Hungary

11

10

11

Iceland

0.3

0.3

0.4

Ireland

12

11

12

Israel

2

1

1

Italy

NA

4

4

Japan

94

111

112

Lithuania

NA

1

3

Netherlands

31

19

16

New Zealand

11

24

25

Norway

3

3

3

Poland

30

48

60

Russian Federation

68

78

141

South Africa

5

5

5

Spain

39

36

NA

Switzerland

14

13

11

UK

24

33

37

USA

668

630

543

Total

1522

1557

1527

Source: After IDF (2005). a Production figures for processed cheese in Austria, Greece, Italy, Sweden and Cyprus are included with natural cheeses, not specified or not reported. b NA, not available.

Processed Cheese and Analogues: An Overview

5

cheeses, i.e. an annual growth rate of 1.8% from 2004 to 2014 (IDF, 2005). Nevertheless, annual production data (×1000 tonnes) for processed cheese in some selected countries are as follows: 30–40 (Egypt in 2007; M. Abd El-Salam, personal communication), 8.7 (Syria in 2007; A.-H. Klandar, personal communication) and 113.4 (Brazil in 2007; Associac¸a˜ o Brasileira das Ind´ustrias de Queijo or ABIQ, 2008). It is safe to suggest that the demand for processed cheese in countries of the Far East is expected to rise due to an increase in annual income and the westernisation of consumer taste for pizza and hamburgers. Consequently, similar growth may also occur in the urban populations of China, India, South America, the Middle East and possibly Africa. There are no data available for world production figures of processed cheese analogues.

1.4 Principles of manufacturing stages The complexity of the manufacture of processed cheese and its analogues is well known, and is primarily influenced by the chemical interactions between the dairy constituents and the emulsifying salts, and these aspects will be reviewed in detail in different chapters. In addition, the rate of these interactions is governed by the application of heat, the duration of heating and processing, and the rate of shear applied during production, all of which will affect the quality of the final product. Nevertheless, the different stages of manufacture of processed cheese products including analogues are similar (Fig. 1.1) and the diversity of these technologies are briefly discussed in subsequent sections.

1.4.1 Natural cheeses The successful production of processed cheese is dependent on the proper quality and selection of natural cheeses. It is possible to use one or more varieties of cheese or blends of cheeses of different degrees of maturation (Cari´c & Kal`ab, 1993; Guinee et al ., 2004; Kapoor et al ., 2007). In general, the formulation for using Cheddar cheese (i.e. mild, medium or mature flavour) may consist of different ratios (Table 1.2) and such typical blends provide the desirable elasticity character in the final product. The criteria for selection of natural cheese include flavour, texture, consistency and level of acidity. Degraded cheese (off-flavour or microbial defects) should not be used in processed cheesemaking as the quality of the final product will be reduced or unacceptable. When the cheeses have been selected, the products are removed from the wrapper, de-rinded, cleaned and ground before processing. This physical treatment of natural cheese facilitates an easier melt, ensures proper blending of the added ingredients, and enhances better contact between the emulsifying salts and cheese components.

1.4.2 Formulation of a balanced mix The main components of natural cheeses are fat, solids-not-fat (SNF) (mainly protein, minerals and sodium chloride) and moisture. Hence, formulation of a balanced mix is based on the proximate composition of the natural cheeses used, including ingredients added for the fortification of the SNF and/or fat contents (e.g. dairy powders, ‘cheese base’ – CB)

6

Processed Cheese and Analogues

Miscellaneous additives

Fortification of the milk proteins Natural cheeses (shredded)

Mixing and blending

Standardisation of the fat content Homogenisation (optional)

Fill metal cans

Add emulsifying compounds Add salt and water

Processing kettle/cooker

Processed/melted cheese (block, slices, spread, sauces)

Steriliser

Filling machines

Cooling

Storage

Cartoning

Cooling

Dispatch Fig. 1.1 Schematic illustration showing the manufacturing stages of processed cheese products. Note that dotted line represents an alternative route; for cheese analogue use different ingredients, and some of the processing stages may not be applicable, e.g. use of metal cans.

Table 1.2 Some typical ratios of recommended blends of Cheddar cheese for the manufacture of processed cheese products. Natural cheese Type of processed cheese products

Mild

Medium

Mature ← 25–30 →

Block

70–75

Slices

30–40

50–60

10

Slices

55

35

10

Spread

30

50

20

and processed cheese re-work, standardisation of the fat level (e.g. cream, anhydrous milk fat or AMF, or butter), and added water or condensate from direct steam injection during the heating stage. However, some adjustments of the balanced mix should be taken into account when using food ingredients such as meat, fish or liquid additives (e.g. colouring matter – flavouring agents).

Processed Cheese and Analogues: An Overview

7

Skimmed milk powder (SMP) tends to improve the quality and stability of processed cheese, and the recommended level of fortification is ∼10–12 g 100 g−1 . Caseinates and whey protein concentrates (WPC) are added at a rate of 5–7 g 100 g−1 to the blend; higher rates of fortifications will affect the stability, flavour and structure of the product (Cari´c & Kal`ab, 1993; Guinee et al ., 2004). The maximum permitted amount of caseinates in processed cheesemaking in the EU is 5 g 100 g−1 (Citro et al ., 1998). However, CB produced from whole milk can be used to replace up to 80 g 100 g−1 of natural cheeses. The proximate chemical composition of Cheddar type CB is similar to natural cheese, and its use in processed cheesemaking has been reported by Rubin & Bjerre (1984), Tamime et al . (1990, 1991), Ganguli (1991), Park et al . (1993), Jang et al . (1993), Abdel-Hamid et al . (2002), Awad (2003) and Kycia et al . (2006).

1.4.3 Emulsifying salts In general, emulsifying salts consist of monovalent cation (sodium-Na) and a polyvalent anion (phosphate); for more details refer to Chapter 4. These salts are normally added at a rate of up to 3 g 100 g−1 and, for pH adjustment, food grade citric acid is used; in addition, sodium chloride (NaCl) may be added to the cheese blend for adjusting the level of salt in the final product. Emulsifying salts are not amphiphilic and hence are not emulsifiers per se (Dalgleish, 1989). However, emulsifying salts promote, with the aid of heat and shear, a series of concerted physicochemical changes in the cheese blend which, as a consequence, result in rehydration of the aggregated para-casein and its conversion into an active emulsifying agent. Although the primary functions and/or effects of emulsifying salts during the manufacture of processed cheese will be detailed elsewhere, Cari´c & Kal`ab (1993) and Guinee et al . (2004) reported that these salts supplement the functional properties of milk protein. In brief, they: • • • • • •

remove calcium (Ca2+ ) ions from the micelle; peptise and solubilise the protein; hydrate and swell the protein; emulsify the fat and stabilise the emulsion; control and stabilise the pH level; and form an appropriate structure of processed cheese after cooling.

Although the use of emulsifying salts is important during the manufacture of processed cheese, overdose of specific emulsifying agents (i.e. high in phosphorus content) can lead to bitterness in processed cheese slices (Mayer, 2001). The same author reported that bitter slices showed very weak or even no αs1 - and β-caseins region, but only γ-casein and low-molecularweight peptides, and contained high concentrations of hydrophilic and hydrophobic peptides.

1.4.4 Addition of miscellaneous additives The primary objective of flavouring processed cheese products is to provide the consumer with a wider choice, which may lead to increased consumption. A wide range of flavouring materials has been used in processed cheese products (see Chapter 5) and a selective list for possible novel products is shown in Table 1.3.

8

Processed Cheese and Analogues

Table 1.3

Food products and flavouring agents currently used in processed cheese production.

Additive

Comment

References

Goat’s milk cheese or casein Addition of such component(s) had no effect on flavour, but improved the consistency of the product

Fredriksen & Steinsholt (1978)

Chocolate

Blending processed cheese and chocolate for the manufacture of a nutritious product

Vajda et al . (1983)

Hydrolysate of processed cheese

Processed cheese waste was hydrolysed Kunizhev et al . (1984) with hydrochloric acid and added to the blend at a rate of 5–25 g 100 g−1

Mashed potato

The blend consisted of Gouda cheese, emulsifying salts, mashed potato, curry powder and sweet corn

Shinozaki & Imagawa (1985) (see also Awad, 2003)

Decolorised blood protein

The protein was added to the milk before making a fresh cheese by acidification and centrifugation

Vareltziz & Buck (1985)

Prawns, salami, bacon and paprika

These additives enhanced the niche market of processed cheese

Anonymous (1987) and Abeid et al . (2001)

Different types of margarine, The manufactured product was fats and oils acceptable and more economical

Radovets et al . (1987) (see also Bodenstein et al ., 1990; Greim et al ., 1990; T¨urko˘glu et al ., 2002)

Calcium salts and phosphatidic acid

These additives were used to produce a Doleˇza´ lek & Nezda˘ril˜ık (1987) dietetic product, and clinical tests gave (see also Samodurov et al ., 1990) positive results

Vegetable protein

Soya and chickpea flour enhanced the consistency of the product

Nuts and dried fruit

Prepare the cheese paste and, while still Schoegel & Daurelles (1991) hot, pour into the packaging container (see also Maslov et al ., 1992) in which these additives are placed

Iron fortification

No effect on quality

Zhang & Mahoney (1991) and El-Sayed et al . (1997)

Egg protein

Affected the texture and formation of clumps

Hong (1992)

Smoke condensate

The recipe and the manufacturing processes have to be modified

Solo’eva et al . (1994) and McIlveen & Vallely (1996) (see also Niketi´c & Krˇsev, 1990)

Extract of concentrated fruit juices and/or fruit pulp

Improved organoleptic properties and enhanced the mineral content of the product

Lapshina et al . (1994), El-Shabrawy et al . (2002) and Awad et al . (2003a)

Meat emulsion

Development of a novel cheese-meat burger

Guinee & Corcoran (1994)

Mustard oil

Suitable as partial substitution of milk fat

Grigorov et al . (1995)

El-Neshawy et al . (1988) (see also Cari´c et al ., 1990; Ahmed et al ., 1995; DingMei et al ., 2008)

Processed Cheese and Analogues: An Overview

Table 1.3

9

(Continued)

Additive

Comment

References

Buffalo’s milk cheese

The age of the matured cheese used in the recipe influenced the quality of the processed cheese

Joshi & Thakar (1996) (see also Singh et al ., 1993; Tiwari et al ., 1996; Joshi & Thakar, 1996)

Plant protein isolates

Reduced the flavour acceptability as the El-Sayed (1997) level is increased to 15 g 100 g−1

Blue cheese taste

Blending Blue cheese with Emmental and casein to produce a good flavour processed cheese product

Wheat fibre

Improved quality of the product without Noli (1998) affecting the sensory properties

Okara

Acceptable product made with up to 15 g 100 g−1 Okara plus skimmed milk powder and starch

Real del Sol et al . (2002)

Casein hydrolysate or supernatant

The hydrolysed product (i.e. after 4 h, improved the emulsifying activity of the casein) was used at a ratio of 3:1 with ordinary emulsifier to produce a good-quality processed cheese with no effect on the flavour of the product

Kwak et al . (2002)

Transglutaminase (Tg-ase)

Milk gels (i.e. rennet coagulation) De Sa & Bordingnon-Luiz (2010) treated with Tg-ase and later used during the manufacture of processed cheese improved the physical properties (i.e. reduced syneresis index and increased consistency index) of the product, possibly due to the occurrence of enzymatic cross-linking of the protein matrix

Lubbers et al . (1997)

Another additive widely used as a preservative in processed cheese products are generally known as bacteriocins. These are polypeptide compounds produced by many lactic acid bacteria and can inhibit the growth of pathogenic and undesirable microorganisms in dairy and food products (Tamime et al ., 2006). An example of such a bacteriocin, which has been commercialised, is nisin, and is produced by certain strains of Lactococcus lactis subsp. lactis. Nisin has been shown to possess antibacterial activity against Grampositive bacteria, such as heat resistant spore-formers (e.g. Clostridium spp. and Bacillus spp.) and pathogenic microorganisms belonging to the genera Staphylococcus, Listeria and Salmonella. For more information regarding the use of nisin and other preservatives (e.g. potassium sorbate) in processed cheesemaking, the reader is referred to some comprehensive reviews and research reports (Delves-Broughton, 1987, 1998a,b; Hurst & Hoover, 1991; Plockova et al ., 1997; Delves-Broughton & Friis, 1998; JungHoon & Floros, 1998; Turtell & Delves-Broughton, 1998). Some suggested dairy ingredients employed during the manufacture of processed cheese products are listed in Table 1.4.

10

Processed Cheese and Analogues

Table 1.4 products.

Some suggested dairy ingredients employed during the manufacture of processed cheese

Ingredients/product type

References

Processed cheese spreads Palm oil was used for the preparation of processed cheese spread, but affected its sensory characteristics

Salam (1988a,b) (see also Azzam, 2007; Calvo et al ., 2007)

Natural cheese flavours (i.e. obtained from Cheddar and Parmesan cheeses) were added to fresh cheese and used successfully to produce processed cheese spread; this approach of flavouring was useful in replacing mature cheeses by up to 15 g 100 g−1 in the blend

Kuli´c & Cari´c (1990)

Incorporating starch solution (1–25 g 100 g−1 in water, milk, buttermilk or ultrafiltered permeate) into the cheese curd maintains the creaminess of low- or fat-free cheese spreads; the addition of hydrocolloids in the cheese blend improves the texture of the product

Quiblier et al . (1991), Kokane et al . (1996) and Gokhale et al . (1999)

Addition of glycerol (5 g 100 g−1 ) improved the spreadability of the processed cheese product

Kombile-Moundouga & Lacroix (1991)

Incorporation of butter residue into the cheese blend improved the sensory properties of high-fat spreadable cheese

Abou-Zeid (1993)

Replacement of mature Ras cheese (an Egyptian variety) by up to 80 g 100 g−1 with enzyme-treated retentate improved the flavour, colour and consistency of the product

Aly et al . (1995)

Chakka (an Indian fermented milk), cheeses (pickled or brined cheeses, Queso Blanco, Ras, Ricotta or low-fat Mozzarella), Labneh (Middle Eastern concentrated yoghurt) and fermented barley (i.e. a Labneh-like product) were used successfully in the preparation of processed cheese spread

Dholu et al . (1990, 1994), McGregor et al . (1995), Hanna & Nader (1996), Tukan et al . (1998), Hanna (1999), Abdel-Hamid et al . (2000), Modler & Emmons (2001), Awad et al . (2003b), El-Shibiny et al . (2007) and Awad & Salama (2010)

Addition of whey protein concentrate (WPC) (20–25 g 100 g−1 total solids) to the cheese blend improved the texture and body of the product

Abd El-Salam et al . (1996, 1997) and El-Khamy et al . (1997) (see also Kebary et al ., 2001; Hui et al ., 2006; Pinto et al ., 2007; Shazly et al ., 2008)

The whiteness of processed cheese spreads was improved by increasing the content of WPC and emulsifying salts in the blend, but the product tended to become darker during storage, possibly due to the Maillard browning reaction

Abd El-Salam et al . (1998)

Replacement of dairy fat with fat-substitutes up to 40 g 100 g−1 with Dairy-Lo™ improved the sensory score of the product, whilst Maltrin® and Crestar® increased the rate of oiling off and meltability of low-fat processed cheese spreads

Kebary et al . (1998) (see also Lee & Brummel, 1990; Anonymous, 1992; Swenson et al ., 2000)

The use of denatured whey protein, which was modified with succinic anhydride, improved the spreadability of processed cheese

Fayed & Metwally (1999)

Taiz cheese (a Yemeni smoked variety) used at a rate of 30 g 100 g−1 in the cheese blend had the highest organoleptic score of processed cheese spread when compared with the control

Saleem et al . (2003)

Processed Cheese and Analogues: An Overview

Table 1.4

11

(Continued)

Ingredients/product type

References

Cheddar cheese (low fat and full fat) was made from a mixture of buffaloes’ and cows’ milk, and the cheeses (i.e. fresh and mature) were used in the blend with different stabilisers to produce good-quality spreads

Rabo et al . (2004)

The addition of ι-carrageenan (0.25 g 100 g−1 ) to the cheese blend improved the firmness of processed cheese and spreads, and was more effective than κ-carrageenan

Cernikova et al . (2007, 2008)

Cholesterol-reduced processed cheese spread was made by cross-linking β-cyclodextrin (91.5 g 100 g−1 was removed), and had significantly higher scores for gumminess, brittleness, yellowness, bitterness and elasticity, and significantly lower scores for processed cheese flavour and slimy texture compared with the control product

Kim et al . (2009) and SooYun et al . (2009)

Low-sodium processed cheese spread was made from ultrafiltered Edam cheese (i.e. the brine was prepared from a mixture of NaCl and KCl at a ratio of 1:1). The meltability was low and oil separation was high of the product compared with the control, and sensory scores of low-sodium processed cheese were high

Amer et al . (2010)

Processed cheese (blocks and slices) Formulation for the manufacture of foamed processed cheese was made from Cheddar cheese (young and mature), cream, yoghurt, emulsifying salts, starch and other dried dairy powders and, after melting the blend, it was homogenised and whipped

Bode et al . (1986)

Enzyme-modified Cheddar cheese (lipase-treated) was suitable as a flavour enhancer for processed cheese

Lee & Ahn (1986)

The addition of WPC (∼26 g 100 g−1 total solids), trisodium citrates and calcium to replace 20–25 g 100 g−1 of the natural cheese in the blend improved the firmness of the product, but reduced the meltability of the cheese

Gupta & Reuter (1990, 1992, 1993) and Thapa & Gupta (1992a,b, 1996) (see also Gupta et al ., 1984; Metwally et al ., 1984; Prajapati et al ., 1991, 1992; French et al ., 2002; Mleko & Lucey, 2003; Kapoor & Metzger, 2004; Gustaw & Mleko, 2007)

The size of protein aggregates, firmness and elasticity of the product were influenced by the type of low-molecular-weight emulsifier added and the pH level of the rennet casein used

Lee et al . (1996)

Factors influencing the pink discoloration of annatto (emulsion or solution) used in processed cheese included the following: cooking temperature, continuous heating, type and blend of emulsifying salt, amount of coloured cheese in the blend and amount of whey powder added

Shumaker & Wendorff (1998)

Good-quality processed cheese was made on an industrial scale containing increased levels of potassium salt (i.e. 75–80 g 100 g−1 ) of that of the sodium content of the final product

Reps et al . (1998; 2009) and Iwanczak et al . (2001)

Processing the cheese blend containing WPC under atmospheric conditions, hydrogen donors and iron increased the content of conjugated linoleic acid (CLA) in processed cheese; in addition, the processing temperature (75 vs. 90◦ C) increased the content of CLA in the product and spread

Shantha et al . (1992), Shantha & Decker (1993), Garcia-Lopez et al . (1994) Luna et al . (2005), Calvo et al . (2007), Zhang et al . (2007) and JunHo et al . (2009) (continued)

12

Processed Cheese and Analogues

Table 1.4

(Continued)

Ingredients/product type

References

Low-fat processed cheese was produced using carrageenan and microcrystalline cellulose and ultrafiltered sweet buttermilk

Bullens et al . (1995) and Raval & Mistry (1999) (see also Trivedi et al ., 2008a,b)

Reduced-fat cheese containing lecithin was acceptable, but was less elastic in processed cheese

Drake et al . (1999)

Addition of ultra-high pressure-treated whey protein to the cheese blend improved the texture and body of the product

Lee et al . (2006)

The application of concentrated milk (i.e. vacuum evaporation and ultrafiltration) for Cheddar cheesemaking influenced the overall functionality and structure of processed cheese

Mistry et al . (2006)

The addition of 1-monoglycerides affected the sensory properties of processed cheese due to the off-flavour

Bunka et al . (2007)

Sudanese white cheese (presumably a fresh and brined product) was used to produce Sudanese processed cheese

El-Diam & Intisam (2007) (see also Kaminarides et al ., 2006)

1.4.5 Heat treatment The level of heating applied during the manufacture of processed cheese products ranges between 72 and 145◦ C; in brief, these products are categorised as ‘pasteurised’ or ‘sterilised’ (for more details refer to Chapter 7). In general, products that are sterilised are higher in water activity, which requires the additional security of high temperature processing conditions to eliminate the main threat of clostridial spores that can germinate and grow during the shelf-life if the product is not refrigerated. Sterilised products are not generally aseptically produced due to the complexity of the packaging, e.g. triangular foil portions. However, the pasteurised products are those heated to 72–95◦ C by means of direct steam injection under vacuum. This heating usually takes place in a batch cooker, and can be in concert with high or low mechanical/shear action. The important point is to have a minimum filling temperature of 72◦ C to ensure adequate pasteurisation of the packaging. Sterilised processed cheese products are normally heated to a temperature of 140◦ C for 10 s (corresponding to an Fo 8 value). The time/temperatures combinations that are widely used range between 128 and 145◦ C. It is obvious that the higher the temperature, the shorter the hold time. The widespread introduction of refrigeration of these processed cheese products has generally meant that these products have two barriers (i.e. high processing temperature and cold storage of the product) that prevent product spoilage.

1.4.6 Homogenisation The equipment (i.e. pilot and large-scale) employed for the manufacture of processed cheese products does not require homogenisation of the melted cheese blend because it is designed to provide an excellent shear effect to produce an emulsion of the fat droplets in a continuous hydrated phase. High-shear cookers basically simulate the homogenisation effect

Processed Cheese and Analogues: An Overview

13

by producing extremely fine fat droplets, and modern continuous cookers with tangential steam injectors produce the same effect, the speed of the mixing device of the cooker controlling the ‘creaming’ effect in the product. However, if the homogenisation stage is required, it would be installed downstream of the cooker.

1.4.7 Filling machines and packaging materials Different types of packaging materials, such as glass jars, metal tin cans, laminated aluminium foils, collapsible metal or plastic tubes, laminated plastics, ‘squeezy’ plastic bottles and heat-shrink or heat-melt sheets or pouches, are widely used to package processed cheese products, including analogues (refer to Chapter 8 for further details including types of filling machines). Some patented and developed packaging materials for processed cheese products are summarised in Table 1.5, and some examples of packaging materials and systems are shown in Fig. 1.2. In general, processed cheese slices are packaged individually in laminated plastic material, and a set of slices (e.g. 6 or 12) is stacked and overwrapped in similar material(s). Alternatively (i.e. an older method), unwrapped slices are packed in laminated plastic material and, to inhibit the slices from sticking to each other, parchment paper is inserted between the slices of processed cheese. Processed cheese packed in metal tin cans (see Pillonel et al ., 2002) exhibited the least chemical changes and microbiological quality during the storage period (at 30◦ C and 60% relative humidity (RH) and at ∼7◦ C and 80% RH) compared with parallel products packed in polystyrene or low-density polyethylene tubs (Goyak & Babu, 1991a,b). While the keeping quality of processed cheese spread packaged in glass jars for 3 months at 25–30◦ C or 5–8◦ C was superior to the same product packaged in different types of Egyptian-made polymeric laminated materials or imported polyamide sheets, there was a slight change in the microbiological quality and sensory scores, but the temperature of storage had a greater effect on the quality of the product. In addition, packages made from different polymers leached out substances that absorbed in the UV spectrum in solution simulating the aqueous phase of the product, and glass jars were recommended for packaging processed cheese due to their inertness (Metwally et al ., 1996; see also El-Shibiny et al ., 1996; Alves et al ., 2007). Table 1.5

Examples of some patented packaging materials for processed cheese products.

Type of package

References

Multilayer of oriented films from propylene copolymers and unplasticised Saran (i.e. heat shrinkable), suitable for block-type processed cheese

Schirmer (1986)

Daime (1987) Cylindrical pack with a lid (shipping container) that is suitable for gas flushing with N2 and CO2 to protect the individual wrapped portions of processed cheese Coated aluminium foil for wrapping processed cheese (i.e. standard specifications)

BSI (1987)

Packaging system for single portions of processed cheese

Rabier & Bonnin (1992)

A package for packing triangular portions of processed cheese

Bernard et al . (1992) and Weber et al . (1993)

14

Processed Cheese and Analogues

Fig. 1.2 Some illustrations of packaging materials used for processed cheese and analogues sold in the UK market. (See Plate 1.1 for colour figure.)

1.5 Conclusions In summary, the technology of processed cheesemaking, including analogues, has evolved dramatically over the past century. It was to some extent an art, where manufacturers tended to blend different cheeses and select emulsifying salts (types and amounts) based largely on experience. Developments in emulsifying salt blends over the past few decades to suit processed cheese and analogues producers have been achieved, but there is a lack of knowledge about the exact mechanisms involved and they are still not clear since there are multiple reactions simultaneously occurring. There is no doubt that increased consumption of processed cheese products worldwide is mainly due to consumer changes in food habits (i.e. popularity and acceptability of fast food and pizza), and the product is more widely accepted by the younger consumer because it has a milder flavour than natural cheeses. Variations in existing definitions and standards for processed cheese products are evident in many countries, and international standards appear to be difficult to harmonise because of possible conflicts with national standards. Future developments in technology will encompass further reliance on automation and product safety. The following chapters reflect these aspects.

References Abd El-Salam, M.H., Al-Khamy, A.F., El-Garawany, G.A., Hamed, A. & Khader, A. (1996) Composition and rheological properties of processed cheese spread as affected by the level of added whey protein concentrates and emulsifying salt. Egyptian Journal of Dairy Science, 24, 309–322.

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15

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Mann, E.J. (1978a) Processed cheese. Dairy Industries International , 43(2), 31–32. Mann, E.J. (1978b) Processed cheese. Dairy Industries International , 43(3), 35–36. Mann, E.J. (1981) Processed cheese. Dairy Industries International , 46(2), 13–14. Mann, E.J. (1983a) Processed cheese. Dairy Industries International , 48(10), 11–13. Mann, E.J. (1983b) Processed cheese. Dairy Industries International , 48(12), 9–11. Mann, E.J. (1986) Processed cheese. Dairy Industries International , 51(2), 9–10. Mann, E.J. (1987) Processed cheese. Dairy Industries International , 52(4), 11–12. Mann, E.J. (1990) Processed cheese. Dairy Industries International , 55(11), 12–13. Mann, E.J. (1993) Processed cheese. Dairy Industries International , 58(1), 14–15. Mann, E.J. (1995) Processed cheese and related products. Dairy Industries International , 60(5), 19–20. Mann, E.J. (1997) Processed cheese. Dairy Industries International , 62(2), 16–17. Mann, E.J. (1999) Processed cheese. Dairy Industries International , 64(1), 12–13. Mann, E.J. (2003) Processed cheese. Dairy Industries International , 68(6), 35–36. Marchesseau, S., Gastaldi, E., Lagaude, A. & Cuq, J.L. (1997) Influence of pH on protein interactions and microstructure of process cheese. Journal of Dairy Science, 80, 1843–1849. Maslov, A.M., Alekseev, N.G., Lupinskaya, S.M. & Orlov, V.V. (1992) Production of fruit flavoured cheese. Dairy Science Abstracts, 54, 17. Mayer, H. (2001) Bitterness in processed cheese caused by an overdose of a specific emulsifying agent? International Dairy Journal , 11, 533–542. McCarthy J. (1990) Part 3. World Dairy Situation 1990 – Butter: the World Market – Imitation Cheese Products, Document No. 249, pp. 45–52, International Dairy Federation, Brussels. McGregor, J.U., Tejookaya, U.P. & Gough, R.H. (1995) Optimizing parameters for the development of processed Queso Blanco cheese. Cultured Dairy Products Journal , 30(2), 27, 29–31. McIlveen, H. & Vallely, C. (1996) The development and acceptability of a smoked processed cheese. British Food Journal , 98(8), 17–23. Mistry, V.V., Hassan, A.N. & Acharya, M.R. (2006) Microstructure of pasteurized process cheese manufactured from vacuum condensed and ultrafiltered milk. Lait , 86, 453–459. Mleko, S. & Foegeding, E.A. (2000) Physical properties of rennet casein gels and processed cheese analogs containing whey proteins. Milchwissenschaft , 55, 513–516. Mleko, S. & Foegeding, E.A. (2001) Incorporation of polymerized whey proteins into processed cheese analogs. Milchwissenschaft , 56, 612–615. Mleko, S. & Lucey, J.A. (2003) Production and properties of processed cheese with reduced lactose whey. Milchwissenschaft , 58, 498–502. Merkenich, K., Maurer-Rothmann, A., Walter, E., Scheuber, G. & Klostermeyer, H. (1992a) Additives for processed cheese. European Patent Application, EP 0 491 298 A1. Merkenich, K., Maurer-Rothmann, A., Walter, E., Scheuber, G. & Klostermeyer, H. (1992b) Processed cheese preparation. European Patent Application, EP 0 491 299 A1. Merkenich, K., Maurer-Rothmann, A., Scheuber, G., Walter, E., Albertsen, K. & Wilmsen, A. (1994) Use of stabilized dried milk protein in the production of processed cheese and cheese preparations, and methods of manufacturing such products. PCT International Patent Application, WO 94/01000. Metwally, M., Abd-El-Gawad, I.A., Khorshid, M.A. & El-Sayed, M. (1984) The use of concentrated whey in making cheese spread. Annals of Agricultural Science (Moshtohor), 21, 749–752. Metwally, M.M., El-Shibiny, S., El-Died, S.M. & Assem, F.M. (1996) Effect of packaging materials on the keeping quality of processed cheese. Egyptian Journal of Dairy Science, 24, 1–12. Meyer, A. (1973) Processed Cheese Manufacture, Food Trade Press, London. Modler, H.W. & Emmons, D.B. (2001) The use of continuous Ricotta processing to reduce ingredients cost in ‘further processed’ cheese products. International Dairy Journal , 11, 517–523. Mortensen, H. (1991) Imitation cheese products will gain importance. Scandinavian Dairy Information, 5(2), 14–15.

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Muir, D.D., Tamime, A.Y., Shenana, M.E. & Dawood, A.H. (1999) Processed cheese analogues incorporating fat-substitutes: 1. Composition, microbiological quality and flavour changes during storage at 5◦ C. Lebensmittel Wissenschaft und Technologie, 32, 41–49. Niketi´c, G. & Krˇsev, L. (1990) Investigations on the possibility of the production of smoked processed cheese. Dairy Science Abstracts, 52, 162. Noli, B. (1998) Wheat fibre: a beneficial ingredient for processed cheese. European Dairy Magazine, 9(4), 35–36. Park, J.N., Lee, K.I. & Yu, J.H. (1993) The effect of emulsifying salts on the texture and flavour of block process cheese made with UF cheese base. Dairy Science Abstracts, 55, 97. Pereira, R.B., Bennett, R.J., Hemar, Y. & Campanella, O.H. (2001) Rheological and microstructureal characteristics of model processed cheese analogues. Journal of Texture Studies, 32, 349–373. Pereira, R.B., Bennett, R.J., McMath, K.L. & Luckman, M.S. (2002) In-hand sensory evaluation of textural characteristics in model processed cheese analogues. Journal of Texture Studies, 33, 255–268. Pillonel, L., Tabacchi, R. & Bosset, J.O. (2002) Long term study of volatile compounds from deep frozen canned processed cheese proposed as a control standard. Mitteilungen aus Lebensmittelunterschung und Hygiene, 93, 140–153. Pinto, S., Rathour, A.K., Prajapati, J.P., Jana, A.H. & Solanky, M.J. (2007) Utilization of whey protein concentrate in processed cheese spread. Natural Product Reliance, 6, 398–401. Plockova, M., Stepanek, M., Demnerova, K., Curda, L. & Svirakova, E. (1997) Effect of nisin for improvement in shelf-life and quality of processed cheese. Dairy Science Abstracts, 59, 866. Prajapati, P.S., Gupta, S.K., Patil, G.R. & Patel, A.A. (1991) Cost estimation of a cheese flavoured spread. Asian Journal of Dairy Research, 10, 158–169. Prajapati, P.S., Gupta, S.K., Patil, G.R. & Patel, A.A. (1992) Development of cheese-flavoured low-fat spread. Cultured Dairy Products Journal , 27(3), 16, 18, 20. Price, W.V. & Bush, M.G. (1974a) The process cheese industry in the United States: a review. I. Industrial growth and problems. Journal of Milk and Food Technology, 37, 135–152. Price, W.V. & Bush, M.G. (1974b) The process cheese industry in the United States: a review. II. Research and development. Journal of Milk and Food Technology, 37, 179–198. Quiblier, J.P., Carion, N. & Maubois, J.-L. (1991) Proc´ed´e pour l’introduction d’amidon dans des du genre fromage et produit obtenus. French Patent Application, FR 2 661 316 A1. Rabier, A. & Bonnin, Y. (1992) Packaging for single unit portions of processed cheese. French Patent Application, FR 2 670 188 A1. Rabo, F.H.R.A., El-Aasser, M.A., Zeidan, M.A. & Mohamed, M.M. (2004) Characterisation of low fat processed Cheddar cheese spreads prepared from mixture of buffalo and cow milk. 9th Egyptian Conference for Dairy Science and Technology, pp. 605–615. Radovets, L.V., Malygina, A.M., Makarenko, N.V. & Portonova, M.S. (1987) New fat component for processed cheeses. Dairy Science Abstracts, 49, 629. Raval, D.M. & Mistry, V.V. (1999) Application of ultrafiltered sweet buttermilk in the manufacture of reduced-fat process cheese. Journal of Dairy Science, 82, 2334–2343. Real del Sol, E., Ortega, O., Reynieri, P., Rocamora, Y. & Gonz´alez, J. (2002) Use of Okara in processed cutting cheese. Dairy Science Abstracts, 64, 1047. Reps, A., Iwanczak, M., Wisneiwska, K. & Dajnowiec, F. (1998) Processed cheese with an increased potassium content. Milchwissemschaft , 52, 690–693. Reps, A., Wisneiwska, K. & Kuzmicka, M. (2009) Possibilities of increasing the potassium content of processed cheese spread. Milchwissemschaft , 64, 176–179. Rubin, J. & Bjerre, P. (1984) Method for producing cheese base. Dairy Science Abstracts, 46, 41. Sachdeva, S., Tewari, B.D. & Singh, S. (1988) Recent developments in processed cheese technology: a review. Indian Dairyman, 40, 415–423. Samodurov, V.A., Dolgoschinova, V.G. & Pruidze, G. (1990) Resource-saving technology for processed cheese with vegetable ingredients. XXIII International Dairy Congress, II, 535.

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Salam, A.E. (1988a) Texture of processed cheese related with their fat and dry matter content. Alexandria Science Exchange, 9, 45–52. Salam, A.E. (1988b) Texture of processed cheese as affected by different blend ingredients. Alexandria Science Exchange, 9, 167–175. Saleem, R.M., Habeeb, W.H., Ghaleb, A.A. & Al-Shibani, M. (2003) The use of Taiz cheese in processed cheese spread. Egyptian Journal of Dairy Science, 31, 139–145. Santos, B.L., Resurreccion, A.V.A. & Garcia, V.V. (1989) Quality characteristics and consumer acceptance. Journal of Food Science, 54, 468–471, 474. Schar, W. & Bosset, J.O. (2002) Chemical and physico-chemical changes in processed cheese and ready made fondue during storage: a review. Lebensmittel-Wissenschaft und Technologie, 35, 15–20. Schoegel, F. & Daurelles, J. (1991) Process for the manufacture of paste-type food products and the products obtained using this process. Dairy Science Abstracts, 53, 270. Schrader, K. & Hoffman, W. (2008) Rheological properties and microstructure of selected processed cheeses. Deutche Milchwirtschaft , 59, 615–618. Schirmer, H.G. (1986) Oriented films from propylene copolymers and unplasticized Saran. United States Patent Application, US 4 608 302. Shantha, N.C. & Decker, E.A. (1993) Conjugated linoleic acid concentration in processed cheese containing hydrogen donors, iron and dairy-based additives. Food Chemistry, 47, 257–261. Shantha, N.C., Decker, E.A. & Ustunol, Z. (1992) Conjugated linoleic acid concentration in processed cheese. Journal of the American Oil Chemists’ Society, 69, 425–428. Shaw, M. (1984) Cheese substitutes: threats or opportunity. Journal of the Society of Dairy Technology, 37, 27–31. Shazly, A.B., Mahran, G.A., El-Senaity, M.H., El-Aziz, M.A. & Fatouh, A.E. (2008) Improving low-fat processed cheese spread using whey protein concentrate or butter milk curd. Egyptian Journal of Dairy Science, 36, 83–95. Shimp, L.A. (1985) Process cheese principles. Journal of Food Technology, 39(5), 63–69. Shinozaki, T. & Imagawa, A. (1985) Cheese containing mashed potato and manufacturing process therefore. European Patent Application, EP 0 155 782 A1. Shumaker, E.K. & Wendorff, W.L. (1998) Factors affecting pink discoloration in annatto-colored pasteurized process cheese. Journal of Food Science, 63, 828–831. Singh, S., Tiwari, B.D. & Sachdeva, S. (1993) Suitable blend formulations of buffalo milk Cheddar cheese and fresh curd for processed cheese and cheese spread. Japanese Journal of Dairy and Food Science, 43, A111–A116. Smith, B.L. (1990) Codex Alimentarius: Abridged Version, pp. 12.10–12.16, Food and Agriculture Organization of the United Nations, Rome. Solo’eva, O.I., Skakunova, E.D. & Kazartseva, G.V. (1994) Processed cheese with aromatized emulsions. Dairy Science Abstracts, 56, 206. Song, J.C., Park, H.J. & Shin, W.C. (1992) A study and textural characteristics of imitation processed cheese formulated by delactosed nonfat dry milk. Dairy Science Abstracts, 54, 394. SooYun, K., EunKyung, H., JoungJwa, A. & Haesoo, K. (2009) Chemical and sensory properties of cholesterol-reduced processed cheese spread. International Journal of Dairy Technology, 62, 348–353. Swenson, B.J., Wendorff, W.L. & Lindsay, R.C. (2000) Effects of ingredients on the functionality of fat-free process cheese spread. Journal of Food Science, 65, 822–825. Tamime, A.Y., Kalab, M., Davies, G. & Younis, M.F. (1990) Microstructure and firmness of processed cheese manufactured from Cheddar cheese and skim milk powder cheese base. Food Structure, 9, 23–37. Tamime, A.Y., Davies, G. & Younis, M.F. (1991) Production of processed cheese using Cheddar cheese and cheese base: 2. Production of a cheese base from skim milk powder. Milchwissenschaft , 46, 495–499.

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Tamime, A.Y., Muir, D.D., Shenana, M.E., Kalad, M. & Dawood, A.H. (1999) Processed cheese analogues incorporating fat-substitutes: 2. Rheology, sensory perception of texture and microstructure. Lebensmittel Wissenschaft und Technologie, 32, 50–59. Tamime, A.Y., Skriver, A. & Nilsson, L.E. (2006) Starter cultures. Fermented Milks (ed. A.Y. Tamime), pp. 11–52, Blackwell Publishing Ltd., Oxford. Thapa, T.B. & Gupta, V.K. (1992a) Rheology of processed cheese foods with added whey protein concentrates. Indian Journal of Dairy Science, 45, 88–92. Thapa, T.B. & Gupta, V.K. (1992b) Changes in the sensoric and rheological characteristics during storage of processed cheese food prepared with added whey protein concentrates. Indian Journal of Dairy Science, 45, 140–145. Thapa, T.B. & Gupta, V.K. (1996) Chemical and sensory qualities of processed cheese foods prepared with added whey protein concentrates. Indian Journal of Dairy Science, 49, 129–137. Thomas, M.A. (1977) The Processed Cheese Industry, Department of Agriculture, Richmond, New South Wales. Tiwari, B.D., Sachdeva, S. & Singh, S. (1996) Effect of processing variables on the quality and shelf-life of processed cheese spread from Buffalo milk Cheddar cheese. Indian Journal of Dairy Science, 49, 259–269. Trivedi, D., Bennett, R.J., Hemar, Y., Reid, D.C.W., SiewKim, L. & Illingworth, D. (2008a) Effect of different starch on rheological and microstructural properties of (I) model processed cheese. International Journal of Food Science and Technology, 43, 2191–2196. Trivedi, D., Bennett, R.J., Hemar, Y., Reid, D.C.W., SiewKim, L. & Illingworth, D. (2008b) Effect of different starch on rheological and microstructural properties of (II) commercial processed cheese. International Journal of Food Science and Technology, 43, 2197–2203. Tukan, S.K., Humeid, M.A. & Khalayleh, N. (1998) Developoment of spreadable processed cheese from white brined Nabulsi cheese and Labneh. Dirasat of Agricultural Science, 25, 416–424. T¨urko˘glu, H., Ceylan, Z.G. & C ¸ a˘glar, A. (2002) Some microbiological properties of processed cheese made with various vegetable oils at different levels. Dairy Science Abstracts, 64, 950. Turtell, A. & Delves-Broughton, J. (1998) International acceptance of nisin as a food preservative. The Use of Nisin in Cheesemaking, Overview of Iceland’s Dairy Industry, Terminology for Milk Protein Fractions, Biofilms on Dairy Plant Surfaces: What’s New , Document No. 329, pp. 20–23, International Dairy Federation, Brussels. Vajda, G., Ravasz, L., Karacsonyi, B. & Tabajdi, G. (1983) Products made from cheese and chocolate. UK Patent Application, GB 2 113 969 A. Vareltziz, K.P. & Buck, E.M. (1985) The use of decolorized blood protein in cheese spread. Journal of Food Quality, 8, 21–26. Weber, J.C., Bernard, J.Y. & Bonnin, Y. (1993) Box for packaging food products, and particularly for packaging portions of processed cheese. French Patent Application, FR 2 686 325 A1. Zehren, V.L. & Nusbaum, D.D. (2000) Process Cheese, 2nd edition, Cheese Reporter Publishing Company, Madison. Zhang, D. & Mahoney, A.W. (1991) Iron fortification of process Cheddar cheese. Journal of Dairy Science, 74, 353–358. Zhang, W., Kakuda, Y. & Hill, A.R. (2007) Conjugated linoleic acid (CLA) in processed cheese. Milchwissenschaft , 62, 174–177.

2 Current Legislation on Processed Cheese and Related Products M. Hickey

2.1 Introduction and background For many centuries, cheesemaking has been used to preserve the nutritional value of milk. With the emergence of larger cheese factories, in the last decades of the 19th century, efforts were initiated to extend the shelf-life of cheese to facilitate access to more distant markets and tropical climates. The origin of processed cheese has been attributed to the many and diverse cooked cheese products which were produced in Europe, such as cheese fondue, Kochk¨ase (cook cheese), Welsh rarebit, and heat preservation of soft cheeses such as Camembert. Cheese fondue, where cheeses such as Gruy`ere or Emmental were shredded, wine or kirsch added and heated gently with continuous stirring in a copper vessel, contains many of the fundamentals used in processed cheese production. Indeed the French term for processed cheese is fromage fondu. The presence of tartrates in the white wine used may have acted similarly to emulsifying salts; for a time, tartrates were used as emulsifying salts but, due to their tendency to causing sandiness, they fell out of favour compared to the citrates and phosphates which are used to the present time (Berger et al., 1989). In the late 1800s, some German cheese manufacturers managed to extend the shelflife of soft cheeses, such as Camembert, Brie and Limburger, by canning; however, these did not involve thermal processing. In 1899, Jan Eyssen of Oosthuisen, the Netherlands, the founder of Kaasfabriek Eyssen, to this day a processed cheese and cheese spread manufacturing company in the same town, was granted a British patent for canning Dutch semi-soft cheese (Eyssen, 1899). His process involved cleaning and subsequently kneading the cheese, without the use of heat or emulsifying salts, and hermetically sealing the resultant product in cans. The challenges of producing stable hard cheese, such as Cheddar, Gruy`ere or Emmental, proved more of a challenge as the heat caused the structure to break down and fat and moisture to exude. Then in Thun in Switzerland in 1911, Walter Gerber and Fritz Strettle made the breakthrough using Emmental cheese with sodium citrate as an emulsifying salt to produce a homogeneous flowing mass, which when it cooled was the first true processed cheese (Meyer, 1973; Berger et al., 1989; Caric & Kal´ab, 1993; Guinee et al., 2004). In the United States of America (USA) in 1916, James L. Kraft was issued with his first major patent involving shredding and gradually heating Cheddar cheese to a temperature Processed Cheese and Analogues, First Edition. Edited by A.Y. Tamime. © 2011 Blackwell Publishing Ltd. Published 2011 by Blackwell Publishing Ltd.

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of ∼80◦ C, with continuous stirring while heating. This started the US processed cheese industry where manufacturers developed their own techniques for processing Cheddar-type cheeses, some using citrate emulsifying salts, others phosphate salts. Patents were issued in the USA to cover some of these developments (Kosikowski, 1977; Berger et al., 1989). In the intervening 90 years, a wide range and diversity of processed cheese and related products have evolved in many countries; differing legislative and consumer requirements in different countries has contributed to this diversity. Products have been designated with names such as processed cheese, pasteurised processed cheese, spreadable processed cheese, cheese spread, cheese food, cheese preparation, cheese product, imitation cheese, cheese analog/analogue and more. Formats include blocks, triangles, slices, tubs, glass jars, tubes and aerosol cans, to mention just a few. Indeed such is the range and diversity of products designated as processed cheese and related products throughout the world that in the last 14 years the Codex Alimentarius Commission, which implements the joint FAO/WHO foods standards programme, has failed to make progress in updating its original standards for processed cheese and related products developed originally in 1978. These standards are discussed later. Any discussion on definitions of processed cheese and related products must therefore be based on looking at legislation in different countries. Such legislation varies from the very detailed and specific, as for example in the USA, Canada and Germany to the very general as for example in France. The UK and the Netherlands had specific legislation that addressed processed cheese, but the relevant legislation was repealed in the mid-1990s.

2.2 Definitions and standards of identity 2.2.1 Background and evolution The early impetus and demands for food standards often resulted from demands of manufacturers who wish to protect their products and brands from similar products that they regarded as inferior in quality and also cheaper, particularly those with differences in ingredients or composition. Definitions, standards and related requirements thus developed tended to reflect the manufacturing processes, ingredients and chemical composition at the particular point in time. Such an approach results in the need for regular revision of these standards to take into account process and product innovations, emergence of new functional ingredients and food additives, evolving developments in hygiene and food safety, and changing consumer and societal demands. Furthermore, a significant proportion of food law and regulation requires scientific or technological input and interpretation. To understand these points it is worth considering the origins of standards and legislation governing food production and composition that date back to the Middle Ages. Many will have heard of the Reinheitsgebot (the Purity Order), which concerned the purity of beer and originated in Bavaria in 1516 (Eden, 1993; Rieck, 2008). This listed the only permitted ingredients for beer as water, barley and hops. The original order also set the maximum price of beer at a mere 2 Pfennig per Maß; of course this provision disappeared a very long time ago. It should be noted that the list of ingredients did not include yeast; it would be the mid 1800s before the role of microorganisms in food fermentations was recognised.

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Nevertheless, it was 1987 before the requirements of the Reinheitsgebot were fully lifted in Germany, as the result of a decision of the European Court of Justice (ECJ, 1987). Even to this day certain German beers claim they comply with the Reinheitsgebot. By the middle of the 19th century, concerns about the adulteration, purity and wholesomeness of foods led to the development of food legislation in many different jurisdictions. Nowadays the basis for food legislation is given as food safety, consumer protection and fair trade. The words may differ, but the fundamentals have not really changed.

2.2.2 Legislation in the European Union (EU) Access to EU legislation Following its adoption, EU legislation is published in the L-Series of the Official Journal of the European Union. It may also be accessed using the EUR-LEX website (http:// eur-lex.europa.eu/RECH_naturel.do). The use of this website is facilitated by knowing the type (directive, regulation, decision, or COM-final), the year and the number of the relevant legislation. In this chapter, the necessary information will be given when referring to specific legislation. The most recent legislation is usually available electronically in PDF format, while the earlier legislation may be directly accessed in HTML (Hypertext Mark-up Language) format only; the appendices are a problem in this format. This problem may be overcome by requesting TIFF (Tagged Image File Format) images of the original official journal document by e-mail, and the relevant website link is provided quickly, which allows access to the images. Amendments to legislation are also published in the official journal; however, these normally have just the text that is being changed. Consolidated texts of most legislation can be accessed electronically, but such texts come with a warning that they are not official texts. Nonetheless, such consolidated legislation, incorporating the amendments into the original text, can be very useful, as they facilitate use of the documents. Other national and specialised websites, such as those of the United Kingdom (UK) Food Standards Agency (www.foodstandards.gov.uk), the Food Safety Authority of Ireland (www.fsai.ie) and the food law pages of the Department of Food Biosciences of the University of Reading (www.reading.ac.uk/foodlaw/main.htm), are a few examples of sites that contain links to the legislative texts. EU legislation on natural cheeses There are some provisions for certain varieties of cheese registered according to the requirements contained in European Regulation 2081/92 on the protection of geographical indications (PGI) and protection designations of origin (PDO) (EU, 1992b) and Regulation 2082/92 on Certificates of Specific Character (also referred to as Traditional Speciality Guaranteed or TSG) (EU, 1992c). The Annex to Regulation 1107/96, as amended, on the registration of products as laid down in Article 17 of the former regulation, lists protected products (EU, 1996b). Regulation 2301/1997 on entry of certain names in the ‘Register of certificates of specific character’ provided for in the latter regulation has just three registered cheeses: one from Italy (Mozzarella), one from the Netherlands (Boerenkaas) and one from Sweden (Hush˚allsost) (EU, 1997).

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Regulation 2204/90 (EU, 1990b) allows the use of casein in the manufacture of cheese only if such a use can be shown to be necessary. The Annex of Regulation 2742/90 (EU, 1990a), which lays down detailed rules for the application of regulation 2204/90 (EU, 1990b), specifies such permitted uses: to date use in processed cheese to a maximum level of 5 g 100 g−1 is the only such use permitted. Since the casein manufacturing subsidy has been eliminated for all practical purposes, there have also been discussions as to whether this Regulation is still necessary. At this time no decision has been taken, although its fate is probably linked to the outcome of the discussions on the manufacturing subsidy. Apart from these regulations, there is no specific EU legislation on cheese or processed cheese. To get a more complete oversight on the legislation on processed cheese and related products within the EU, it is necessary to look at a selection of Member States. However, before going on to look at these, it is necessary to consider some horizontal provisions that apply to all Member States; in particular, those relating to food hygiene, food labelling and food additives are particularly relevant to processed cheese and related products. EU hygiene legislation The early legislative work in the EU was largely taken up with market regulation; it was not until 1985 that the first Community hygiene measure for milk was adopted in Directive 85/397 (EU, 1985b). This initiated a process of harmonising hygiene standards within the Community in order to facilitate intra-Community trade without compromising existing Member State hygiene rules. It covered all aspects of the production, transport and processing of milk from farm to the final consumer. This was followed in 1992 by a new directive on the hygiene of milk and milk products, Directive 92/46 (EU, 1992a), which became effective from 1 January 1994. This Directive contained animal health requirements for raw milk, hygiene requirements for registered holdings, hygiene requirements in milking, collection and transport of milk to collection centres, standardisation centres, treatment establishments and processing establishments. For the first time, uniform EU-wide hygiene standards were created as the earlier Directive 85/397 (EU, 1985b) applied to intra-Community trade only. Directive 92/46 (EU, 1992a) laid down minimum compositional standards for milk, and also standards for the maximum plate count and somatic cell count for raw milk at collection from dairy farms intended for the production of certain milk-based products; this includes cheese, processed cheese and related products. Following a recommendation in the EU White Paper on Food Safety in 2000, a major review was carried out on the EU Hygiene Directives (EU, 2000b). Prior to this review, there were a total of 16 commodity-specific EU Directives and one Directive on general food hygiene, which had been gradually developed in the period from 1964 and had given a high level of protection to the consumer. However, they comprised a mixture of different disciplines (hygiene, animal health, official controls, etc.) and were detailed and complex. It was decided to overhaul the legislation to improve, simplify and modernise it, and also to separate aspects of food hygiene from animal health and food control issues. The review aimed for a more consistent and clear approach throughout the food production chain from ‘farm to fork’. A package of new hygiene rules were adopted in April 2004 by the European Parliament and the Council. They became applicable from 1 January 2006 and, in the case of milk and

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milk products, replace Directive 92/46 (EU, 1992a). The new rules are Regulations and not Directives, making them binding in Member States without the necessity for national legislation to be enacted to implement their provisions. Instead of all the hygiene requirements being embodied in a single piece of legislation, however, the hygiene requirements for the dairy sector are now contained across at least six different regulations. The three main Regulations are (a) Regulation 852/2004 on the hygiene of foodstuffs (EU, 2004d); (b) Regulation 853/2004 laying down specific hygiene rules for food of animal origin – Annex III Section XI thereof contains specific requirements for raw milk and dairy products (EU, 2004e); and (c) Regulation 854/2004 laying down specific rules for the organisation of official controls on products of animal origin intended for human consumption (EU, 2004f). Then, in early December 2005, two important additional regulations were published, Regulation 2074/2005 (EU, 2005b) and Regulation 2076/2005 (EU, 2005c). In addition to laying down implementing measures and transitional measures, these also contain important amendments and derogations to the original regulations. Furthermore, in 2006, Regulation 1662/2006 (EU, 2006b) was published, amending Regulation 853/2004, which contained a replacement to the complete Section XI of Regulation 853/2004, the section addressing milk and milk products. Fortunately, a consolidated version of Regulation 853/2004 (EU, 2004e), incorporating all the amendments up to 24 April 2009, is available on the EURLEX website. Microbiological criteria for foodstuffs are laid down in Regulation 2073/2005 (EU, 2005a). These included criteria for cheeses made from pasteurised milk, cheeses from raw milk, cheeses made from milk which have undergone a heat treatment lower than pasteurisation and for unripened soft cheeses. There are no specific microbiological requirements laid down for processed cheese and related products in the latter regulation. Guidance documents on food hygiene have also been developed by the Commission on Regulation 852/2004 (EU, 2004d; see EU, 2005e,f, 2006d) and Regulation 853/2004 (EU, 2004e; see EU, 2005d). As a result of a May/June 2006 audit in UK by the Food and Veterinary Office (FVO) of the European Commission, specific hygiene issues were noted as regards, inter alia, cheese recovery. As a consequence, a specific EU decision on all the issues concerned was published, which is of relevance to processed cheese manufacture (EU, 2006a). Though the decision related to the production of the specific factory, the UK Food Standards Agency issued a letter to all heads of environmental health services and directors of trading standards in England stating that premises involved in cheese recovery operations must be approved under the terms of Regulation 853/2004 (EU, 2004e) such as (a) that hazard analysis critical control points (HACCP) system and procedures, records and raw material specifications must demonstrate clearly how hazards associated with cheese recovery are controlled by the food businesses, and (b) that raw materials are fit for purpose. In addition, it was stated that appropriate traceability arrangements must be in place. This did not necessarily change the existing legal situation, but focused attention on such operations. Probably, as a consequence of this, the Association de l’industrie de la fonte de fromage de l’UE (Association of the processed cheese industry in the EU, ASSIFONTE) decided in September 2006 to establish a special working group on good manufacturing practices (GMP) for processed cheese. These were published in 2008 (ASSIFONTE, 2008). ASSIFONTE together with European Dairy Association (EDA) and the European Association of the Dairy Trade (EUCOLAIT) also started work on a manual for cheese recovery.

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Processed Cheese and Analogues

EU food labelling legislation Horizontal European labelling requirements for foods are contained in the EU Labelling Directive 2000/13 (EU, 2000a), as amended. It should be noted that the scope of this directive applies to the labelling of foodstuffs to be delivered as such to the ultimate consumer, or to mass caterers (defined as restaurants, hospitals, canteens and other similar mass caterers). Hence, they may not necessarily apply directly to products in so far as they may be intended for further manufacture. In such instances, the products are normally traded to meet detailed specifications between the purchaser and vendor. Compliance with such specifications, especially where written and signed by both parties, would be governed by contract law. The horizontal food labelling requirements include the following provisions: • • • • • •

Name of the food. List of ingredients including ingredients or food additives; if vitamins or minerals are added, these should be indicated. An indication of the net quantity. The date of minimum durability should be indicated. Special conditions of storage and use that would affect the minimum durability. Name and address of manufacturer or seller: this information should be given in addition to the identification mark required by the hygiene regulations outlined above.

As regards the name of the food, a hierarchy of requirements is as follows: • •

•

•

When the product has a legal name specified in EU legislation, then that name should be used. Where there is no EU legal name, the name under which a product is sold shall be the name provided for in the legislation and administrative provisions applicable in the Member State in which the product is sold to the final consumer or to mass caterers. Where neither of the above provisions apply, the name under which a product is sold shall be the name customary in the Member State in which it is sold to the final consumer or to mass caterers; or description of the foodstuff, and if necessary of its use, which is clear enough to let the purchaser know its true nature and distinguish it from other products with which it might be confused. The use in the Member State of marketing of the sales name under which the product is legally manufactured and marketed in the Member State of production shall also be allowed. However, this has qualifications: (a) where the other labelling requirements would not enable consumers in the Member State of marketing to know the true nature of the foodstuff and to distinguish it from foodstuffs with which they could confuse it, in which case, the sales name shall be accompanied by other descriptive information which shall appear in proximity to the sales name, and (b) this name cannot be used where the product so named is so different, in the Member State of sale, as regards its composition or manufacture, from the foodstuff known there under that name that the provisions of point above are not sufficient to ensure correct information for consumers.

Current Legislation on Processed Cheese and Related Products

31

These requirements for the name of the food incorporate the most up-to-date provisions of the Cassis de Dijon principle of mutual recognition, based on one of the keystone rulings of the European Court of Justice in 1979 (ECJ, 1978). Basically, this ruling established or confirmed the principle that Member States accept products that comply with the legislation and standards of other Member States, if they provide at least an equivalent level of protection to their own. This principle has important implications for the product names and other labelling provisions of processed cheese and related products, in the absence of harmonised European legislation for such products. Another labelling requirement worthy of discussion is that requiring an indication of the quantity of an ingredient or category of ingredients used in the manufacture of a foodstuff in certain circumstances. This is usually referred to as quantity ingredient labelling (QUID), and is required in the following circumstances: • • • •

where the ingredient concerned appears in the name under which the foodstuff is sold or is usually associated with that name by the consumer; or where the ingredient concerned is emphasised on the labelling in words, pictures or graphics; or where the ingredient concerned is essential to characterise a foodstuff and to distinguish it from products with which it might be confused because of its name or appearance; or in other cases as determined by the Commission, assisted by the Standing Committee on the Food Chain and Animal Health (SCFCAH). However, the directive also specifies that QUID labelling is not compulsory:

• • • •

where the drained net weight of which is indicated as required for a solid food sold in a liquid medium; or where the quantities of the relevant ingredient is already required to be given on the labelling under Community provisions; or for an ingredient which is used in small quantities for the purposes of flavouring; or for ingredients, which, while appearing in the name under which the food is sold, is not such as to govern the choice of the consumer in the country of marketing because the variation in quantity is not essential to characterise the foodstuff or does not distinguish it from similar foods; where in doubt this shall be determined by the Commission, assisted by the Standing Committee on the Food Chain and Animal Health (SCFCAH).

From the above, it may be that the key issue in determining if the cheese content would be subject to QUID labelling for processed cheese and related products is whether variations in the cheese content in the country of marketing would govern the choice of consumers. This is far from clear and interpretation may well vary from Member State to Member State. An early draft of UK Guidelines on QUID labelling gave processed cheese as one of the products where QUID might not apply; however, the final copy, circulated in 1999, excluded this example. Furthermore, it is also stated that there are just examples given in the guidelines and other products may also be subject to exemption from QUID. It is believed the exclusion of processed cheese was to align the UK examples with those of the Commission which produced equivalent Community guidelines.

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Processed Cheese and Analogues

Table 2.1 Requirements for fat-related nutrient claims on solid foodstuffs in the EU under Regulation No. 1924/2006 (EU, 2006b). Claim Fat free

a

Requirement for fat content a

−1

Additional requirements

≤0.5 g 100 g

–

−1

Low-fat

≤3 g 100 g

–

Reduced-fat

25% less fat than the reference standard product

–

Light or lite

Same as for ‘reduced’ claim, i.e. 25% less fat than the reference standard product

Claim shall be accompanied by an indication of the characteristic that makes the product ‘light’, i.e. fat

Regulation 1924/2006 specifically prohibits nutrient claims of the form ‘X% fat-free’.

Regulation (EC) 1924/2006, which has been in force since 1 July 2007, aimed to ensure that nutrition and health claims made on foodstuffs comply with specified requirements (EU, 2006c). A list of permitted nutrition claims and their specific conditions of use is included in the Annex to Regulation (EC) 1924/2006 (EU, 2006c). Table 2.1 shows the requirements for fat content claims in this regulation. Furthermore, nutrition or health claims may not be made that are inconsistent with generally accepted nutrition and health principles, or if it encourages excessive consumption of a particular food, or is not consistent with a good diet. In this regard nutrient profiles are being developed to address this principle. These profiles have not been finalised at yet but may have implications for claims on cheeses, including processed cheese and related products, especially as regards saturated fat and sodium (or added salt) levels. In December 2007, guidance on the implementation of Regulation 1924/2006 (EU, 2006c) was published by the EU Commission (EU, 2007f). EU legislation of food additives From the 1960s through to the mid-1970s, the EU established a series of basic directives addressing the use of colours, preservatives, antioxidants, emulsifiers, stabilisers and thickeners; these were amended over the years. During that time specific additive provisions were included in vertical legislation on certain foods and in other cases authorisation for their use was left to Member States. Inevitably this led to differences between the legislative provisions of Member States and this hindered the free movement of foodstuffs within the open market. Thus harmonisation of this area became a major priority. With the move to horizontal legislation, as proposed in the White Paper on the Completion of the Internal Market in 1985, steps were initiated to address additives in a horizontal and more comprehensive manner (EU, 1985a). Firstly, the use of additives in foods throughout the EU was addressed under the additive framework Directive 89/107/EEC (EU, 1989), the flavourings Directive 88/388 (EU, 1988) and, in 1994 and 1995, specific additive directives were adopted addressing the following: • •

Colours: Directive 94/36 (EU, 1994b). Sweeteners: Directive 94/35 (EU, 1994a) as amended.

Current Legislation on Processed Cheese and Related Products

•

33

Additives other than colours and sweeteners: Directive 95/2 (EU, 1995c), as amended (for simplicity, this is sometimes referred to as the Miscellaneous Additives Directive).

Furthermore food additives must at all times comply with the approved criteria of purity, and these criteria are outlined in three Commission Directives: • • •

Sweeteners by Directive 95/31/EC (EU, 1995a) as amended. Colours by Directive 95/45/EC (EU, 1995b), as amended. Additives other than colours and sweeteners by Directive 96/77/EC (EU, 1996a) as amended.

The Framework Additive Directive 89/107/EEC (EU, 1989) has the following definitions: •

•

An additive is ‘any substance not normally consumed as a food in itself and not normally used as a characteristic ingredient of food whether or not it has nutritive value, the intentional addition of which to food for a technological purpose in the manufacture, processing, preparation, treatment, packaging, transport or storage of such food results, or may be reasonably expected to result, in it or its by-products becoming directly or indirectly a component of such foods’ (Article 1.2). A processing aid is ‘any substance not consumed as a food ingredient by itself, intentionally used in the processing of raw materials, foods or their ingredients, to fulfil a certain technological purpose during treatment or processing and which may result in the unintentional but technically unavoidable presence of residues of the substance or its derivatives in the final product, provided that these residues do not present any health risk and do not have any technological effect on the finished product’. Footnote to Article 1.3 a.

This Directive excludes flavourings and substances added as nutrients from the scope of the additives governed by its provisions; the latter refers to substances, such as vitamins, minerals and trace elements. Annex II lays down three basic principles for the approval of use of additives, which may be summarised as follows: (a) that a technological need can be demonstrated and that need cannot be achieved by other means that are economical or technologically practical; (b) their use does not present a hazard to human health at the levels of use proposed based on the scientific evidence available; and (c) their use does not mislead consumers. Annex I of this Directive lists 25 additive functional categories (Table 2.2); the definitions of these categories are given in the specific directives on colours, sweeteners and additives other than colours and sweeteners. The Colours Directive 94/36 (EU, 1994b) has five Annexes, listing 43 permitted food colours and the provisions for their use. Annex II lists foods which may not contain added colours except where specifically provided for in Annexes III, IV or V; this Annex II list does not include processed cheese or related products. Annex III allows the ‘orange’ colours carotenes (E160a), paprika extract (E160c), both at quantum satis level, and annatto, bixin and norbixin (E160b) at 15 mg kg−1 in unflavoured processed cheese. These are the only colours permitted in unflavoured processed cheese. Annex IV also contains the provisions for annatto, bixin and norbixin

34

Processed Cheese and Analogues

Table 2.2 The 25 additive functional classes listed in the EU Framework Additive Directive 89/107/EEC, as amended (EU, 1989). Colour

Modified starch

Preservative

Sweetener

Antioxidant

Raising agent

Emulsifier

Anti-foaming agent

Emulsifying salt

Glazing agent

Thickener

Flour treatment agent

Gelling agent

Firming agent

Stabiliser

Humectant

Flavour enhancer

Sequestrant

Acid

Enzyme

Acidity regulator

Bulking agent

Anti-caking agent

Propellent gas and packaging gas

Note: Two additional additive functional classes (carriers and foaming agents) are defined in Directive 95/2, as amended (EU, 1995c).

(E160b), at a level of 15 mg kg−1 for flavoured processed cheese, as this is one of the colour groups that is permitted for specified uses only. Annex V Part 1 lists 15 colours permitted in foods other than those listed in Annexes II and III at quantum satis level ; consequently, these colours are allowed in flavoured processed cheese. Annex V Part 1 includes the ‘orange’ colours carotenes (E160a) and paprika extract, capsanthin and capsorubin (these three colours grouped together as E160c). Finally, Annex V Part 2 lists 18 colours that may be used, singly or in combination, in a list of specified foods at a maximum level of 100 mg kg−1 ; this list includes flavoured processed cheese, but not unflavoured processed cheese. Furthermore, the maximum levels of the individual colours sunset yellow FCF (E110), azorubine (carmosine) (E122), ponceau 4R (cochineal A) (E124) and brown HT (E155) may not exceed 50 mg kg−1 . The use of all colours is subject to the normal technical justification based on need. It should be mentioned that this Directive contains provisions that refer to processed cheese only, and there is no mention of other processed cheese product names, such as cheese preparations, cheese spreads or cheese food; nonetheless, it appears safe to assume that, since processed cheese is not defined or standardised at Community level, the term is used generically and applies to all processed cheese products. Directive 95/2 on additives other than colours and sweeteners (EU, 1995c) is quite long, complex and detailed. Its provisions may be summarised as follows: •

The latest consolidated text contains definitions of 24 additive functions (Article 1.3 (a)–(w) and Article 1.4). Included are definitions of two functions, carriers and foaming agents, not listed in Annex I of the Framework Directive. Additives are listed in the Annexes without specified functions. It is up to food manufacturers to assign the

Current Legislation on Processed Cheese and Related Products

• • •

•

• •

•

• •

35

principal or main additive function to each additive in product labelling, recognising that an additive may have more than one function in a food. The functional ingredients edible gelatine, certain starches, casein and caseinates are not considered as food additives. Article 2.3 lists foods where the permission to use the additives listed in Annex I do not apply unless specifically allowed for. This article does not list processed cheese. Annex I lists 114 E numbers and specific food additives that are generally permitted for use in foods not referred to in Article 2.3 or Annex II. The use of the additives in this Annex, which includes the citrates, are recognised as emulsifying salts, stabilisers and thickeners, such as the gums, alginates, agar, carrageenans, celluloses and modified starches, would be permitted in all types of processed cheese, at least in theory, where their use meets the basic principles outlined in the discussion on Directive 89/107 (EU, 1989). The quantum satis principle is often misinterpreted as meaning that one may use as much as one likes. However, this is incorrect: the term is defined in Article 2.8 as meaning ‘that no maximum level is specified. However, additives shall be used in accordance with good manufacturing practice, at a level not higher than is necessary to achieve the intended purpose and provided that they do not mislead the consumer’. Annex II lists foods where a limited number of Annex I additives may be used. This Annex does not include any specific provisions for processed cheese types. Annex III addresses conditionally permitted preservatives and antioxidants. It has four parts. (a) Part A deals with sorbates, benzoates and p-hydroxybenzoates, and permits the use of sorbates at a maximum level of 2000 mg kg−1 in processed cheese. (b) Part B addresses sulphur dioxide and sulphites. (c) Part C addresses other preservatives, and permits the use of nisin in processed cheeses, at a maximum level of 12 mg kg−1 . Potassium nitrate, sodium nitrate and propionates (the latter is used for surface treatment only) are permitted in cheese analogues, but not in processed cheese. Cheese analogues are not defined but, since processed cheese analogues are referred to in Annex IV (e.g. for phosphates and silicates), it is unlikely that the use of these additives is permitted in processed cheese type analogues. (d) Part D addresses other antioxidants. Annex IV deals with ‘Other Permitted Additives’, and is the most complicated of the annexes to comprehend. It is often best to look at each additive of interest, and then look to see if it is permitted for a particular product of interest. Phosphates, the other major group of emulsifying salts, are addressed as a group in this Annex, and the specified maximum levels apply to their use singly or in combination, expressed as phosphate ion (P2 O5 ). For processed cheese and processed cheese analogues, the phosphates are allowed at a maximum level so expressed of 20 g kg−1 . The other permitted additives from this Annex are the silicates (E numbers from E551 to E559) for use as anti-caking agents in sliced or grated processed cheese and processed cheese analogues. Annex V addresses permitted carriers and carrier solvents, and shall not be discussed further. Annex VI deals with additives for use foods for infants and young children, and thus is not relevant as regards processed cheese.

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Processed Cheese and Analogues

Forthcoming changes as regards additives In 2006, the European Commission published a package of legislative proposals that aimed to upgrade rules for additives (EU, 2007c), flavourings (EU, 2007b) and to introduce harmonised legislation on food enzymes (EU, 2007d). It also proposed the creation of a common authorisation procedure for food additives, flavourings and enzymes, based on scientific opinions from the European Food Safety Authority (EFSA) (EU, 2007a). Following inputs from the European Parliament, four new regulations were adopted on 16 December 2008 as follows: (a) Regulation 1331/2008 on a common authorisation procedure for food additives (EU, 2008a), (b) Regulation 1332/2008 on food enzymes (EU, 2008b), (c) Regulation 1333/2008 on food additives (EU, 2008c), and (d) Regulation 1334/2008 on flavourings and certain food ingredients with flavouring properties for use in foods (EU, 2008d). Article 30 of Regulation 1333/2008 (EU, 2008c) refers to the creation of ‘Community lists of food additives’, but Article 31, headed Transitional measures, states that ‘until the establishment of Community lists of food additives, the Annexes to Directives 94/35, 94/36 and 95/2 shall be amended where necessary, by measures designed to amend non-essential elements of those Directives, adopted by the Commission in accordance with the regulatory procedure with scrutiny referred to in Article 28 (4)’ (EU, 1994a,b, 1995c). In Article 34 titled Transitional provisions, it is indicated that the provisions in certain articles and annexes of the three Directives referred to in Article 31, food additives already permitted therein shall continue to apply until transfer to this regulation has been completed. The use of functional ingredients, such as starch and gelatine in processed cheese or related products, are not covered in EU legislation, but their use should be within the provisions of Regulation 1234/2007 of 22 October 2007 (EU, 2007e), as amended, establishing a common organisation of agricultural markets and on specific provisions for certain agricultural products in that by their use they do not replace milk ingredients. The legislation of some Member States addresses the use of these functional ingredients, which will be reviewed in subsequent section. On the other hand the use of casein and caseinates in processed cheese is specifically addressed in Regulation 2742/90 (EU, 1990a). This specifies a maximum level of 5 g 100 g−1 for use in processed cheese, and it lays down detailed rules for the application of Council Regulation 2204/90 (EU, 1990b). European legislation on food packaging materials Processed cheese and related products may be packed in a differing packaging formats, e.g. plastic film, foil wrappers, plastic tubs, tubes, aerosol cans. These packaging materials should comply with the general requirements of Regulation 1935/2004 (EU, 2004c), and the particular requirements such as contained in Directive 2002/72 (EU, 2003), as amended by Directive 2004/19 (EU, 2004b) and Directive 2004/1 (EU, 2004a). It is normal for processors to specify to their packaging suppliers that their products comply with the requirements of these directives.

2.2.3 Legislation in the UK Up to the beginning of the 21st century, England and Wales had common legislation, signed by the appropriate minister of the UK government and the Secretary of State for

Current Legislation on Processed Cheese and Related Products

37

Wales. Parallel, separate, but similar legislation was enacted for Scotland and Northern Ireland; however, some differences could and sometimes did occur. From 2000, with the establishment of the Welsh Assembly, separate but similar legislation for Wales was enacted. The primary source of UK legislation is by Acts of Parliament, primarily those of the Westminster Parliament; secondary legislation in the form of Statutory Instruments (SIs), or Statutory Regulations and Orders (SROs), are enacted under specified sections of the enabling Act or Acts. Details of the current legislation in the UK as well as the separate legislation applicable to Scotland, Wales and Northern Ireland may be found via the relevant link on the (UK) Foods Standards Agency website (www.foodstandards.gov.uk) or that of the Office of Public Sector Information (OPSI; www.opsi.gov.uk/legislation/uk.htm). In searching the OPSI website it is necessary to know the year and number of the Act or Statutory Instrument of interest. The availability of repealed legislation, as is the case with cheese legislation, is more of a challenge, but the relevant provisions shall be outlined in one of the subsequent sections. Background to UK legislation In the 1850s, there was increasing concern on the issues of food purity and food adulteration based on the identification of such issues by analysts and medical doctors. This led to the adoption of three separate pieces of legislation addressing food adulteration; one such was the Adulteration of Food and Drugs Act 1860 (HMSO, 1860). However, this was ineffective, but it paved the way for the enactment of the Sale of Food and Drugs Act 1875 (HMSO, 1875). The main requirements of the 1875 Act were: • • • • •

that nothing should be added to food for sale which would be injurious to health; that sale of food that was not of the proper nature, substance or quality was prohibited; that [public] analysts be appointed; that purchasers of a food were entitled [empowered] to have it analysed; and that the officers entitled to obtain samples for submission to an analyst were specified.

Although it was not without its critics, this Act, with subsequent amendments, enlargement and consolidation, remained in force for the next 60 years (Monier-Williams, 1951). In the early 1930s, a Departmental Committee on the Composition and Description of Food was established to look into the whole area of definitions, standards, labelling and advertising. This Committee was in favour of a limited number of standards, the main aim of which would be to inform consumers of what they were purchasing (Monier-Williams, 1951). Their report in 1934 resulted in a new consolidated Sale of Food and Drugs Act 1938 (HMSO, 1938). The 1938 Act remained in place until it was replaced by the Sale of Food and Drugs Act 1955 (HMSO, 1955). Then, as the result of a number of food scares in the 1980s, due to salmonella, listeria and bovine spongiform encephalopathy (BSE), the Food Safety Act 1990 (HMSO, 1990), was enacted. This was a broad measure which created a more systematic structure of UK food law and tightened up on offences, enforcement powers and penalties. The first pieces of UK legislation that set standards for dairy products were (a) The Butter and Margarine Act 1907 (HMSO, 1907; French & Phillips, 2000), (b) The Condensed Milk Regulations 1923 (HMSO, 1923a), and (c) The Dried Milk Regulations 1923

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Processed Cheese and Analogues

(HMSO, 1923b). However, the first cheese regulations were not adopted until the Cheese Regulations 1965 (HMSO, 1965; Davis, 1966). On hygienic legislation, in or about 1912, the quality and purity of milk supply became the focus of attention. World War I interfered with the enforcement of the Milk and Dairies (Consolidation) Act 1915 (HMSO, 1915) but, by 1918, a tentative system of milk grading was in operation. The production of clean and safe milk was first seriously addressed under the Milk and Dairies Amendment Act 1922 (HMSO, 1922a) and the Milk (Special Designations) Order 1922 (HMSO, 1922b), which encompassed different grades for raw milk. When the UK joined the then European Economic Community on 1 January 1973, European legislation began to have a major role in shaping the evolving national legislation. However, as outlined in the discussion of European legislation earlier, harmonisation of legislation on vertical legislation did not start until the 1970s and on hygienic aspects of milk production until the mid-1980s. European Directives have to be enacted into the laws of Member States, while Community Regulations are binding in their entirety on Member States. In the latter case, the relevant Statutory Instruments references the requirements contained therein and outline particular elements, such as interpretations/definitions, specify the competent authority, address administration, detail offences, defences and penalties, and specify certain schedules. Where the European regulations specify general provisions, the UK Statutory Instrument may lay down more specific requirements, and may address national provisions where discretion or optional provisions are delegated to Member States. UK legislation on cheese As mentioned above, the first UK cheese legislation was contained in the Cheese Regulations 1965 (HMSO, 1965; Davis, 1966). These applied to England and Wales; Scotland and Northern Ireland had separate but identical legislation. These regulations had a definition of cheese and specified the requirements for hard, soft, whey cheese, processed cheese and cheese spread. These standards were amended on a number of occasions but, in 1970, were replaced by the Cheese Regulations 1970 (HMSO, 1970); they re-enacted, with amendments, the 1965 Regulations and so contained many of the earlier provisions. The original 1970 Cheese Regulations were amended in 1974 and 1984 (HMSO, 1974, 1984). The equivalent Scottish Regulations were the Cheese (Scotland) Regulations 1970 (HMSO, 1984; The Stationery Office, 1970a, 1974, 1984); those for Northern Ireland were the Cheese Regulations (Northern Ireland) 1970 (The Stationery Office, 1970b). The Cheese Regulations 1970, as amended, outlined requirements for Processed Cheese and Cheese Spread, the latter could also be named Cheese Food. Under these regulations, cheese was the only dairy product that could be used in a product called processed cheese, while other milk products could be used in products called cheese spread or cheese food. Detailed compositional requirements for a named variety of processed cheese, processed cheese and cheese spread were also included as shown in Table 2.3. Where a variety name, other than Cheddar, that had specified compositional requirements in Schedule 1 of the Cheese Regulations (Table 2.4) was used in the name of a processed cheese the resultant processed cheese had to comply with the compositional requirements for that variety. It may be observed that the compositional requirements for cheese spread, and by extension cheese food, covered all products, including those with

Current Legislation on Processed Cheese and Related Products

Table 2.3 Compositional requirements (g 100 g−1 ) for processed cheese and cheese spread in the UK Cheese Regulations 1970, as amended, which were repealed in 1996. Moisture content (maximum)

Product name

Qualifier

Fat-in-dry Matter (FDM)

Processed cheese

Cheddara

Maximum 48

43

Full-fat

Maximum 48

48

Medium-fat

Maximum 48, minimum 20

48

Skimmed milk

Maximum 10

48

Minimum 20

60

Cheese spread or cheese food

Source: After HMSO (1970). a For compositional requirements for other specified named varieties, see Table 2.4. Table 2.4 Compositional requirements (maximum g 100 g−1 ) for certain named variety cheese, other than Cheddar, in Schedule 1 of the UK Cheese Regulations 1970, as amended, which were repealed in 1996. Cheese name

Fat-in-dry matter (FDM)

Moisture

Blue Stilton, Derby and Leicester

48

42

Cheshire, Dunlop, Gloucester and Double Gloucester

48

44

Caerphilly, Wensleydale and White Stilton

48

46

Lancashire

48

48

Edam

40

46

Goudaa

48

43

Danablu

50

47

Danbo

45

46

Havarti

45

50

45

44

45

40

a

Samsoe b

Emmental b

45

38

Tilsiterb

45

47

Limburger

50

50

Saint Paulin

40

56

Gruy`ere

Svecia

45

41

Provolone

45

47

Source: After HMSO (1970). a Different compositional requirements for Loaf Edam, Baby Edam, Baby Loaf Edam and Baby Gouda not included. b Alternative names given for Emmental, Gruy`ere and Tilsiter not included in this table.

39

40

Processed Cheese and Analogues

cheese variety names. As an alternative to the descriptors, such as full-fat, medium-fat, etc. (see Table 2.3), the minimum fat content or the minimum fat-in-dry matter (FDM) and the maximum moisture content could be declared. The use of starch and gelatine was allowed in processed cheese, cheese spread or cheese food. While additive provisions were included in the 1970 Regulations, these were replaced by the EU legislation on food additives as discussed in section 2.2.2. The Cheese Regulations 1970 (HMSO, 1970), as amended, were repealed and replaced by the short-lived Cheese and Cream Regulations 1995 (HMSO, 1995). These maintained the definitions of processed cheese and cheese spread from the 1970 Cheese Regulations, as amended. However, these 1995 Regulations in turn were repealed by the Food Labelling Regulations 1996 (HMSO, 1996); while the definition of cheese and compositional requirements for Cheddar and 11 other territorial cheeses were included, the definitions of processed cheese and cheese spread were not included. So what is the present status of processed cheese-type products in the UK? It is likely that the status of the name of a processed cheese, a cheese spread or cheese food, which were defined in the repealed regulations, have become ‘customary names’ in the UK (i.e. name customary in the Member State in which it is sold, as discussed in section 2.2.2). Probably the best advice is contained in the 1997 UK Local Authority Coordination Body on Trading Standards (LACOTS) opinion on cheese names, which indicated that customary names could be used if they did not depart from the original compositional profile. They also indicated that use of the terms, such as full-fat, medium-fat, hard and soft in relation to a cheese, would indicate the true nature of the food as required by Regulation 8 of the Food Labelling Regulations 1996. It must be stressed that the LACOTS advice contains the warning that only the courts have the authority to interpret statute law; their advice was based on the information provided and might be revised in the light of further information, and was not intended to be a definitive guide, or substitute for the relevant law (LACOTS, 1997). LACOTS is now known as the Local Authorities Coordinators of Regulatory Services (LACORS). Their advice is now intended for guidance for their local council colleagues only and access to much of their advice is restricted. Furthermore, if terms such as reduced fat or other such nutritional claims are used, then these should be in line with the relevant EU regulation in this area (EU, 2006c). In the UK, labelling regulations customary names are not given preferential status and may be used, but so can designations which are a description of the product sufficiently precise to inform the consumer of the true nature of the product and to enable the food to be distinguished from products with which it could be confused. However, the existence from 1966 to 1996 of definitions are understood to change the position somewhat, particularly regarding what could be construed as misleading consumers. It is possible that products with some minor but insignificant changes could also be given the name ‘processed cheese’. However, products formerly termed cheese spread or cheese food would not become processed cheese where they are significantly different in composition or ingredients used. The only certain way this can be established is in the courts and to date this has not been the subject of case law. A personal informal survey on 39 processed cheese products on the UK and Irish markets had just 5 (12.8%) that were designated as processed cheese, 20 (51.3%) named cheese food and 14 (35.9%) called cheese spreads; these products included both branded

Current Legislation on Processed Cheese and Related Products

41

and multiple private labels. Thus, the great majority of products use processed cheese product names, rather than processed cheese, while even those designated as processed cheese contained milk products other than cheese. As regards QUID labelling, 29 (74.4%) of the products surveyed had the cheese content labelled, while the remaining 10 (25.6%) did not.

2.2.4 Legislation in the Republic of Ireland Background to Irish legislation The Irish Parliament (Oireachtas) consists of the President and two Houses of the Oireachtas (Dail Eireann and Seanad Eireann), which are responsible for enacting new legislation in Ireland. A proposal for new legislation is published as a Bill, which becomes an Act and is declared law when it is agreed by both houses of the Oireachtas and signed by the President. Acts frequently give powers to specific ministers of Government (particularly those with responsibility for health and agriculture and food) to make secondary laws known as Statutory Instruments (SIs) in relation to food. The SIs can be written in the form of Regulations or Orders and detail specific rules and give enforcement powers to a particular authority. The similarity to the UK legislative process, on which it was based, will be apparent. Indeed, from the foundation of the state in 1922 until mid-century, reference was often made to Acts of the UK Parliament, such as the Food and Drugs Act 1875, as discussed earlier, which had application in the whole of Ireland at the time of its enactment. For instance such references were contained in the Dairy Produce Act 1924 (The Stationery Office Dublin, 1924) and the Sale of Food and Drugs (Milk) Act 1935 (The Stationery Office Dublin, 1935). Until joining the European Economic Community in 1973, Ireland had quite limited legislation governing the composition of foods. Indeed it may be argued that such legislation was not really necessary, because, as an exporter of the majority of its food products, Irish manufacturers frequently adhered to the compositional standards and requirements of its main export market, the UK and production for the home market reflected the same requirements. Irish legislation on cheese There is not, and has never been, specific Irish legislation on cheese or processed cheese. Processed cheese and related products manufactured and labelled to meet UK legislation have not had problems when sold on the Irish market. This facilitated both producers and consumers. Indeed it might be claimed that the size of the home market would create problems if this were not the case. Nonetheless, in the case of reduced-fat variants of processed cheese products, where UK legislation had specific compositional requirements in its legislation, these can be designated with claims, such as reduced-fat, provided it meets the EU legislation on nutrition and health claims as regards a reduced-fat claim (EU, 2006c). Another possible approach for products intended for the Irish market alone would be to manufacture in accordance with the Codex Alimentarius Standards for processed cheese,

42

Processed Cheese and Analogues

which shall be discussed later. However, since these are generally regarded as out of date and more restrictive than the corresponding UK legislation, they are not used in practice. This conclusion is reinforced by the results from my personal informal survey, as outlined at the end of the previous section (UK legislation on cheese), which indicate that the products on the Irish market generally conform with those on the UK market and not to the Codex Alimentarius standards. The possibility of certain products imported from other Member States of the EU, i.e. using the Cassis de Dijon principle, possibly accounts for any differences that exist. Of course all relevant horizontal European legislation applying to foodstuffs, as discussed in section 2.2.2, applies in Ireland.

2.2.5 Legislation in Germany In discussions on the legislation of other Member States of the EU, the focus shall be on relevant aspects of their cheese legislation only. The provisions of horizontal EU legislation shall not be addressed. The German cheese legislation is detailed in the K¨aseverordnung (the Cheese Order) (Behr’s Verlag, 2008). This addresses four products, which are designated as Erzeugnisse aus K¨ase (products made from cheese): (a) Schmelzk¨ase (Processed Cheese), (b) Schmelzk¨asezuberitungen (Processed Cheese Preparations), (c) K¨asezuberitungen (Cheese Preparations), and (d) K¨asekompositionen (Cheese Compositions). Of these products, Schmelzk¨ase and Schmelzk¨asezuberitungen are those of the greater economic importance. However, §13 addresses the description Kochk¨ase (Cooking Cheese) that may be used in the place of Schmelzk¨ase when only Sauermilchquark or Labquark and with the addition of Schnittk¨ase (sliced cheese) (without rind or skin) at up to 8% in the finished product are used in manufacture; of other dairy products, only cream, butter or clarified butter is used for production. In the present version of the K¨aseverordnung, Schmelzk¨ase (Processed Cheese) is defined as the product in which a minimum of 50 g 100 g−1 on a dry matter basis comes from cheese and together with other milk products manufactured by melting through using heat and emulsifying salts. It is worth mentioning that in the earlier 1995 version of the K¨aseverordnung, the use of other milk products was not included in the definition. Schmelzk¨asezuberitungen (Processed Cheese Preparations) are products made from other milk products, or added foods, from cheese, or from processed cheese, or from mixtures of cheese and processed cheese, by melting under the influence of heat and emulsifying salts. Cheese and processed cheese preparations may not contain more than 15 g 100 g−1 of the total weight of the finished product of added foodstuffs. The use of starch and gelatine is permitted in Schmelzk¨asezuberitungen, but not in Schmelzk¨ase. The compositional requirements for Schmelzk¨ase, Schmelzk¨asezuberitungen and Kochk¨ase are outlined in Table 2.5. Erzeugnisse aus K¨ase (products made from cheese) may only be marketed according to the levels of FDM content as outlined in Table 2.6. In the labelling of these products, either the fat content descriptors as outlined in Table 2.6, or the fat content in dry matter with the designation ‘ . . . % Fett i. Tr’ (FDM g 100 g−1 ) should be used. Schmelzk¨ase (Processed Cheese) or Schmelzk¨asezuberitungen (Processed Cheese Preparations) made from Frischk¨ase (fresh cheese) that has more than 82 g 100 g−1 moisture content the wording ‘Wassergehalt mehr als 82%’ (water content more than 82 g 100 g−1 ) is required on the label. Streichf¨ahigem Schmelzk¨ase (Spreadable Processed Cheese) should have an indication of the product’s spreadability.

Current Legislation on Processed Cheese and Related Products

¨ (processed Table 2.5 Compositional requirements (g 100 g−1 ) for Schmelzkase ¨ ¨ cheese), Schmelzkasezuberitungen (processed cheese preparations) and Kochkase ¨ (cooking cheese) in the German Kaseverordnung (Cheese Order). Minimum dry mattera

Product Schnittf¨ahiger Schmelzk¨ase (slices, FDM ≥ 50)

50

Schnittf¨ahiger Schmelzk¨ase (slices, FDM < 50)

34

Streichf¨ahiger Schmelzk¨ase (spread, FDM ≥ 50)

40

Streichf¨ahiger Schmelzk¨ase (spread, FDM < 50)

30

Schmelzk¨asezuberitungen

20

Kochk¨ase Dopplerahmstufe (double cream)

42

Rahmstufe (cream)

36

Volfettstufe (full-fat)

34

Fettstufe (fat)

32

Dreiviertelfettstufe (three-quarters fat)

29

Halbfettstufe (half-fat)

26

Viertelfettstufe (quarter fat)

24

Magerstufe (lean)

22

Source: After Behr’s Verlag (2008). a The minimum dry matter provisions do not apply to Schmelzk¨ase (Processed Cheese) and Schmelzk¨asezuberitungen (Processed Cheese Preparations) made from Frischk¨ase (fresh cheese). FDM, fat-in-dry matter. Table 2.6 Compositional requirements (g 100 g−1 ) for fat content ¨ a (products from cheese) under the descriptors for Erzeugnisse aus Kase ¨ German Kaseverordnung. Product fat descriptor Dopplerahmstufe

Fat-in-dry matter (FDM) Minimum 60 and maximum 87

Rahmstufe

Minimum 50

Volfettstufe

Minimum 45

Fettstufe

Minimum 40

Dreiviertelfettstufe

Minimum 30

Halbfettstufe

Minimum 20

Viertelstufe

Minimum 10

Magerstufe

<10

Source: After Behr’s Verlag (2008). a Erzeugnisse aus K¨ase (products from cheese) include Schmelzk¨ase (Processed Cheese) and Schmelzk¨asezuberitungen (Processed Cheese Preparations).

43

44

Processed Cheese and Analogues

Erzeugnisse aus K¨ase (products made from cheese) may use the name of a standard variety in the cheese name provided they have the fat content in dry matter that is specified for the relevant standard variety. The identification for processed cheese may also include the name of a standard variety for which a fat content in dry matter of 45 g 100 g−1 or more is specified, if the fat content in dry matter of the processed cheese is not more than 2.5 g 100 g−1 lower than that of the relevant standard variety. In §28 of the K¨aseverordnung special mention is made of the Cassis de Dijon principle, as outlined in section 2.2.2. It states that K¨ase (cheese) and Erzeugnisse aus K¨ase (products made from cheese) produced outside Germany, which do not correspond to the specifications of the German legislation, are permitted to be marketed if they are produced in accordance with the laws of the country of origin and are marketable there. However, they are permitted only if the differences from German requirements are clearly indicated and legible on the packaging of the product; such an indication must be provided in connection with the product name, where the details in the ingredients list would not ensure against the consumer being misled. The name of the product of the country of origin may also be used.

2.2.6 Legislation in the Netherlands The Netherlands is an example of a country where the legislation on processed cheese has changed in recent years. Up to 1998, the Netherlands cheese legislation was contained in the Landbouwkwaliteitswetsbeschikking Kaasproducten 1981, as amended. It included provisions for: • • • •

Smeltkaas (Processed Cheese); Smeltkaasproduct (Processed Cheese Product); Kaaspoeder (Cheese Powder); and Smeltkaaspoeder (Processed Cheese Powder).

Smeltkaas was defined as the cheese product obtained by melting of natural cheese with the aid of heat and emulsifying salts. The use of milk products other than cheese was permitted in up to a maximum of 5 g 100 g−1 lactose in the finished product; however, in the case of named variety processed cheese (e.g. Processed Gouda), the use of milk ingredients was limited to cream, butter and butteroil. For named single variety types at least 75 g 100 g−1 of the cheese had to be of the named variety, and the remainder of the cheese had to be of a similar variety. The product names for such named variety cheese had to be ‘gesmolten . . . kaas’ or ‘smeerkaas’. Compositional requirements for fat and dry matter contents were specified, and these differentiated between gesmolten kaas (i.e. should be sliceable) and smeerkaas (i.e. should be spreadable). Permitted food additives were also listed in the legislation before being superseded by the relevant EU Directives discussed in section 2.2.2. Smeltkaasproduct was defined as the cheese product obtained by melting cheese with the aid of heat and emulsifying agents. At least 51 g 100 g−1 of the product solids had to come from natural cheese. Compositional requirements for fat and dry matter contents were specified, and the product name had to be followed by the percentage of FDM content. The use of other milk products was permitted at levels above 5 g 100 g−1 and casein

Current Legislation on Processed Cheese and Related Products

45

was permitted, the latter within the provisions allowed by EU regulation (EU, 1990b). Permitted food additives were listed, with a larger list than for Smeltkaas, but these were later superseded by the relevant EU Directives discussed in section 2.2.2. As regards functional ingredients, there is no mention of other ingredients, such as starch or gelatine, being permitted in Smeltkaas or Smeltkaasproduct. The use of starch was specifically permitted in Smeltkaaspoeder. The 1981 legislation, as amended, was withdrawn by the Warenwetbesluit Zuivel in 1994 (Lexius, 1994), and partly replaced by the Keuringsreglement COKZ Kaas that was adopted in 1998, and the latest text (to April 2008) may be accessed (Lexius, 1998). These make no mention of Smeltkaas, Smeltkaasproduct or Smeltkaaspoeder. Sources in Nedsmelt, the Dutch Processed Cheese Producers Association, have indicated that, to their understanding, there is now no prohibition on the use of starch or gelatine in processed cheese (Nedsmelt, personal communication). Thus, at this time there is no specific legislation in the Netherlands that defines or regulates processed cheese. It is understood that, as a major exporter of cheese, they will formally recognise the Codex Alimentarius standards concerning cheese, which will be discussed later. However, this may not apply to the Codex standards on processed cheese and processed cheese preparations, as these have not been revised since their original adoption in 1978.

2.2.7 Legislation in France The French legislation on cheese (fromage) and processed cheese (fromage fondu) is contained in the 2007 French Cheese Decree (Anonymous, 2007); this replaced an earlier decree dating from 1988 (Anonymous, 1988). The requirements as regards processed cheese are quite general. The name fromage fondu is reserved for the product obtained by melting and emulsifying cheese or a mixture of cheeses, possibly with other dairy products, with heat at a temperature of 70◦ C for 30 s (or equivalent combination). The use of food additives is governed by EU food additive legislation, as discussed earlier, but for fromage fondu the addition of functional ingredients, such as gelatine and starch, is not permitted. A minimum dry matter content 40 g 100 g−1 of finished product and a minimum FDM of 40 g 100 g−1 is specified. For fromage fondu qualified by the term ‘all´ege’ (light), a minimum dry matter content of 31 g 100 g−1 of finished product is specified. The permitted milk ingredients specified include milk and buttermilk, partly or totally dehydrated, and milk protein preparations; other permitted ingredients specified are salt, herbs and spices, water, flavourings and other foods, which flavour the product, the latter to a maximum of 30 g 100 g−1 of the finished product. The 2007 French Cheese Decree (Anonymous, 2007) introduced a new definition for a product named ‘sp´ecialit´e fromag`ere fondue’ (processed cheese specialty), which is defined as the dairy product, other than fromage fondu as defined above, prepared from cheese and other dairy products. This product is produced by similar production techniques to fromage fondu, but the minimum dry matter content is specified as 25 g 100 g−1 and, where the name is supplemented by the word ‘light’, the minimum dry matter content of 20 g 100 g−1 is specified. The other main difference is that gelatine and starch is permitted to a maximum level of 10 g kg−1 of finished product, either alone or combined or in combination with stabilisers or thickeners allowed as additives.

46

Processed Cheese and Analogues

Table 2.7 Requirements specified for certain fat content (g 100 g−1 ) qualifiers for fromage fondue ´ ` fondue (processed cheese) and specialit e´ fromagere (processed cheese specialities) in the 2007 French Cheese Decree.

Fat content term

Fat content requirement expressed as fat-in-dry matter (FDM)

Triple cr`eme

>75

Double cr`eme

>60 and <75

Cr`eme de

>50 and <60

All´eg´e

>10 and <30

Maigre

<10

Source: Anonymous (2007).

Specific rules apply to the use of fat content terms as outlined in Table 2.7. The fat content (g 100 g−1 ) should be indicated, but this is not necessary when the product has nutritional labelling giving the fat content.

2.2.8 Legislation in Denmark Danish legislation on cheese, including processed cheese, is contained in the Mælkeproduktbekendtgørelsen (Executive Order on Milk Products) (Ministeriet for Familie- og Forbrugeranliggender, 2004); this replaced an earlier 1993 Executive Order. The definition of smelteost (Processed Cheese) is given in paragraph 3 of Kapitel (Chapter) 4 under Osteproduckter (Cheese Products) as ‘The mælkeprodukt (milk product) made of cheese, with or without the addition of other dairy products, milk and water, which is mixed, melted and emulsified using smeltesalte (melting or emulsifying salts) and possibly emulsifiers.’ In the manufacture of processed cheese, cheese must be the largest single ingredient, with the exception of water. The use of smeltesalte (emulsifying salts) or emulgerende (emulsifiers) can only be justified by the technological need for the melting of cheese or curd. Processed cheese can only be called ‘Flødesmelteost’ (processed cream cheese) when the product FDM content is at least 60 g 100 g−1 . A variety name, using any of the 45 such varieties mentioned in Annex 4 of the Order, can be used, provided that at least 75 g 100 g−1 of that variety is included and the cheese variety used meets the specified characteristics of that type. Processed cheese intended for export to developing countries must have the characteristics of being smooth with a glossy surface, of uniform white to yellow colour, and a consistency that is tough and elastic, not short and brittle.

2.2.9 Legislation in Sweden Swedish legislation on ost (cheese), including sm¨altost (processed cheese), is contained in the Livsmedelsverkets f¨oreskrifter om mj¨olk och ost (Food Regulations on milk and cheese)

Current Legislation on Processed Cheese and Related Products

47

LIVSFS 2003:39, which came into force on 1 January 2005, replacing the earlier 1972 legislation (Livsmedelsverket, 2003). These regulations, which are quite brief, apply to products produced in Sweden for sale within the country. In accordance with the Cassis de Dijon principle, these regulations do not apply to products lawfully produced or marketed in a Member State of the EU or in another country covered by the European Economic Area (EEA) agreement (i.e. Norway, Iceland and Liechtenstein); neither do they apply to products not intended for sale within the country. Sm¨altost (processed cheese) is defined as a product obtained by melting and emulsifying of cheese. Milk constituents, dairy products and water may be added. Processed cheese sold with the additional designation light or similar expressions shall have a maximum FDM of 15 g 100 g−1 . Pre-packages of processed cheese must be marked with an indication of the average fat content.

2.2.10 Legislation in Spain Spanish cheese legislation is contained in the Real Decreto (Royal Decree) 1113/2006, which lays down standards for quesos (cheeses) in Anexo (Annex) I and quesos fundidos (processed cheeses) in Anexo (Annex) II (Ministerio de la Presidencia de Espa˜na, 2006). The definition of processed cheese is given as the product obtained by grinding, mixing, melting and emulsification of one or more varieties of cheese, with or without the addition of milk, dairy products and other foodstuffs. The minimum dry matter content for quesos fundidos is 35 g 100 g−1 but if the words para untar (spread) or para extender (spreadable) are used, the minimum dry matter is 30 g 100 g−1 . Based on its fat content, expressed as FDM, processed cheese can be called (a) Extragraso (high fat) if it contains a minimum of 60 g 100 g−1 ; (b) Graso (fat) if it contains at least 45 g 100 g−1 and less than 60 g 100 g−1 ; (c) Semigraso (semi- or half-fat) if it contains at least 25 g 100 g−1 and less than 45 g 100 g−1 ; (d) Semidesnatado (semiskimmed) if it contains at least 10 g 100 g−1 and less than 25 g 100 g−1 ; and (e) Desnatado (skimmed) if it contains less than 10 g 100 g−1 . The name of a variety of cheese may be used [e.g. queso . . . fundido (processed . . . cheese) or . . . fundido (processed . . . )] if this constitutes at least 50 g 100 g−1 of the raw materials. That cheese variety must represent at least 75 g 100 g−1 of the mixture cheese used in making the product, and the remaining 25 g 100 g−1 should be of a similar variety(s). The names of more than one variety may be used on condition that only those varieties were used which constitute at least 50 g 100 g−1 of raw materials and none of them may be lower than 10 g 100 g−1 of raw materials. The addition of other dairy products is limited by the quantity of lactose, which may not exceed 6 g 100 g−1 of the finished product, excluding any added flavouring, spices, condiments and other foods added for flavouring purposes. The quantity of the added ingredients for flavouring purposes may not exceed 30 g 100 g−1 . The replacement of all or part of the milk fat, milk protein or both with non-milk ones in the production of processed cheese is expressly prohibited. Labelling with the minimum content of fat (g 100 g−1 ) is required, except when this information is part of nutrition labelling, or the descriptor names according to fat content outlined earlier (e.g. extragraso, graso) are used.

48

Processed Cheese and Analogues

2.2.11 Legislation in Italy Italian legislation on processed cheese is quite old, and is contained in the Presidential Decree of November 1953 (Ministero dell’Economia e delle Finanze di Italia, 1954). The definition of processed cheese is given as the product obtained by melting one cheese or a mixture of cheeses, with the possible addition of other milk products, including milk powder, casein and whey concentrates, with or without the addition of mineral salts, spices and aromas or when it is authorised by internal legislation, with the possible addition of vitamins; in addition, dissolving or emulsifying salts may be added in an amount not to exceed 3 g 100 g−1 . The addition of lean ham is authorised on condition that the product clearly states processed cheese with ham. The use of an ‘appellation d’origine’ is allowed for a processed cheese on condition that only that cheese is used. The use of name of any other cheese variety, covered by the Stresa Convention, is permitted if a minimum of 75 g 100 g−1 of that cheese is used, and the remainder of the cheese is of a similar quality. Processed cheeses cannot be made in the form and with the characteristic external features of the cheeses protected by the Stresa Convention, but this does not apply to the rectangular form given to processed cheese, which does not exhibit the external features of natural cheese. The cheese varieties covered by the Stresa Convention and mentioned in the Italian Presidential Decree were Gorgonzola, Parmigiano Reggiano, Camembert, Brie, Saint-Paulin, Gruy`ere, Samsoe, Provolone, Fontina, Asiago, Caciocavallo, Emmental, Sbrinz, Maribo, Danbo, Svecia, Herregaards, Gudbrandsdalsost, Noekkelost, Roqueforte, Pecorino Romano, Fiore Sardo, Pinzgauer Bergk¨ase and protocols added Edam, Gouda, Leyde, Frise, Fynbo, Elbo, Tybo, Havarti Danablu, Marmora, Adelost. Since the Convention was concluded, some of these varieties are now protected designations under EU legislation. The minimum FDM content shall be given, but in processed cheeses containing a minimum 45 g 100 g−1 , this may be replaced by the term full cream.

2.2.12 Legislation in the Czech Republic Legislation on processed cheese (taven´em s´yrem) in the Czech Republic is contained in the decree laying down the requirements for milk and milk products, ice creams and edible fats and oils (Ministry of Agriculture of the Czech Republic, 2003). Processed cheese is defined as cheese, which was cooked (melted) using added emulsifying salts. The product is designated processed cheese, or as processed cheese product (tavene´y s´yrov´y v´yrobek) if it contains more than 5 g 100 g−1 lactose. Table 2.8 shows the ingredients other than cheese used for the production of processed cheese and related products. The FDM or fat content, the dry matter content and any flavouring used shall also be labelled. The product may be designated as low-fat if the processed cheese has FDM content up to 30 g 100 g−1 (note that this term will also be governed henceforth by the EU regulation on nutritional and health claims, which shall limit the fat content of a low-fat claim to products with a maximum of 3 g 100 g−1 fat). A processed cheese can be called high-fat with a minimum FDM content of 60 g 100 g−1 .

Depends on the product type and in a quantity sufficient to give the final product a distinctive (characteristic) taste but in quantities not exceeding one-sixth of the total solids content in the finished product, and provided that they supply only the characteristic taste and that they are not sugars

Spices and herbs (seasoning vegetables)

Other wholesome foods (unobjectionable for health)

×, Not allowed; , permitted.

Source: After Ministry of Agriculture of the Czech Republic (2003).

×

×

Bacterial cultures

Sugars (carbohydrates with sweetening properties)

Salt

Enzymes

but not more than 5 g 100 g−1 lactose in the final processed cheese

×

Other milk components

but 51 g 100 g−1 of dry matter must come from cheese

For fat content standardisation only

Butter, butterfat, cream, concentrated butter

Processed cheese product

Variety not named

Named variety

Processed cheese and spreadable processed cheese

General survey of ingredients other than cheese for the production of processed cheese and related products in legislation of the Czech Republic.

Ingredients other than cheese

Table 2.8

Current Legislation on Processed Cheese and Related Products 49

50

Processed Cheese and Analogues

2.2.13 Legislation in Hungary Hungarian legislation for processed cheese (¨omlesztett sajt) and related products (¨omlesztett sajtk´esztm´eny) is outlined in Chapter 7 of the Codex Alimentarius Hungaricus on Dairy Products (Ministry of Agriculture and Rural Development of Hungary, 2008). The 2008 version contained some minor changes from the earlier edition of 2004. The general definition of processed cheese is the milk product made from one or more variety of cheese, milk components and/or other foods (or without them) by grinding, mixing, heat treatment (melting) and emulsification. Based on the composition and ingredients used, processed cheeses fall into three categories: named variety processed cheese, processed cheese, and processed cheese products. All three products may be produced with sliceable or spreadable texture. The former products can be characterised by firmness (i.e. probe penetration) value of maximum 90, while that of the spreadable ones is 91–240 at 18◦ C. Also based on the fat content (expressed as FDM), the processed cheeses may fall into five categories: rich in fat (zs´ırd´us), fatty (zs´ıros), semi-fat (f´elzs´ıros), lean (zs´ırszeg´eny) and skimmed (sov´any). Plain (unflavoured) and flavoured varieties are permitted. As Hungary is now part of the EU, horizontal community legislation on food additives, food hygiene and safety, and food labelling apply to processed cheese and related products. The category of named variety processed cheese is the product, made exclusively from cheese(s), with the following milk fat products permitted for moisture and fat adjustment, namely cream, butter, butterfat, butteroil. The product must contain at least 75 g 100 g−1 of named cheese(s) in the cheese blend in semi-hard and spreadable cheeses. The remaining cheese portion must be cheese of similar type. The minimum dry matter content of the named semi-hard processed cheeses shall not be more than 4 g 100 g−1 lower than the minimum dry matter of the named cheese that it is made from, or the arithmetic average of the dry matter of the cheeses used. Flavourings (except for sugar) may be used to produce flavoured varieties. Safe bacterial cultures may also be added. The category processed cheese is the product, made from cheese(s), and for moisture and fat adjustment butterfat products (cream, butter, butteroil) and other milk products (listed as milk concentrate, milk powder, milk protein concentrate, whey protein concentrate, whey cream, whey butter, whey powder and edible casein) can be used; the amount of the latter group of milk products is limited by the amount of lactose in the end product not exceeding 5 g 100 g−1 . The other optional ingredients permitted for named variety processed cheese may also be used, and the use of flavourings for the manufacture of flavoured processed cheeses and of spices is also permitted. The category processed cheese product (e.g. processed cheese cream) is the product, made from cheese(s), with butterfat products for water and fat adjustment, and other milk products may again be used. The amount of cheeses is specified as a minimum 51 g 100 g−1 in the dry matter of the end-product. The lactose content is not limited, and the use of sugar is permitted for this category. Otherwise the same provisions as for processed cheese outlined above apply. Other requirements for all processed cheese and related products include that the fat content descriptor and texture (sliceable or spreadable) shall be declared in accordance with the specified requirements outlined in Table 2.9. Furthermore, the FDM content (in

Current Legislation on Processed Cheese and Related Products

51

Table 2.9 Compositional requirements (g 100 g−1 ) specified for certain fat content qualifiers for processed cheese and related products in Hungarian legislation.a Minimum dry matter content

Fat descriptor

Fat-in-dry matter (FDM)

Semi-hard processed cheeses and processed cheese products

Spreadable named variety processed cheeseb, Spreadable processed cheeseb, Spreadable processed cheese productb

Rich in fat (Zs´ırd´us)

Minimum 60

52

44

Fatty (Zs´ıros)

Minimum 45 and maximum 60

48

41

Semi-fat (F´elzs´ıros)

Minimum 25 and maximum 45

40

31

Lean (Zs´ırszeg´eny)

Minimum 10 and maximum 25

36

29

Skimmed (Sov´any)

Maximum 10

34

29

Source: After Ministry of Agriculture and Rural Development of Hungary (2008). a These apply to these two product categories only; specific compositional requirements apply to the separate category of named variety processed cheeses. b The same minimum dry matter levels apply to processed cream cheese, which is regarded as an example of this category in Hungary.

multiples of 5 g 100 g−1 , the figure used being that of the multiple immediately below the actual value, e.g. an FDM of 47 g 100 g−1 would be declared as 45 g 100 g−1 ) and/or the actual fat content shall be stated. In the case of processed cheeses and related products made from a blend of more than one cheese variety, the name of the cheese that provides the typical flavour may be used. The processing procedure, if carried out over 100◦ C, shall be declared on the packaging of the product, where the procedure results in a sterile product. Sensory and textural requirements as regards shape, appearance, interior, texture, odour and taste are also specified.

2.2.14 Legislation in the USA Introduction and background At the outset, it should be pointed out that this section addresses US federal legislation only. Up to 1900, there was little federal legislation addressing food standards. The individual States controlled domestically produced and distributed foods; however, this control was markedly inconsistent from state to state. From the early 1880s, the US Department of Agriculture (USDA) Division of Chemistry (renamed the Bureau of Chemistry in 1901), under Harvey Wiley who had been appointed its chief chemist in 1883, began researching the adulteration and misbranding of food (and drugs) on the market. Though without any regulatory powers, the Division published their findings in a ten-part series entitled Foods and Food Adulterants. Based on these results, Wiley started to lobby for a federal law to set standards for food and drugs in interstate trade. In this he was assisted and supported

52

Processed Cheese and Analogues

by state regulators, consumer bodies, medical doctors, pharmacists and certain journalists. Their efforts coincided with a general trend for increased federal regulations in all matters pertinent to safeguarding public health. State laws provided varying degrees of protection against practices such as misrepresenting the ingredients of food products or medicines (Swann, 2008). It should also be added that in the early 1900s, the food industry strongly supported national food legislation in order to obtain national uniformity in regulatory requirements and to build credibility for the food supply (Porter & Earl, 1992). Despite considerable debate on the issue of constitutionality surrounding the rights of the individual States, Congress enacted the Food and Drugs Act 1906 (Pub. L. No. 59–384 34 STAT. 768 (1906)), sometimes called the Wiley Act in honour of its chief advocate (see www.fda.gov/opacom/laws/wileyact.htm). This Act was aimed at ‘preventing the manufacture, sale, or transportation of adulterated or misbranded or poisonous or deleterious foods, drugs, medicines, and liquors, and for regulating traffic therein, and for other purposes’. Congressional Acts identify and grant broad authority to federal agencies to interpret their provisions into the US Code, with the relevant enforcement agencies identified. Under the Pure Food and Drugs Act 1906, responsibility for administration and examination for ‘adulteration’ or ‘misbranding’ were granted to Wiley’s USDA Bureau of Chemistry (USDABOC) (USA National Archives and Records Administration, 1906). Over the years the name of this body has changed to the more familiar Food and Drug Administration (FDA). Despite the vigour with which the USDABOC pursued its new powers, the intentions of the original Act did not really succeed in establishing regulation at the federal level. Firstly, it regulated the adulteration and mislabelling of foods in interstate trade in their original packages, based on their labelling. However, when bulk packages were opened and repacked, responsibility for control reverted to the individual states. Secondly, it did not have the clear mandate to develop standards for foods. Thirdly, in challenges, the courts upheld State regulations that differed from, or were additional to, those imposed at the federal level (Porter & Earl, 1992). Over the next 25 years amendments were made to the original Act, but in the early 1930s, because of ongoing problems, the federal regulators, consumer groups and the media again pressed for a new act with more powers and scope. It took 5 years to be passed, but the Federal Food, Drug, and Cosmetic (FDC) Act of 1938 was finally adopted (see www.fda.gov/opacom/laws/fdcact/fdctoc.htm). This Act is sometimes referred to as Title 21, Chapter 9 of the US Code (21 USC 9). As well as extending the scope of the earlier Act to cover cosmetics and therapeutic devices, this new Act repealed the Food and Drugs Act 1906 and contained the following new provisions of relevance to food: (a) allowed that safe tolerances be set for unavoidable poisonous substances, (b) permitted standards of identity, quality, and fill-of-container to be set, (c) authorised the inspection of manufacturing premises, and (d) added the use of court injunctions to the previous penalties of seizures and penalties. This law, although it has been subject to frequent amendments in the intervening years, remains the basis for federal regulation by the FDA to the present day. The FDA is now responsible for about 80% of the US food supply. The exceptions are as regards the safety, wholesomeness, labelling and packaging of meat, poultry and certain egg products, which are the responsibility of the US Department of Agriculture (Swann, 2008). The Code of Federal Regulations (CFR) is the consolidated source of the general and permanent rules developed by the relevant US government departments and/or their administrative agencies and is also published in the Federal Register (USA National

Current Legislation on Processed Cheese and Related Products

53

Archives and Records Administration, 2009). It is divided into 50 titles that represent broad areas that are subject to federal regulation. For instance Title 7 covers Agriculture, administered by the USDA, and Title 21 deals with Food and Drugs, administered by the FDA. Each volume of the CFR is updated once each year and is issued on a quarterly basis. It is published by the Office of the Federal Register, an agency of the National Archives and Records Administration. Titles 1–16 are updated as of 1 January, Titles 17–27 are updated as of 1 April, Titles 28–41 are updated as of 1 July, and Titles 42–50 are updated as of 1 October. Each title is divided into chapters, and each chapter is further subdivided into parts that cover specific regulatory areas. For example Part 133 covers cheese and related cheese products, including processed cheese products addressed in this chapter. Large parts may be subdivided into subparts. All parts are organised in sections, and most citations in the CFR are provided at the section level. The full format of such citations are as in the following example for Pasteurised Process Cheese 21 CFR Chapter I Part 133 Subpart B §133.169. However, an abbreviated form, with just the part and subpart letter, such as 21 CFR §133.169, is commonly used. Table 2.10 lists the CFR references for the products addressed in this chapter. The latest CFR is also available online at www.access.gpo.gov/nara/cfr/cfr-table-search.html#page1. The online documents are available as ASCII text and PDF files. Processed cheese products in the CFR The US standards for processed cheese and related products are among the most extensive and detailed to be found anywhere in the world. This reflects the importance of the processed cheese market in that country. The CFR contains provisions for 12 processed cheese products (see Table 2.10). The three main products are ‘Pasteurized Process Cheese’ (PPC), ‘Pasteurized Process Cheese Food’ (PPCF) and ‘Pasteurized Process Table 2.10 US standards of identity specified in 21 CFR Part 133 for different processed cheese products. Standard of identity name

CFR Ref.

‘Pasteurized Blended Cheese’

133.167

‘Pasteurized Blended Cheese with fruits, vegetables and meats’

133.168

‘Pasteurized Process Cheese’

133.169

‘Pasteurized Process Cheese with fruits, vegetables and meats’

133.170

‘Pasteurized Process Pimento Cheese’

133.171

‘Pasteurized Process Cheese Food’

133.173

‘Pasteurized Process Cheese Food with fruits, vegetables and meats’

133.174

‘Pasteurized Cheese Spread’

133.175

‘Pasteurized Cheese Spread with fruits, vegetables and meats’

133.176

‘Pasteurized Neufchatel Cheese Spread with other foods’

133.178

‘Pasteurized Process Cheese Spread’

133.179

‘Pasteurized Process Cheese Spread with fruits, vegetables and meats’

133.180

Source: After USA National Archives and Records Administration (2009).

54

Processed Cheese and Analogues

Cheese Spread’ (PPCS). Products outside these standards can and do exist, e.g. pasteurised prepared cheese product or just cheese product. These products cannot use a name prescribed for the standardised product. Rather than address all the 12 standards, and since there are many common provisions, only the three main products will be discussed further. PPC is defined as the food prepared by comminuting and mixing, with the aid of heat, one or more cheeses of the same or two or more varieties, for manufacturing with a permitted emulsifying agent into a homogeneous plastic mass. During its preparation, the PPC is heated to a minimum of 65.6◦ C for a minimum of 30 s, which may be verified by a phosphatase test. The use of certain standardised cheeses is not allowed in manufacture, such as cream, Neufchatel, cottage, low-fat cottage, cottage dry curd, cook cheese, hard grating, semi-soft part-skimmed, part-skimmed spiced, and skimmed milk cheeses. As regards food additives, a list of permitted emulsifying agents, preservatives, acidifying agents and an anti-sticking agent are outlined in Table 2.11. The emulsifying agents may be used singly or as mixtures to a maximum level of 3 g 100 g−1 in the finished product. Acidifying agents may be added, but the quantity is limited by specifying that the pH of the product is not below 5.3. The sorbates may be used alone or in combination at a maximum level of 0.2 g 100 g−1 , and the propionates at a maximum level of 0.3 g 100 g−1 as an anti-mould agent in pre-packed cuts and slices. Lecithin may also be used as an anti-sticking agent in these formats to a maximum level of 0.3 g 100 g−1 . The name of a PPC in conformance with this standard must contain the name(s) of the cheese varieties used, e.g. ‘Pasteurized Processed Gouda Cheese’, or ‘Pasteurized Process Gouda and Monterey Jack Cheese’, or ‘Pasteurized Processed Gouda blended with Monterey Jack Cheese’ or ‘Pasteurized Process Blend of Edam and Monterey Jack Cheese’, with the cheese variety names in order of their inclusion weight. Special labelling provisions apply to Gruy`ere and Swiss cheeses (in conformance with the standards for those cheeses as outlined in 21 CFR §133.149, 21 CFR §133.195 and 21 CFR §133.196) are used, and the weight of Gruy`ere cheese is not less than 25% of the weight of both; in this case the name ‘Pasteurized Gruyere Cheese’ may be used. The name ‘Pasteurized American Cheese’ may be used for the product made from Cheddar, washed curd, Colby, or granular cheese varieties, or any mixture of two or more of these cheeses. When these cheeses are used in mixtures with other varieties of cheese, then the ingredient may be designated American cheese. The other dairy ingredients that may be added are limited to cream, anhydrous milk fat (AMF) and dehydrated (dried) cream, to a maximum of 5 g 100 g−1 of the finished product. The addition of water, salt, harmless artificial colouring, and spices or flavourings (other than those that simulate the flavour of any age or variety of cheese) is also permitted. There are very detailed provisions for the amounts of different types of cheese that may be used, as are the compositional requirements for moisture and fat; these are linked to and closely based on the compositional requirements of the standardised cheese varieties used. PPCF and PPCS standards are similar to those for PPC, except the additional optional dairy ingredients permitted include milk, skimmed milk, buttermilk, cheese whey, and their partly or totally dehydrated (dried) forms, AMF, dehydrated cream, albumin from cheese whey, and skimmed milk cheese for manufacturing. PPCS must be spreadable at 21.1◦ C as it is specified in the legislation. The varieties of cream, Neufchatel, cottage, creamed cottage, cook, skimmed milk cheese for manufacturing, hard grating cheese,

Current Legislation on Processed Cheese and Related Products

55

Table 2.11 Comparison of food additives permitted in certain processed cheese products in USA and Canadian legislation. USA Additive namea Annatto

Canada

PPC

PPCF

PPCS

PC

PCF

PCS

b

b

b

√

√

√

√

√

β-Carotene

b

b

b

√

Chlorophyll

b

b

b

√

√

√

Paprika

b

b

b

√

√

√

√

√

Riboflavin

b

b

b

√

Turmeric

b

b

b

√

√

√

β-Apo-8 -carotenal

b

b

b

√

√

√

Ethyl β-apo-8 -carotenoate

b

b

Sodium carboxymethylcellulose (carboxymethylcellulose, cellulose gum, sodium cellulose glycolatec Dipotassium hydrogen phosphatea Disodium diphosphatea Calcium hydrogen phosphatea Sodium aluminum phosphate Sodium polyphosphatea Sodium (mono-, di-, tri-) phosphates Tetrasodium diphosphatea Tricalcium phosphatea Citrates (sodium, potassium and calcium) Tartrates (sodium and sodium potassium) Sodium gluconate Lecithin Mono- and di-glycerides Sorbic acid and its sodium, potassium and calcium salts Propionic acid and its sodium and calcium salts Nisin Acetic acid Calcium carbonate

b

√

√

√

√

√

√

√

×

×

√

√

√

√

√

√

√

√

√

√

√

√

× √

× √

× √

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

× √

× √

×

√

√

√

× √d

× √d

× √

√d

√d

√

× √

× √

√ √

√

√

√

√

√

√

√

√

√

√

√

√

× √

× √

× √

√

√

√ (continued)

56

Processed Cheese and Analogues

Table 2.11

(Continued) USA

Additive name

a

Citric acid Lactic acid

Canada

PPC

PPCF

PPCS

PC

PCF

PCS

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

Malic acid Phosphoric acid

√

√

Potassium bicarbonate

×

×

Potassium carbonate

×

×

Sodium bicarbonate

×

×

Sodium carbonate

×

×

Tartaric acid

×

×

Carrageenan (including calcium, ammonium, potassium and sodium salts)

×

×

Carob bean gum (locust bean gum)

×

×

Guar gum

×

×

Tragacanth gum

×

×

×

×

Xanthan gum

×

×

Gelatin

×

×

Sodium alginate

×

×

Propylene glycol alginate

×

×

Dioctyl sodium sulfosuccinate

×

×

Oat gum

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

√

×

×

×

×

×

×

×

×

×

×

×

×

×

×

×

×

×

×

×

×

√

√ √ √ √ √ √ √ √ √f

√e

√ √ √ × √ √ × √ ×

Source: adapted from USA National Archives and Records Administration (2009) and Minister of Justice Canada (2009). a Alternative names are used for some additives in the different legislations; in such cases the name of the relevant additive in Codex Alimentarius is used. b The use of harmless artificial colouring is permitted; no specific list of the permitted colours is included in the relevant standards. c Sodium cellulose glycolate is not specifically mentioned in the US legislation but it is an alternative name for sodium carboxymethylcellulose in Codex Alimentarius. d Permitted in slices and cuts in consumer-sized packages only. e The Canadian legislation also mentions Irish Moss Gelose, but this is an alternative name for carrageenan. f Permitted when the gums and alginates are also used. PPC, ‘Pasteurized Process Cheese’; PPCF, ‘Pasteurized Process Cheese Food’; PPCS, ‘Pasteurized Process Cheese Spread’; PC, Processed Cheese; PCF, Processed Cheese Food; PCS, Processed Cheese Spread. √ , Permitted; ×, not permitted.

Current Legislation on Processed Cheese and Related Products

57

semi-soft part-skimmed cheese, and part-skimmed spiced cheese cannot be used alone or in combination with each other as the cheese ingredient(s) for these products. Safe and suitable enzyme-modified cheese may be used in both these product types. There are also detailed requirements for the amounts of certain other cheese that must be used for their manufacture. Additional food additives permitted in PPCS are shown in Table 2.11. The gums, gelatin, carboxymethylcelluloses, carrageenan and alginates, can be used singly or as mixtures at a maximum level of not more than 0.8 g 100 g−1 and, when these are used, dioctyl sodium sulphosuccinate is also permitted at a maximum level of 0.5 g 100 g−1 . Nisin is also permitted at a level of 250 mg kg−1 . The use of certain specified sugars are permitted for sweetening purposes. The moisture content of a PPCF is maximum of 44 g 100 g−1 and the fat content a minimum of 23 g 100 g−1 . The moisture content of PPCS is minimum greater than 44 g 100 g−1 and maximum 60 g 100 g−1 , and the fat content is not less than 20 g 100 g−1 . The use of starch and gelatin is not permitted in any of the above products. It should be mentioned that ‘Pasteurized Cheese Spread’ (see Table 2.10) is the subject of a different standard (21 CFR §133.175); it differs from PPC in one respect only: it does not permit the use of the emulsifying agents listed in 21 CFR §133.179.

2.2.15 Legislation in Canada As is the case in the USA, in Canada, agriculture and food regulation is administered at both federal and individual provincial levels, derived from the Constitution Act 1867 and jurisprudence/case law, and based on the division of powers between the provinces and federal government (Sections 91 and 92 of the Constitution Act 1867). Together with immigration, agriculture was the only other domain defined as having both provincial and federal competency in 1867. The federal government has competency/powers over trade and commerce, but the Provinces have jurisdiction to matters over ‘property and civil rights’. The Provinces have competency and jurisdiction in matters related to health, but federal government plays direct role in licensing of food and drugs. National agricultural marketing boards that practise supply management are matters of both federal and provincial jurisdiction, the two orders effectively delegating their respective powers (over inter-provincial and intra-provincial trade and commerce) to the marketing boards. In this section, only the federal legislation is considered. Canadian food legislation that prescribes the standards of composition, quality and other properties of certain foods are contained in the Canadian Food and Drug Regulations; a consolidated up-to-date version is accessible online (Minister of Justice Canada, 2009). In conformity with the country’s bilingual policy, Canadian legislation is produced in both French and English. The provisions related to food are contained in Part B of these regulations, and dairy products are addressed in Division 8, with detailed provisions for cheeses to be found from B08.030 to B08.054. The standards for processed cheese and related products are listed in Table 2.12. These comprise Processed (Named Variety) Cheese, Processed Cheese Food and Processed Cheese Spread, and those products with named added ingredients which flavour or characterise the products, such as spices, condiments, fruits, vegetables, pickles, relishes, nuts, prepared/preserved meats and fish. The three main types

58

Processed Cheese and Analogues

Table 2.12 Legislation for processed cheese and related products in the Canadian Food and Drug Regulations. Name

F&DR Ref.

Processed (naming the variety) Cheese

B08.040

Processed (naming the variety) Cheese with (naming the added ingredients)

B08.041

Processed Cheese Food

B08.041.1

Processed Cheese Food with (naming the added ingredients)

B08.041.2

Processed Cheese Spread

B08.041.3

Processed Cheese Spread with (naming the added ingredients)

B08.041.4

Source: After Minister of Justice Canada (2009).

are similar to the corresponding products in the USA, but the requirements are not necessarily the same; for example, Table 2.11 compares the food additive provisions of USA and Canadian legislation in some of the main equivalent processed cheese products. Some of the compositional requirements as regards permitted milk-based ingredients, minimum cheese content, maximum moisture and minimum fat are shown in Table 2.13. The compositional requirements for moisture and fat in Processed (Named Variety) Cheese are a bit more complex, based on whether they are made from one or more than one cheese Table 2.13 Some compositional requirements for processed cheese products as specified in the Canadian Food and Drug Regulations.

Product

Added milk and milk products

Minimum cheese content (g 100 g−1 )

Moisture content (g 100 g−1 )

Milk fat content (g 100 g−1 )

Processed (naming the variety) Cheese

Added milk fat onlya

NSb

Based on named cheese(s) moisture

Based on named cheese(s) fat content

Processed (naming the variety) Cheese with (naming the added ingredients)

Added milk fat only

NSb

Based on named cheese(s) moisture

Based on named cheese(s) fat content

Processed Cheese Food

Yes

51

Maximum 46

Minimum 23

Processed Cheese Yes Food with (naming the added ingredients)

NS

Maximum 46

Minimum 22

Processed Cheese Spread

Yes

51

Maximum 60

Minimum 20

Processed Cheese Yes Spread with (naming the added ingredients)

NS

Maximum 60

Minimum 20

Source: adapted from Minister of Justice Canada (2009). a By way of exception, in the case of Processed Skim Milk Cheese, skimmed milk powder, buttermilk powder and whey powder may also be added. b NS, not specified, but controlled indirectly by the constraints on the use of other milk ingredients and compositional requirements with regard to milk fat.

Current Legislation on Processed Cheese and Related Products

59

variety and whether the maximum permitted moisture content of the cheese, or the average maximum permitted moisture content of the mixture of cheeses, is less than 40 g 100 g−1 or greater than or equal to 40 g 100 g−1 . In these cases, tolerances are specified by which moisture content of the end-product may exceed the permitted moisture content for the cheese (or mixture of cheeses). Similarly, tolerances are specified for the amount by which the fat content of the end-product may be under the minimum permitted fat content for the cheese (or mixture of cheeses). In the case of Processed Skim Milk Cheese, the maximum moisture is 55 g 100 g−1 and the maximum fat content is 7 g 100 g−1 .

2.2.16 Legislation in Australia and New Zealand Historically, Australia and New Zealand had separate legislation, and indeed that remains partly the situation to this day. However, in 1995, Australia and New Zealand signed a Joint Food Standards Setting Treaty, which committed both countries to the development and implementation of a single set of food standards. The Food Standards Treaty provides for a bi-national agency, now called Food Standards Australia New Zealand (FSANZ), to undertake the relevant food standards development for both Australia and New Zealand. FSANZ has produced a Food Standards Code, which is regularly updated and contains the joint standards developed to date (FSANZ, 2009). The present Food Standards Code addresses cheese, including processed cheese briefly, in Standard 2.5.4. This Standard defines processed cheese as a product manufactured from cheese and products obtained from milk, which is heated and melted, with or without added emulsifying salts, to form a homogeneous mass. No other compositional requirements are given in the present standard. Section 1.3.1 of the Food Code addresses food additives, with Schedules 1–4 specifying the additives that may be added to specified foods. Schedule 1 lists food additives and levels permitted by food type; category 1.6 lists cheese and cheese products with annatto, sorbates, nisin, natamycin, nitrates, phosphoric acid and two silicates. A note also states that additives in Schedules 2, 3 and 4 are also permitted. Schedule 2 lists, alphabetically and numerically by International Numbering System (INS) number, 174 miscellaneous additives and flavouring (excluding quinine and caffeine) permitted at GMP level in the foods, including cheese and cheese products, as mentioned in Schedule 1. Schedule 3 lists, alphabetically and numerically by INS number, 27 colours permitted at GMP in the foods, as mentioned in Schedule 1, the foods including cheese and cheese products. Schedule 4 lists, alphabetically and numerically by INS number, 12 specific colours permitted at a maximum concentration of 290 mg kg−1 in the foods, other than beverages, as mentioned in Schedule 1, the foods including cheese and cheese products. Schedule 5 lists 21 functional classes and their definitions for food additives (see Table 2.14).

2.2.17 Legislation in Japan Cheese legislation in Japan is governed by Ministerial Ordinance on Milk and Milk Products Concerning Compositional Standard, and Fair Competition Codes on Cheese. This defines three product varieties: (a) Processed cheese (1st Class), (b) Cheese foods (2nd Class), and (c) Process cheese like products categorised into Foods Using Milk and

60

Processed Cheese and Analogues

Table 2.14 The 21 additive functional classes listed in the Food Standards Australia New Zealand (FSANZ) Food Code Section 1.3.1, Schedule 5. Acidity regulatora

Foaming agent

Anti-caking agent

Gelling agent

Antioxidant

Glazing agent

Bulking agent

Humectant

Colour

Intense sweetener

Colour fixative

Preservative

Emulsifierb

Propellent

Firming agent

Raising agent

Flavour enhancer

Sequestrant

Flavouring

Stabiliser

Source: adapted from FSANZ (2009). a Acid is a subcategory. b Emulsifying salt is a subcategory.

Milk Products as Principal Raw Materials (FUMMP) (3rd Class). The requirements are very general. Processed cheese is defined as the product which is made from natural cheese by grinding, heating to melt, and emulsifying; casein, skimmed milk powder (SMP), lactose, etc. may be added which, when combined with non-dairy ingredients (for providing flavour, texture or specific nutrition), is equal to or less than one-sixth on a dry basis. The lactose level should be equal to or less than 5 g 100 g−1 . Cheese food is made from natural cheese or processed cheese by grinding, heating to melt, and emulsifying; in this case, the cheese content is clearly defined as equal to or greater than 51 g 100 g−1 . While not clear from the legislation, it is known that starch is used in processed cheese in Japan to provide a stringy texture (Japanese Committee of the International Dairy Federation, personal communication).

2.2.18 Legislation in Mercosur/Mercosul Mercosur (the name is derived from Mercado Com´un del Sur in Spanish) or Mercosul (from Mercado Comum do Sul in Portuguese) translates as the Southern Common Market or the Common Market of the South. It was founded in 1991 under the Treaty of Asunci´on by Argentina, Brazil, Paraguay and Uruguay, who still remain as the only full members. The original treaty was later amended and updated by the 1994 Treaty of Ouro Preto (Brazil). The role and purpose is to promote free trade and the easy movement of goods, people and currency. Current associate members are Bolivia, Chile, Colombia, Ecuador and Peru (except for Chile, these also form the Comunidad Andina, the Andean Community

Current Legislation on Processed Cheese and Related Products

61

of Nations, founded in 1969). Venezuela has applied for full membership, but has not yet been ratified by Brazil and Paraguay, while Mexico has Observer status. The founding treaty was weakened by the collapse of the Argentinean economy in 2001 and continues to be dogged by internal conflicts over trade policy, between, for example, Brazil and Argentina, Argentina and Uruguay, Paraguay and Brazil. Many obstacles have yet to be addressed before the development of a common currency. Nonetheless, in 2004, Mercosur/Mercosul issued a joint letter of intention for future negotiations towards integrating all of South American countries. The prospect of increased political integration within the organisation, as per the EU, though advocated by some, is still uncertain. To date it has published some common food standards, one of which is the regulation of identity and quality for various types of processed cheese products including UHT processed cheese, namely MERCOSUL/GMC/RES. No. 134/96 (Mercosur/Mercosul, 2006). This is available in Portuguese only. The definition of processed cheese is given as the product obtained by grinding, mixing, melting and emulsification by means of heat and emulsifying agents one or more varieties of cheese, with or without addition of other milk products and/or source of milk solids and/or spices, condiments, food, or other substances in which the cheese is the predominant raw material milk ingredient. UHT processed cheese is the melted cheese that has received a subsequent heat treatment to between 135 and 145◦ C for 5–10 s or any other equivalent time/temperature combination. The maximum moisture content is set at 70 g 100 g−1 and the minimum fat content at minimum 35 g 100 g−1 for both processed cheese and UHT processed cheese. The ingredients specified are cheese and permitted emulsifying salts; optional ingredients that may be used are cream, butter, AMF or butteroil, milk, water, processed cheese, milk powder, caseinates, cheese powder, other milk solids, sodium chloride, condiments, spices, other food substances, nutritive sweeteners, starches, modified starches, air, nitrogen, carbon dioxide and inert gases. The optional non-milk ingredients other than water, alone or combined, should not exceed 30 g 100 g−1 of the final product. Starches or modified starches may not exceed 3 g 100 g−1 of the final product. The food additives, with maximum levels permitted, are given for the functional categories of colours, preservatives, acidity regulators, stabilisers, emulsifying salts, flavours and anti-caking agents (for shredded and sliced processed cheese only). The legislation includes, among the hygiene provisions, that the use of cheese not fit for human consumption is prohibited; only cheese that is not suitable for sale to the public due to problems with shape or other such physical defects is allowed, and then only where the quality of the final product is not affected. A minimum processing temperature of 80◦ C for a minimum of 15 s, or other equivalent temperature/time combinations, is specified and, other than the UHT product, the finished product should be kept at a temperature below 10◦ C. Labelling requirements, such as regards product names, are also addressed. Designations in Portuguese, such as Queijo Processado (processed cheese) or Queijo Fundido (processed cheese) or Queijo Processado (pasteurised processed cheese), are allowed; for the UHT products, Queijo Processado UAT or Queijo Fundido UAT shall be used. When spices and/or condiments and/or other foods are added to the name of the product

62

Processed Cheese and Analogues

as outlined above, the name will be supplemented with the word ‘con’ followed by the name of the relevant added ingredient(s), e.g. con cebolla (with onion). When flavourings are used, the supplemental word ‘sabor’ shall be used followed by the name of the flavour, except where the use of flavours is to restore the natural flavours of the cheese that may have been lost during preparation. Furthermore, where a particular variety of cheese is used at a minimum of 75 g 100 g−1 in the mixture of cheeses used as raw material, the products may be designated Queijos . . . Processado, Queijo . . . Fundido (both meaning processed . . . cheese), or Queijo . . . Processado Pasteurizado (pasteurised processed . . . cheese) or Queijo . . . Processado UAT) or Queijo . . . Fundido UAT (processed . . . cheese UHT) with the name of the predominant variety filling the blank spaces. The terms ‘ralado’ (shredded), ‘fatiado’ (slices, square), ‘em rodelas’ (slices, round), ‘em fatias’ (slices), ‘unt´avel para untar’ (spreadable) or other such may be used where appropriate. It is assumed that the equivalent Spanish terms may also be used.

2.2.19 Legislation in Chile Chile is an Associate Member of Mercosur/Mercosul, and the influence of the standard of that organisation may be seen in the country’s legislation on quesos procesados (processed cheeses). The Chilean organisation in charge of the issue of regulations is the National Institute of Standards (Instituto Nacional de Normalizaci´on, INN), which is member of the International Organisation for Standardisation (ISO) and the Comisi´on Panamericana de Normas T´ecnicas (COPANT) (Panamerican Committee for Technical Standards). Norma Chilena 2092 of 1999 describes two types of processed cheese manufacture: (a) process cheese, and (b) UHT process cheese according to the temperature of heat treatment used (Instituto Nacional de Normalizaci´on Chile, 1999). This standard includes the following: • • • •

General requirements for both types (i.e. flavour, odour and colour). Ingredients required, such as cheese from one or several varieties and emulsifying salts approved by the Chilean Food Sanitary Regulation. Optional ingredients, e.g. dairy cream, butter, butteroil, water, caseinates and other milk solids, salt (NaCl), spices, nitrogen and other inert gases. The following additives can be used: propionic acid (or its sodium, potassium or calcium salts) as a preservative; sodium bicarbonate and calcium carbonate as acidity regulators; and sodium, potassium or calcium citrates or lactates as emulsifier/stabiliser; all of them with maximum levels according to Chilean Food Sanitary Regulation.

The standard also has regulations about processing, hygienic requirements, packing regulations, sampling and analytical methods to control the end-product. In this standard there are no differences between block and spreadable processed cheese because in Chile processed cheese is known by the consumers as cream cheese, which is only spreadable. As regards the compositional specifications, only the FDM is reported and the figures quoted range between 35 and 79 g 100 g−1 .

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The Chilean Food Sanitary Regulations 1976, as amended (Ministero de Salud Republica de Chile, 2008), establish the following standards for quesos procesados (processed cheese). Total aerobic mesophilic count Enterobacteriaceae Staphylococcus aureus

n = 5, c = 2, m = 103 , M = 104 n = 5, c = 2, m = 10, M = 102 n = 5, c = 1, m = 10, M = 102

2.2.20 Legislation in some Middle Eastern countries Turkey Only spread-type processed cheese is marketed in Turkey. It may be either plain or flavoured/garnished; no blocks or slices are available commercially. An updated processed cheese (eritme peyniri) standard was published in 2008 (Turkish Standards Institution, 2008). This replaced an earlier standard dating from 1989. There are two classes of processed cheese, Class 1 and Class 2, and four fat classes specified as follows: (a) full-fat (FDM 45 g 100 g−1 ), (b) regular-fat (FDM 30 g 100 g−1 ), (c) semi-fat (FDM 20 g 100 g−1 ) and (d) low-fat (FDM 10 g 100 g−1 ). A maximum moisture content of 60 g 100 g−1 is given in the standard, with a minimum pH of 5.5 and a maximum salt (sodium chloride) level of 7 g 100 g−1 . Microbiological criteria are set at maximum coliform count of 100 colony-forming units (cfu) in 1 g, with the yeast and mould count also less than 100 per g. Escherichia coli and Staphylococcus aureus should be absent. There are also chemical composition and microbiological quality requirements laid down in the legislation for raw milk used for the manufacture of processed cheese (Ministry of Agriculture of Turkey, 2000). The requirements are as follows: • • • • • •

Total viable bacteria count at 30◦ C: <105 cfu mL−1 . Salmonella: nil in 25 mL. Staphylococcus aureus: maximum 100 cfu g−1 . Protein: minimum 2.8 g 100 g−1 Lactic acid: 0.135–0.20 g 100 g−1 . Density: minimum 1.028.

Permitted food additives for processed cheese are given in two separate pieces of legislation: the colours (carotenes, paprika extract, annatto/bixin/norbixin, curcumin and tartrazine), the preservatives (the sorbates and the propionates for surface application on cheese analogues and nisin), which are permitted in all processed cheeses, with additional colours (curcumin/turmeric, tartrazine, quinoline yellow, sunset yellow FCF, orange yellow S, cochineal/carminic acid/carmines, carmosin, ponceau 4R/cochineal red A, allura red AC, patent blue V, indigotine/indigo carmine, brilliant blue FCF, green S, brilliant black BN/black PN, brown HT, lycopene, β-apo−8 -carotenol (C 30), β-apo−8 -carotenic acid

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Processed Cheese and Analogues

ethyl ester (C30) and lutein) permitted in flavoured processed cheese (Ministry of Agriculture of Turkey, 2007). The monophosphates, diphosphates, triphosphates, polyphosphates and magnesium trisilicate are also permitted (Ministry of Agriculture of Turkey, 2008). Maximum levels for these additives are also specified in the legislation. Lebanon The Lebanese standards for processed cheese are contained in Standard No. 463/2001 (Lebanese Standards Institution, 2001). It should be mentioned that these are legally binding standards, not voluntary standards. Processed cheese (cooked cheese) is defined as the nutritional product made from shredded natural cheeses, melted, heated (to a minimum of 70◦ C for 30 s or more) and the use of permitted additives. The product should be smooth in texture, free from gas holes and uniform in colour (the colour should be yellowish). The chemical composition of Lebanese processed cheese products is shown in Table 2.15. The specified hygiene requirements include that all the steps of the cheese production shall follow the specific parts of the international conditions of the Codex Alimentarius Commission as outlined in the Recommended International Code of Practice General Principles of Food Hygiene (CAC/RCP 1, 1969 Rev. 2, 1985) pending publication of the Lebanese standard. In particular, the product shall be (a) free of total coliforms (g−1 ), (b) free of faecal coliforms (g−1 ), (c) free of salmonella (25 g−1 ), and (d) free of Listeria monocytogenese (g−1 ). The product may contain the following optional ingredients: • • • • •

• •

Cream, butter and butteroil and others milk products. Salt (sodium chloride). Vinegar. Spices and other vegetable seasonings in sufficient quantities to characterise the product. For the purpose of flavouring the product, sugar and other foods properly cooked or otherwise prepared may be added in sufficient quantity to characterise the product; these ingredients shall not exceed 30 g 100 g−1 of the final product. Starter cultures of harmless bacteria and enzymes. The permitted food additives are shown in Table 2.16; it is forbidden to add fat and proteins that are not derived from milk.

Table 2.15

The gross chemical composition (g 100 g−1 ) of Lebanese processed cheese products. Specifications

Product

Fat-in-dry matter (FDM)

Moisture content

Processed cheese (a)

40 (minimum)

40 (minimum)

Processed cheese (b)

30–40

33 (minimum)

Processed cheese (low-fat)

20–30

31 (minimum)

Processed cheese (very low-fat)

20 (maximum)

31 (minimum)

Source: After Lebanese Standards Institution (2001).

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Table 2.16 Permitted additives in Lebanese processed cheese products. Functional category

Specific additive

Maximum amount added

Emulsifying salts

Sodium, potassium and calcium salts of mono-, di-, tri- and polyphosphoric acids

20 g kg−1

Sodium, potassium and calcium salts of citric acids

Based on GMP

Citric acid and/or phosphoric acid with sodium hydrogen carbonate and/or calcium carbonate

Based on GMP

Lecithin

Based on GMP

Acidifying/pH controlling agents

Citric, phosphoric, acetic and/or lactic acid acids, and sodium hydrogen carbonate and/or calcium carbonate

Based on GMP

Colouring matter

Annatto

15 mg kg−1

β-Carotene, chlorophyll (including copper chlorophyll), riboflavin, oleoresin of paprika and/or curcumin

Based on GMP

Sorbic acid and its sodium and potassium salts or propionic acid and its sodium and calcium salts

3 g kg−1

Nisin

12.5 mg kg−1

Taste enhancers

Sodium glutamate

Based on GMP

Stabilisers

Gums (Arabic, locust, karaya, guar, agar-agar, xanthan, Based on GMP and/or sodium carboxymethylcellulose), alginic acids of sodium, potassium, calcium ammonium salts and/or propylene glycol esters, pectin and/or gelatin

Preservatives

Source: After Lebanese Standards Institution (2001). GMP, good manufacturing practice.

Egypt Egypt has two standards for processed cheese products as specified by the Egyptian Standard Organisation, one for processed cheese and processed cheese spread and the other for processed cheese and processed cheese spread made with vegetable fat (Abd El-Salam et al ., 2005; Egyptian Standard Organization, 2002a,b). Strictly the latter is a processed cheese analogue, and not strictly within the scope of this chapter. Again, these are legally binding standards, not voluntary standards. Processed cheese is defined as the product made by heating a blend of shredded natural cheeses (different varieties and degrees of maturity) and an emulsifying agent, with slow constant stirring, until a homogeneous emulsified mass is obtained. This product is packaged while still hot and in a liquid state. Other dairy and non-dairy ingredients may be added. The end-products are used for both direct consumption and for food service purposes (Abd El-Salam et al., 2005; Egyptian Standard Organization, 2002a,b). The compositional specifications for processed cheeses and spreads are outlined in Table 2.17, which compares the Egyptian, Syrian and Iranian requirements. Fat descriptors, based on FDM content, are also specified; these apply to the Egyptian product standards only. The similarity with the compositional requirements in the Codex standards for processed cheese and processed cheese preparations, as shown in Table 2.18, may also be noted.

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Processed Cheese and Analogues

Table 2.17 Comparison of chemical composition standards (g 100 g−1 ) for processed cheeses in some Middle Eastern countries. Egypt

Syria

Iran

Maximum moisture DMb

Minimum DM

Minimum DM

Fat descriptora

FDM

PC

PCS

Minumum FDM

PC

PCS

Minumum DM

PC

PCS

High-fat

>65

47 (53)

55 (45)

65

53

45

65

53

45

Full-fat

60–65

48 (52)

56 (44)

60

52

44

60

52

44

55–60

49 (51)

56 (44)

55

51

44

55

51

44

50–55

50 (50)

57 (43)

50

50

43

50

50

43

45–50

52 (48)

59 (41)

45

48

41

45

48

41

Three quarters-fat

40–45 35–40

54 (46) 56 (44)

61 (39) 64 (36)

40 35

46 44

39 36

40 35

46 44

39 36

Half-fat

30–35

58 (42)

67 (33)

30

42

33

30

42

33

25–30

60 (40)

69 (31)

25

40

31

25

40

31

Low-fat

20–25

62 (38)

71 (29)

20

38

29

20

38

29

15–20

63 (37)

71 (29)

15

37

29

15

37

29

10–15

64 (36)

71 (29)

NA

NA

NA

10

36

29

<10

66 (34)

71 (29)

NA

NA

NA

<10

34

29

Fat-free

Data compiled from Egyptian Standard Organization (2002b), Abd El-Salam et al . (2005) and Syrian Arab Standards and Metrology Organisation (2001); Iranian Standard (2003). a The fat descriptors apply to Egyptian standards only. b Maximum moisture levels only are given in the Egyptian standards; the dry matter content (i.e. in parentheses) are included in the table to facilitate comparison. PC, processed cheese; PCS, processed cheese spread; NA, not applicable; FDM, fat-in-dry matter; DM, dry matterb.

Syria The Syrian standard for processed cheeses is contained in Decision No. 232 of 1986 (Syrian Arab Standards and Metrology Organization, 1986). The general conditions include requirements that the product has a defined colour and flavour, without any off-flavours. Morphological textural defects, such as fissures, splits and holes, should be absent as should yeasts and moulds. Animal and vegetable fats and oils should not be used. Compositional requirements are outlined in Table 2.17, which compares the Syrian Egyptian and Iranian requirements. The similarity with the compositional requirements in the Codex standards for processed cheese and processed cheese preparations, as shown in Table 2.18, may also be noted, but FDM levels below 15 g 100 g−1 are not included. Iran In Iran, the standards for processed cheese are contained in Iranian Standard (2003). Three types of processed cheese products are recognised: processed cheese blocks, processed cheese food, and processed cheese spread. The main ingredients are different varieties of

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67

Table 2.18 Compositional requirements (g 100 g−1 ) for minimum dry matter (DM) based on fat-in-dry matter (FDM) content in the Codex standards for different processed cheese products. Processed cheese products (minimum DM) NVSPCa , SPC and PCP a

FDM

NVPC and PC

(PCF and PCS)

65

53

45

60

52

44

55

51

44

50

50

43

45

48

41

40

46

39

35

44

36

30

42

33

25

40

31

20

38

29

15

37

29

10

36

29

<10

34

29

Data compiled from FAO/WHO (2007). The values in the table apply to those named varieties for which no international standards exist. For a named cheese variety subject to an international (Codex) standard, the minimum FDM of the end-product shall not be less than that prescribed for that variety. For named variety processed cheese the minimum DM for such a named variety processed cheeses shall not be more than 4 g 100 g−1 lower than that prescribed for that variety. Furthermore, national legislation, where such exists, takes precedence over the figures in the above table for cheese varieties where no international standards exist. NVPC, named variety processed cheese; NVSPC, named variety spreadable processed cheese; PC, processed cheese; SPC, spreadable processed cheese; PCP, processed cheese preparations; PCF, processed cheese food; PCS, processed cheese spread. a

cheese, with phosphate and citrate emulsifying salts. The permitted level of the emulsifying salts is 4 g 100 g−1 and the maximum level of phosphate (as P) is 0.9 g 100 g−1 . Optional ingredients include cream, butter, ghee, salt (maximum level 1 g 100 g−1 ), vinegar, permitted spices and permitted flavouring agents, sugar, glucose or other natural sweeteners, microbial cultures, enzymes, whey powder and milk powder. The use of citric, phosphoric, acetic and lactic acids are permitted as acidity regulators, as are the colours annatto and β-carotene and sorbates at maximum level of 1000 mg kg−1 . The pH is specified as ranging from 5.0 to 5.6 and a minimum protein content of 12 g 100 g−1 is laid down. The compositional specifications for the FDM and corresponding minimum dry matter content

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Processed Cheese and Analogues

in processed cheeses and processed cheese spreads are outlined in Table 2.17, which compares the Iranian requirements with those of Egypt and Syria. Again, the similarity with the compositional requirements in the Codex standards for processed cheese and processed cheese preparations, as shown in Table 2.18, may be noted.

2.2.21 Codex Alimentarius standards Background and introduction In 1954, the IDF drew attention to the need for international agreement on terminology for milk and milk products to protect consumers and producers from misleading descriptions. In 1957, this suggestion was discussed at the 9th Session of the Conference of the Food and Agricultural Organisation of the United Nations (FAO), and a resolution was agreed that its Director-General, in consultation with IDF and other interested organisations, should invite all member governments to nominate experts to a committee to develop standards for certain milk and milk products. The resultant body became known as the Joint FAO/WHO Committee of Government Experts on the Code of Principles Concerning Milk and Milk Products (CGECPMMP), and its first meeting was held in Rome in September 1958 (FAO/WHO, 2008). This body remained in place until 1994 when it was renamed and re-established as the Codex Committee on Milk and Milk Products (CCMMP). The Codex Alimentarius Commission itself was established in 1962, to implement the joint FAO/WHO foods standards program. Its present structure is outlined in Fig. 2.1. Through the CGECPMMP and its successor the CCMMP, the Codex Alimentarius Commission developed, inter alia, international standards for cheese in general and 35 individual cheese varieties and three to encompass processed cheese and processed cheese preparations between 1963 and 1978. Reports of the CGECPMMP meetings are not readily accessible electronically, but progress can be followed by tracking the CAC reports over the years. The report of the third Session of the CAC indicates that the CGECPMMP was already considering a revised draft standard for processed cheese products at its eighth Session in May 1965 (FAO/WHO, 1965). The next mention of the situation is in the report of the seventh Session of CAC in 1970 when the Commission reviewed several aspects of the work of the CGECPMMP, including the problems connected with the draft standards for processed cheese products (FAO/WHO, 1970). In the Report of its tenth Session in 1974, the CAC was asked to resolve a disagreement between the CGECPMMP and the Codex Committee on Food Labelling (CCFL) on the labelling of ingredients in the three draft recommended standards for processed cheese and processed cheese preparations that had advanced to Step 8. The full discussion was outlined in the report of the CAC (FAO/WHO, 1974). The great majority of delegations present concurred with the view of the CCFL and the Commission decided that a complete list of ingredients should be required to be declared on the labels for the products concerned. It took a further 5 years until, finally, in 1979, in a report to the Codex Alimentarius Commission, the Chair of the CGECPMMP reported that work had been completed on the three standards that related to processed cheese; with the final work completed, it had

Current Legislation on Processed Cheese and Related Products

69

Codex Alimentarius Commission

Codex Secretariat

General Subject Committees

Food Additives

Commodity Committees

Codex Executive Committee

Codex Task Forces

Milk and Milk Products

Regional Committees

Europe Antimicrobial Resistance

Contaminants in Foods

Fats and Oils

North America and South West Pacific

Food Labelling

Fish and Fishery Products

Asia

Food Hygiene

Cocoa Products and Chocolate Adjourned

Africa

General Principles Meat Hygiene Adjourned Nutrition and Foods for Special Dietary Uses

Near East Fresh Fruit and Vegetables

Pesticide Residues Processed Fruits and Vegetables Residues of Veterinary Drugs Import/Export Inspection and Certification Systems Methods of Sampling and Analysis

Cereals, Pulses and Legumes Adjourned

Sugars Adjourned Vegetable Proteins Adjourned

Natural Mineral Waters Adjourned

Fig. 2.1

Latin America And Caribbean

Structure of the Codex Alimentarius Commission.

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Processed Cheese and Analogues

agreed that they should be submitted to governments for acceptance (FAO/WHO, 1979). The three standards for Processed Cheese Products adopted were as follows: • • •

CODEX-STAN A-8(a) – 1978 Named variety of process(ed) cheese and spreadable process(ed) cheese (now renumbered as CODEX-STAN 285 – 1978). CODEX-STAN A-8(b) – 1978 Process(ed) cheese and spreadable process(ed) cheese (now renumbered as CODEX-STAN 286 – 1978). CODEX-STAN A-8(c) – 1978 Cheese preparations as process(ed) cheese food and process(ed) cheese spread (now renumbered as CODEX-STAN 287 – 1978).

Note: FAO/WHO (1978a, 1978b, 1978c) standards have now been revoked, but may still be found in reference FAO/WHO (1979). These standards represented the consensus of opinion among Codex members at that time on the description, permitted ingredients, compositional requirements, permitted food additives and labelling of processed cheese products. Codex standards were originally intended to be adopted by the member countries of the Codex Alimentarius Commission; however, this could only be encouraged and they were not binding in law. The formal recognition of Codex standards as reference points for facilitating international trade and resolving disputes in the World Trade Organisation (WTO) has increased their significance, role and profile.

The Codex general standard for named variety of processed cheese (CODEX-STAN 285 – 1978) In this standard addressing products, such as Processed Cheddar Cheese, Processed Emmental Cheese, the definition of the product is given as the product made by grinding, mixing, melting and emulsifying with the aid of heat and emulsifying agents one or more varieties of cheese, with or without the addition of foodstuffs. The addition of cream, butter and butteroil, in quantities necessary to achieve specified compositional requirements, were the only other milk products permitted. Salt, vinegar, spices and other vegetable seasonings could be added to characterise the product. Foods other than sugars could be added in sufficient quantity to characterise the product provided these additions, calculated on the basis of dry matter, do not exceed one-sixth of the weight of the total solids of the final product. Cultures of harmless bacteria and enzymes were also permitted. The food additives that were permitted were emulsifiers (strictly speaking the citrate and phosphate emulsifying salts, plus sodium carbonate and sodium hydrogen carbonate), six acidity regulators, six colours, and as preservatives the sorbates, propionates and nisin. A heat treatment of 70◦ C for 30 s or any equivalent time/temperature was specified. When a cheese variety name was used, a minimum 75 g 100 g−1 of that variety had to be used, and the remaining cheese should be of a similar type; where more than one variety name was used, then only the named varieties could be used in manufacture. Detailed compositional requirements were proscribed, specifying that the FDM content could not be less than that laid down for those varieties covered by an international standard (i.e. Codex), and the minimum dry matter content could not be more than 4 g

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71

100 g−1 lower than the minimum dry matter content specified for the named cheese variety. Consequently, for Processed Cheddar Cheese, the minimum dry matter content would be 57 g 100 g−1 , based on the minimum dry matter of Cheddar of 61 g 100 g−1 as contained in the original 1966 Codex Standard for Cheddar (FAO/WHO, 2000). Lengthy tables specified the minimum dry matter for set FDM ranges for both processed and spreadable processed named variety cheeses when no international standards existed for the varieties (see Table 2.18). However, national legislation for named varieties other than those subjects of international (Codex) standards had to be followed where such existed. The proscribed names were Process(ed) . . . Cheese, Process(ed) Cheese, Spreadable Process(ed) . . . Cheese, or Spreadable Process(ed) Cheese, where the blank spaces included the name of the variety of cheese used, for example Processed Cheddar Cheese. Where more than one variety was named, the order of the variety names should be in order of inclusion of the variety, e.g. Processed Cheddar and Gouda Cheese. The fat content had to be declared, as FDM in multiples of 5 g 100 g−1 (the figure used being that multiple immediately below the actual composition) and/or as percentage by mass. Process(ed) cheese or spreadable process(ed) cheese which carried the name of a single variety of cheese covered by an international individual cheese standard was exempt from the declaration of the fat content. The Codex general standard for processed cheese (CODEX-STAN 286 – 1978) The definition in this case was the same as that for named variety processed cheese mentioned above. However, in addition to cream, butter and butteroil, the use of other milk products was permitted, but only to a maximum of 5 g 100 g−1 lactose in finished product. In most other aspects, the standard was similar, but products could not be designated by a cheese variety name in connection with the name ‘Process(ed) Cheese’ or ‘Spreadable Process(ed) Cheese’; nonetheless, mention may be made on the label of the name of a cheese variety which gives a characteristic flavour to the product (e.g. process(ed) cheese with . . . . A lengthy table specified the minimum dry matter for set of FDM ranges for both processed and spreadable processed cheeses (see Table 2.18). The fat content had to be declared, as FDM in multiples of 5 g 100 g−1 (the figure used being that multiple immediately below the actual composition) and/or as percentage by mass. The same food additives were permitted in this standard as in Codex Standard 285 – 1978 mentioned above. Processed cheese preparations (CODEX-STAN 287 – 1978) The definition here was similar to that of the other Codex standards; however, the list of permitted ingredients was more liberal. The use of cream, butter, butteroil and other milk products was permitted. A minimum cheese requirement of 51 g 100 g−1 was set. This is the only one of the three standards that sets a minimum limit for the cheese content. It was understood the other two standards would have higher cheese contents and, indeed, some would argue that the compositional requirements would ensure this indirectly. The consequences of this difference in the three standards proved a major stumbling block in the task of revising the Codex standard(s). Furthermore, there were no other restrictions on

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Processed Cheese and Analogues

the amount of other milk products in this case. The food additive list permitted those used in the other standards and in addition five gums, carboxymethylcelluloses, agar-agar, some alginates, pectins, carrageenan and gelatin (though this is now regarded as an ingredient and not a food additive), were permitted. Sodium glutamate was also permitted as a taste intensifier. Starch was not listed as a permitted optional ingredient in this standard. As in the case of Codex General Standard for Processed Cheese 286 – 1978, processed cheese preparations could not be designated by a cheese variety name in connection with the name processed cheese preparation (or process(ed) cheese food or cheese spread), but again mention could be made of the name of a cheese variety on the label in close proximity to the label declarations. A table again specified the minimum dry matter based on FDM ranges (see Table 2.18). The name of the product was specified as Process(ed) Cheese Preparation, or where national regulations distinguish between Process(ed) cheese food and Process(ed) cheese spread, these names could apply. The requirements for declaration of fat content were similar to those for processed cheese. Review of the existing Codex standards By the early 1990s, it was realised that the 1978 standards had become out of date due to product and process innovations and changes. The national legislation of some major producing countries reflected some of the aspects of the standards (for example that of the USA, Hungary, Egypt and Iran), but none had incorporated or adopted them in their entirety. For the last 15 years, Codex has endeavoured to redraft its standard(s) for processed cheese, but has failed to make any significant progress. The growing importance of Codex standards as a significant reference point in the WTO has undoubtedly contributed to this, with countries reluctant to accept a standard that differed from their own legislative requirements. The differences outlined in discussing national legislation above serves to outline the problems, which are mainly due to (a) definitions, (b) the need for a minimum cheese content and maximum levels of non-cheese dairy ingredients, (c) the use of the additive classes of stabilisers and thickeners and the related ingredients starch and gelatin, and (d) the product names included or excluded from any such new standard (e.g. cheese spread, cheese food). Indications are that the present efforts at revision will fail due to lack of any progress. At the meeting of the Codex Committee on Milk and Milk Products, held in Auckland, New Zealand in February 2010, decisions were taken to propose the discontinuation of the work on the development of an updated or revised draft standard and to revoke the three existing standards to the Codex Alimentarius Commission (FAO/WHO, 2010a). At its meeting in July 2010 the Commission agreed to revoke the existing standards but postponed a decision on the discontinuation of the work on a new or revised daft standard until its 2011 session, pending consideration by interested FAO/WHO Regional Coordinating Committees of the necessity and the scope of regional standards for processed cheese and reporting their findings to the 2011 Session of the Commission (FAO/WHO, 2010b). The task of addressing the additive provisions for processed cheese and processed cheese preparations in the Codex General Standard for Food Additives (CODEX STAN 192 – 1995) shall pass to Codex Committee on Food Additives (CCFA), which is responsible for developing that standard (FAO/WHO, 2009).

Current Legislation on Processed Cheese and Related Products

73

Imitation processed cheese and cheese analogues Processed cheese-like products that contain vegetable (or animal) fats and oils and/or proteins of vegetable origin (e.g. soya protein) also are produced (e.g. section 2.2.20 on Egyptian standards). These are characterised by the use of ingredients that replace milk products (e.g. fat and protein in particular). Such products are outside the scope of this review, but should/would be designated as ‘imitation processed cheese’, ‘cheese analogue’ or, for example, ‘blends of cheese, milk products and vegetable oil’. They are not generally governed by specific legislation, though provisions of the Codex General Standard for the Use of Dairy Terms (CODEX STAN 206-199) and the EU Regulation 1234/2007 (EU, 2007e), which includes the protection of dairy designations, would apply. In addition, their labelling requirements would be regulated under general food labelling legislation and standards. In particular, their product names, advertising and packaging should not mislead consumers to a material degree as to their true nature, i.e. lead consumers to think they are cheese or processed cheese products.

2.3 Summary and conclusions There are many products throughout the world that are designated as processed cheese or processed cheese preparations. Their requirements as regards permitted ingredients, detailed compositional requirements and product names differ somewhat from country to country. It is unclear if the general consumer understands, or is influenced in purchasing, by the use of product names as specified in international or national legislation. This may be why countries such as the UK and the Netherlands have repealed much of their detailed cheese legislation in the last 10–15 years. The diversity of products worldwide may also explain why revision of the existing Codex standards has proved so difficult, and has led to the questioning if there is a need for such standards in any case, as their existence does not seem to promote or hinder international trade.

2.4 Acknowledgements I gratefully acknowledge my thanks and appreciation to a number of individuals for their inputs and contributions to this chapter. Without their help and assistance it would have been impossible to cover the range of countries and the diverse languages involved. To Adnan Tamime, the editor of this technical series, Barbaros Ozer, Imad Toufeili, Marice Oliveira, Mohamed Abd El-Salam and Hamid Ghoddusi for providing the legislation on ˇ ıpkov´a, Milcom servis a.s., Turkey, Mercosur, Chile, Egypt, Lebanon and Iran. Jarmila St´ Prague for providing an electronic copy of the legislation of the Czech Republic, and a special thank you to Ivo Piska, Teagasc Moorepark Food Research Centre, for his diligent work in translating the legislation of his native country. Thanks to my IDF colleagues, Zsigmond Mat´ocza, Hungarian Dairy Research Institute, Budapest for supplying a translation of the Hungarian legislation and Massimo Forino, Comitato Italiano della FIL-IDF, for supplying an electronic version of the Italian legislation. Kaoru Koide and Shiro Kawabata of the Japanese National Committee of IDF provided the information and details on

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Processed Cheese and Analogues

processed cheese legislation in Japan. Last, but by no means least, my good friends and IDF colleagues Claus Heggum, of the Danish Agriculture and Food Council for supplying both the previous and current Danish legislation; Marie-Louise Bogemann, Nedsmelt (the Netherlands Processed Cheese Producers Association), for the information on the present and past legislation of the Netherlands; and Karen Armitage, Dairy Australia for providing the information on cheese contained in the former Australian Food Code.

References Abd El-Salam, M.H., El-Shibiny, L. & Ahmed, N.S. (2005) Studies in processed cheese in Egypt. A review. Egyptian Journal of Dairy Science, 33, 129–141. Anonymous (1988) D´ecret no 88-1206 du 30 d´ecembre 1988 portant application de la loi du 0108–1905 sur les fraudes et falsifications en matiere de produits ou de services et de la loi du 02-07-1935 tendant a l’organisation et al’assainissement du marche du lait en ce qui concerne les fromages. Journal Officiel de la R´epublique Fran¸caise, 30 D´ecembre, 16753–16758. Anonymous (2007) D´ecret no 2007-628 du 27 avril 2007 relatif aux fromages et sp´ecialit´es fromag`eres. Journal Officiel de la R´epublique Fran¸caise, 0101 (Texte 14 sur 91 NOR: ECOC0750331D), 7628–7637. ASSIFONTE (2008) Guidelines for a Good Manufacturing Practice (GMP) for Processed Cheese, Secr´etariat G´en´eral, Association de L’industrie de la Fonte de Fromage de l‘ UE, Berlin. Behr’s Verlag (2008) K¨aseverordnung 1986, update to February 2008. Available at www.behrskompakt.de/katalog/index.php?mode = index&id = 125. Berger, W., Klostermeyer, H., Merkenich, K. & Uhlmann, G. (1989) Development of the processed cheese market. Processed Cheese Manufacture: A JOHA Guide, pp. 11–25, BK Ladenburg GmbH, Ladenburg. Caric, M. & Kal´ab, M. (1993) Processed cheese products. Cheese: Chemistry Physics and Microbiology (ed. P.F. Fox), vol. 2, pp. 467–505, Chapman & Hall, London. Davis, J.G. (1966) The new cheese regulations. Journal of the Society of Dairy Technology, 19, 119–120. ECJ (1978) Judgment of the court of 20 February 1979 Rewe-Zentral AG v Bundesmonopolverwaltung f¨ur Branntwein (Federal Monopoly Administration for Spirits) measures heaving an effect equivalent to quantitative restrictions. 120/78 Cassis de Dijon, European Court of Justice, Brussels. ECJ (1987) Commission of the European Communities v Federal Republic of Germany. Failure of a state to fulfil its obligations, purity requirement for beer. C 178/84. European Court of Justice, Brussels. Eden, K.J. (1993) History of German brewing. Zymurgy, 16 (No. 4 Special). Available at www.brewery.org/brewery/library/ReinHeit.html. Egyptian Standard Organization (2002a) Standard Specifications of Processed Cheese and Spreads with Vegetable Fat , Standard No. 1132, Part 1 Processed cheese, Part 2 Processed cheese spread, Ministry of Agriculture, Cairo. Egyptian Standard Organization (2002b) Standard Specifications of Processed Cheese and Spreads, Standard No. 999, Part 1 Processed cheese, Part 2 Processed cheese spread, Ministry of Agriculture, Cairo. EU (1985a) Completing the internal market: white paper from the Commission to the European Council COM (85) 310, June 1985. Available at http://europa.eu/documents/comm/white_papers/pdf/ com1985_0310_f_en.pdf. EU (1985b) Council Directive 85/397/EEC of 5 August 1985 on health and animal-health problems affecting intra-Community trade in heat-treated milk. Official Journal of the European Commission, L226, 13–29.

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EU (1988) Council Directive 88/388/EEC of 22 June 1988 on the approximation of the laws of the Member States relating to flavourings for use in foodstuffs and to source materials for their production. Official Journal of the European Commission, L184, 61–66. EU (1989) Council Directive 89/107/EEC of 21 December 1988 on the approximation of the laws of the Member States concerning food additives authorized for use in foodstuffs intended for human consumption. Official Journal of the European Commission, L40, 27–33. EU (1990a) Commission Regulation 2742/90 of 26 September 1990 laying down detailed rules for the application of Council Regulation (EEC) No. 2204/90. Official Journal of the European Commission, L264, 20–21. EU (1990b) Council Regulation (EEC) No. 2204/90 of 24 July 1990 laying down additional general rules on the common organization of the market in milk and milk products as regards cheese. Official Journal of the European Commission L201, 7–8. EU (1992a) Council Directive 92/46/EEC of 16 June 1992 laying down health rules for the production and placing on the market of raw milk, heat-treated milk and milk-based products. Official Journal of the European Commission, L268, 1–32. EU (1992b) Council Regulation (EEC) No. 2081/92 of 14 July 1992 on the protection of geographical indications and designations of origin for agricultural products and foodstuffs. Official Journal of the European Commission, L208, 1–8. EU (1992c) Council Regulation (EEC) No. 2082/92 of 14 July 1992 on certificates of specific character for agricultural products and foodstuffs. Official Journal of the European Commission, L208, 9–14. EU (1994a) European Parliament and Council Directive 94/35/EC of 30 June 1994 on sweeteners for use in foodstuffs. Official Journal of the European Commission, L237, 3–12. EU (1994b) European Parliament and Council Directive No. 94/36/EC of 30 June 1994 on colours for use in foodstuffs. Official Journal of the European Commission, L237, 13–29. EU (1995a) Commission Directive 95/31/EC of 5 July 1995 laying down specific criteria of purity concerning sweeteners for use in foodstuffs. Official Journal of the European Commission, L178, 1–19. EU (1995b) Commission Directive 95/45/EC of 26 July 1995 laying down specific purity criteria concerning colours for use in foodstuffs. Official Journal of the European Commission, L226, 1–45. EU (1995c) European Parliament and Council Directive No. 95/2/EC of 20 February 1995 on food additives other than colours and sweeteners. Official Journal of the European Commission, L61, 1–40. EU (1996a) Commission Directive 96/77/EC of 2 December 1996 laying down specific purity criteria on food additives other than colours and sweeteners. Official Journal of the European Commission, L339, 1–69. EU (1996b) Commission Regulation (EC) No. 1107/96 of 12 June 1996 on the registration of geographical indications and designations of origin under the procedure laid down in Article 17 of Council Regulation (EEC) No. 2081/92. Official Journal of the European Commission, L148, 1–10. EU (1997) Commission Regulation (EC) No. 2301/97 of 20 November 1997 on the entry of certain names in the ‘Register of certificates of specific character’ provided for in Council Regulation (EEC) No. 2082/92 on certificates of specific character for agricultural products and foodstuffs. Official Journal of the European Commission, L319, 8–9. EU (2000a) Directive 2000/13/EC of the European Parliament and of the Council of 20 March 2000 on the approximation of the laws of the Member States relating to the labelling, presentation and advertising of foodstuffs. Official Journal of the European Commission, L109, 29–42. EU (2000b) White Paper on Food Safety (COM (1999) 719 final). Available at http://eurlex.europa.eu/LexUriServ/LexUriServ.do?uri = COM:1999:0719:FIN:EN:PDF

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EU (2003) Corrigendum to Commission Directive 2002/72/EC of 6 August 2002 relating to plastic materials and articles intended to come into contact with foodstuffs. Official Journal of the European Commission, L39, 1–42. EU (2004a) Commission Directive 2004/1/EC of 6 January 2004 amending Directive 2002/72/EC as regards the suspension of the use of azodicarbonamide as blowing agent. Official Journal of the European Commission, L7, 45–46. EU (2004b) Commission Directive 2004/19/EC of 1 March 2004 amending Directive 2002/72/EC relating to plastic materials and articles intended to come into contact with foodstuffs. Official Journal of the European Commission, L71, 8–21. EU (2004c) Regulation (EC) No. 1935/2004 of the European Parliament and of the Council of 27 October 2004 on materials and articles intended to come into contact with food and repealing Directives 80/590/EEC and 89/109/EEC. Official Journal of the European Commission, L338, 4–17. EU (2004d) Regulation (EC) No. 852/2004 of the European Parliament and of the Council of 29 April 2004 on the hygiene of foodstuffs. Official Journal of the European Commission, L226, 3–21. EU (2004e) Regulation (EC) No. 853/2004 of the European Parliament and of the Council of 29 April 2004 laying down specific rules for food of animal origin. Official Journal of the European Commission, L226, 22–82. EU (2004f) Regulation (EC) No. 854/2004 of the European Parliament and of the Council of 29 April 2004 laying down specific rules for the organisation of official controls on products of animal origin intended for human consumption. Official Journal of the European Commission, L139, 83–127. EU (2005a) Commission Regulation (EC) No. 2073/2005 of 15 November 2005 on microbiological criteria for foodstuffs. Official Journal of the European Commission, L338, 1–26. EU (2005b) Commission Regulation (EC) No. 2074/2005 of 5 December 2005 laying down implementing measures for certain products under Regulation (EC) No. 853/2004 of the European Parliament and of the Council and for the organisation of official controls under Regulation (EC) No. 854/2004 of the European Parliament and of the Council and Regulation (EC) No. 882/2004 of the European Parliament and of the Council, derogating from Regulation (EC) No. 852/2004 of the European Parliament and of the Council and amending Regulations (EC) No. 853/2004 and (EC) No. 854/2004. Official Journal of the European Commission, L338, 27–58. EU (2005c) Commission Regulation (EC) No. 2076/2005 of 5 December 2005 laying down transitional arrangements for the implementation of Regulations (EC) No. 853/2004, (EC) No. 854/2004 and (EC) No. 882/2004 of the European Parliament and of the Council and amending Regulations (EC) No. 853/2004 and (EC) No. 854/2004. Official Journal of the European Commission, L338, 83–88. EU (2005d) Guidance Document Implementation of Certain Provisions of Regulation (EC) No. 853/2004 on the Hygiene of Food of Animal Origin, European Commission: Health and Consumer Protection Directorate-General, Brussels. EU (2005e) Guidance Document on the Implementation of Certain Provisions of Regulation (EC) No. 852/2004 on the Hygiene of Foodstuffs. European Commission: Health and Consumer Protection Directorate-General, Brussels. EU (2005f) Guidance Document on the Implementation of Procedures Based on the HACCP Principles, and on the Facilitation of the Implementation of the HACCP Principles in Certain Food Businesses. European Commission: Health and Consumer Protection Directorate-General, Brussels. EU (2006a) Commission Decision of 13 October 2006 prohibiting the placing on the market of curd cheese manufactured in a dairy establishment in the United Kingdom. Official Journal of the European Commission, L283, 59–61.

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EU (2006b) Commission Regulation (EC) No. 1662/2006 of 6 November 2006 amending Regulation (EC) No. 853/2004 of the European Parliament and of the Council laying down specific hygiene rules for food of animal origin. Official Journal of the European Commission, L320, 1–10. EU (2006c) Corrigendum to Regulation (EC) No. 1924/2006 of the European Parliament and of the Council of 20 December 2006 on nutrition and health claims made on foods. Official Journal of the European Commission, L12, 3–18. EU (2006d) Guidelines for the development of Community guides to good practice for hygiene or for the application of the HACCP principles, in accordance with Article 9 of Regulation (EC) No. 852/2004 on the hygiene of foodstuffs and Article 22 of Regulation (EC) No. 183/2005 laying down requirements for feed hygiene. http://ec.europa.eu/food/food/biosafety/hygienelegislation/ guidelines_good_practice_en.pdf. EU (2007a) Amended Proposal for a Regulation of the European Parliament and of the Council establishing a common authorisation procedure for food additives, food enzymes and food flavourings (presented by the Commission pursuant to Article 250 (2) of the EC Treaty) (COM (2007) 0672 final). http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=COM:2007:0672:FIN:EN:PDF. EU (2007b) Amended proposal for a Regulation of the European Parliament and of the Council on flavourings and certain food ingredients with flavouring properties for use in and on foods and amending Council Regulation (EEC) No. 1576/89, Council Regulation (EEC) No. 1601/91, Regulation (EC) No. 2232/96 and Directive 2000/13/EC (presented by the Commission pursuant to Article 250 (2) of the EC Treaty) (COM (2007) 0671 final). Available at http://eurlex.europa.eu/LexUriServ/LexUriServ.do?uri = COM:2007:0671:FIN:EN:PDF. EU (2007c) Amended proposal for a Regulation of the European Parliament and of the Council on food additives (presented by the Commission pursuant to Article 250 (2) of the EC Treaty) (COM (2007) 0673 final). Available at http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri = COM:2007:0673:FIN:EN:PDF. EU (2007d) Amended Proposal for a Regulation of the European Parliament and of the Council on food enzymes and amending Council Directive 83/417/EEC, Council Regulation (EC) No. 1493/1999, Directive 2000/13/EC of the European Parliament and of the Council, and Council Directive 2001/112/EC and Regulation (EC) No. 258/97 of the European Parliament and of the Council (presented by the Commission pursuant to article 250 (2) of the EC Treaty) (COM (2007) 0670 final). Available at http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri = COM:2007:0670:FIN:EN:PDF. EU (2007e) Council Regulation (EC) No. 1234/2007 of 22 October 2007 establishing a common organisation of agricultural markets and on specific provisions for certain agricultural products (Single CMO Regulation). Official Journal of the European Commission, L299, 1–249. EU (2007f) Guidance on the implementation of Regulation No. 1924/2006 on Nutrition and Health Claims made on Foods: Conclusions of the Standing Committee on the Food Chain and Animal Health. Available at http://ec.europa.eu/food/food/labellingnutrition/claims/ guidance_claim_14–12-07.pdf. EU (2008a) Regulation (EC) No. 1331/2008 of the European Parliament and of the Council of 16 December 2008 establishing a common authorisation procedure for food additives, food enzymes and food flavourings. Official Journal of the European Commission, L354, 1–6. EU (2008b) Regulation (EC) No. 1332/2008 of the European Parliament and of the Council of 16 December 2008 on food enzymes and amending Council Directive 83/417/EEC, Council Regulation (EC) No. 1493/1999, Directive 2000/13/EC, Council Directive 2001/112/EC and Regulation (EC) No. 258/97. Official Journal of the European Commission, 354), 7–15. EU (2008c) Regulation (EC) No. 1333/2008 of the European Parliament and of the Council of 16 December 2008 on food additives. Official Journal of the European Commission, L354, 16–33. EU (2008d) Regulation (EC) No. 1334/2008 of the European Parliament and of the Council of 16 December 2008 on flavourings and certain food ingredients with flavouring properties for use in and on foods and amending Council Regulation (EEC) No. 1601/91, Regulations (EC) No. 2232/96

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and (EC) No. 110/2008 and Directive 2000/13/EC. Official Journal of the European Commission, L354, 34–50. Eyssen, J.H. (1899) An improved process for keeping and packing cheese and the like. United Kingdom Patent Application, GB189811207(A). FAO/WHO (1965) Report of the Third Session of the Codex Alimentarius Commission. Alinorm 65/30. Part IV. Section D. Para 57. Available at www.fao.org/docrep/meeting/005/ 31879e/31879e00.htm. FAO/WHO (1970) Report of the Seventh Session of the Joint FAO/WHO Codex Alimentarius Commission, Alinorm 70/43, Part XVI, Para 198. Available at www.fao.org/docrep/meeting/005/ a3025e/a3025e00.htm. FAO/WHO (1974) Report of the Tenth Session of the Joint FAO/WHO Codex Alimentarius Commission, Alinorm 74/44, Part III, Paras 265–279. Available at www.fao.org/ docrep/meeting/005/f2595e/F2595E04.htm#ch3.22. FAO/WHO (1979) Report of the Thirteenth Session of the Joint FAO/WHO Codex Alimentarius Commission, Alinorm 79/38, Part VII, Para 511. Available at www.fao.org/ docrep/meeting/005/ac315e/AC315E07.htm#p510. FAO/WHO (2000) Codex International Standard for Cheddar (CODEX STAN C-1-1996). Codex Alimentarius Milk and Milk Products, 2nd edn, pp. 63–64, Secretariat of the Joint FAO/WHO Food Standards Programme, Rome. FAO/WHO (2007) Codex Alimentarius Milk and Milk Products, pp. 63–75, Codex Alimentarius Commission, Rome. FAO/WHO (2008) Codex Alimentarius Procedural Manual , 18th edn, Codex Alimentarius Commission, Food and Agriculture Organization of the United Nations, Rome. FAO/WHO (2009) Codex General Standard for Food Additives (CODEX STAN 192-1995). Available at www.codexalimentarius.net/gsfaonline/CXS_192e.pdf. FAO/WHO (2010a) Report of the Ninth Session of the Codex Committee on Milk and Milk Products. Auckland, New Zealand, 1–5 February 2010, p. 5, Codex Alimentarius Secretariat, Rome. Available at www.codexalimentarius.net/web/archives.jsp?year=10 FAO/WHO (2010b) Report of the Thirty-Third Session Codex Alimentarius, Geneva 5–9 July 2010, pp 15–17, Codex Alimentarius Secretariat, Rome. Available at www.codexalimentarius.net/web/ archives.jsp?year=10 French, M. & Phillips, J. (2000) Standards and central government 1899–1938. Cheated not Poisoned: Food Regulation in the United Kingdom 1875–1938 , pp. 124–157, Manchester University Press, Manchester. FSANZ (2009) Australia New Zealand Food Standards Code. Available at www.foodstandards. gov.au/thecode/foodstandardscode. Guinee, T.P., Caric, M. & Kal´ab, K. (2004) Pasteurized processed cheese and substitute/imitation cheese products. Cheese: Chemistry Physics and Microbiology (eds P.F. Fox, P.L.H. McSweeney, T.M. Cogan & T.P. Guinee), vol. 2, pp. 349–394, Elsevier Academic Press, London. HMSO (1860) Adulteration of Food & Drink Act 1860. 23 & 24 Vict. c.84, HMSO, London. HMSO (1875) Sale of Food & Drugs Act 1875. 38 & 39 Vict. c. 63, HMSO, London. HMSO (1907) The Butter and Margarine Act 1907, HMSO, London. HMSO (1915) Milk and Dairies (Consolidation) Act 1915. 5 & 6 Geo. V c.66. HMSO, London. HMSO (1922a) Milk and Dairies (Amendment) Act 1922, 13 & 13 Geo. V c.54, HMSO, London. HMSO (1922b) The Milk (Special Designations) Order, 1922, SRO 1922 No. 1332, HMSO, London. HMSO (1923a) The Public Health (Condensed Milk) Regulations 1923, SRO 1923 No. 509, HMSO, London. HMSO (1923b) The Public Health (Dried Milk) Regulations, 1923, SRO 1923 No. 1323, HMSO, London. HMSO (1938) The Sale of Food & Drugs Act 1938, 1 & 2 Geo VI c.56, HMSO, London. HMSO (1955) The Sale of Food & Drugs Act 1955, 4 & 5 Eliz II c.16, HMSO, London.

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HMSO (1965) The Cheese Regulations 1965, SI No. 2199 of 1965, HMSO, London. HMSO (1970) The Cheese Regulations 1970, SI 1970 No. 94, HMSO, London. HMSO (1974) The Cheese (Amendment) Regulations 1974, SI 1974 No. 1122, HMSO, London. HMSO (1984) The Cheese (Amendment) Regulations 1984, SI 1984 No. 649, HMSO, London. HMSO (1990) The Food Safety Act 1990, c.16, HMSO, London. HMSO (1995) The Cheese and Cream Regulations 1995, SI 1995 No. 3240, HMSO, London. HMSO (1996) The Food Labelling Regulations 1996, SI 1996 No. 1499, HMSO, London. Instituto Nacional de Normalizaci´on (1999) Productos l´acteos-Queso procesado o fundido y queso procesado UHT (Ultra High Temperature) o fundido UHT-Requisitos, Norma Chilena 2092 de 1999, Chile. Iranian Standard (2003) Milk and Milk Products – Processed cheese – Specifications, ISIRI No. 4659, Institute of Standards and Industrial Research of Iran, West Bahar Street, Sardar Jangal Boulivard, Pounak, Tehran. Kosikowski, F.V. (1977) Process cheese and related types. Cheese and Fermented Milk Products, pp. 382–406, Edwards Brothers, Ann Arbor, MI. LACOTS (1997) Labelling of Food – Cheese – Query LAC 17 97 14. www.lacors.gov.uk/lacors/ search.aspx?Nso=1&prev=41+32+53+4003+4000&Ne=4000+0+2000+3000+5000+6000+ 7000+8000+9000+10000+11000&N=41+32+53+4003&No=1240&Ns=DOC_PUBLISHED &tl=10000&id=. Lebanese Standards Institution (2001) Lebanese Standards of Processed Cheese, Standard No. 463 (2001), Republic of Lebanon, Libnor, Ministry of Industry, PO Box 55120, Beirut. Lexius (1994) Warenwetbesluit Zuivel. Available at http://lexius.nl/warenwetbesluit-zuivel. Lexius (1998) Keuringsreglement COKZ kaas. Available at http://lexius.nl/keuringsreglement-cokzkaas/. Livsmedelsverket (2003) Livsmedelsverkets f¨oreskrifter om mj¨olk och ost, LIVSFS 2003: 39. Mercosur/Mercosul (2006) Regulamento T´ecnico MERCOSUL de Identidade e Qualidade de Queijo Processado ou Fundido, Processado Pasteurizado e Processado ou Fundido U.H.T. (UAT). MERCOSUL/GMC/RES. No. 134/96. Available at www.mercosur.int/show?contentid = 606. Meyer, A. (1973) Processed Cheese Manufacture, Food Trade Press, London. Minister of Justice Canada (2009) Food and Drug Regulations CRC, c. 870. Available at http://laws.justice.gc.ca/en/showtdm/cr/C.R.C.-c.870. Ministeriet for Familie- og Forbrugeranliggender (2004) Mælkeproduktbekendtgørelsen (Executive Order on Milk Products) BEK nr 335 af 10/05/2004, Copenhagen. Available at https://www.retsinformation.dk/print.aspx?id = 8011 Ministerio de la Presidencia de Espa˜na (2006) Real Decreto 1113/2006, de 29 de septiembre, por el que se aprueban las normas de calidad para quesos y quesos fundidos. Bolet´ın Oficial del Estado, num. 239, 34717–34720. Ministero de Salud Republica de Chile (2008) Chilean Food Sanitary Regulations 1996 (Reglamento Sanitario de los Alimentos) Dto. No. 977/96 (updated to May 2008). Available at www.minsal.cl/juridico/977%20DE%201996_modificado.doc. Ministero dell’Economia e delle Finanze di Italia (1954) Decreto del Presidente della Ruppubblica 18 novembre 1953 n. 1099 Esecuzione della Convenzione internazionale sull’uso dei nominativi di origine e delle dominazioni dei fromaggi, firmata a Stresa il 1◦ giugno 1951 e del Protocollo aggiuntivo alla Convenzione suddetta, firmato all’Aja il 18 juglio 1951. Gazzetta Ufficiale della Repubblica Italiana, 47, 618–629. Ministry of Agriculture and Rural Development of Hungary (2008) Codex Alimentarius Hungaricus, Prescription Nr. 1-3/51–1, Dairy Products, 3rd edn, 2008, chapter 7. Available at www.omgk.hu/Mekv/1/13511.pdf. Ministry of Agriculture of the Czech Republic (2003) Decree (Public Notice) of 6 March 2003 laying down the requirements for milk and milk products, ice creams and edible fats and oils. Sb´ırka z´akon`u e` (Legal Gazette No.) 77/2003 , 32, 2488–2516.

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Ministry of Agriculture of Turkey (2000) Quality of Raw Milk Used for the Manufacture of Processed Cheese, Turkish Food Codex, Codex No. 2000/06. Available at www.tarim.gov. tr/TarimPortal.html?LanguageID = 1. Ministry of Agriculture of Turkey (2007) Food Additives, Turkish Food Codex, Codex No. 2007/49. Available at www.tarim.gov.tr/TarimPortal.html?LanguageID = 1. Ministry of Agriculture of Turkey (2008) Food Additives, Turkish Food Codex, Codex No. 2008/69. Available at www.tarim.gov.tr/TarimPortal.html?LanguageID = 1. Monier-Williams, G.W. (1951) Historical aspects of the pure food laws. British Journal of Nutrition, 5, 363–367. Porter, D.V. & Earl, R.O. (1992) Contextual factors affecting the regulation of misbranded food. Food Labeling: Toward National Uniformity (eds D.V. Porter & R.O. Earl), pp. 35–62, National Academy Press, Washington, DC. Rieck, N. (2008) Reinheitsgebot: German Beer Purity Law, 1516. Available at www3.sympatico.ca/ n.rieck/docs/Reinheitsgebot.html. Swann, J.P. (2008) History of the FDA. Available at www.fda.gov/oc/history/historyoffda/ fulltext.html. Syrian Arab Standards and Metrology Organization (SASMO) (1986) Decision N 232◦ . Standard regulation: article 404 recreated in 1986 regarding the Processed Cheeses, (U.D.C: 638-358, S.N.S: 404/1986). Available at www.sasmo.org/en/index.php. The Stationery Office (1970a) The Cheese (Scotland) Regulations 1970, SSI 1970 No. 108. HMSO, Edinburgh. The Stationery Office (1970b) The Cheese Regulations (Northern Ireland) 1970, SR & O (N.I.) 1970 No. 14, HMSO, Belfast. The Stationery Office (1974) The Cheese (Scotland) Amendment Regulations 1974, SSI 1974 No. 1337, HMSO, Edinburgh. The Stationery Office (1984) The Cheese (Scotland) Amendment Regulations 1984, SSI 1984 No. 847, HMSO, Edinburgh. The Stationery Office Dublin (1924) The Dairy Produce Act 1924, No. 58/1924, Dublin. The Stationery Office Dublin (1935) Sale of Food and Drugs (Milk) Act, 1935, No. 3/1935, Dublin. Turkish Standards Institution (2008) Processed Cheese Standard, Standard No: TS 2176/T1:2008, Ankara. Available at www.tarim.gov.tr/TarimPortal.html?LanguageID = 1. USA National Archives and Records Administration (1906) Pure Food and Drug Act of 1906 United States Statutes at Large (59th Cong., Sess. I, Chp. 3915) 768–772, Washington, DC. http://coursesa.matrix.msu.edu/∼hst203/documents/pure.html. USA National Archives and Records Administration (2009) US Code of Federal Regulations (2009) The Office of the Federal Register National Archives and Records Administration, Washington, DC.

3 Effects of Natural Cheese Characteristics and Processing Conditions on Rheology and Texture: The Functionality of Cheese Components in the Manufacture of Processed Cheese T.P. Guinee 3.1 Definition of processed cheese products: an introduction Processed cheese products (PCPs) are cheese-based foods prepared by comminuting, blending and melting one or more natural cheeses, water (usually), emulsifying salt (ES), and optional ingredients into a smooth homogeneous blend with the aid of heat and mechanical shear. Following processing, the hot molten product is filled/moulded into a large variety of shapes and sizes of packs, convenient for retail or food service applications. Optional ingredients, which are determined by the type of PCPs, are shown in Table 3.1. There are various types of PCPs, the category/standard of which depend on national legislation. Examples include the Code of Federal Regulations in the USA (USA National Archives and Records Administration, 2008), which defines three standards based on permitted ingredients and composition: (a) Pasteurised Process Cheese, (b) Pasteurised Process Cheese Food, and (c) Pasteurised Process Cheese Spread. International standards for processed cheese were defined by Codex Alimentarius, developed and maintained by the Codex Alimentarius Commission (FAO/WHO, 2007). These standards, which were revoked in 2010, included the following categories of product: • • •

Codex general standard for named variety process(ed) cheese and spreadable process(ed) cheese: Codex-Stan 285-1978. Codex general standard for process(ed) cheese and spreadable process(ed) cheese: Codex-Stan 286-1978. Codex general standard for process(ed) cheese preparations (process(ed) cheese food and process(ed) cheese spread): Codex Stan 287-1978.

According to these standards (Table 3.2), the minimum content of natural cheese was such that it contributed greater than or equal to 51 g 100 g−1 of the dry matter (DM) of the final PCP in the case of processed cheese foods and spreads, and about 82–96 g 100 g−1 DM in named variety of general, processed cheese or spreadable processed cheese depending on the blend of the cheeses, the amount of milk fat required to standardise to the minimum fat-in-dry matter (FDM) content, and the levels of added emulsifying and product flavourings. Processed Cheese and Analogues, First Edition. Edited by A.Y. Tamime. © 2011 Blackwell Publishing Ltd. Published 2011 by Blackwell Publishing Ltd.

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Table 3.1

Ingredients other than cheese used in processed cheese products.a,b

Ingredient type

Main function/effect

Examples

Milk fat

Gives desired composition, texture and meltability characteristics

Cream, butter, anhydrous milk fat

Milk proteins

Give desired compositional specification, texture and meltability characteristics; assist the production of a physicochemically stable product

Milk protein isolates and concentrates, micellar casein powder, skimmed milk powder, acid casein, rennet casein, sodium or calcium caseinates, whey protein isolates and concentrates, milk protein hydrolysates, ultrafiltered milk

Lactose

Low-cost filler; may affect texture (e.g. fluidity) and taste (sweetness)

Whey powder, lactose powder, skim milk powder, evaporated milk, liquid whey

Dairy ingredients

Miscellaneous additives Stabilisers

Assist in formation of a physicochemically stable product; give desired texture and meltability characteristics

(a) Emulsifying salts: sodium phosphates and sodium citrates (b) Hydrocolloids and gums: sodium alginate, κ-carrageenan locus bean gum, guar gum, xanthan gum

Acid regulators/pH controlling agents

Assist control of pH of final product

Food-grade organic acids, e.g., lactic, acetic, citric, phosphoric acid

Flavours

Impart flavour, especially where much young cheese is used

Enzyme-modified cheeses, hydrolysed butteroil, hydrolysed milk proteins, autolysed yeast extracts, paprika, starter culture distillate, smoke extracts

Flavour enhancers

Accentuate flavour

Salt (NaCl), yeast extract

Sweetening agents

Increase sweetness, especially in products targeted to young children

Sucrose, dextrose, corn syrup, hydrolysed lactose

Colours

Impart desired colour

Natural colours: annatto extracts, β-carotene, paprika, curcumin (turmeric), riboflavin, chlorophyll preparations

Preservatives

Retard mould growth; prolong shelf-life

Nisin, sodium and/or potassium salts of sorbic acid or propionic acid

Condiments/ embellishments

Impart variety to appearance, aroma and taste and taste; product differentiation

Sterile preparations of meat, fish, vegetables, nuts and/or fruits

a Compiled using state-of-the-art knowledge of commercial processed cheese operations, and information on processed cheese standards from Codex Alimentarius Commission and from Code of Federal Regulations (Federal Government of the USA) (USA National Archives and Records Administration, 2008). b The ingredients permitted are subject to the prevailing regulations in the region of manufacture.

It should also be noted, however, that many countries have, or had, their own national legislation (e.g. France, Germany, UK), which takes precedence over any other standards in the country of retail sale, and are also subject to the provisions of European Union (EU) labelling requirements. The international specifications of PCPs are reviewed in detail in Chapter 2.

Effects of Natural Cheese Characteristics and Processing Conditions on Rheology and Texture

Table 3.2

83

Ingredient specifications for processed cheese products as defined by Codex Alimentariusa, b

Product category

Permitted ingredients

Named variety processed cheese and spreadable processed cheese

One or more varieties of cheese (added cheese accounting for ∼82 to 96 g 100 g−1 of the final product); milk fat (cream, butteroil) for standardisation of milk fat in final product; water; salt, vinegar, spices, seasonings, flavouring condiments at dry matter levels ≤16.7 g 100 g−1 of dry matter of finished processed cheese, starter culture bacteria, and enzymes, emulsifying salts (sodium, potassium, calcium salts of citric and phosphoric acid) at levels ≤4.0 g 100 g−1 ); pH regulators (food grade organic acids), colours at ≤0.06 g 100 g−1 ; mould inhibitors (sorbic acid, potassium/ sodium sorbate, and/or sodium propionates at levels ≤0.3 g 100 g−1 or nisin at ≤0.001 g 100 g−1 )

Processed cheese and spreadable processed cheese

As for Named variety processed cheese and spreadable processed cheese, except that: (a) in addition to milk fat, the product may also contain other added dairy ingredients in amounts such that their total contribution to lactose content in the final product is at a maximum of 5 g 100 g−1 , (b) the product may not be designated by a cheese variety name, and (c) content of cheese is not specified.

Processed cheese preparations: processed cheese foods and spreads

As for processed cheese and spreadable processed cheese, but with the following extra optional ingredients: (a) other dairy ingredients (milk, skimmed milk, buttermilk, cheese whey, whey proteins, caseins, in wet or dehydrated forms), (b) selected hydrocolloids and gums, and (c) taste intensifiers (sodium glutamate); added cheese accounts for at least 51% of the dry matter of the final product

a Summarised from Codex Alimentarius Standards, which were revoked by the Codex Alimnetarius Commission in 2010 (FAO/WHO, 2007); a decision to continue on the development of a new standard was deferred until the 2011 meeting of the Codex Alimentarius Commission in July (M. Hickey -Personal communication). See Chapter 2 for further details on this and other specific standards. b The composition of the various product categories are detailed in these standards, and relate to minimum contents of dry matter and fat-in-dry matter (FDM).

3.2 Overview of manufacture 3.2.1 Background Processed cheese manufacture essentially involves the conversion of the insoluble cheese protein, which in rennet-curd cheese varieties is calcium phosphate para-caseinate and in acid-curd cheese varieties is casein (close to the isoelectric pH), into a hydrated dispersible form (e.g. sodium para-caseinate or sodium-calcium phosphate para-caseinate, sodium caseinate) that binds water, emulsifies the free fat released from the cheese during processing (or that is added by way of butter or butteroil to the formulation), and thereby creates a physicochemical stable PCP. The latter conversion is mediated by the action of the added ES (e.g. sodium salts of phosphates or citrates) that are typically added at levels of 1.5–3 g 100 g−1 . The ES are not emulsifying agents per se, but rather buffering and calcium-binding salts. Together, with the aid of heat and shear, they mediate the conversion of the insoluble proteins (isoelectric casein in acid-curd cheeses or acid-casein powders; para-casein in rennet-curd cheeses or added rennet casein) to hydrated sodium caseinate or sodium para-caseinate, respectively, to a degree dependent inter alia on the blend of ES per se, cheese composition and processing conditions.

Fig. 3.1

Storage

Hot fill, Portioning, Packaging

Processing: Heat to ~ 85 °C Shear continuously

Blending (mixer)

• Dairy Ingredients • Acidifying agents: -Organic acids • Colours • Favours/enhancers • Preservatives • Gums and/or • Sweetening agent -Sugar -Hydrolysed starches (syrup solids)

Optional ingredients

Emulsifying salts, Water

Schematic illustration of the manufacture of processed cheese products, and two cooker types: high shear rate (top) and low shear rate (bottom).

Processing Kettle/Cooker

Cheese: clean, remove rind, comminute

Formulation

84 Processed Cheese and Analogues

Effects of Natural Cheese Characteristics and Processing Conditions on Rheology and Texture

85

3.2.2 Manufacture The manufacture of PCPs generally involves the following steps, as summarised in Fig. 3.1. • • • • • • •

Formulation: deciding on the different types and levels of ingredients to be included. Cleaning and size reducing of the cheese by shredding, grating and/or mincing. Blending of comminuted cheese with ES, water and optional ingredients to ensure homogeneity of all materials and uniform end-product quality. Processing (heating of the blend while continuously shearing) of the blend into a smooth, uniform, molten product, which is in effect the hot processed cheese. Homogenisation of the hot molten product (optional). Hot filling of the molten product into packs. Cooling and storage, during which time the product sets and acquires the texture characteristics of the final processed cheese.

Formulation Formulation of blend involves selection of the correct type and quantity of natural cheeses, ES, water and optional ingredients to give a PCP with the desired composition, flavour textural and functional properties. Cheese is the major ingredient in all PCPs, accounting for >51 g 100 g−1 DM in all cases. Its characteristics have a major influence on the properties of the finished PCP. The types of levels of other ingredients also influence functionality (Guinee, 2009; see Chapters 4, 8 and 10) and are not discussed here. Size reduction of cheese The function of size reduction is to maximise the surface area of the cheese, and to thereby facilitate interaction with other blend ingredients (e.g. water, ES), heat transfer to the blend during subsequent processing, and the formation of a uniform molten blend and consistent product. It is achieved by one or more processes, including cutting moulded cheeses into segments, which are degraded by shredding, grating or mincing using specialised equipment (see Chapters 6 and 7). Processing of the blended formulation Processing the blended formulation refers to the heating of the formulation/blend by direct or indirect steam injection in a cooker (kettle) typically to ∼75–85◦ C for 1–5 min, while constantly agitating/shearing. The primary functions of processing are to kill any potential pathogenic and spoilage microorganisms in the blend, and to promote the formation of a physicochemically stable product with the desired sensory, texture and cooking characteristics. It does this by promoting: • •

uniform distribution of all formulation ingredients; the dissolution of the ES which then interact with and hydrate the protein from the cheese (calcium phosphate para-casein) and/or other sources (e.g. dairy ingredients, such as rennet casein, acid casein, calcium caseinate);

86

• • •

Processed Cheese and Analogues

dispersion of the free fat released from the formulation ingredients (e.g. cheese, butteroil, butter) during processing into uniform, usually smaller sized, droplets; emulsification and stabilisation of dispersed fat droplets by the hydrated protein; and conversion of the formulation/blend to a finished processed cheese with uniform appearance and texture.

The blend thickens progressively, and simultaneously becomes creamier with holding time at 70–95◦ C. Homogenisation The hot molten cheese mass may be homogenised, with typical first- and second-stage pressures of 15 and 5 MPa, respectively. Homogenisation has a number of effects: (a) it assists further mixing, and size reduction of any coarse particles or undissolved particles (e.g. of ES, milk protein ingredients, cheese rind), and (b) promotes a finer dispersion of fat droplets which leads to a smoother and creamier hot blend, and thicker and firmer consistency in the final processed cheese. Homogenisation is frequently applied in the manufacture of high moisture (e.g. ≥55 g 100 g−1 ) processed cheese spreads to promote thickening and creaming; it is not normally used in the manufacture of block cheese products, where the high viscosity causes clogging/blockage of the valves. Cooling and storage of the hot molten processed cheese Following hot-pack moulding/filling, PCPs are typically cooled/stored to 4–8◦ C to prolong shelf-life. The hot molten blend sets during this period to form a characteristic body which, depending on blend formulation, processing conditions, cooling rate and storage temperature, may vary from firm and sliceable to soft and spreadable. Factors thought to contribute to the structure formed on cooling include: •

• •

interactions between the protein aggregates, strands and/or the protein on the surface of emulsified fat globules (van Vliet & Dentener-Kikkert, 1982; Marchesseau et al., 1997); fat crystallisation; the formation of an amorphous structure (or gel) based on the aggregation of calciumphosphate complexes may also contribute to the structure of PCPs.

The positive correlations between the degree of emulsification and firmness or elasticity, and the inverse relationship between the degree of emulsification and flowability of PCPs support the structural contribution of emulsified fat globules (Rayan et al., 1980; Cari´c et al., 1985; Savello et al., 1989).

3.3 Microstructure of PCPs The microstructure of PCPs consists of an emulsion of discrete rounded fat droplets of varying size (typically 0.3–5μm) in an aqueous phase in which dispersed protein is aggregated

Effects of Natural Cheese Characteristics and Processing Conditions on Rheology and Texture

87

to varying degrees into a polymer like network (Kimura et al., 1979; Rayan et al., 1980; Taneya et al., 1980; Heertje et al., 1981; Lee et al., 1981; Savello et al., 1989; Tamime et al., 1990; Heertje, 1993; Marchesseau & Cuq, 1995; Marchesseau et al., 1997). The protein phase consists of varying proportions of individual protein particles (aggregates) and strands that appear to be formed through end-to-end association of casein/para-caseinate aggregates. The matrix strands are generally finer than those of natural cheese, but vary in thickness according to the texture of the PCP. Hard sliceable PCPs contain strands that are thicker, more electron dense and numerous than those in soft spreadable PCP. For a given formulation and composition, the degree of strand thickness and product elasticity increases as the pH is reduced from 6.1 to 5.4 (Marchesseau et al., 1997), and as the time of holding/shearing at high temperature prior to cooling is increased (Kal´ab et al., 1987; Heertje, 1993). The latter changes in microstructure reflect alterations in the proportions of different types of protein interactions: hydrophobic, electrostatic, hydrogen bonds, and residual calcium cross-links (Marchesseau & Cuq, 1995).

3.4 Principles of processed cheese manufacture 3.4.1 Destabilisation and dehydration of milk during the manufacture of natural cheese Cheeses may be generally categorised as rennet-curd (e.g. most varieties including Cheddar, Gouda, Emmental, Camembert, Blue-types) or acid-curd (e.g. Quark, Cream cheese) or somewhat higher pH (e.g. ∼5.4). The manufacture of rennet-curd cheeses involves (a) hydrolysis of the casein-micelle stabilising κ-casein, (b) the liberation of the highly charged hydrophilic Met106 –Val169 caseino-macropeptide into the milk serum (whey), and (c) the resultant aggregation of the destabilised micelles into aggregates that knit into a gel. In acid-curd cheeses, gelation is brought about by the acidification of the cheese milk toward the isoelectric pH (e.g. ∼5.0–4.6) of caseins and aggregation of the destabilised micelles, or casein micelle-denatured whey protein composite particles (where the milk has been high heat treated to induce thermal denaturation and interaction of denatured whey proteins with casein through thiol-disulphide interchange, e.g. thermoQuark, Fromage Frais). In both rennet- and acid-curd cheese types, the protein aggregates knit/fuse together into strands that overlap into a repeating gel/matrix that enmeshes the fat globules. Following gel formation, the resultant milk gel is subjected to a number of operations that promote: (a) the release of whey; (b) an approximate fivefold to tenfold concentration of the casein, fat and micellar calcium phosphate (in rennet-cud cheeses) components; and (c) a transformation to a curd with much higher DM content than the original milk gel (e.g. ∼45 g 100 g−1 for Cheddar curd at whey drainage). These operations differ according to type (rennet-curd or acid-curd) and variety but typically include (a) cutting/stirring the gel into curd particles, stirring, heating, and pH reduction of the resultant curd–whey mixture, (b) physical removal of expelled whey (whey drainage), (c) moulding of the drained curd particles into a solid mass, (d) salt addition, and/or (e) pressing. During the dehydration process of the gel, casein concentration and aggregation continue (beyond that at gel cutting) via various types of intra- and inter-molecular interactions, including calcium

88

Processed Cheese and Analogues

bridging (between glutamate and aspartate residues, colloidal calcium phosphate bridges between phosphserine residues), hydrophobic interactions between lipophilic domains, and electrostatic interactions (other than calcium bridging). The strength of these interactions is modulated by pH, ionic strength, calcium content and temperature.

3.4.2 Characteristics of protein in natural cheeses The protein in rennet-curd cheeses occurs as aggregates of fused para-casein micelles; the para-casein aggregates are insoluble owing to the combined effects of the following. •

•

•

The hydrolysis, by rennet, of the κ-casein at the peptide bond Phe105 –Met106 , and liberation of the highly charged, hydrophilic Met106 –Val169 caseino-macropeptide into the milk serum (whey). Ultracentrifugation of skimmed milk and the corresponding rennet-induced milk gel indicate hydration is reduced from ∼3.7 g water g−1 casein in the casein micelle in the milk to ∼2.7 g water g−1 para-casein in the para-casein micelle in the rennet gel. The dehydration effects of the cheesemaking operations (gel cutting, acidification, heating, stirring, salting, pressing), which reduce the hydration from ∼2.7 g water g−1 para-casein in the uncut gel to ∼1.5 g water g−1 para-casein in the cheese (assuming a typical Cheddar-like cheese composition of ∼25 g protein and 38 g moisture 100 g−1 ). The attendant inter- and intra-protein linkages mediated by the cross-linking effect of calcium (attached to acidic amino acid residues, such as glutamate and aspartate) and colloidal calcium phosphate (attached to serine phosphate groups), and hydrophobic interactions between uncharged amino acid residues.

The calcium content of cheeses varies widely (e.g. from ∼15–18 mg g−1 casein in Bluetype to 35 mg g−1 in Emmental cheeses) owing to inter-variety differences in pH at set (rennet addition), scald temperature, drain pH, pH and moisture content of the curd at moulding, and degree of whey expressed from the moulded curd (Table 3.3). Moreover, because of the relatively high calcium level, equivalent to a concentration in moisture phase of ∼1000–1200 mg 100 g−1 in Blue types or 2300–3100 mg 100 g−1 in Emmental, most (∼50–60 g 100 g−1 of total at pH ∼5.2) of the calcium and phosphate in natural rennetcurd cheeses is insoluble and in association with the casein. The proportion of insoluble calcium increases as the pH is increased between 5.0 and 6.0 (Guinee et al., 2000a; Ge et al., 2002), but decreases on ageing (Hassan et al., 2004), probably as an indirect consequence of proteolysis and the cleavage of water-soluble calcium-casein phosphopeptides from the parent water-insoluble para-casein by residual coagulant and other proteinases/peptidases in the cheese. The protein in acid-curd cheeses occurs in the form of insoluble casein or casein–whey protein aggregates. The latter occur in cheeses prepared by high-heat treatment (HHT) of milks or curds obtained by high-concentration factor ultrafiltration of acid milk gels. HHT of the milk results in denaturation of whey proteins (β-lactoglobulin, α-lactalbumin) that interact with κ-casein via thiol-catalysed disulphide interchange, to an extent that increases with the temperature and duration of the heat treatment. Hydrophobic, electrostatic and

Effects of Natural Cheese Characteristics and Processing Conditions on Rheology and Texture

Table 3.3

89

Calcium and protein contents in retail samples of different cheese varieties

Cheese

Protein (g 100 g−1 )

Calcium (mg 100 g−1 )

Cottage cheese A

15.2

65

Cottage cheese B

Calcium (g g−1 casein) 4.3

16.3

170

10.4

Cream Cheese

7.6

80

10.6

Stilton Cheese

22.7

400

17.6

Italian fresh Mozzarella

18.9

371

19.6

Bavarian Blue

15.1

310

20.5

Irish Blue

19.0

400

21.1

French Brie A

17.7

380

21.5

Cambozola

12.9

300

23.3

Cheshire A

22.7

560

24.7

Cheshire B

21.2

540

25.5

French Brie B

18.2

500

27.5

Low-moisture part skimmed Mozzarella

26.0

730

28.1

Camembert

18.8

530

28.2

Cheddar

24.0

690

28.8

Port Salut

20.3

600

29.6

Emmental

28.1

1 000

35.6

Source: Morepark data. A and B refers to different retail samples of any one variety.

covalent disulphide bonds (where the cheese milk has been subjected to HHT) maintain the integrity of the aggregates in acid-curd cheeses. In contrast to rennet-curd cheeses, the casein matrix of acid-curd cheeses have the full complement of caseins (including the κ-casein glycomacropeptide), but relatively low levels of calcium and inorganic phosphate (e.g. ∼100 mg 100 g−1 , ∼5.8 mg g−1 protein), owing to the low pH of the gel at whey separation (∼4.7 compared with 5.8–6.5 for most rennet-curd varieties), and the ensuing solubilisation of micellar/colloidal calcium phosphate and its loss in the whey. As a result of the differences in casein composition (presence/absence of κ-casein glycomacropeptide) and mineral composition, the potential of acid casein to hydrate and bind water is much higher than that of rennet casein when the pH is readjusted to that of native milk, i.e. ∼6.7 (from 4.6) (Sood et al., 1979). In both rennet- and acid-curd cheese types, the protein aggregates knit/fuse together into strands that overlap into a repeating gel/matrix that enmeshes the fat globules. The fat in natural cheeses occurs mainly as globules or as partly coalesced globules/small pools of fat enclosed by native milk fat globule membrane (NMFGM) comprising mainly proteins and phospholipids; the NMFGM prevents the leakage of free fat and greasiness/‘sweating’ of the cheese. The moisture is largely immobilised within para-casein/casein aggregates.

90

Processed Cheese and Analogues

3.4.3 Effects of heating/shearing cheese (protein) Heating (to temperatures applied to processed cheese manufacture) and shearing of natural cheese usually results in the formation of a heterogeneous, gummy, pudding-like mass that undergoes extensive oiling-off and moisture exudation during manufacture and on cooling. These defects arise from the following. •

•

•

Further dehydration/aggregation and shrinkage of the para-casein/casein matrix as affected by (a) increased hydrophobic interactions as induced by the relatively low pH of cheese (for most cheeses, ∼4.6–5.6) and high temperature applied during processing, (b) the precipitation of soluble (serum) calcium and phosphate, leading to further calcium/phosphate-mediated interactions between the para-casein molecules (especially in rennet-curd cheeses), and (c) the consequential decline in pH and negative charge. Destabilisation of the native milk fat emulsion, formation of non-globular fat, and lique faction and coalescence of the latter, due to physical damage to, and removal of, the NMFGM. The absence of an active emulsifying agent to re-emulsify the free fat.

The above effects may be considered as a more extreme form of the shearing/heating applied to the curd during the manufacture of ‘pasta-filata’ cheeses where the heating conditions (e.g. heating at 57–60◦ C while kneading/stretching with screw type augers or baffles) of the curd at the desired pH (5.3–5.8, depending on the calcium-to-casein ratio) are applied to provide a controlled aggregation of the curd protein to form fibres and limited coalescence of fat to impart the desired stringiness and free oil when the finished cheese (e.g. Mozzarella, pizza cheese, string cheese) is subsequently cooked on pizza (Guinee, 2003; Kindstedt et al., 2004). Indeed, the effect of heating as a means of providing controlled protein destabilisation and moisture expulsion are exploited in several areas of dairy product/ingredient manufacture (e.g. protein recovery from milk in the form of casein powders, moisture regulation in cheese), while shearing of native fat globules is the basis of fat recovery from cream as butter or anhydrous butteroil.

3.4.4 The interaction of emulsifying salt with cheese protein during processing On heating/shearing natural cheese (rennet- or acid-curd) in the presence of the correct ES, a smooth hot-molten blend is formed with no evidence of the defects (phase separation: protein aggregation, oil separation) described above (section 3.4.3). The stability of the cheese (blend) to heating is due to the added ES, which mediate the conversion of the insoluble cheese protein into a hydrated dispersible form (e.g. sodium para-caseinate or sodium-calcium phosphate para-caseinate in rennet-curd cheese, sodium caseinate in acid-curd cheese) that binds water, emulsifies the free fat released from the cheese during processing (or that is added by way of butter or butter oil to the formulation), and thereby creates a physicochemically stable PCP. Similarly, the ES affect the hydration of insoluble/sparingly soluble milk proteins (e.g. rennet casein, acid casein, calcium caseinate) used in the manufacture of PCPs or cheese analogues. The mechanism by which the ES increase

Effects of Natural Cheese Characteristics and Processing Conditions on Rheology and Texture

91

protein hydration involves (a) their pH buffering which increases the pH from typical values of ∼5.2–5.6 in the natural cheese to ∼5.8–6.0 in the PCP blend/formulation, and stabilises it, and (b) their calcium sequestering ability, which leads to the removal of a large portion of the calcium and phosphate (∼80 g 100 g−1 ) attached to the para-casein or casein and its replacement with sodium. At the typical pH of processed cheese (∼5.8–6.0), the ES are sufficiently dissociated to sequester a large portion of the calcium attached to the casein. For example, typically cited pKa values for phosphoric acid are 2.15, 7.2 and 12.4, while those for citric acid are 3.1, 4.8 and 6.4. At this pH, the added sodium phosphates and citrates compete successfully with the casein (carboxyl and phosphoserine groups), not only for caseinate-bound calcium, but also the native colloidal calcium phosphate, initiating its transfer from the para-casein and/or casein and subsequent deposition as insoluble calcium phosphate and/or calcium citrate inclusions (Gaucher et al., 2007; Guinee & O’Kennedy, 2009). The demineralisation of casein at the elevated pH leads to degradation of intra- and inter-casein calcium crosslinks and an increase in negative charge. Both these changes favour a more open reactive para-caseinate/caseinate conformation with a water-binding capacity superior to that of the native cheese casein. The protein matrix of the natural cheese is thereby transformed to a sodium caseinate or para-caseinate dispersion (sol) in acid- and rennet-curd cheeses, respectively (Fox et al., 1965; Nakajima et al., 1975; Lee et al., 1986; Marchesseau et al., 1997; Panouill´e et al., 2004; Gaucher et al., 2007). The ‘reactivated casein’ then binds the free water and emulsifies free fat created during processing, and is thereby central to the formation of a stabilised processed cheese. Owing to presence of a surface layer consisting of hydrated caseinate/para-caseinate, the emulsified fat particles may be considered as a fat-filled protein particle, which can become an integral part of the protein matrix network. These changes are confirmed by (a) the large increase in the level of water-soluble protein during processing (Ito et al., 1976; Cavalier-Salou & Cheftel, 1991; Guinee, 2009) from ∼5 to 20 g 100 g−1 total nitrogen (N) in the natural cheese to ∼60–80 g 100 g−1 total N in processed cheese (Fig. 3.2a), (b) the high levels of water-insoluble calcium and phosphate in PCPs (∼60–80 g 100 g−1 of total, Fig. 3.2b) for a range of levels and type of ES used, and (c) the reduction in fat globule size during processing (see Figs 10.31, 10.32 and 10.33 in Chapter 10). The interactive effects of the type (degree of polymerisation, dissociation constants, molecular mass) and level of ES, pH and processing conditions (time, temperature and shear) determine the degrees of casein demineralisation and hydration during processing. Hence, the type/level of ES and processing conditions have a major influence on the textural and melting attributes of PCPs and cheese analogues (Rayan et al., 1980; Thomas et al., 1980; Lee et al., 1981; Gupta et al., 1984; Cavalier-Salou & Cheftel, 1991; Marchesseau et al., 1997; Brickley et al., 2008; Lu et al., 2008).

3.5 Effects of natural cheese characteristics on PCPs Natural cheeses differ to varying degrees in composition (e.g. protein-to-fat ratio, calcium level), biochemistry (pH, protein characteristics, degrees of degradation of proteins and fats), nutritive value, appearance, flavour, texture and cooking properties. Consequently, many different varieties of natural cheese, and blends thereof, are used in the manufacture

Processed Cheese and Analogues

Insoluble Ca or P (g 100 g−1 total Ca or total P)

Water-soluble and pH.4.6 soluble N (g 100 g−1 total N)

92

(a)

100 80 60 40 20 0 1.0

1.5

2.0

2.5

3.0

3.5

(b)

100 80 60 40 20 0 1.0

1.5

2.0

2.5

3.0

3.5

Level of added emulsifying salt, DSP (g 100 g−1) Fig. 3.2 Levels of water-soluble nitrogen (N) (a, ), insoluble calcium (Ca) (b, ) and insoluble phosphorus (P) (b, ) in processed Cheddar cheese made using different levels of disodium orthophosphate anhydrous (DSP), and level of water-soluble N in the Cheddar cheese before processing (a, ). Note that the intact casein content of the Cheddar cheese was ∼90 g 100 g−1 of total casein. (Source: Moorepark data).

of PCPs so as to differentiate the final PCP product with respect to composition/nutrition, flavour, texture (slicing, shredding, spreading), appearance (colour, matt/sheen appearance), and cooking properties (degrees of flow, browning, shred identity). The effects of some compositional parameters are discussed below.

3.5.1 Calcium content The calcium content of natural cheeses varies markedly with variety (see section 3.4.2). Owing to the inverse relationship between casein hydration and calcium content, variations in cheese calcium have a major impact on the degree of protein hydration and the physical properties of natural cheese (Keller et al., 1974; Lawrence et al., 1984; Kindstedt et al., 2004). A major function of ES in the manufacture of PCPs is the chelation of casein-bound calcium, and its partial removal (along with inorganic phosphorus) from the casein (see

Effects of Natural Cheese Characteristics and Processing Conditions on Rheology and Texture

93

section 3.4.4). Generally, for a given recipe/type of PCP, the weights of ES and cheese are generally fixed. Hence, variations in the calcium content of the natural cheese used, and consequently in the weight ratio of ES to cheese calcium, are likely to affect the level of residual casein-bound calcium following processing. This in turn is likely to influence the degree of casein hydration, its emulsification capacity, and consequently the functional properties of the processed cheese. Kapoor et al. (2007) and Biswas et al. (2008) compared the effects of increasing the calcium content of Cheddar cheese (21 and 27 mg g−1 protein) on the physical properties of processed cheese food (15.0 and 18.5 mg Ca2+ g−1 protein) formulated using cheese, non-fat dry milk powder and butteroil, and containing high or low levels of lactose (∼1.52 and 0.3 g 100 g−1 Cheddar) and salt-in-moisture (S/M) (∼6.4 and 5.0 g 100 g−1 Cheddar). Reducing calcium level resulted in softer and more meltable processed cheeses, but only when the S/M levels of the Cheddar cheeses used were high; however the results were somewhat complicated by random variation in levels of intact casein (79–89 g 100 g−1 of total), pH (5.7–6.2), and protein level in the 2-month-old Cheddar cheeses used. Guinee and O’Kennedy (2009) found that reducing the levels of calcium (from 29.8 through 24.4 to 19.6 mg g−1 casein) and phosphorus (from 20 to 16 mg g−1 casein) in Cheddar cheese (intact casein level, 89 g 100 g−1 of total; protein, ∼18 g 100 g−1 ) had a marked impact on the functionality of the resultant processed Cheddar cheese, leading to significant reductions in fracture stress, fracture strain and firmness of the unheated product, and increases in the extent of flow (Fig. 3.3) and fluidity (loss tangent) on the melted cheese. Regression analysis indicated that the functionality of the processed Cheddar cheese was strongly correlated with the high levels of water-insoluble calcium and phosphate (Guinee & O’Kennedy, 2009), suggesting that the gelation of calcium phosphate (Relyveld, 1977; Becker et al., 2003) may affect the structure–function relationships of processed cheeses.

3.5.2 pH The effect of increasing pH on the physical properties of PCPs may be expected to have two opposing effects, which depend on a number of factors including inter alia the pH region being considered, the calcium-to-casein ratio of the cheese, the level of intact casein, casein solubility, the pH buffering and calcium-chelating properties of specific ES, and degree of shear. The two opposing tendencies are: • •

a tendency toward PCPs that are softer and more flowable on heating, owing to the increased calcium removal by the ES and upward pH adjustment; a tendency toward a firmer product that is less meltable on heating, as a consequence of a higher degree of fat emulsification and consequently higher surface area of the matrix-forming polymer (casein/para-casein).

The matrix of PCPs, which may be defined as a polymer network of interacted hydrated casein/para-caseinate and casein-covered emulsified fat globules, is capable of shrinking or expanding depending on pH, ionic strength and temeperature of the system. Increasing pH may in general be visualised as swelling the polymeric particles leading to greater immobilisation of the system, favouring more viscoelastic (rather than elastoviscous) behaviour and higher meltability. In contrast, shrinking the matrix through pH reduction may be as

94

Processed Cheese and Analogues

160

120

80 17

21

25

0.5

160 Fracture stress (kPa)

29

120 0.45 80 0.4 40 0 17

21

25

Fracture strain (−)

Firmness (N)

200

0.35 29

Flow Method 1 (%)

100 80 60 40 20 0 17

21 25 Calcium-to-casein ratio (mg g−1 casein)

29

Fig. 3.3 Effect of calcium level (expressed as g 100 g−1 casein) in natural Cheddar cheese on firmness (), fracture stress () and fracture strain () of unheated processed cheese, as determined by 70% compression, and on the flowability of the melted processed cheese as measured using modified versions of Price-Olson (•, 180◦ C for 7.5 min) or Schreiber (, 280◦ C for 4 min) methods. Note that the intact casein content of the Cheddar cheese was ∼89 g 100 g−1 of total casein.

envisaged as facilitating greater electrostatic interactions (e.g. between oppositely charged amino acid side-chain proups, and calcium bridges) between the polymer particles and leading to greater elasticity and poorer melt. However, if shrinkage is excessive at low pH, then the matrix may become more particulate and discontinuous, a condition that may promote instability and further alter the physical properties of the PCP. A number of approaches have been used to alter the pH of PCPs. These may be described as direct or indirect.

Effects of Natural Cheese Characteristics and Processing Conditions on Rheology and Texture

•

•

95

Direct: (a) addition of different levels of acid/base at the end of processing to the hot molten PCP prior to cooling (Guinee, 2009), and (b) addition of acid/base to the formulation prior to processing (Marchesseau et al., 1997; Lu et al., 2008). Indirect: (a) altering the pH of the natural cheese used in processing (Olson et al., 1958; Kapoor et al., 2007), and (b) varying the types and levels of ES (Gupta et al., 1984).

Direct methods Direct methods differ in their effects. Firstly, altering pH prior to processing is likely to cause differences in degrees of dissociation of, and calcium chelation by, ES and hence formulation pH, level of casein hydration and fat emulsification during processing (cf. section 3.4.4), and may, especially at low pH values (e.g.<5.6), be expected to prevent formation of a stable product. By contrast, altering pH following processing does not influence the activity of the ES or product formation. Nevertheless, increasing pH has similar effects with both methods. Increasing pH in the region 5.2–6.2 is generally accompanied by decreases in elasticity (elastic shear modulus, G ) and hardness of the unheated PCPs, and by an increase in the flowability and fluidity of the heated PCP (as manifested by an increase in loss tangent, tan δ) (Fig. 3.4). These changes coincide with an increase in casein hydration, which plateaus at ∼80 g 100 g−1 total N at pH values ≥5.8 (Fig. 3.5), reflecting a lower degree of para-casein aggregation and a shift towards a less dense product matrix with finer protein strands at the higher pH values. Conversely, at the lower pH values (<5.6), the processed cheese becomes progressively coarser, increasingly acquires the appearance of a ‘pudding-like’ structure, and becomes unstable and prone to weeping and oiling-off. Ultimately, the effects of increasing pH may be ascribed to (a) an increase in the negative charge of the para-casein at the higher pH values, which favours a higher ratio of repulsive to aggregation forces between the casein particles, and (b) a higher degree of removal of calcium from para-casein matrix in rennet-curd cheeses, enabling dissociated groups (e.g. carboxyl) of amino acid side-chains on the casein to hydrogen bond with water molecules. However, the effect of altering pH in a particular range on the magnitude of changes in the physical characteristics of PCPs has been found to vary with the type of ES (Lu et al., 2008), an effect that may be attributed to variation in the degree of dissociation of the different ES and their potentially active calcium-chelating groups. Indirect methods pH alteration can also have a major effect on the texture of commercial and experimental PCPs (Gupta et al., 1984; Lee & Klostermeyer, 2001), in which the pH is varied by changing, among other factors, the type and level of ES. Low pH (4.8–5.2), e.g. due to the use of monosodium citrate, monosodium phosphate or sodium hexametaphosphate alone, gives short, dry, crumbly cheese which shows a high propensity to oiling-off (Gupta et al., 1984). High pH values (>6.0) give PCPs that tend to be very soft and flow excessively on heating (Gupta et al., 1984). Lee & Klostermeyer (2001) noted similar effects in model processed cheese prepared using vegetable oil, caseinate, and different ES blends varying in the ratio of a long-chain acid sodium polyphosphate to sodium polyphosphate. PCP with the lowest pH (5.0) was grainy and brittle, while the PCP with the highest pH (6.0)

Processed Cheese and Analogues

(a)

450 400 350 300 250 200 150 100 50 0 5.2

5.4

5.6

5.8 pH

6

6.2

6.4

(b)

Sorage modulus, G'

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0.7

300

0.6

250

0.5

200

0.4

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0.3

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50

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0 5.2

5.3

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5.5

5.6

5.7

5.8

5.9

6

6.1

6.2

Loss tangent

Flow of melted processed cheese (%)

96

0 6.3

pH Fig. 3.4 Effect of pH on the cooking characteristics of processed cheese. (a) Heat-induced flowability, as measured using modified versions of Price-Olson method (180◦ C for 7.5 min) () or Schreiber method (280◦ C for 4 min) (); (b) changes in viscoelastic parameters on heating from 25 to 80◦ C: elastic shear modulus, G , at 25◦ C () and maximum value of loss tangent (•). Data are the means of three replicate trials, and error bars show standard deviations. (Source: Moorepark data.)

resembled a thin sticky liquid; products with intermediate pH values (5.2–5.6) ranged from being ‘soft’ solid (egg-white like, at pH 5.2) to ‘soft’ gel-like (pH 5.4). These trends in sensory analysis were supported by rheological analyses which showed marked decreases in G and hardness, and an increase in the loss tangent (tan δ) as the pH was increased. Similar trends were noted by Lee et al. (1981): raising the pH of PCP from 5.75 to 6.05 by increasing the level of added sodium polyphosphate was accompanied by a twofold decrease in hardness (as measured indirectly by penetrometry). Only few studies have investigated the effect of natural cheese pH on the properties of resultant PCPs. Olson et al. (1958) prepared both Cheddar and Dairyworld cheeses with varying pH values by altering the pH of the curd at salting (e.g. for each variety the pH was either ∼5.45 for normal pH cheeses, or ∼6.45 for high pH cheeses). The pH of the normal Cheddar cheeses was ∼5.1 at 10 days and changed to ∼5.12 over the course of the 150day ripening period, while that of the normal Dairyworld cheeses changed from ∼5.1 to ∼5.28 over the same period. The pH of the high pH cheeses at 10 and 150 days were,

Effects of Natural Cheese Characteristics and Processing Conditions on Rheology and Texture

97

90

Water soluble nitrogen levels (g 100 g−1 of total nitrogen)

80 70 60 50 40 30 20 10 0 5.2

5.4

5.6

5.8

6

6.2

6.4

pH of processed cheese Fig. 3.5 Levels of water-soluble nitrogen in Cheddar cheese (•) and in the resultant processed Cheddar cheeses made with varying pH (). Data are the means of three replicate trials, and error bars show standard deviations. (Source: Moorepark data.)

respectively, 5.85 and 5.30 for Cheddar and 5.6 and 5.94 for the Dairyworld cheese. All four cheese types were converted into processed cheese spreads (∼52 g 100 g−1 moisture) after various ripening times (10, 30, 60, 90, 150 days), and the pH was standardised to ∼5.5 by the addition of lactic acid at the end of processing. Presentation of these data in graphical format show that the Dairyworld cheeses became softer (as reflected by the increase in penetrometer readings) and more meltable as the pH increased (Fig. 3.6a). However, for the Cheddar cheeses, the effect of increasing pH was less clear (Fig. 3.6b). The response of the measured variables (softness and melt) of the PCPs to the pH of the cheese used in processing in this study may be confounded by differences in the types and levels of proteolysis in the cheeses due to effects of pH at salting on the levels of residual rennet activity in the cheeses, and of the cheese pH on the activity of the residual rennet (no data on proteolysis of the cheeses were presented). However, a subsequent study by the same group (Vakaleris et al., 1962) indicated similar levels of proteolysis in normaland high-pH Cheddar cheeses and normal- and high-pH Dairywold cheeses after similar ripening times. Elsewhere, the data of Kapoor et al. (2007) indicate that increasing the pH of Cheddar cheese from 5.05 to 5.35 increased the firmness and reduced the meltability (flow) of the resultant processed cheese food.

3.5.3 Degree of maturity and intact casein content During maturation of rennet-curd cheeses, such as Cheddar or Gouda, the para-casein is increasingly hydrolysed into peptides and free amino acids during maturation by various enzymatic activities, including residual coagulant and the proteinase and/or peptidase systems of milk, starter culture lactic acid bacteria (LAB), non-starter LAB, secondary cultures and/or exogenous enzyme preparations (Upadhyay et al., 2004). The level of intact casein, as measured by the levels of total N insoluble at pH 4.6 (casein

Processed Cheese and Analogues

pH of cheese

6 5.8 pH DN pH DS

5.6 5.4 5.2 5

0

50

100

150

Penetromeeter depth (cm)

98

140 120 100 80 60 40 20 0

200

Penetrometer DN Penetrometer DS 5

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Age of cheese (days) 180 Melt on heating (%)

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6.5

pH of cheese Melt DN Melt DS

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pH of cheese

6.0

pH CN pH CS

5.8 5.6 5.4 5.2 5.0 0

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200

Penetrometer depth (cm)

pH of cheese (a) 80 60 40 20 0 5.0

70 Melt on heating (%)

Penetrometer CN Penetrometer CS

5.2

5.4 5.6 pH of cheese

5.8

6.0

Melt CN Melt CS

60 50 40 30 20 10 0 5.0

5.2

5.4 5.6 pH of cheese (b)

5.8

6.0

Fig. 3.6 (a) Changes in pH of normal pH Dairyworld (r) and sweet Dairyworld (p) cheeses during maturation, and the effect of these changes in pH on the penetrometry and meltability of the resultant processed cheeses. (b) Changes in pH of normal pH Cheddar (•) and sweet Cheddar (•) cheeses during maturation, and the effect of these changes in pH on the penetrometry and meltability of the resultant processed cheeses. (Figures drawn using data from Olson et al., 1958.)

Effects of Natural Cheese Characteristics and Processing Conditions on Rheology and Texture

99

300 250 200 150 100 50 0

0 5 10 15 20 25 pH 4.6 Soluble N in Cheddar cheese (g 100 g−1 total N)

Flowability of melted processed Cheddar (%)

Firmness of processed Cheddar (N)

isoelectric pH) in water, decreases concomitantly with para-casein hydrolysis. The early hydrolysis of αs1 -casein at the Phe23 –Phe24 peptide bond, by residual chymosin, results in a marked weakening of the para-casein matrix and reductions in fracture stress and firmness of Cheddar cheese (Creamer et al., 1982). The weakening was attributed to loss of the peptide (αs1 -casein f14 – 24 ), which is strongly hydrophobic and confers intact αs1 -casein with strong self-association and aggregation tendencies in the cheese environment. How do the changes in intact casein content and level of water-soluble nitrogen in natural cheese affect the properties of the resultant PCP? Studies in the author’s laboratory on processed Cheddar cheese indicate that a reduction in intact casein content from ∼95 to 80 g 100 g−1 of total casein, as measured by an increase in the level of pH 4.6 soluble N in the range 5–20 g 100 g−1 of total N, significantly reduced firmness and fracture force (stress) of the unheated PCP, and increased the flowability of the melted product (Fig. 3.7). Similar trends were reported by Brickley et al. (2007) who also found that the increase in pH 4.6 soluble N from ∼5 to 20 g 100 g−1 of total N, as the cheese was aged over 168 days, reduced the elastic shear modulus (G ) of the resultant unmelted PCPs at 30◦ C and increased the loss tangent of the melted cheese at temperatures in the range 60–80◦ C. Arnott et al. (1957) examined the relationship between the content of free tyrosine in Cheddar cheese (on maturation over 320 days at ∼7◦ C) and the flowability of the resultant processed Cheddar on melting at 100◦ C for 15 min. Meltability increased linearly with tryrosine content when a critical tyrosine level (∼0.16 mg under test conditions) was reached (after ∼100 days maturation); below this level, no relationship between tyrosine level and flow of the melted PCP was evident. Similarly, increasing the levels of proteolysis in acid-curd cheese (Lazaridis et al., 1981) and ultrafiltration retentates (Sood & Kosikowski, 1979) by treatment with fungal proteinase from Aspergillus oryzae, prior to their used in processed cheese manufacture, increased the meltability of the PCPs. Although increased proteolysis in the acidified curd cheese gave PCPs with consistently higher meltability, the PCPs generally had shorter texture, faulty body, and grainy mouth-feel when proteolysis was excessive, i.e. >32 g 100 g−1 total N soluble in 12% trichloroacetic acid and 0.2% phosphotungstic acid (Lazaridis et al., 1981). A subsequent study by the same group (Mahoney et al., 1982) reported that optimal

40 30 20 10 0

0 5 10 15 20 25 pH 4.6 Soluble N in Cheddar cheese (g 100 g−1 total N)

Fig. 3.7 Effect of primary proteolysis (as measured by level of pH 4.6 soluble N) in Cheddar cheese with low calcium (, ) or high calcium (•, ) on the firmness and flow on melting of the resultant processed cheeses. Note that the calcium contents of the high- and low-calcium Cheddar cheeses were 28 and 20.4 mg g−1 protein, respectively. (Source: Moorepark data.)

100

Processed Cheese and Analogues

flowability of the processed chemically acidified curd was obtained when the proteolysis products were mainly in the molecular mass range 10–25 kDa; by contrast, high levels of smaller peptide sizes (<11 kDa) in the curd gave PCPs that were short, grainy, had a bitter taste, and overflowed on cooking. The extent of increase in meltability of PCPs with degree of maturity and proteolysis in the natural cheese used in processing is influenced by a number of factors such as pH (Vakaleris et al., 1962) and calcium content of the natural cheese used (Figs 3.3 and 3.7), and the degree of shear during processing (Garimella Purna et al., 2006). Processed cheeses with a high proportion of young cheese with relatively high intact casein levels (e.g. >95 g 100 g−1 , pH 4.6 soluble N < 5 g 100 g−1 total N) give processed cheeses that are very firm and sliceable, but melt very poorly. Vakaleris et al. (1962) reported that Cheddar cheeses with high pH (e.g. ∼5.6) formed processed cheeses that had very low meltability compared with those from the corresponding normal pH Cheddar cheeses (pH ∼5.0–5.2), which gave acceptable melt values at ≥60 days when the level of pH 4.6 soluble N reached values of ≥16 g 100 g−1 of total N, despite the levels of pH 4.6 soluble N being similar in both the control and high-pH cheeses at all stages of the 150-day ripening period. While the latter study did not present data on cheese composition, it is possible that the poor melt of the high-pH cheeses even at levels of pH 4.6 soluble N ≥ 16 g 100 g−1 of total N could have been associated with higher calcium levels in the high pH cheese (Vakaleris et al., 1962), a higher ratio of casein-bound-to-soluble calcium owing to the higher pH, and an altered type of proteolysis products (e.g. ratio of hydrophobic to hydrophilic peptides, ratio of peptides to free amino acids). The effects of increasing proteolysis in natural cheese on the texture and meltability are probably related to: • • •

the higher water solubility of proteolytic degradation products than the parent intact casein/para-casein; a lower content of intact casein/para-casein contributing to the formation of a structure that supports deformation and limits flow on heating; an alteration in the hydrophilic/lipophilic characteristics of the protein, and an alteration in the degree of fat emulsification.

In model experiments with processed Gouda cheese, Ito et al. (1976) reported an inverse relationship between the age (and hence level of proteolysis) and its emulsifying capacity (defined as mL added oil absorbed per g cheese protein). A lower degree of emulsification, due to greater proteolysis, would be expected to reduce the contribution of emulsified fat globules to structure formation, favour more oil release during melting, and improve the flowability of the melted PCP (Rudan & Barbano, 1998; Guinee et al., 2000b). However, its is noteworthy that Tamime et al. (1990) noted little difference in the fat droplet sizes in model processed cheeses formulated from cheese and/or cheese bases that differed in the levels of proteolysis prior to processing, while Brickley et al. (2007) reported that increasing the level of proteolysis in Cheddar cheese (by ageing) prior to processing resulted in a marked reduction in the mean size of fat globules in the resultant processed cheeses. The effects of the degree of cheese maturity, and hence intact protein, has long been recognised and reflected in industrial practices. Thus, the use of cheese age as a major selection criterion for blend formulation at commercial level is common practice.

Effects of Natural Cheese Characteristics and Processing Conditions on Rheology and Texture

101

Block processed cheeses with good sliceability and elasticity are generally formulated with a high proportion of young cheese (85–95 g 100 g−1 intact protein) in the blend whereas predominantly medium-mature to ripe cheese (60–85 g 100 g−1 intact casein) is used for cheese spreads. It is also generally recognised in practice that interior, bacterialripened hard and semi-hard cheese varieties, such as Cheddar, Gouda and Emmental, give firmer, longer-bodied processed products than surface ripened cheeses (e.g. mould-ripened, such as Camembert and Blue cheese; bacterial-ripened, such as Ersom and Limburger). The latter cheeses generally have a higher pH and undergo more extensive proteolyis than the former during ripening (Reps, 1993; Brennan & Cogan, 2004; Spinnler & Gripon, 2004), and are, therefore, likely to have a relatively low degree of intact casein. The level of intact casein in any variety may be influenced by a myriad of factors (e.g. age, ripening conditions, milk pretreatments, composition, types of coagulant/cultures, addition of exogenous enzymes). Hence, the measurement of intact casein content (e.g. by level of protein insoluble in water at pH 4.6, gel electrophoresisis/densitometry, and/or reversed phase high pressure liquid chromatography) is being used increasingly as a quality control tool in commercial selection of, and determining the suitability of, natural cheese for specific processed cheese recipes. However, the response of processed cheese functionality to intact casein level is influenced by many other factors such as gross composition, ˇ etina, 2004), a fact worthy of calcium level and pH (Marchesseau et al., 1997; Piska & Stˇ consideration when formulating commercially.

3.6 Effects of processing conditions Alteration in processing conditions, especially shear and time, is well known and exploited in practice as a means of effecting large changes in the characteristics of PCPs. The effects are most evident in the manufacture of high-moisture (e.g. 55–60 g 100 g−1 ) spreadable PCPs, where high shear (as affected, for example, by the use of suitable cooker design) and, to a lesser extent, long processing time leads to a more rapid, and greater degree of, thickening of the hot molten formulation. First, this is critical for transforming the hot formulation/blend from a liquid consistency to a creamy viscous consistency with the desired degree of ‘hold’ and ‘stand up’ so as to optimise filling/packaging (e.g. minimise ‘splashing’ or ‘sticking’ to the foil); and, second, it imparts the desired creamy spreadable characteristics in the final product. In the absence of high shear, it is generally very difficult to achieve the desired transformation in the latter. Likewise, altering the processing time and degree of shear during the commercial manufacture of block/sliceable PCPs generally is routinely exploited as a means of differentiating the textural (e.g. firmness, brittleness) and melt characteristics (melt time, degree of flow, viscosity/fluidity) of the final products. The effects of the different processing parameters are discussed separately below.

3.6.1 Time For a given block processed cheese formulation (g 100 g−1 ) (fat ∼24.5, protein ∼20, moisture ∼49, pH ∼5.75), increasing the processing time from 1 to 32 min at 80◦ C increased the firmness (Fig. 3.8a) and elastic shear modulus (G ) at 25◦ C (by ∼12.6 Pa min−1 in the range 1–32 min) of the unheated PCP, and reduced the flow (Fig. 3.8b) and

102

Processed Cheese and Analogues

Flow of melted processed cheese (%)

Firmness of processed cheese (N)

120 100 80 60 40 20 0

0

8

16

24

32

400 300 200 100 0

0

8 16 24 Processing time (min)

32

Processing time (min) Fig. 3.8 Effect of processing time on the properties of processed cheese. The intact casein content of the Cheddar cheese was ∼81 g 100 g−1 of total casein. Data are the means of three replicate trials, and error bars show standard deviations. (Source: Moorepark data.)

fluidity (by about – 0.03 units reduction in maximum loss tangent for every 1-min increase in processing time) of the heated/melted PCP. Simultaneously, the degree of fat emulsification increased with temperature (see Fig. 10.33 in Chapter 10). The extent of these changes, which are consistent with those reported elsewhere, depends on other processing conditions (e.g. shear, temperature), formulation (e.g. degree of proteolysis, calcium level) and composition (e.g. moisture) of the product (Rayan et al., 1980; Harvey et al., 1982; Glenn et al., 2003; Shirashoji et al., 2006). Factors likely to contribute to the changes in texture and meltability of PCPs on increasing the holding time include changes in: •

•

• •

ratio of bound water to free water within the product matrix, which increases initially (at least up to 15 min at 95◦ C) and then decreases on holding for longer times (e.g. up to 30 min at 95◦ C) (Csøk, 1982); degree of fat dispersion and emulsification, which increases initially and then decreases with pronged holding time (e.g. >1 h), as indicated by larger fat globules at a microstructural level (Heertje, 1993); protein surface area, as affected by changes in the degree of fat emulsification and protein aggregation; level of casein hydration or aggregation of the protein phase.

Excessive holding time at the high temperatures (e.g. 75–90◦ C) of processing can induce a situation known as ‘over-creaming’, whereby the product becomes overly firm and short, acquires a dull, matt pudding-like consistency, and is prone to oiling-off. At a microstructural level, over-creaming is paralleled by a marked increase in protein aggregation and an increase in the size of fat particles (pools/fields) (Kal´ab et al., 1987; Heertje, 1993). The reduction in casein hydration is supported by the decrease in the level of watersoluble nitrogen, which for a processing temperature of 80◦ C decreases from ∼70 to 35 g 100 g−1 of total N as the processing time is increased from 1 to 32 min (Guinee et al., unpublished results). In contrast to the above-mentioned trends, Swenson et al. (2000) reported that increasing the processing time at 75◦ C from 1 to 15 min reduced the firmness of fat-free processed cheese spreads (∼59 g moisture 100 g−1 ) and increased the flow on heating.

Firmness (N)

110 90 70 50 65

75 85 Processing temperature (°C)

95

Flow of melted processed cheese (%)

Effects of Natural Cheese Characteristics and Processing Conditions on Rheology and Texture

103

20 15 10 5 0 65

75 85 Processing temperature (°C)

95

Fig. 3.9 Effect of processing temperature on the properties of processed cheese. The intact casein content of the Cheddar cheese was ∼90 g 100 g−1 of total casein. Data are the means of three replicate trials, and error bars show standard deviations. (Source: Moorepark data.)

3.6.2 Temperature For a given block processed cheese formulation (g 100 g−1 ) (fat ∼24.5, protein ∼20, moisture ∼49, pH ∼5.75), increasing the processing temperature from 70 to 95◦ C for a processing time of 4 min increased the firmness (Fig. 3.9a) and G at 25◦ C (at ∼6 Pa per 1◦ C) of the unheated PCP, and reduced the flow (Fig. 3.9b) and fluidity of the melted PCP, as indicated by a linear decrease of about – 0.037 units per 1◦ C in the maximum loss tangent at temperatures above 50◦ C. Confocal laser scanning microscopy showed that degree of fat emulsification changed little with temperature in the range 70–80◦ C, but increased slightly as the temperature was further raised to 95◦ C (see Fig. 10.33 in Chapter 10). These trends are consistent with those reported elsewhere for the effect of temperature in the range 74–86◦ C on the meltability of processed American cheese (44 g moisture 100 g−1 ) (Glenn et al., 2003) and in the range 80 to 140◦ C on the firmness (as measured by penetrometry) of processed Emmental (details of composition or other processing conditions not given) (Lee et al., 1981). Higher temperatures are likely to alter the number and/or balance of the different attractive forces (e.g. hydrophobic to electrostatic interactions) between the casein particles, resulting in a product matrix that is strengthened but yet sufficiently continuous and voluminous. The strength of hydrophobic interactions (e.g. between hydrophobic protein domains) tends to increase as the temperature is raised to 60–70◦ C, at which point they decrease slowly, while electrostatic interactions (e.g. between oppositely charged groups on the protein) tend to increase with temperature (Bryant & McClements, 1998). It is noteworthy that the level of protein strand formation in processed cheese increases with temperature (Heertje et al., 1981). However, in the above study (Fig. 3.9), we did not find any significant decrease in the level of water-soluble nitrogen, which varied from ∼65 to 70 g 100 g−1 of total N, on increasing the temperature from 70 to 95◦ C. Nevertheless, the mean fat globule size decreased slightly at temperatures above 80◦ C (see Fig. 10.33 in Chapter 10), suggesting some shrinkage and aggregation of the protein phase. The results of Lee et al. (1981) conflict with the conclusions of Meyer (1973), who concluded that increasing temperature from 90 to 130–145◦ C, as used in ultra-high temperature (UHT) treatment of long-life PCPs (e.g. spreads, pastes, dips), markedly reduces the viscosity and increase the ‘liquidity’. This was attributed to possible hydrolysis of polyphosphates

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Processed Cheese and Analogues

(which are frequently used to induce a thick creamy consistency in high-moisture PCPs), degradation of casein, and unfolding of the casein/para-casein aggregates. Degradation changes in milk proteins (e.g. cleavage of phosphoserine groups, N -acetylyneuraminic acid, and thiol groups) at temperatures of 100–140◦ C have been discussed by Walstra and Jenness (1984). It is feasible that the loss of such charged/hydrophilic groups could facilitate greater interaction between the altered caseins, a reduction in hydration, and consequently casein shrinkage, which in turn may favour a lower degree of matrix continuity and greater system mobility, especially in a high-moisture/low-protein product. It is noteworthy that raising the processing temperature of processed cheese from 115 to 140◦ C significantly reduced its water-holding capacity, as determined by observing the level of fluid/serum expressed following 6 months of storage, or by measuring the amount of serum released on ultracentrifugation of the product (Marchesseau & Cuq, 1995). Undoubtedly, the effects of altering processing temperature are influenced by factors such as the concentrations of protein and fat, degree of proteolysis, temperature region, presence of whey protein, and pH, factors that are expected to influence protein denaturation, charge and the balance of attractive to repulsive forces (Walstra & Jenness, 1984; Marchesseau et al., 1997; Bryant & McClements, 1998; Lucey et al., 2003, Guinee, 2009).

3.6.3 Shear

100 80 60 40 20 0

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Flow of melted processed cheese (%)

Firmness of processed cheese (N)

A study from the author’s laboratory evaluated the effect of increasing the agitation speed during processing (Stephan Machine UMM/SK 5K 7; A. Stephan u S¨ohne GmbH & Co, Hameln, Germany) in block processed cheese (g 100 g−1 ) (fat ∼24.5, protein ∼20, moisture ∼49, pH ∼5.75). Increasing the speed from 300 to 2700 revolutions per minute (rpm) significantly increased the firmness and elasticity modulus (25◦ C) of the unheated PCP but significantly reduced the level of flow (Fig. 3.10) and the fluidity (as reflected by lower phase angle at temperatures of 50–90◦ C) of the melted product. These results are consistent with those of Garimella Purna et al. (2006) who found that increasing the processing speed from 450 to 1450 rpm in block processed cheese (∼44 g moisture 100 g−1 ) significantly increased the firmness of the unheated product and the viscosity of the melted cheese at 85◦ C. Moreover, the melted cheese congealed more quickly on cooling, as reflected

100 80 60 40 20 0

0

1000 2000 Agitator motor speed (rpm)

3000

Fig. 3.10 Effect of agitator motor speed (shear) during processing temperature on the properties of processed cheese. The intact casein content of the Cheddar cheese was ∼84 g 100 g−1 of total casein. Data are the means of three replicate trials, and error bars show standard deviations. (Source: Moorepark data.)

Effects of Natural Cheese Characteristics and Processing Conditions on Rheology and Texture

105

by a reduction in the time in which the melted cheese attained a viscosity of 500 Pa·s on reducing the temperature from 85 to 25◦ C. The above trends with increasing shear/agitation are consistent with the increase in degree of fat emulsification (Rayan et al., 1980) and the concomitant increase in protein surface area available for aggregation and structure contribution (cf. sections 3.3, 3.4.4). Conversely, the data of Glenn et al. (2003) indicate little or no effect of agitation speed (50 or 150 rpm) on the melt score (flow) of heated processed cheese (44 g moisture 100 g−1 ) when studying the interaction of processing temperature, time and shear.

3.7 Conclusions PCPs are composites formulated by heating and shearing natural cheeses, water, ES and optional ingredients, such as milk proteins, at high temperatures. ES, though not emulsifying agents per se, are central to inducing hydration/dispersion of the insoluble cheese protein (casein, calcium phosphate para-casein) via their calcium-sequestering and pHbuffering functions. The hydrated protein (caseinate, para-caseinate) binds free water and emulsifies free fat released on processing (shearing/heating) the natural cheese, and thereby facilitates product formation and stabilisation. On cooling, the hot stable processed cheese mix sets to form the characteristic body and texture, which can vary from soft and spreadable to firm and elastic depending on formulation and processing conditions. The product may be described as an interconnected polymer network, in which protein aggregates and hydrated caseinate/para-caseinate covered fat globules interact to varying degrees and influence the extent of matrix continuity. Natural cheese for processing may vary in several respects, such as type of casein and its solubility, pH, degree of mineralisation (especially calcium to casein ratio), and intact casein content (a measure of the percentage of total protein that is not hydrolysed by proteinases/peptidases in the cheese). These variables affect the physical characteristics (e.g. rheology, viscoelastic changes on heating, cooking properties) of PCPs to varying degrees and can be interactive. Hence, a reduction in intact casein content or an increase in pH generally reduces the firmness of unmelted PCPs and increase the degree flow and the fluidity of the melted PCP. Conversely, increasing calcium content has the opposite effect, probably as a consequence of a reduction in the ratio of ES (sequestering agent) to content of casein-bound calcium phosphate. The exact effect of pH depends on whether the natural cheese used for processing varies in pH, or whether, and how, the pH of the PCP is adjusted (e.g. by ES blend, by addition of acid or base before or after processing). For a given processed cheese formulation, variation in processing conditions have been found to markedly change the physical characteristics of the resultant PCP. Increasing processing time, temperature and agitation (shear) increases the firmness and elasticity of the uncooked PCPs and reduces the degree of flowability and fluidity on cooking. The effects of variations in cheese characteristics, pH and processing conditions on PCPs may be attributed ultimately to their impact on the structural matrix. The latter parameters alter the structure and integrity/continuity of the network because of their influence on shrinkage or expansion of the matrix aggregates and hence the matrix continuity and

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voluminosity per se: (a) pH affects the degree of ionisation and interactivity of acidic/basic groups on the polypeptide backbone, (b) the magnitude of temperature influences the various types of protein/polymer interactions differently, and (c) and the degree of proetolysis affects the solubility/hydration of the casein/para-casein.

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Guinee, T.P. (2003) Role of protein in cheese and cheese products. Advanced Dairy Chemistry (eds P.F. Fox & P.L.H. McSweeney), vol. 1, pp. 1083–1174, Kluwer Academic/Plenum Publishers, New York. Guinee, T.P. (2009) The role of dairy ingredients in processed cheese products. Dairy-derived Ingredients (ed. M. Corredig), pp. 507–538, Woodhead Publishing, Oxford. Guinee, T.P. & O’Kennedy, B.T. (2009) The effect of calcium content of Cheddar-style cheese on the biochemical and rheological properties of processed cheese. Dairy Science and Technology, 89, 317–333. Guinee, T.P., Harrington, D., Corcoran, M.O., Mulholland, E.O. & Mullins, C. (2000a) The composition and functional properties of commercial Mozzarella, Cheddar and analogue pizza cheese. International Journal of Dairy Technology, 53, 51–56. Guinee, T.P., Auty, M. A. E., Mullins, C. Corcoran, M.O. & Mulholland, E.O. (2000b) Preliminary observations on effects of fat content and degree of fat emulsification on the structure-functional relationship of Cheddar-type cheese. Journal of Texture Studies, 31, 645–663. Gupta, S.K., Karahadian, C. & Lindsay, R.C. (1984) Effect of emulsifier salts on textural and flavour properties of processed cheeses. Journal of Dairy Sci ence, 67, 764–778. Harvey, C.D., Morris, H.A. & Jenness, R. (1982) Relation between melting and textural properties of process Cheddar cheese. Journal of Dairy Science, 65, 2291–2295. Hassan, A., Johnson, M.E. & Lucey, J.A. (2004) Changes in the proportions of soluble and insoluble calcium during the ripening of Cheddar cheese. Journal of Dairy Science, 87, 854–862. Heertje, I. (1993) Structure and function of food products: a review. Food Structure, 12, 343–364. Heertje, I., Boskamp, M.J., van Kleef, F. & Gortemaker, F.H. (1981) The microstructure of processed cheese. Netherlands Milk and Dairy Journal , 35, 177–179. Ito, T., Okawachi, Y. & Muguruma, Y. (1976) Relationship between the emulsifying capacity of cheese and the size of casein during ripening. Journal of the Faculty of Agriculture, Kyushu Univ ersity, 20, 79–85. Kal´ab, M., Yun, J. & Yiu, S.H. (1987) Textural properties and microstructure of process cheese food rework. Food Microstructure, 6, 181–192. Kapoor, R., Metzger, L.E., Biswas, A.C. & Muthukummarappan, K. (2007) Effect of natural cheese characteristics on process cheese properties. Journal of Dairy Science, 90, 1625–1634. Keller B., Olson N.F. & Richardson T. (1974) Mineral retention and rheological properties of Mozzarella cheese made by direct acidification. Journal of Dairy Science, 57, 174–180. Kimura, T., Taneya, S. & Furuichi, E. (1979) Electron microscopic observation of casein particles in processed cheese. Proceedings of the 20th International Dairy Congress, pp. E239–240, Paris. Kindstedt, P.S., Cari´c, M. & Milanovi´c, S. (2004) Pasta-filata cheeses. Cheese: Chemistry, Physics and Microbiology (eds P.F. Fox, P.L.H. McSweeney, T.M. Cogan & T.P. Guinee), 3rd edn, vol. 2, pp. 251–277, Elsevier Academic Press, Amsterdam. Lawrence R.C., Heap H.A. & Gilles J. (1984) A controlled approach to cheese technology. Journal of Dairy Science, 67, 1632–1645. Lazaridis, H.N., Rosenau, J.R. & Mahoney, R.R. (1981) Enzymatic control of meltability in a direct acidified cheese product. Journal of Food Science, 46, 332–335 and 339. Lee, B.O., Kilbertus, G. & Alais, C. (1981) Ultrastructural study of processed cheese. Effect of different parameters. Milchwissenschaft , 36, 343–348. Lee, B.O., Paquet, D. & Alais, C. (1986) Etude biochemique de la fonte des fromages IV. Effect du type de sels de fonte et de la nature de la mati`ere prot´eique sur la peptisation. Utilisation d’un syst`eme rnod`ele. Le Lait , 66, 257–267. Lee, S.K. & Klostermeyer, H. (2001) The effect of pH on the rheological properties of reduced-fat model processed cheese spreads. Lebensmittel Wissensenschaft und Technologie, 34, 288–292. Lu, Y., Shirashoii, N. & Lucey, J.A. (2008) Effects of pH on the textural properties and meltability of pasteurized process cheese made with different types of emulsifying salts. Journal of Food Science, 73, E363–E369.

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Lucey J.A., Johnson M.E. & Horne D.J. (2003) Invited review: perspectives on the basis of the rheology and texture properties of cheese. Journal of Dairy Science, 86, 2725–2743. Mahoney, R.R., Lazaridis, H.N. & Rosenau, J.R. (1982) Protein size and meltability in enzymetreated, direct-acidified cheese products. Journal of Food Science, 47, 670–671. Marchesseau, S. & Cuq, J.L. (1995) Water-holding capacity and characterization of protein interactions in processed cheese. Journal of Dairy Research, 62, 479–489. Marchesseau, S., Gastaldi, E., Lagaude, A. & Cuq, J.-L. (1997) Influence of pH on protein interactions and microstructure of process cheese. Journal of Dairy Science, 80, 1483–1489. Meyer, A. (1973) Processed Cheese Manufacture, Food Trade Press, London. Nakajima I., Kawanishi, G. & Furuichi, E. (1975) Reaction of melting salts upon casein micelles and their effects on calcium, phosphorus and bound water. Agricultural and Biological Chemistry, 39, 979–987. Olson, N.F., Vakaleris, D.G., Price, W.V. & Knight, S.G. (1958) Acidity and age of natural cheese as factors affecting the body of process cheese spread. Journal of Dairy Science, 41, 1005–1016. Panouill´e M.T., Nicolai T. & Durand, D. (2004) Heat-induced aggregation and gelation of casein submicelles. International Dairy Journal , 14, 297–303. ˇ etina, J. (2004) Influence of cheese ripening and rate of cooling of the processed Piska, I. & Stˇ cheese mixture on rheological properties of processed cheese. Journal of Food Engineering, 61, 551–555. Rayan, A.A., Kal´ab, M. & Ernstrom, C.A. (1980). Microstructure and rheology of process cheese. Scanning Electron Microscopy, III, 635–643. Relyveld, E. (1977) Calcium phosphate gel for absorbing vaccines. United States Patent No. 4 016 252. Reps, A. (1993) Bacterial surface-ripened cheeses. Cheese: Chemistry, Physics and Microbiology (eds P.F. Fox, P.L.H. McSweeney, T.M. Cogan & T.P. Guinee), 3rd edn, vol. 2, pp. 137–172, Elsevier Academic Press, Amsterdam. Rudan, M.A. & Barbano, D.M. (1998) A dynamic model for melting and browning of Mozzarella cheese during pizza baking. Australian Journal of Dairy Technology, 53, 95–97. Savello, P.A., Ernstrom, C.A. & Kal´ab, M. (1989) Microstructure and meltability of model process cheese made with rennet and acid casein. Journal of Dairy Science, 72, 1–11. Shirashoji, N. Jaeggi, J.J. & Lucey, J.A. (2006) Effect of trisodium citrate concentration and cooking time on the physicochemical properties of pasteurized process cheese. Journal of Dairy Science, 89, 15–28. Sood, S.M., Gaind, D.K. & Dewan, R.K. (1979). Correlation between micelle solvation and calcium content. New Zealand Journal of Dairy Science and Technology, 14, 32–34. Sood, V.K. & Kosikowski, F.V. (1979) Process Cheddar cheese from plain and enzyme treated retentates. Journal of Dairy Science, 62, 1713–1718. Spinnler, H.-E. & Gripon, J.-C. (2004) Surface mould-ripened cheeses. Cheese: Chemistry, Physics and Microbiology (eds P.F. Fox, P.L.H. McSweeney, T.M. Cogan & T.P. Guinee), 3rd edn, vol. 2, pp. 155–174, Elsevier Academic Press, Amsterdam. Swenson, B.J., Wendorff, W.L. & Lindsay, R.C. (2000) Effects of ingredients on the functionality of fat-free process cheese spreads. Journal of Food Sci ence, 65, 822–825. Tamime, A.Y., Kal´ab, M., Davies, G. & Younis, M.F. (1990) Microstructure and firmness of processed cheese manufactured from Cheddar cheese and skim milk powder cheese base. Food Structure, 9, 23–37. Taneya, S., Kimura, T., Izutsu, T. & Buchheim, W. (1980) The submicroscopic structure of processed cheese with different melting properties. Milchwissenschaft , 35, 479–481. Thomas, M.A., Newell, G., Abad, G.A. & Turner, A.D. (1980). Effect of emulsifying salts on objective and subjective properties of processed cheese. Journal Food Sci ence, 45, 458–466. Upadhyay, V.K., McSweeney, P.L.H., Magboul, A.A.A. & Fox, P.F. (2004) Proteolysis in cheese during ripening. Cheese: Chemistry, Physics and Microbiology (eds P.F. Fox, P.L.H. McSweeney, T.M. Cogan & T.P. Guinee), 3rd edn, vol. 1, pp. 391–433, Elsevier Academic Press, Amsterdam.

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USA National Archives and Records Administration (2008) US Code of Federal Regulations 2008. The Office of the Federal Register National Archives and Records Administration, Washington, DC. Available at www.access.gpo.gov/cgi-bin/cfrassemble.cgi?title=200 821. Vakaleris, D.G., Olson, N.F. & Price, W.V. (1962) Effects of proteolysis of natural cheese on body and melting properties of pasteurized process cheese spread. Journal of Dairy Science, 45, 492–494. van Vliet, T. & Dentener-Kikkert A. (1982) Influence of the composition of the milk fat globule membrane on the rheological properties of acid milk gels. Netherlands Milk and Dairy Journal , 35, 261–265. Walstra, P. & Jenness, R. (1984) Dairy Chemistry and Physics, pp. 162–185. John Wiley & Sons, New York.

4 Functionality of Ingredients: Emulsifying Salts J.A. Lucey, A. Maurer-Rothmann and S. Kaliappan

4.1 Introduction Processed cheese(s) was developed during the early part of the 20th century. There was interest in the development of a processing method that would extend the shelf-life of ‘natural’ cheese. In the absence of emulsifying salts, oiling-off and moisture exudation were observed during or after heating. Citrate was discovered to prevent this oiling-off and citrate helped produce a smooth and shelf-stable product. Later, phosphates and other salts were also found to be suitable for this purpose. In the USA the Code for Federal Regulations (CFR, 2003) (Pasteurized Process Cheese: 21 CFR 133.169; Pasteurized Process Cheese Food : 21 CFR 133.173 and Pasteurized Process Cheese Spread : 21 CFR 133.179) identifies 13 types of emulsifying salts that can be used in processed cheese manufacture, either singly or in combination with each other, and allows for the addition of up to 3 g 100 g−1 (of the emulsifying salts excluding the contribution from any water in hydrate forms of these salts). Emulsifying salts are sometimes called melting salts, and they are not true emulsifiers. Instead, the emulsifying salts disperse the insoluble caseins in the cheese curd, and these solubilised caseins can then act as emulsifiers and form the membrane layer around the liquid fat released during heating and shearing of natural cheeses. It is possible through careful cheese selection (e.g. processed cheese made from mostly aged cheese) to produce a processed cheese product without adding emulsifying salts (Price & Bush, 1974); however, it is very difficult to predict whether the blend of cheese will require emulsifying salts or not until it is processed. In addition, the texture can be mealy (Zehren & Nusbaum, 1992). True emulsifiers, e.g. low-molecular-weight surfactants, are not normally used in the manufacture of processed cheese as they produce weak emulsions, and oiling-off is observed during storage or heating (Zehren & Nusbaum, 1992). One exception is their recent use in nonfat processed cheese (Lucey et al., 2009). Casein hydrolysates have also been suggested as possible substitutes for emulsifying salts in processed cheesemaking (Kwak et al., 2002), and they would be able to emulsify the fat (i.e. reduce free oil formation) just like the solubilised caseins do in the cheese curd created by the action of emulsifying salts, but would not have the other functions of the emulsifying salts (e.g. calcium binding, protein hydration). Similarly, water-soluble caseinates could emulsify the fat if added during the manufacture of processed cheese; moreover, casein hydrolysates can impart bitter flavour. Food grade salts that have the ability to function Processed Cheese and Analogues, First Edition. Edited by A.Y. Tamime. © 2011 Blackwell Publishing Ltd. Published 2011 by Blackwell Publishing Ltd.

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as ion-exchangers, buffers, and Ca2+ sequestrants have been used as emulsifying salts, although only salts of citric and phosphoric acids are used commercially. The properties of the most common types of emulsifying salts are listed in Table 4.1. There have been a number of reviews on the properties of emulsifying salts used for processed cheesemaking (Palmer & Sly, 1944; Meyer, 1973; Thomas, 1973; Cari´c et al., 1985; Zehren & Nusbaum, 1992; Cari´c & Kal´ab, 1993; Berger et al., 1998; Guinee et al., 2004). However, Palmer and Sly (1944) listed the following properties that are required for an ideal emulsifying salt: • • • • •

The salt should be a powerful emulsifying agent capable of changing the molten cheese into a smooth, creamy, free-flowing emulsion, entirely free from oil separation. On cooling, this emulsion should solidify to a firm-bodied cheese with smooth texture and good slicing quality. The flavour of the cheese should not be adversely affected by the presence of the emulsifying salts. On storing the processed cheese, the emulsifying salts should not show any tendency to crystallise out. The emulsifying salts should be easily soluble, free of harmful impurities, and available at a reasonable cost.

4.2 Main types of emulsifying salts 4.2.1 Citrate Citrates are the salts of citric acid. In the nomenclature of the International Union of Pure and Applied Chemistry (IUPAC), citric acid is 2-hydroxypropane-1,2,3-tricarboxylic acid. Depending on the dissociation steps, citric acid forms citrates, hydrogen citrates and dihydrogen citrates. Citrate-based salts are obtained by replacing the acidic hydrogen atoms with cations from the tribasic citric acid. For example, neutralisation of H+ ions of citric acid with Na+ ions results in three types of salts: mono-, di- and trisodium citrate. Sodium citrate was the first emulsifying salt used to make processed cheese (Zehren & Nusbaum, 1992). From the processed cheese point of view, trisodium citrate (TSC) dihydrate (NaH2 C6 H5 O7 ·2H2 O) is one of the most important emulsifying salts. Citrate salts are water soluble, and their pH values range from around 3.8 to 8.2 for a 1 g 100 mL−1 solution, with an increase with pH with the greater replacement of H+ with Na+ . Monosodium and disodium citrates result in an acidic product and poor texture including oiling-off, so they are not used alone but might be used in blends to correct the pH of processed cheese (Thomas, 1973; Cari´c & Kal´ab, 1993; Fox et al., 2000). TSC dihydrate is a common choice of an emulsifying salt for processed cheese makers, and is often used for the manufacture of slices or sliceable blocks, but not spreads (Meyer, 1973; Zehren & Nusbaum, 1992). Other forms of citrates, such as potassium or ammonium citrates, were evaluated for use in the manufacture of low-sodium processed cheese (Karahadian & Lindsay, 1984). At high levels they tend to impart a bitter taste to the product (Gupta et al., 1984) that becomes more pronounced during storage (Thomas, 1973).

TSP

Na2 H2 P2 O7

SAPP ASPP

Sodium acid pyrophosphate

Acid sodium pyrophosphate

8.5

Na3 C6 H5 O7 · 2H2 O

Trisodium citrate dihydrate

a

75

High

15

12

6

12

9

85

Solubility at 20◦ C (g 100 g−1 )

XX

0/X

XX

XXX

XXX

XXX

XXX

XXX

Buffering abilitya

Approximate or practical experience ranks of these properties are as follows: 0, none; X, weak; XX, moderately strong; XXX, strong.

Source: data compiled from Lampila & Godber (2002) and Maurer-Rothmann & Scheurer (2005).

Citrates TSC

7.0

Na5 P3 O10 (NaPO3 )n

Sodium tripolyphosphate

STPP

9.8

4.2

10.2

12

9

4.4

pH of 1 g 100 g−1 solution

Sodium hexametaphosphate (Graham’s salt) SHMP

Polyphosphates

Disodium dihydrogen diphosphate

Tetrasodium pyrophosphate

Na4 P2 O7

Na3 PO4 ·12H2 O

Na3 PO4

Na2 HPO4 · 2H2 O

Na2 HPO4

NaH2 PO4

TSPP

Diphosphates (pyrophosphates)

Sodium phosphate tribasic

DSP-2

Trisodium phosphate dodecahydrate

DSP

MSP

Disodium phosphate dihydrate

Disodium hydrogen phosphate

Sodium phosphate dibasic

Disodium phosphate

Monosodium dihydrogen phosphate

Sodium phosphate monobasic

Monosodium phosphate

Orthophosphates

Acronym Chemical formula

Properties of the most common emulsifying salts used for the manufacture of processed cheese products.

Common names

Table 4.1

0/X

XXX

XX

XX

XX

0/X

0/X

0/X

Calcium-binding ability/ion exchangea

0

0/X

XX

XXX

XXX

0

0/X

0

Creaminga

112 Processed Cheese and Analogues

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4.2.2 Phosphate-based Ellinger (1972a,b) and Molins (1991) have reviewed the applications and properties of phosphates used in foods. Phosphates are the salts of phosphoric acid. A distinction is drawn between monomeric (single phosphate) and polymeric (multiple) phosphates. The monophosphates are also better known under the name orthophosphates. Polymeric phosphates are obtained from the acid orthophosphates through heat treatment and splitting off of the water of condensate, which is why they are called condensed phosphates. The polymeric phosphates can be subdivided into three groups: linear chain-forming polyphosphates, ring-forming metaphosphates and cross-linked ultra-phosphates. Ring-forming or cross-linked phosphates are not used in the manufacture of processed cheese. The linear chain-forming components can be distinguished in two groups, the short-chain and long-chain polyphosphates. For the manufacture of processed cheese, the most important emulsifying salts are the short-chain polyphosphates (diphosphates and triphosphates) and the long-chain polyphosphates (Graham’s salts), which are often (incorrectly) called hexametaphosphates. The real hexametaphosphates are ring-forming, and are not used in processed cheesemaking. Polyphosphates consist of a mixture of phosphates of different chain lengths formed during the production of these emulsifying salts. In most cases, glassy and non-crystalline compounds are obtained for the long-chain polyphosphates. The generic formula for polyphosphates is Mn+2 Pn O3n+1 where M stands for one equivalent of a metal ion, hydrogen, and so on (Van Wazer, 1973). For n = 1, this generic formula represents the orthophosphate; for n = 2, the pyrophosphate; and for n = 3, the tripolyphosphate. The solubility of some phosphates in water is listed in Table 4.1. It should be noted that some condensed phosphates are difficult to dissolve in solution at the maximum levels due to slow solubility and hydrolysis. For example, sodium tripolyphosphate (STPP) is one of the most poorly soluble sodium phosphates, and is also the slowest to dissolve (Lampila & Godber, 2002). Although long-chain polyphosphates have very high maximum solubility, the rate of dissolution can be slow.

Orthophosphates Phosphoric acid can form three sodium salts via the replacement of hydrogen with sodium (due to titration with NaOH). These salts are (a) monosodium dihydrogen phosphate (MSP), (b) disodium hydrogen phosphate (DSP), and (b) trisodium phosphate (TSP). All phosphates, from orthophosphates through to the polyphosphates, behave like highly charged anions. The orthophosphate ion is considered to be a tetrahedron in which the phosphate ion is surrounded by four oxygen atoms and it contains one strong acid function and two weak acids functions. When processed cheese manufacturers are trying to reduce the sodium content, the corresponding potassium salts are sometimes used. The sodium and potassium salts of orthophosphoric acid are soluble in water, and show distinct buffering properties. DSP is one of the main types of emulsifying salts used in the processed cheese industry, either alone or with combination of other salts (Zehren & Nusbaum, 1992). Orthophosphates are

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excellent buffers, and are mostly used to stabilise the pH of processed cheese. Monosodium and trisodium phosphates are used for the manufacturing of processed cheese mainly to correct the pH value. Condensed phosphates (short chain) The condensed short-chain (n = 2 or 3) phosphates used for the production of processed cheese are soluble in water. The strong buffering capacity of the orthophosphates decreases with increasing chain length of the polyphosphates. The condensed phosphates possess an excellent binding capacity for polyvalent cations. The long-chain polyphosphates behave like ion exchangers; they are also very efficient at causing protein solubilisation, and the soluble protein content in processed cheese increases with increasing polyphosphate addition (Lee & Alais, 1980). There are three short-chain condensed phosphates that are of technological relevance: sodium acid pyrophosphate (SAPP), tetrasodium pyrophosphate (TSPP) and sodium tripolyphosphate (STPP). Among the pyrophosphates (n = 2), TSPP is sometimes used in processed cheesemaking. TSPP is a neutral salt, and it readily complexes or precipitates alkaline earth metals including Ca2+ (Ellinger, 1972a,b). TSPP has the lowest water solubility at 20◦ C of any of the common types of the emulsifying salts used in the production of processed cheese (see Table 4.1) so care should be taken when TSPP is added during the manufacture of the product. If water is being added in the cheese mix, it is better to not add the TSPP at the same time. Among tripolyphosphates (n = 3), STPP is used in small amounts as high levels can produce astringency in food products (Ellinger, 1972a). Phosphates having more than three phosphorus atoms per chain are described as amorphous phosphates or polyphosphates. Glassy phosphates (linear, long chain) The technologically interesting glassy phosphates show an average degree of condensation of 4 to 25. The degree of condensation describes the number of phosphorus atoms (P) present per molecule on an average basis. The tetra-polyphosphate possess four P atoms in the chain; hence, the average degree of condensation is 4. Graham’s salt (sodium hexametaphosphate; SHMP) has an average degree of condensation of 10 to 25. Combinations of different glassy phosphates are used as emulsifying salts. The high-molecular-weight Madrell salt is very poorly water soluble. Depending on their chain length, polyphosphates have varying influence on the creaming of processed cheese (see section 4.3.4). Hydrolysis of condensed phosphates Orthophosphates are the starting material for the production of all condensed phosphates. The production of condensed phosphates involves significant heat to achieve the removal of water. This indicates that in the presence of water these condensed phosphates are thermodynamically unstable. All condensed phosphates (n ≥ 2) are subject to hydrolysis, where the phosphates revert back to simple orthophosphate compounds. The low-molecular-weight phosphates, including pyrophosphates, tripolyphosphates and

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tetrapolyphosphates, break down primarily through ‘end group’ hydrolysis (clipping) in which a terminal phosphate tetrahedron is cleaved from the tail. The hydrolysis of long-chain phosphates involves both clipping of the end groups to form orthophosphates and ‘random cleavage’ of the middle of the chain to form trimetaphosphates (McCullough et al., 1956). The velocity of hydrolysis depends on the concentration of phosphate, temperature, pH and the presence of divalent cations (Ca2+ acts as catalyst) (Shen & Morgan, 1973). Under acidic conditions, polyphosphates hydrolyse rapidly, and they are stable in neutral and weak alkaline pH at room temperature (Corbridge, 1980). The overall polyphosphate degradation rate increases with an increase in the polyphosphate chain length, but approaches a limiting value after the chain length is about 10 (Shen & Morgan, 1973). The hydrolysis rate usually increases with temperature, but may be negligible at ambient temperature. Only at higher temperatures (>60◦ C) is a significant hydrolysis of the polyphosphates observed (MaurerRothmann & Scheurer, 2005). It should be noted that most hydrolysis rates reported in the literature are obtained from (dilute) aqueous solutions. In practice, it is likely that the hydrolytic breakdown is low in most processed cheese applications (Maurer-Rothmann & Scheurer, 2005). The rate of hydrolysis in processed cheese probably depends on processing temperature, pH, water content, Ca2+ concentration and storage temperature. Other types of phosphate-based emulsifying salts Although the potassium salts of phosphoric acids are more soluble than the corresponding sodium salts, they are not commonly used in processed cheesemaking as at high levels they impart a bitter taste to the product. Sodium aluminium phosphates (SALP) (Na15 Al28 (PO4 )8 ·H2 O) is sometimes used in the production of processed cheese, but is more commonly used in the manufacture of imitation/analogue cheeses. SALP can be used at the maximum 3 g 100 g−1 level in processed cheese, and does not exhibit crystal development. Other forms of phosphates, such as ammonium phosphates, glycerol-phosphates and sodium magnesium phosphate, have also been tried in processed cheesemaking (Zehren & Nusbaum, 1992).

4.2.3 Other types of emulsifying salts There have been reports that tartrates, the salts of tartaric acid (IUPAC name: 2,3dihydroxybutanedioic acid), the lactates, and the salts of lactic acid (IUPAC name: 2-hydroxypropanoic acid) have been tried as emulsifying salts. As it is not possible to produce acceptable processed cheese quality from tartrates due to the formation of crystals in the product during storage, these types of emulsifying salts are no longer used (Zehren & Nusbaum, 1992). Tartaric acid from wine, added as an ingredient, acts as a calcium-sequestering agent in Swiss cheese fondue. Sodium potassium tartrate (Rochelle salt) was also tried as an emulsifying salt in the production of processed cheese, but abandoned due to texture defects and propensity to develop sandiness. Sodium salts of trihydroxyglutaric acids have been used alone or in combination with other emulsifying salts, and have been reported to produce processed cheese with good consistency (Thomas,

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1973). Diglycolic acid and its salts have also been suggested as possible emulsifying salts (Thomas, 1973).

4.3 Properties and roles of emulsifying salts used in processed cheese Emulsifying salts have the ability to influence several critical events, such as Ca2+ binding, pH adjustment, casein dispersion and fat emulsification, and structure formation in the manufacture of processed cheese. The effects of the emulsifying salts on these interrelated events are reflected in the functional properties of processed cheese, and thus form the criteria for the selection of a particular type of emulsifying salts. Although the detailed chemistry of emulsifying salts in the production of processed cheese is not fully understood, the various roles of these salts are summarised in the following sections. Some of the possible reactions occurring during the manufacture of processed cheese are shown in Fig. 4.1.

4.3.1 Calcium binding/ion exchange Both orthophosphates and polyphosphates form soluble complexes with metal ions. The orthophosphate complexes are very weak for the alkali and alkaline earth metals, and only become important for transition metals such as iron (Van Wazer, 1973). Polyphosphates form relatively strong complexes with the alkali and alkali earth metal as well as transition metals (Van Wazer, 1973). This metal-binding capacity increases with increasing chain length. It is thought that an ideal emulsifying salt combines a monovalent/divalent cation with a polyvalent anion (Thomas, 1973; Cari´c & Kal´ab, 1993). The Ca2+ binding by Fat emulsification Casein dispersion

Possible creaming

Casein aggregation and gel formation

Ca2+ chelation Holding Temp. Heating

Cooling

Addition of ES Shearing Time Fig. 4.1 Schematic illustration of possible reactions occurring during the manufacture of processed cheese; creaming may only occur for some type of processed cheeses. ES, emulsifying salts.

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117

an emulsifying salt is governed by a competing equilibrium between soluble complex formation and insoluble precipitate as shown. Ca2+ + emulsifying salts ⇔ Ca2+ − emulsifying salts complex ⇔ Ca2+ − emulsifying salts precipitate The resulting reaction product (i.e. Ca complex or precipitate) stability is a function of its solubility product (Van Wazer & Callis, 1958). The effectiveness of emulsifying salts in binding Ca2+ depends on valency, type of ionic species forming the emulsifying salt, pH, ionic strength, temperature, etc. Sodium orthophosphates ionise completely even at high concentrations, whereas the ionisation of polyphosphates decreases with increasing chain length (Batra, 1965). The salts of monovalent cations are more capable of dispersing caseins than those of multivalent cations, and the ability to bind Ca2+ increases with the valency of the anion. It is generally considered that phosphates have better Ca2+ -binding ability than citrates, and their binding ability is strongly influenced by pH, particularly for short-chain phosphates. However, the complexing ability is dependent on the number of moles of phosphorus present, and is not a function of chain length (Van Wazer & Callis, 1958). According to Van Wazer & Callis (1958), the Ca-complexing ability of emulsifying salts (on a similar molar basis) increases in the order orthophosphate < citrate < pyrophosphate < hexametaphosphate. However, the Ca2+ complexing trends seen in pure solution of a single emulsifying salt might be different when mixtures of salts are used in a complex cheese system. It has been reported that the level of Ca2+ ions needed to form Ca-phosphate precipitates increases with increasing chain length (Batra, 1965; Ellinger, 1972a). The Ca2+ -binding ability of orthophosphates is limited below pH 6 and, in the vicinity of pH 6, calcium phosphates are formed. For the long-chain polyphosphates, this function is better described as ion exchange, as the monovalent sodium ions of the polyphosphates are exchanged by Ca2+ ions from the cheese curd. The divalent cations are bound significantly stronger than the monovalent ions of the polyphosphate. SHMP is widely used to remove Ca2+ from hard water without forming the insoluble sediments that occur with the use of emulsifying salts like TSP (Zehren & Nusbaum, 1992). In natural cheeses like Cheddar, the majority of the residual calcium in the product is associated with the caseins (Hassan et al., 2004), although the exact proportion depends on the age and cheesemaking conditions. The addition of emulsifying salts presumably results initially in the complexation of calcium present in the serum phase and, then if sufficient emulsifying salts is added, the calcium associated with the casein is removed. TSC is unable to form some type of Ca–citrate cross-link with the caseins in processed cheese; rather it forms insoluble complexes (possibly even tiny crystals) that can be hard to extract from the matrix of the product (Shirashoji et al., 2006). Pyrophosphate can form casein/calcium/pyrophosphate complexes (Zittle, 1966; Vujicic et al., 1968; Mizuno & Lucey, 2005, 2007), and probably this helps cross-link the network in processed cheese (Zehren & Nusbaum, 1992). SHMP binds Ca2+ from the native colloidal calcium phosphate, which disperses the casein micelles, but these new calcium phosphates can associate with the dispersed caseins (Mizuno & Lucey, 2005) and probably a similar mechanism occurs in processed cheese. Cari´c et al. (1985) indicated that the use of emulsifying salts

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Processed Cheese and Analogues

increased the proportions of insoluble calcium and phosphorus in processed cheese compared with the initial natural cheese.

4.3.2 pH adjustment, buffering and titration behaviour In processed cheese manufacture, the final product pH is related to the pH and buffering ability of the particular emulsifying salts used as well as the added amount. For processed cheese, the pH value is important for several reasons: it affects the protein configuration, solubility, and the extent to which emulsifying salts bind Ca2+ (Cari´c & Kal´ab, 1993). The emulsifying salts used in the production of processed cheese are generally basic in nature, and their use results in an increase of pH from natural cheese (∼5.2) to pH ∼5.6–6.0. The pH of processed cheese generally increases linearly with the emulsifying salts concentration, especially if the salt type is alkaline in nature (Cari´c & Kal´ab, 1993). For consistent processed cheese performance, the pH of the finished cheese should not vary more than ±0.05 pH units from the target pH (5.6–6.0). The buffering capacity of TSC is in the pH range 5.3–6.0, but its addition to cheese usually only results in a small pH increase (<0.4 pH units at the 3 g 100 g−1 usage level) (Zehren & Nusbaum, 1992). The orthophosphates and pyrophosphates possess high buffering capacities in the pH ranges 2–3, 4.5–9.0 and 10–12 (McCullough, 1973). In orthophosphates, the replacement of hydrogen with sodium results in an increase in the pH of a solution of this emulsifying salt, and also increases the pH of the processed cheese made from this salt (Fig. 4.2). The buffering capacity of the sodium polyphosphates decreases with increasing chain length, and is effectively zero for the longer chain

pH of processed cheese

7.5

7.0

6.5

6.0

5.5

5.0 MSP DSP

TSP TSPP SAPP STPP SHMP TSC Types of emulsifying salts

Fig. 4.2 Impact of type of emulsifying salt on the pH of processed cheese. Approximately 2.2 g 100 g−1 of emulsifying salt was used in each case. MSP, monosodium phosphate; DSP, disodium phosphate; TSP, trisodium phosphate; TSPP, tetrasodium pyrophosphate; SAPP, sodium acid pyrophosphate; STPP, sodium tripolyphosphate; SHMP, sodium hexametaphosphate; TSC, trisodium citrate. (Data redrawn from Gupta et al., 1984. Reproduced by permission of the Journal of Dairy Science.)

Functionality of Ingredients: Emulsifying Salts

119

Haedness (force at 80% compression, N)

phosphates (n > 10). For example, the use of SHMP alone in processed cheese results in low-pH cheeses since this emulsifying salt has minimal buffering ability, and the pH of the product is similar to the initial raw material (Fig. 4.2; Gupta et al., 1984). To correct (increase) the pH, another type of emulsifying salt should be blended with SHMP. This decrease in buffering capacity with chain length is due to the corresponding reduction in the number of weak acid functions per molecule (McCullough, 1973). An increase in the pH of processed cheese increases the net negative charge on the caseins, and increases the electrostatic repulsion in the casein matrix. The increased charge repulsion at high pH should result in a more open and looser processed cheese network with better water-binding capacity and emulsifying ability during the manufacture of the product (Marchesseau et al., 1997; Fox et al., 2000). Moreover, with an increase in pH, the hydrophobic interactions between individual casein molecules should decrease as there is an increase in electrostatic repulsion (Horne, 1998; Lucey et al., 2003). In processed cheese production, a complex situation was observed for the impact of pH on the firmness of the product made with various types of emulsifying salts. Lu et al. (2008) made processed cheese with various different types of emulsifying salts, keeping the amount of salts constant (2 g 100 g−1 ), and independently varied the pH of the final product. In addition, the same authors also reported that at pH 5.3 and 5.6, processed cheese made with DSP decreased in hardness with an increase in pH, whereas the product made with TSC increased in hardness; there were no differences in the hardness of processed cheese made with TSPP or SHMP over this pH range (Fig. 4.3). Several processed cheeses (made with TSPP, SHMP and DSP) exhibited an increase in hardness with an increase in pH from ∼5.6 to 5.9.

TSC

65.0

SHMP

TSPP

DSP

b, C b, F f, FG

60.0 d, G

ef, B 55.0

a, AB

e, D c, A

g, A

c, D i, H

50.0 h, E 45.0

40.0

5.3

5.6 pH of processed cheese products

5.9

Fig. 4.3 Hardness of processed cheeses made with different types of emulsifying salts (2 g 100 g−1 ) with different pH values. The data represents means (n ≥ 4) while the error bars represent standard deviations. Different lower case letters indicate significant differences (P < 0.05) between pH values for the same type of emulsifying salt. Different capitalised letters indicate significant differences (P < 0.05) between different types of emulsifying salt at a single pH value. For abbreviations (TSC, SHMP, TSPP and DSP) refer to Fig. 4.2. (After Lu et al., 2008. Reproduced by permission of John Wiley & Sons.)

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Processed Cheese and Analogues

Processed cheese made with very low pH values tends to be crumby and have low-melt. The pH of most processed cheese samples is usually between 5.5 and 6.0. As the pH of cheeses in the blends used for manufacture of processed cheese can show considerable variation, the emulsifying salt has to be able to correct and stabilise the pH at the desired value. Often a combination of emulsifying salts or commercial blends, such as JOHA and SOVA, are necessary. Orthophosphates and condensed phosphates contain one strong acid or ionised group (hydrogen atom) per phosphorus atom. Moreover orthophosphates contain one weak acid function (there is another weak acid group, but it is too weak to be titrated) (McCullough, 1973). The phosphate units at the ends of a polyphosphate chain are called end groups, and they share one oxygen atom with the adjacent phosphate unit. Each of the other phosphate units of the polyphosphate chain is called a middle group; they share two oxygen atoms with adjacent phosphate units and each unit has one strong acid function (McCullough, 1973). It should be noted that cations like Ca2+ greatly interfere with the pH titration behaviour of phosphates as they can form insoluble calcium phosphates especially around pH 6 (Visser, 1962).

4.3.3 Casein dispersion, protein hydration and fat emulsification Cooking and shearing help reduce the viscosity of the processed cheese mix; these processes help to produce a homogeneous smooth fluid mass (Fig. 4.4a). In contrast, processed cheese made without emulsifying salts exhibit considerable oiling-off and a rough texture (Fig. 4.4b). Heating also destroys microorganisms and helps to dissolve the emulsifying salts. Fast heating has been reported to yield a more fluid product (Thomas, 1973). Casein dispersion, caused by the mechanical and thermal energies applied to the cheese mass, is another important event during the manufacture of processed cheese (Glenn et al., 2003). After the caseins become dispersed, the fat is emulsified by these solubilised caseins and, during cooling, a new cheese matrix is formed. Dispersion (solubilisation, peptisation or swelling) of the caseins is caused by two main factors: (a) chelation of Ca2+ from the casein-bound calcium phosphate by the emulsifying salt, which removes calcium phosphate cross-links and exposes charged phosphoserine residues thus increasing charge repulsion between the casein particles; and (b) increase in pH due to the addition of the emulsifying salts, which increases charge repulsion between caseins. Casein dispersion during cooking is therefore very dependent on the type and concentration of the emulsifying salts used. In practice, casein dispersion can be increased by increasing the concentration of the emulsifying salts used in processed cheese, and this results in increased final product hardness because after cooling this highly dispersed material produces a finer and harder matrix (Shirashoji et al., 2006). Different studies have tried to quantify casein dispersion by various methods. Thomas et al. (1980) measured the water-soluble nitrogen content whereas Lee et al. (1980) and Dimitreli et al. (2005) measured it as casein peptisation, which was the ratio of soluble casein nitrogen (measured after ultracentrifugation at 300 000 g for 45 min at 20◦ C) to total casein content. The levels of water-soluble nitrogen and casein peptisation have been related to the effectiveness of different emulsifying salts in promoting emulsification of the fat content by casein (Guinee et al., 2004). Orthophosphates and TSC have been reported

Functionality of Ingredients: Emulsifying Salts

(a)

121

(b)

(c)

Fig. 4.4 Some properties of processed cheese. (a) Typical process cheese made with emulsifying salts: no oiling-off and a smooth appearance. (b) Processed cheese made without any emulsifying salt: considerable oiling-off occurs. (c) Processed cheese that has been over-creamed: the structure is brittle and crumbly. (Reproduced courtesy of Nobuaki Shirashoji, Morinaga Milk Industry Co. Ltd., 1-835 Higashihara Zama, Kanagawa 288-8583, Japan.) (See Plate 4.1 for colour figure.)

to have a very poor casein-dispersing ability compared with pyrophosphates or longerchain phosphates (Lee et al., 1986; Molins, 1991; Dimitreli et al., 2005; Mizuno & Lucey 2005). Dispersion increases with an increase in pH (Lee et al., 1986). Processed cheese contains a considerable amount of solubilised proteins, presumably some proteins that were solubilised during heating and reassociated during cooling, but the remainder stays in the serum phase (Thomas et al., 1980). Protein dispersion helps to increase moisture absorption. The highly charged anionic nature of polyphosphates causes them to be attracted to, and to orient themselves along, the positively charged sites of other long-chain polyelectrolytes, such as proteins (Van Wazer & Callis 1958). This should increase the charge repulsion between the caseins at pH values above their isoelectric point (i.e. all processed cheese samples), and thus increase their solubility. For example, SHMP is widely used to increase protein hydration. The use of polyphosphates in processed cheesemaking has been reported to cause the formation of protein strands (Cari´c & Kal´ab, 1993).

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Fat emulsification can be increased by using very high speed shearing (e.g. Stephan-type cookers) or homogenisation, and this increases the viscosity of the processed cheese (e.g. useful in spreads). The fat globules in milk are surrounded by membrane proteins and, unless homogenised, fat acts as an inert filler in milk gels and cheese. Homogenisation increases the consistency of acidified milk products as the proteins on the newly created fat particles become an active part of the casein gel network. Increasing the homogenisation treatment greatly increases the surface area of protein-stabilised fat globules, and probably a similar situation occurs in processed cheese. Homogenisation also limits the mobility of the casein strands/clusters, which restricts melt (Lucey, 2008). Cooking time also has been reported to influence the textural properties, and the size of fat droplets in processed cheese decreases with an increase in the cooking time (Rayan et al., 1980). In natural cheeses like Cheddar and Swiss (which are popular raw materials for processed cheesemaking), a considerable amount of the water in the cheese is loosely bound, and can be expressed by hydraulic pressure (called ‘juice’) (Lucey & Fox, 1993). The amount of expressible water decreases during ripening due to mineral equilibria shifts and proteolysis, which creates new charged groups. In contrast, Shirashoji et al. (2006) reported that it was only possible to express a small quantity of juice when very low levels of emulsifying salts were added in processed cheese, i.e. when the cheese had not been completely dispersed and emulsified. This indicates that in processed cheese the dispersion of casein and chelation of the indigenous calcium phosphate alters the state of water, and reduces the amount of highly mobile water relative to natural cheese.

4.3.4 Creaming and structure formation during cooling and storage During the manufacture of processed cheese, the addition of emulsifying salts and cooking causes the dispersion of the caseins (due to Ca2+ chelation), and the system has a fluid pourable consistency (low viscosity). The complete dissolution of the original structure in the cheese blend is accompanied by a significant change in viscosity (first, a viscosity increase through water uptake into the casein network, and later a decrease in viscosity during the heating process due to weakening of protein interactions). A point is reached in the cooking process where the caseins are as dispersed as they can be under the specific conditions (i.e. pH, amount/type of emulsifying salts, temperature, etc.) of the manufacture of processed cheese. However, processed cheese manufacturers have noted that the prolongation of cooking time and the use of particular types of emulsifying salts may cause an increase in the viscosity of the melted cheese after some cooking time, which is the so-called ‘creaming’ or creaming reaction (Zehren & Nusbaum, 1992). It is known that the creaming reaction affects the characteristics of the final product (Berger et al., 1998). Excessively long cooking time can result in the formation of a pudding-like gel of melted cheese mass in the cooker (i.e. over-creaming) or a crumbly and dry texture in the final product (Fig. 4.4c); both are considered defects. TSPP is known to promote creaming, and care must be taken in its use in processed cheese to avoid over-creaming. It is well known that TSPP is very effective at dispersing caseins in milk systems, and under certain conditions can cause gelation even at pH > 6 (Mizuno & Lucey, 2007). Probably,

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123

in processed cheese a similar phenomenon might occur, i.e. TSPP initially causes extensive rapid casein dispersion and then promotes slow casein aggregation/gelation. Panouill´e et al. (2003) observed that heat-induced aggregation of the casein micelles could occur in the presence of sodium polyphosphates, and that this aggregation was dependent on the concentration of casein and pH. Some studies (Shimp, 1985; Berger et al., 1998) have suggested that the creaming reaction only occurs in the presence of the fat in the cheese. Conversely, in a recent study, Lee et al. (2003) showed that the creaming reaction could also be observed in a fat-free process cheese analogue. SHMP has been reported to have a very slow creaming effect (Meyer, 1973). Originally, it was thought that ‘over-emulsification’, or the creation of an excessive amount of new fat surface area that was covered by casein, was involved in the formation of hard cheese (Shimp, 1985). Lee et al. (2003) suggested that during cooking protein–protein associations occur via their exposed non-polar groups, and these protein interactions caused creaming and firm cheese. Shirashoji et al. (2006) observed during the holding (without shear) of processed cheese made with ≥1.5 g TSC 100 g−1 at 80◦ C that there was a decrease in the loss tangent (an increase in the elastic character) and an increase in the storage modulus or stiffness (loss tangent and storage modulus are parameters measured using small amplitude oscillatory rheology). Shirashoji et al. (2006) also reported that if a very low TSC concentration was used (0.25 g 100 g−1 ) then the processed cheese was under-emulsified, and that the hot product did not have a high loss tangent or increase in storage modulus during holding. This suggests that if insufficient emulsifying salt is added during the manufacture of processed cheese to adequately disperse the caseins, then the fat is poorly emulsified and little creaming is observed. Udayarajan et al. (2005) suggested that the increase in storage modulus value and decrease in loss tangent of natural Cheddar cheese during holding at high temperature was due to heat-induced formation of additional Ca phosphate cross-links between the caseins as Ca2+ phosphate has inverse solubility. If this protein association or creaming proceeds too far, then a network can be formed because the system is still being sheared and the texture will be disrupted. During cooling, there is association of the caseins via hydrogen bonding. The type of structure and number of interactions formed during cooling depends on degree of dispersion, possible cross-linking of casein by new Ca phosphate complexes (e.g. with the use of TSPP or polyphosphates) and the cooling conditions. Slower rates of cooling result in ˇ etina, 2003) because there is more time for firmer products (Thomas, 1973; Piska & Stˇ the caseins to rearrange and find the most optimum aggregation conditions that minimise charge repulsion between particles at the pH value of the cheese (e.g. 5.8). Rapid cooling is sometimes used for spreads if they have been subjected to severe creaming reaction to prevent the formation of an over-creamed product (i.e. a pudding-like texture) whereas slow cooling is used for blocks to help build firmness (Meyer, 1973). Citrates do not show much influence on the creaming of processed cheese. Orthophosphates do not possess any creaming effect; however, this can be balanced out by mechanical shearing and the addition of rework. TSPP is usually not used alone as an emulsifying salt in processed cheese as it results in a hard texture and can cause over-creaming or thickening during cheese manufacture (Meyer, 1973). High moisture processed cheeses

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require more creaming than low moisture products. This is because there is less protein available to bind fat and water in high moisture product.

4.3.5 Antimicrobial activity Citric acid is generally not used as an antimicrobial agent in foods although it has been shown to possess activity against some moulds and bacteria (Davidson et al., 2002). Probably, the mechanism of inhibition by citrate is likely to be related to its ability to chelate metal ions. Many non-starter lactic acid bacteria can ferment citrate, and may produce gas as an end-product if they contaminate the product post-heat treatment. Orthophosphates have relatively poor antimicrobial activity due to their low-metal chelating ability (Davidson et al., 2002). Pyrophosphates and polyphosphates have been shown to inhibit many Gram-positive bacteria, which are more susceptible than Gram-negative bacteria. Tanaka (1982) and Tanaka et al. (1986) demonstrated that DSP along with sodium chloride, water activity, water content, pH and lactic acid all interacted to prevent the outgrowth of Clostridium botulinum in full-fat processed spreads. The statistical models developed by Tanaka and co-researchers have been widely adopted by processed cheese manufacturers and regulators (e.g. Food and Drug Administration, FDA) to indicate/predict whether specific formulations will prevent the outgrowth of C. botulinum. Ter Steeg and Cuppers (1995) have attempted to account for safety differences in reduced-fat processed cheese spreads as well as products that used citrate as an emulsifying salt. Eckner et al. (1994) showed that toxin production by C. botulinum occurred much sooner in processed cheese made with DSP compared with polyphosphate. Long-chain polyphosphates at levels ≤1% inhibited the growth of C. tyrobutyricum in processed cheese (L¨ossner et al., 1997). The mechanism of inhibition of bacteria by polyphosphates is likely to be related to its ability to chelate metal ions from binding sites on the cell walls of microorganisms, while there has also been some indications that polyphosphates may interfere with RNA function and metabolic activities of bacterial cells (Ellinger, 1972b). Spore-forming bacteria, for example C. botulinum, are a concern in processed cheese because they survive heat processing, and heating may activate the spores. Microbiological safety of processed cheese has traditionally relied on heat to destroy vegetative pathogens, the specific formulation (e.g. pH and NaCl content) to prevent growth of surviving heat resistant spore-formers, and refrigeration to prevent growth of any re-contaminating bacteria. Some processed cheese products are stored at ambient temperature, and this obviously increases the microbial safety concerns of this low-acid food product.

4.3.6 Crystal formation and other properties of emulsifying salts The other possible effects of emulsifying salts on processed cheese include flavour and colour. Sometimes phosphates can impart soapy and bitter flavours to the product. Citrates can have a negative influence on the colour and appearance of the product. Potassium salts can impart bitter or chemical flavour notes if too much is added as a sodium substitute. Possible factors that may contribute to crystal formation by emulsifying salts in processed cheese are listed in Table 4.2. However, processed cheese made with citrate (alone or with DSP) can be marbled with noticeable surface crystals (‘bloom’ or ‘haze’) that

Functionality of Ingredients: Emulsifying Salts

Table 4.2

125

Crystal formation in processed cheese including some causes and possible remedies.

Cause

Action

High pH in process cheese promotes crystal development

Reduce concentrations of DSP or TSP (at high pH phosphate crystals are more likely to form, so need to lower the concentration of orthophosphate added) Reduce citrate concentration Reduce long-chain polyphosphate concentration Use natural cheese with lower pH value

Undissolved emulsifier during cooking

Use solutions of emulsifier instead of dry salt Provide sufficient mixing to disperse emulsifier Use emulsifiers with more rapid hydration Provide formulas with added water to allow ease of dissolution of the emulsifiers Check emulsifier grind size for variation

Very high cooking temperatures (heat-induced calcium phosphate)

Reduce cook temperature and time Change type of emulsifier used

High orthophosphate levels causing crystals

Do not exceed a ratio of 4 parts orthophosphate to 1 part water Check ingredients for unaccounted sources of orthophosphate Avoid long holding times during refrigerated (months) storage, which cause hydrolysis of polyphosphates Avoid long holding times during heating (hours), which cause hydrolysis of polyphosphates Avoid cheese with poor emulsifying properties (e.g. such as a combination of extreme parameters like cheese with low moisture, low-fat, high pH, and high salt) Avoid surface sweating on cheese from humid rooms when handling cooled finished blocks; if unavoidable, then lower orthophosphate level as much as possible Switch from loose fitting packaging to tightly adherent packaging Do not allow cheese to warm more than 1.5◦ C with loose outer wrap if it is then placed into cooler that allows for condensation on the inside of the package Avoid low temperature storage, which causes low solubility

TSPP crystals

When adding TSPP, make sure it is finely dispersed and do not allow the TSPP to contact free water (TSPP will ‘shell’ when contact with water from exothermic heating causing fusion with TSPP and water)

Calcium citrate crystals

Avoid a situation where process cheese is produced with a low degree of protein hydration Avoid cheese with poor emulsifying properties (e.g. such as a combination of extreme parameters like cheese with low moisture, low-fat, high pH, and high salt) Reduce citrate levels when the level of natural cheese-based casein modification is low, and if formulated with a dried dairy ingredient that has high casein content and high casein-associated calcium content (such as milk protein concentrate or rennet casein) Avoid excessive acidification when preparing the blend or prior to cooking (solubilises calcium) Decrease or remove sources of surface deformation or ‘scuffing’

Exceeding the 85/15 ratio for blends of orthophosphates and citrates

The processed cheese industry in the USA often uses an 85/15 rule of thumb when using blends of citrates and orthophosphate; this rule suggests that no more than 15 g 100 g−1 of the other type of emulsifying salt should be mixed in a blend During conventional processing using orthophosphate and citrate emulsifiers together (moderate shear, not exceeding 95◦ C, and using total emulsifier concentrations of 2–3 g solids 100 g−1 ) the citrate or the orthophosphate solids should not drop below 85 g 100 g−1 of the total emulsifier solids (continued)

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Processed Cheese and Analogues

Table 4.2

(Continued)

Cause

Action

Calcium tartrate crystals

Avoid using tartrates such as sodium potassium tartrate (Rochelle salt) as they are prone to exhibiting sandiness

Lactose crystallisation

Reduce lactose to water concentrations to below 16 g 100 g−1 Prevent frozen water in the cheese; if unavoidable, then reformulate the lactose to water percentages to below 10 g 100 g−1

Tyrosine crystals

Avoid use of sandy cheese, with tyrosine crystals, as that could provide ‘seeding’ for emulsifier crystals Limit or remove cheese with excessive tyrosine crystals Filter hot cheese if unavoidable

Sorbic acid

Do not exceed 0.4 g 100 g−1 in the finished formula; maximum permitted level in processed cheese is 0.2 g 100 g−1 ; use potassium sorbates as they have very high water solubility

Source: adapted from Milani & Lucey (2009). DSP, disodium phosphate; TSP, trisodium phosphate; TSPP, tetrasodium pyrophosphate.

have been identified as tricalcium citrate tetrahydrate (Scharpf & Kichline, 1969). Calcium citrate crystals have been observed even when TSC was added as the minor fraction of an emulsifying salt blend with mostly orthophosphate, e.g. 2.3 and 0.6 g 100 g−1 of sodium phosphate and sodium citrate, respectively (Scharpf & Kichline, 1969). The use of a very high total emulsifying salts concentration (close to 3 g 100 g−1 ) results in the dissolution of all the original protein-bound calcium in raw material cheese. In cheeses that had a high Ca content it could result in a large increase in the various calcium complexes in the serum phase. The calcium citrate (created by the action of the emulsifying salt blend) may become supersaturated in the serum and crystallise. It has been claimed that 50% more TSC is needed for the manufacture of a satisfactory processed cheese compared to the levels required by polyphosphates (Meyer, 1973). If polyphosphates were used instead of orthophosphates less crystals may be observed as the polyphosphates associate with caseins, and may not cause as great an elevation of the concentration of calcium complexes in the serum phase. Scharpf & Kichline (1968) studied the formation of phosphate crystals in processed cheese, and developed statistical models that predicted the amount of orthophosphates that could safely be added to the cheese blend without crystal formation for a range of pH values. Due to the alkaline nature, the concentration of orthophosphate added as an emulsifying salt should be reduced to lessen the risk of crystal formation that is encouraged by the high pH. The main crystal species they observed was disodium phosphate dodecahydrate (Scharpf & Kichline, 1968), but calcium may also be involved in these crystals (Meyer, 1973). TSPP has a low solubility and may not dissolve completely during the manufacture of processed cheese (Rayan et al., 1980). TSPP may recrystallise after processing (if the addition level is too high or if the emulsifying salt did not hydrate adequately) causing the formation of large lumps, Ca pyrophosphate crystals and the discoloration of the cheese in the vicinity of the crystals (Templeton & Sommer, 1936; Thomas, 1973; Pommert et al., 1988). Calcium complexes formed with polyphosphates may also have a higher solubility than the disodium phosphate dodecahydrate (calcium) crystals that are usually formed with the use of DSP.

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Presumably, an increase in the water content of processed cheese would reduce the risk that the cheese serum would become supersaturated with disodium phosphate dodecahydrate. Thus, higher moisture processed cheese products (e.g. spreads) can tolerate higher usage rates for DSP. A distinction can be made between surface crystals and crystals that form throughout the cheese. Surface crystals are encouraged by a loose package, presence of air, water condensation inside the package, imperfections of the surface, and temperatures variations. The growth of surface crystals is accelerated by moisture movement, which can be caused by storage temperature fluctuations. Crystals that form throughout a block of processed cheese indicate that the serum phase is supersaturated in that species. The development of crystals throughout a block of the product is encouraged by excessive use of an emulsifying salt that is prone to crystal formation (e.g. DSP), presence of ‘seed’ materials (e.g. undissolved emulsifying salt), pH values at or above 6 for calcium phosphate crystals, and low storage temperatures as the solubility of many salts (and lactose) decreases at low temperature. Calcium tartrate crystals, which are sandy, frequently develop when tartrates are used as an emulsifying salt, and this has contributed to their lack of use in processed cheesemaking (Sommer, 1930). Sometimes, crystals dissolve during storage leaving behind an open hole filled with serum (Meyer, 1973).

4.4 Selection of emulsifying salt A range of factors are usually considered when trying to select a particular type of emulsifying salt. •

•

•

Age of the cheese: more emulsifying salt is needed for young natural cheese because it contains high level of unhydrolysed (often called ‘intact’) casein content. Young cheese also has a higher insoluble calcium content (i.e. bound to protein) compared to aged cheese (Hassan et al., 2004). In addition, young cheese provides firmness/body to the processed cheese, and an increase in the proportion of aged cheese in a blend may require a change in the type of emulsifying salt in order to maintain a firm body. Composition of the cheese: for the same moisture content, a higher level of fat (i.e. lower protein content) requires less emulsifying salt. Low-fat cheeses need stronger ion exchange (e.g. more emulsifying salt or a stronger Ca2+ -binding type) than higher fat cheeses due to the high protein content in low-fat cheese. Cheeses with higher calcium content and higher pH values will tend to produce firmer processed cheese (Olson et al., 1958) unless the processing conditions, including the level of emulsifying salt added, are varied. Cheese with very low pH (e.g. 4.95) tends to produce short- and weak-bodied processed cheese whereas high pH cheese (>5.2) produces a curd that can be difficult to process. The type and amount of emulsifying salts can be used to regulate the final pH of the processed cheese, although it is more difficult to solve the textural defects caused by natural cheese with abnormal pH values. Re-work : the amount of re-work to be used (i.e. leftovers from previous runs, breakdowns, trim from making the ribbons from chill rollers, etc.). Usually there is limit to how much re-work can be used in a formulation. There have been some reports that

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larger amounts of re-work can be used in processed cheese if the re-work is treated with surface active agents (true emulsifiers) (Lauck, 1972). Type of process cheese: blocks, slices, spreads, sauce or analogue/imitation require different types of emulsifying salt to be added in the formulation. Target characteristics: brittle, firm, soft, sliceable, melting, non-melting, peelability of slices and/or string formation in the product are controlled by the type of emulsifying salt used. Target composition: pH, milk protein level, and level of non-dairy solids dictates what type of emulsifying salt should be used. Manufacturing conditions: mixing, cooking time/temperature, batch or continuous cooking, temperatures and times involved in operations like pumping, cooling and packaging dictate what type/blend of emulsifying salts should be used. Cost of the emulsifying salts: usually these salts are cheaper than cheese solids so processed cheese manufacturers might want to try to add as much emulsifying salt(s) as possible, but there is a risk of crystallisation as well as maximum permitted levels by regulations. Unique (propriety) requirements for each product: there is a strong creaming reaction required for processed cheese spread. Often blends of emulsifying salts are used as no one type of salt can fit every need.

In general, with the same level of usage, polyphosphates produce harder, non-melting cheese; while weaker calcium binders, such as orthophosphates like DSP and TSC, produce softer, easy to melt cheese. MSP and TSP are usually used in combination with other phosphates to adjust cheese pH. MSP makes crumbly processed cheese that easily oils off. Advantages to processed cheese made with DSP include an emulsifying salt that easily dissolves in cookers as well as having good flavour and melt/flow. DSP also has some bacteriostatic effects. The disadvantage of DSP is the strong potential for crystal formation due to the low solubility of this type of emulsifying salt. DSP, alone or with TSP, is often used in the manufacture of processed cheese blocks at usage levels <1.8 g 100 g−1 (Toy & Walsh, 1987); however, higher DSP levels can be used in processed cheese spreads due to the higher moisture content in the product. The disadvantages of using TSP in processed cheese are that the high pH can cause spoilage, off-flavour and crystal formation. The hydrated forms of DSP and TSP are usually used because these forms are likely to have a lower concentration of pyrophosphates (due to the production methods used for these emulsifying salts). TSPP is usually used at low levels (usually in conjunction with orthophosphates) for firm and restricted melt cheese, and it has high bacteriostatic effects (Zehren & Nusbaum, 1992). TSPP has a strong creaming effect, and thus is very suitable in high moisture spreads and sauces. Long-chain polyphosphates (like SHMP) decrease melt, and do not provide the long texture required for good slicing properties so their usage is carefully controlled in slice applications. In higher water content processed cheese products such as dips, SHMP can be used to minimise syneresis. Cheese that is gritty and mealy can be caused by excessive use of polyphosphates or too low a pH. Processed cheese made with TSC melts at a lower temperature than DSP cheese, and has a less sharp flavour than phosphates; it is widely used (alone or in a blend) in the production of slices, but not common for spreadable products. Disadvantages for TSC

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include the risk of crystal formation, and citrates also have minimal bacteriostatic effects. Thomas (1973) recommended that in the manufacture of processed cheese, the addition of small proportions of DSP to TSC gives better results than the use of TSC alone as an emulsifying salt, and suggested a rate of 9 parts TSC to 1 part DSP (similar to the 85/15 rule often used in the USA). Increasing the concentration of emulsifying salts (i.e. all types) decreases the melt characteristic and increases the firmness of the processed cheese, if pH is kept constant. This is due to increased casein dispersion during cooking, and also greater fat homogenisation, which during cooling results in a firmer network.

4.5 Conclusion Emulsifying salts play a key role in the production of high-quality processed cheeses. These salts can impact the properties of processed cheese via a series of related physicochemical reactions including calcium binding/ion exchange, pH adjustment, casein dispersion, protein hydration and protein aggregation. Until recently, processed cheese manufacturing was to some extent an art, where a cheesemaker selected the types of cheeses used in the blend, as well as the types and amounts of emulsifying salts, based largely on experience. Although considerable information now exists on the impact of individual emulsifying salts on the properties of processed cheese, the exact mechanisms involved are still not clear since there are multiple reactions simultaneously occurring. Industrially, blends of emulsifying salts are often used (e.g. JOHA), but much of the information about how mixtures of salts behave is proprietary. Crystal formation is a concern with some types of emulsifying salts, which often limits their usage levels. The processed cheese industry has over the years developed some rules of thumb to help avoid crystal formation, although it is often not clear why some cheeses develop crystals while others of similar composition do not.

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Dimitreli, G., Thomareis, A.S. & Smith, P.G. (2005) Effect of emulsifying salts on casein peptization and apparent viscosity of processed cheese. International Journal of Food Engineering, 1, 1–15. Eckner, K.F., Dustman, W.A. & Rys-Rodriguez, A.A. (1994) Contribution of composition, physicochemical characteristics and polyphosphates to the microbial safety of pasteurized cheese spreads. Journal of Food Protection, 57, 295–300. Ellinger, R.H. (1972a) Phosphates as Food Ingredients, CRC Press, Cleveland. Ellinger, R.H. (1972b) Phosphates in food processing. Handbook of Food Additives (ed. T.E. Furia), 2nd edn, pp. 617–780, CRC Press, Cleveland. Fox, P.F., Guinee, T.P., Cogan, T.M. & McSweeney, P.L.H. (2000) Fundamentals of Cheese Science. Aspen Publishers, Gaithersburg. Glenn, T.A., Daubert, C.R. & Farkas, B.E. (2003) A statistical analysis of creaming variables impacting process cheese melt quality. Journal of Food Quality, 26, 299–321. Guinee, T.P., Cari´c, M. & Kal´ab, M. (2004) Pasteurized processed cheese and substitute/imitation cheese products. Cheese: Chemistry, Physics and Microbiology (eds P.F. Fox, P.L.H. McSweeney, T.M. Cogan & T.P. Guinee), 3rd edn, vol. 2, pp. 349–394, Elsevier, London. Gupta, S.K., Karahadian, C. & Lindsay, R.C. (1984) Effect of emulsifier salts on textural and flavor properties of processed cheese. Journal of Dairy Science, 67, 764–778. Hassan, A., Johnson, M.E. & Lucey J.A. (2004) Changes in the proportions of soluble and insoluble calcium during the ripening of Cheddar cheese. Journal of Dairy Science, 87, 854–862. Horne, D.S. (1998) Casein interactions: casting light on the black boxes, the structure in dairy products. International Dairy Journal , 8, 171–177. Karahadian, C. & Lindsay, R.C. (1984) Flavor and texture of reduced-sodium process American cheeses. Journal of Dairy Science, 67, 1892–1904. Kwak, H.S., Choi, S.S., Ahn, J. & Lee, S.W. (2002) Casein hydrolysate fractions act as emulsifiers in process cheese. Journal of Food Science, 67, 821–825. Lampila, L.E. & Godber, J.P. (2002) Food phosphate. Food Additives (eds A.L. Branen, P.M. Davidson, S. Salminen & J.H. Thorngate), 2nd edn, pp. 809–896, Marcel Dekker, New York. Lauck, R.M. (1972) Using salvage cheese in preparing pasteurized process cheese. United States Patent Application No. 3697292. Lee, B.O. & Alais, C. (1980) Etude biochimique de la fonte des fromages - II. Evolution des phosphates et des metaux. Lait , 60, 130–139. Lee, B.O., Paquet, D. & Alais, C. (1980) Etude biochimique de la fonte des fromages I. Mesure de la peptisation. Lait , 60, 589–596. Lee, B.O., Paquet, D. & Alais C. (1986) Etude biochimique de la fonte des fromages. VI. Effet du type de sels de fonte et de la nature de la mati`ere prot´eique sur la peptisation. Utilisation d’un syst`eme mod`ele. Lait , 66, 257–267. Lee, S.K., Buwalda, R.J., Euston, S.R., Foegeding, E.A. & McKenna, A.B. (2003) Changes in the rheology and microstructure of process cheese during cooking. Lebensmittel Wissenschaft und Technologie, 36, 339–345. L¨ossner, M., Maier, S., Schiwek, P. & Scherer, S. (1997) Long-chain polyphosphates inhibit growth of Clostridium tyrobutyricum in processed cheese spreads. Journal of Food Protection, 60, 493–498. Lu, Y., Shirashoji, N. & Lucey, J.A. (2008) Effects of pH on the textural properties and meltability of pasteurized process cheese made with different types of emulsifying salts. Journal of Food Science, 73, 363–369. Lucey, J. A. (2008) Some perspectives on the use of cheese as a food ingredient. Dairy Science & Technology, 88, 573–594. Lucey, J.A. & Fox, P.F. (1993) Importance of calcium and phosphate in cheese manufacture: a review. Journal of Dairy Science, 76, 1714–1724. Lucey, J.A., Johnson, M.E. & Horne, D.S. (2003) Perspectives on the basis of the rheology and texture properties of cheese. Journal of Dairy Science, 86, 2725–2743.

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Lucey, J.A., Brickley, C.A., Govindasamy-Lucey, S., Johnson, M.E. & Jaeggi, J. 2009. Low-fat and fat-free cheese with improved properties. United States Patent Application No. 20090068311. Marchesseau, S., Gastaldi, E., Lagaude, A. & Cuq, J.L. (1997) Influence of pH on protein interactions and microstructure of process cheese. Journal of Dairy Science, 80, 1483–1489. Maurer-Rothmann, A. & Scheurer, G. (2005) Stabilization of Milk Protein Systems: A JOHA Guide, BK Giulini GmbH, Germany McCullough, J.F., Van Wazer, J.R. & Griffith, E.J. (1956) Structure and properties of the condensed phosphates. XI. Hydrolytic degradation of Graham’s salt. Journal of the American Chemical Society, 78, 4528–4533. McCullough, J.F. (1973) pH titration of phosphorous compounds. Environmental Phosphorus Handbook (eds E.J. Griffith, A. Beeton, J.M. Spencer, & D.T. Mitchell), pp. 327–340, John Wiley & Sons, New York. Meyer, A. (1973) Processed Cheese Manufacture, Food Trade Press, London. Milani, F.X. & Lucey, J.A. (2009) Avoiding defects in process cheese. University of Wisconsin-Dairy Pipeline, 21(1), 1–2, 6–7. Mizuno, R. & Lucey, J.A. (2005) Effects of emulsifying salts on the turbidity and calcium–phosphate–protein interactions in casein micelles. Journal of Dairy Science, 88, 3070–3078. Mizuno, R. & Lucey, J.A. (2007) Properties of milk protein gels formed by phosphates. Journal of Dairy Science, 90, 4524–4531. Molins, R.A. (1991) Phosphates in Food , CRC Press, Boca Raton, FL. Olson, N.F., Vakaleris, D.G., Price, W.V. & Knight, S.G. (1958) Acidity and age of natural cheese as factors affecting the body of pasteurized process cheese spread. Journal of Dairy Science, 41, 1005–1016. Palmer, H.J. & Sly, W.H. (1944) Cheese melting salts and their properties. Journal of the Society of Chemical Industries, 63, 363–367. Panouill´e, M., Nicolai, T. & Durand, D. (2003) Heat induced aggregation and gelation of casein submicelles. International Dairy Journal , 14, 297–303. ˇ etina, J. (2003) Influence of cheese ripening and rate of cooling of the processed Piska, I. & Stˇ cheese mixture on rheological properties of processed cheese. Journal of Food Engineering, 61, 551–555. Pommert, J.F., Klaebe, A., Perie, J., Lebugle, A. & Puech, J. (1988) Observation and analysis of crystalline phases in processed cheese. Journal of Food Science, 53, 1367–1369, 1447. Price, W.V. & Bush, M.G. (1974) The process cheese industry in the United States: a review II. Research and development. Journal of Milk and Food Technology, 37, 179–198. Rayan, A.A., Kal´ab, M. & Ernstrom, C.A. (1980) Microstructure and rheology of process cheese. Scanning Electron Microscopy, III, 635–645. Scharpf, L.G. & Kichline, T.P. (1968) Effect of phosphorus and pH on type and extent of crystal formation in process cheese. Journal of Dairy Science, 51, 853–857. Scharpf, L.G. & Kichline, T.P. (1969) Properties and chemical characterization of a ‘bloom’ on process cheese slices. Food Technology, 23, 127–129. Shen, C.Y. & Morgan, F.W. (1973) Hydrolysis of phosphorus compounds. Environmental Phosphorus Handbook (eds E.J. Griffith, A. Beeton, J.M. Spencer, & D.T. Mitchell), pp. 241–263, John Wiley & Sons, New York. Shimp, L.A. (1985) Process cheese principles. Food Technology, 39, 63, 64, 66, 68, 138. Shirashoji, N., Jaeggi, J.J. & Lucey, J.A. (2006) Effect of trisodium citrate concentration and cooking time on the physicochemical properties of pasteurized process cheese. Journal of Dairy Science, 89, 15–28. Sommer, H.H. (1930) A case of sandiness in processed cheese. Journal of Dairy Science, 13, 288–290.

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Tanaka, N. (1982) Challenge of pasteurized process cheese spreads with Clostridium botulinum using in-process and post-process inoculation. Journal of Food Protection, 45, 1044–1050. Tanaka, N., Traisman, E., Plantong, P., Finn, L., Flom, W., Meskey, L., & Guggisberg, J. (1986) Evaluation of factors involved in antibotulinal properties of pasteurized process cheese spreads. Journal of Food Protection, 49, 526–531. Templeton, H.L. & Sommer, H.H. (1936) Studies on the emulsifying salts used in processed cheese. Journal of Dairy Science, 19, 561–572. Ter Steeg P.F. & Cuppers, H.G.A.M. (1995) Growth of proteolytic Clostridium botulinum in process cheese products. II: Predictive modeling. Journal of Food Protection, 58, 1100–1108. Thomas, M.A. (1973) The Manufacture of Processed Cheese: Scientific Principles, 1st edn, New South Wales Department of Agriculture, Richmond, Australia. Thomas, M.A., Newell, G., Abad, G.A. & Turner, A.D. (1980) Effect of emulsifying salts on objective and subjective properties of processed cheese. Journal of Food Science, 45, 458–459, 466. Toy, A.D.F. & Walsh, E.N. (1987) Phosphorus Chemistry in Everyday Living, American Chemical Society, Washington, DC. Udayarajan, C.T., Lucey, J.A. & Horne, D.S. (2005) Use of Fourier transform mechanical spectroscopy to study the melting behavior of cheese. Journal of Texture Studies, 36, 489–515. Van Wazer, J.R. (1973) The compounds of phosphorus. Environmental Phosphorus Handbook (eds E.J. Griffith, A. Beeton, J.M. Spencer & D.T. Mitchell), pp. 169–177, John Wiley & Sons, New York. Van Wazer, J.R. & Callis, CF. (1958) Metal complexing by phosphates. Chemical Review , 58, 1011–1046. Visser, S.A. (1962) Occurrence of calcium phosphates in the presence of organic substances, especially proteins. Journal of Dairy Science, 45, 710–716. Vujicic, I., deMan, J.M. & Woodrow, I.L. (1968) Interaction of polyphosphate and citrate with skimmilk proteins. Canadian Institute for Food Science and Technology Journal , 1, 17–21. Zehren, V.L. & Nusbaum, D.D. (1992) Processed cheese, Cheese Reporter Publishing Co. Inc., Madison. Zittle, C.A. (1966) Precipitation of casein from acidic solutions by divalent anions. Journal of Dairy Science, 49, 361–364.

5 Flavours and Flavourants, Colours and Pigment ¨ G. Osthoff, E. Slabber, W. Kneifel and K. Durrschmid

5.1 Introduction The manufacture of processed cheese involves cooking cheese in the presence of a suitable emulsifying salt. While a natural cheese is a living system in which the components will change through catabolic processes due to the action of microorganisms and enzymes, this process is stopped by the heat treatment in the preparation of processed cheese. The resulting product will have a specific taste and flavour that will not be altered by any biological process. Decay of processed cheese is thus only due to chemical changes in its components (as long as the product does not undergo some recontamination with microbes). The sensory qualities of processed cheese are mainly determined by the type of raw material used, so that the strongest cheese flavours are obtained when mature cheeses are used. However, the production of mature cheeses is expensive and these have their own demand, so that alternatives are sought to produce processed cheeses with good sensory attributes. Furthermore, processed cheese is a product to which flavours other than dairy can be added. The aim of this chapter is to provide an overview of the approaches used to produce processed cheese with desired cheese flavours and colours, alternative flavours, and aspects that lead to the decay of flavour during processing and storage. Furthermore, the flavour of processed cheese is discussed in context with the sensory properties of this product.

5.2 Types of processed cheese Processed cheese can be divided into two categories, sliceable and spreadable, but other types (blocks and sauces) are also produced (see Chapter 1). The difference lies mainly in the dry matter content and in corresponding textural properties. Sliceable block types contain in the order of 51–58 g dry matter 100 g−1 , and spreadable types 33–43 g dry matter 100 g−1 , seldom as high as 50 g dry matter 100 g−1 (Berger et al., 1998). Sliceable processed cheese is added to a wide variety of convenience food products like pizza, hamburgers or noodle products. From the published data no discrimination is made between the two types of processed cheese regarding the use of colourants or flavourants or the interactions and decay of these. Processed Cheese and Analogues, First Edition. Edited by A.Y. Tamime. © 2011 Blackwell Publishing Ltd. Published 2011 by Blackwell Publishing Ltd.

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5.3 Raw material It is possible to process almost any type of cheese (Berger et al., 1998). Hard and semi-hard cheeses, such as Cheddar, Emmental, Gouda and Edam, are preferred, with Cheddar being the most widely used cheese because it causes almost no problems. These cheeses have relatively high levels of dry matter and a high level of intact protein to act as structureforming material to ensure the necessary stability of the resulting processed cheese. Other cheeses may also be incorporated for flavouring purposes (Berger et al., 1998), such as Gruy`ere (Burkhalter, 1973), Mozzarella (Callahan & Metzger 1992), Tilsit (Beinert & Oeser 1955), Parmesan (Kulic & Cari´c 1990) and Kashkaval, Kefalotyri and Ras cheeses (Zeidan, 1993). The quality of the raw material used for the manufacture of processed cheese has the greatest impact on the quality of the final product. The type of cheese, the maturity of the cheese and its physical properties are key aspects to be considered. Sensory flaws, for example resulting from malfermentation or microbial contamination, are not corrected by the cooking process. Importantly, the age of natural cheese has an influence on the properties of processed cheese. The rate of proteolysis is highest during the early stages of ripening. In a study of Cheddar cheese ripened for 168 days, the highest proteolysis rate was observed within the first 28 days of the maturation period, after which it slows down (Brickley et al., 2007). During this time it is the degradation of αs1 -casein that is the most important factor that determines the softness of processed cheese. High levels of intact protein give the necessary stability in processed cheese, causing it to be harder but more springy, and easy to fracture. This is also illustrated when Cheddar cheese is substituted with up to 40 g 100 g−1 rennet casein curd in the formulation of processed cheese for cost reduction purposes. No significant differences are observed in terms of flavour, colour and appearance, body and texture and sliceability (Varghese & Sachdeva, 2002). Whey proteins seem not to contribute to processed cheese texture and flavour, so that only low amounts, up to 4.5 g 100 g−1 of cheese solids, can be added to obtain desired characteristics (Suneeta et al., 2007). Not only is the texture affected by the ripening time of the raw material cheese, but also the taste. Different proportions of blending of ripened and green cheeses allows for flavour varieties. As an example, for the Korean taste it has been found that the most suitable blend is equal amounts of Cheddar and Gouda cheeses that have been ripened for 3 months. The resulting processed cheese was shown to contain 10.84 g 100 g−1 water-soluble protein, 0.65 g 100 g−1 non-protein nitrogen (NPN) and 1.17 g 100 g−1 non-casein nitrogen (Kim et al., 1990). Regarding Edam cheese, the best properties of processed cheese are obtained with 3–4 week old Edam, resulting in a clean, buttery and slightly sour flavour. Cheese over 2 months old results in burnt, pungent and bitter taste and also has a negative influence on consistency and fat binding (Rozehnal et al., 1987). In some cases the manufacture of processed cheese is a method for utilising surpluses or cheeses rated as not suitable for further ripening. When immediate processing is not possible, storage of the raw material is necessary and freezing is a good option. Good sensory qualities were obtained with Cheddar cheese that was ripened for 60 and 90 days and then stored frozen at – 17.8◦ C for 2.5 years, and of which up to 50 g 100 g−1 was included in the mixture (Holsinger et al., 1987). Similar results were obtained with Emmental and Gruy`ere cheeses that were stored frozen for up to 18 months. A content of 60–70 g

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100 g−1 Emmental or 30–40 g 100 g−1 Gruy`ere to the processed cheese mixture gave good flavoured products (Burkhalter, 1973). Young Emmental cheese proved the most suitable for frozen storage. However, a problem that can occur in these cheeses is the development of a tallow off-flavour in the rind, which is carried over to the processed cheese. The use of frozen stored Tilsit cheese has also been reported as possible (Beinert & Oeser, 1955). With Cheddar or Edam cheeses as base, flavour varieties may also be created by blending with different types of cheese. Successful blends have been obtained by blending ripened Cheddar cheese with up to 50 g 100 g−1 direct acidified Kashkaval, Kefalotyri and Ras cheeses. The blend received a higher sensory score than the standard processed cheese (Zeidan, 1993). A processed cheese made from 60–75 g 100 g−1 Mozzarella and Cheddar cheeses gave an acceptable flavour, but also allowed good melting properties (Callahan & Metzger, 1992). Good sensory properties were also obtained with Parmesan cheese (Kulic & Cari´c, 1990). Processed cheese with Dutch cheese flavour was developed and contained 60 g 100 g−1 rennet Dutch-type cheese and 10 g 100 g−1 rennet Yaroslavl’ cheese. A processed cheese to be consumed with beer was developed. It contained 15 g 100 g−1 Cheddar cheese with 50 g 100 g−1 fat-in-dry matter (FDM), 25 g 100 g−1 Dutch, Kostrama or other cheeses, with 45 g 100 g−1 FDM and 8 g 100 g−1 Okean paste made from Antarctic krill (Nikolaev et al., 1978). Although sheep’s milk cheese, such as Kashkaval, may be used as raw material, processed cheese made from goat’s milk cheese was shown to result in a weak flavour (Al Dahhan et al., 1985).

5.4 Flavour 5.4.1 Natural flavourants Compared with natural cheese, processed cheese never develops an individual flavour because the cheese ripening microflora that creates the complex flavour cocktail is effectively killed by the heat treatment of the cheese blend. So there is often criticism that processed cheeses only offer a small range of natural flavours, which appears to be much narrower than the range of unprocessed cheeses. Hence, for many consumers processed cheeses taste ‘plastic’, while some say that the flavour is quite mild compared with natural cheeses. Besides this narrow flavour range, processed cheeses normally also lack the textural properties relevant for natural cheeses. This can be seen from the results of a small pilot study, which was performed with students studying for an MSc in Foods Science and Technology in Vienna (unpublished data). A quantitative descriptive sensory analysis of sliced processed cheeses corroborates the above-mentioned experience. A group of six trained panellists evaluated five processed cheese products available in Austria. After several sessions the panel did not identify more than 10 descriptors for describing the products. Two descriptors were used to characterise the appearance (yellow, gloss), three the taste (sweet, sour, salty), two the texture (sticky, creamy), one a trigeminal property (pungent), whereas only two descriptors were used for aroma properties (blue cheese, cheese). Principal components analysis revealed that the panel was able to distinguish reproducibly between the products using this limited array of descriptors (Fig. 5.1). In contrast to these few descriptors, more complex profiles have been reported for Cheddar cheese (Muir &

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PCA results (correlation) : principal component 1 (PC1) vs principal component 2 (PC2) 1.50 PC 2 A

−1.50

B

D Salty E Sour Sticky Glossy Creamy Cheese Pungent Yellow

PC 1

1.50

Sweet Blue cheese

−1.50

C

Fig. 5.1 Principal components analysis (PCA) of a descriptive sensory analysis of five processed cheeses (A–E). Cumulative explained variance is 91%.

Hunter, 1991/2; Piggott & Mowat, 1991; Heisserer & Chambers, 1993; Muir et al., 1995; Murray & Delahunty, 2000; Drake et al., 2001). The food industry is making efforts to offer processed cheese with a more complex flavour profile that meets all the desired quality criteria. For example, products have been introduced that are made by flavouring processed cheeses with a variety of ingredients and additives, ranging from salmon to pineapple. Certainly, the lack of typical cheese flavour can also be mitigated by adding cheese flavours. Cheese flavours Quality and taste intensity of processed cheese depends on the age of the cheese that is used as raw material. For a processed cheese with a Cheddar taste, it would be the age of the Cheddar cheese, while a strong blue cheese taste is obtained from mature blue cheese. It was shown that processed cheese made with varying amounts of Cheddar cheese of different ripening periods varied in flavour intensity and quality (Jung & Yu, 1988). Similar improvements in bland taste was obtained when mature Cheddar cheese was added to non-rennet directly acidified cheese (Wilster, 1980). The flavour intensity of the Cheddar was shown to be ascribed to an increase in free amino acids, with glutamic acid displaying the highest concentration. Similar results, where the use of older cheese results in stronger flavour, was found when Edam cheese was used as raw material (Rozehnal et al., 1987). Since mature cheeses possess their own market segment and their production is expensive as well as time-consuming, manufacturers of processed cheese seek alternatives by sourcing young cheese with desired flavour attributes. Mature cheeses may be blended with younger cheese, or cheese slurries with intense flavour may be produced by accelerated ripening. Accelerated ripening is an innovative technology that offers different options for producing cheeses at proper cost–benefit ratio by using certain enzymes either directly or

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encapsulated form and/or inactivated cells of lactic acid bacteria under different manufacturing conditions (Ardoe & Petterson, 1988; Azarnia et al., 2006) or other organisms such as yeasts (De Wit et al., 2005). These products can be tailor-made for the production of processed cheese. Some examples are described below. When accelerated ripened Cheddar cheese slurries are used, they may be blended with fully ripened cheese to manufacture a processed cheese (Sutherland, 1975; Tewari et al., 1992). It was found that the effect can be ascribed inter alia to glutathione, riboflavin and diacetyl levels. Saluja & Singh (1989) suggested that slurries be added to 25 g solids 100 g−1 from mature Cheddar cheese, which resulted in a processed cheese with acceptable flavour. Pre-incubation of Cheddar cheese or cheese curd with lipase or proteinase results in a slurry with intense cheese flavour, which is used in the production of processed cheese (Lee et al., 1986). Improved flavour was obtained when accelerated ripened Ras cheese (made from raw cows’ milk or a mixture of cow and buffalo milk without using starter cultures), which was directly acidified with the addition of proteinase and esterase from Mucor miehei , was used to manufacture processed cheese instead of 3-month-old Ras cheese (Abdel-Baky et al., 1987). Ultrafiltered retentates of accelerated rapidly ripened cheese may also be used. Aly et al. (1995) produced retentates by ultrafiltration (UF) of a slurry which was prepared by lipolysis with SDS-lipase micelles. The high-protein retentate which is obtained was used to replace as much as 80 g 100 g−1 of Ras cheese in the manufacture of processed cheese. Sensory properties of the resulting processed cheese were found to be superior to the control cheese. Other alternatives for obtaining cheese or dairy flavours are also possible. Tewari & Sachdeva (1991) used Chakka prepared from cow and buffalo milk in various proportions in the formulation of processed cheese. Chakka is the retentate obtained when the whey is drained from Dahi, a yoghurt analogue. They reported an increase in the moisture and a decrease in the pH of the spread with increased proportion of Chakka in the blend. The sensory scores increased when up to 30 g 100 g−1 Chakka was used in the blend, but higher supplementation resulted in decreased score (Tewari & Sachdeva, 1991). Kalle and Deshpande (1977) produced a flavour concentrate by fermentation of cream with Candida lipolytica subsp. planta incorporated into cheese curd for the production of Cheddar cheese. Another alternative is the use of rapidly ripened ultrafiltered retentates. Accelerated ripening by lipolysis may be achieved employing micelles of SDS-lipase. Followed by UF, a high-protein retentate is obtained which was used to replace as much as 80 g 100 g−1 of Ras cheese in the manufacture of processed cheese. Sensory properties were superior to control (Aly et al., 1995). Ultrafiltered cheese base was incorporated with Cheddar cheese. Consumer acceptance test showed that the processed cheese made with 20–30 g 100 g−1 ripened Cheddar cheese (3 month old) and ripened UF cheese base (2 month old) or 50 g 100 g−1 ripened Cheddar cheese (5 month old) and ripened UF cheese base (2 month old) were more acceptable than standard processed cheese (Jang et al., 1991). Pre-blending with blue cheese can also be used to induce some typical flavours. Lubbers et al. (1997) prepared a blend (g 100 g−1 ) of blue cheese (52), Emmental (27), casein (8), emulsifying salts (2.1), NaCl (0.9) and water (10), which was stored for 15 days at 6◦ C. This enhanced the development of Penicillium roqueforti , and the major contributors to flavour, as determined by gas chromatography, were shown to be 2-heptanone and 2-nonanone, the contents of which increased about twofold during the storage time.

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Characteristic cheese flavour in the curd may also be obtained by biochemical and chemical means. Jha & Gupta (1994) employed direct acidification, with the help of lactic acid bacteria, enzymes and additives to produce curd slurries. The curd slurries containing (a) lactic starter culture LF-40, Marzyme and Natur Age (Miles Laboratories, Elkhart, Indiana, USA), (b) lactic starter culture, Marzyme and glutathione, and (c) lactic starter culture, Marzyme, glutathione, cobalt chloride, manganese sulphate, riboflavin and diacetyl all produced optimum cheese flavour for processed cheese spread which was of an acceptable quality. However, the flavour scores of samples containing combination (a) were signifcantly (P < 0.05) higher than all other samples. Other experimental combinations containing either lactic starter culture and Marzyme alone or lactic starter culture, Marzyme, Natur Age and glutathione failed to produce an acceptable cheese flavour. The most frequently encountered problem in the production of non-rennet directly acidified cheeses is the bland flavour. Addition of aged Cheddar cheese has been reported to produce an acceptable flavour (Wilster, 1980). Incorporation of 6-month-old Cheddar cheese (20 and 40 g 100 g−1 ) in cow and buffalo milk Channa spread resulted in improved sensory attributes (Tewari & Sachdeva, 1991). More recently, the use of enzyme-modified cheeses, which are used to impart flavour to imitations of cheese products (Noronha et al., 2008a,b), can be considered as an additional tool to enhance cheese flavour in processed cheese and to produce tailored products. Enzyme modified cheese (EMC) is defined as a concentrated cheese flavour that is natural in origin and which is produced enzymatically mainly via hydrolysis (proteinases, peptidases and lipases) from cheeses of various ages. It is sold as a paste or as dried powders (e.g. EMC powder; McSweeney, 2007). Volatile fatty acids are the major contributors to the flavour of EMCs and the resulting blended processed cheese products (Kilcawley et al., 2006). Each short- and intermediate-chain fatty acid may have their typical share of the flavour. Butanoic acid (C4 ) is perceived as rancid and cheesy, whereas hexanoic acid (C6 ) contributes to a pungent blue cheese flavour (Collins et al., 2003). Today, EMCs with flavours of Cheddar cheese, blue cheese, Italian cheese, goat cheese or Swiss cheese are available from companies producing flavours. EMCs also contain NaCl in the range 1–2 g 100 g−1 , which also might generate some saltiness in addition to the flavour. Meat and seafood flavours Basically, processed cheese is a typical cheese variety. Therefore, the focus of flavour is primarily on cheese. Additional flavours have been included over time, most with brothy or spicy flavours. Added foodstuffs such as ham, salami, mushrooms, prawns and shrimps, normally permitted in quantities up to 15 g 100 g−1 , usually do not have any great influence on the consistency and texture of the processed cheese, provided that the added ingredients are free of bacteriological defects. Components with high salt content (e.g. salted ham) or high acid (e.g. tomato pur´ee) may cause casein coagulation and water drainage. These ingredients are normally added after homogenisation and after the melting process to ensure their integral shapes and texture. For microbial safety, it is advisable to use canned ingredients, with the exception of ham and salami (Berger et al., 1998). A product with meat flavour that was found suitable for processed cheese was obtained from milled pork bone and water by heating at 80◦ C for 10 min. The broth was then concentrated to 70 g 100 g−1 total solids and flavoured with monosodium glutamate, powdered

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onion and garlic, and smoke. Applied in processed cheese, the product resulted in acceptable flavour (Gutierrez et al., 1997). Between 10 and 50 g 100 g−1 of Ras cheese in a processed cheese mixture was replaced by shrimps and stored at 6◦ C for 3 months. The sensory properties were improved, but slight effects were observed on physical properties, such as oiling-off, meltability and elasticity (Abeid et al., 2001). However, inclusion of these ingredients is not sufficient to provide a strong taste. Additional seasonings as used in the manufacture of the ingredient have to be added, as well as flavourants. Fruit and vegetable flavours Spices may be added in quantities of 0.01–1.0 g 100 g−1 . These quantities do not affect consistency and texture of processed cheese products. Spices are usually added at the beginning of the melting process to ensure even distribution through the cheese mass, and also to achieve pasteurisation or sterilisation. When the cheese mass has to be homogenised, coarser spices or particles, such as chives, shrimps or dried meat, have to be added before homogenisation, either in the cooker or in a stirring device. In the latter case, spices or additives that have been pre-sterilised or which have a low level of contamination should be used (Berger et al., 1998). Tiny mushroom pieces, which were steeped in citric acid and boiled in emulsifying salt solution, were blended into the cheese spread at levels of 5, 10 and 15 g 100 g−1 . Acceptable flavour was obtained, but inclusion at 15 g 100 g−1 resulted in defects of body, texture, appearance and colour of the spread (Fathi et al., 2005). Production of fruit-flavoured processed cheese spreads has also been studied. Fruit pulp of guava, mango and banana was added in ratios of 15, 20 and 25 g 100 g−1 to Ras cheese. Total solids and FDM was adjusted before cooking. The pulp resulted in a lower pH after manufacture, and the pH decreased while soluble nitrogen increased during storage (Awad et al., 2003).

5.4.2 Chemical flavourants It has been mentioned above that the inclusion of meat or fruit may not be enough to provide a strong taste. Additional seasonings or flavourants normally have to be added. With regard to the enhancement of cheese flavours, the chemical additives used as flavours in processed cheese include calcium salts of unsubstituted monocarboxylic or C4 to C8 dicarboxylic acids at a concentration of 100–1000 μg g−1 (Hofman & Sloot, 1976) or trans-anethole [1-(p-methoxy-phenyl)prop-1-ene]. For Gouda cheese flavour, these are included at 0.05–2 μg g−1 (Sloot, 1976). For goat’s milk flavour, butanone, 2-pentanone, 2-heptanone, 2-nonanone, caproic acid, n-heptanol, methyl caproate and ethyl caprate have to be added to the cheese blend (Groux & Moinas, 1975). For Provolone cheese, flavour C2 to C10 alkanoic acids have been used (Ney et al., 1973). A cheese flavour is given to a food product by the addition of 2,4-dithiapentane and/or trans-anethole. Addition of the compound or compounds is particularly useful for imparting or enhancing a Gouda cheese flavour (Anonymous, 1975a). The cheese flavour of edible products is improved by the addition of calcium salts of unsubstituted C4 to C8 monocarboxylic or dicarboxylic acids. In particular, the addition of calcium 2-methyl

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butanoate and/or calcium 3-methyl butanoate is useful for improving the old Gouda cheese flavour (Anonymous, 1975b). A total of 51 volatiles in 11 commercial Swiss processed cheeses were identified and quantified by dynamic head space gas chromatography/mass spectrometry and flame ion detector analysis. Most volatiles were present in all the cheeses, but in different ratios. Most components were formed in the raw materials before heat treatment. Heat treatment of the processed cheeses generally decreased the concentration of most alcohols, ketones, esters and terpenoids. Increase in content of aldehydes was related to heat treatment. Terpenes originate from added herbs and spices (Mariaca et al., 1998). The principal flavours other than cheese flavours used in the manufacture of processed cheeses are smoke, walnut and hazelnut, cherry mushroom and onion flavours. Smoked processed cheese was manufactured by replacing 15, 30 and 45 g 100 g−1 of Cheddar cheese with Taiz cheese that had been smoked. Inclusion of 30 g 100 g−1 ranked the highest score for sensory properties (Saleem et al., 2003). Smoked Mozzarella cheese was used in another study, where it was found that inclusion of more than 20 g 100 g−1 of the smoked product would decrease acceptability (El Abassy et al., 1998). Smoked processed cheese was prepared by incorporating 62.53 g 100 g−1 mild Cheddar cheese and 7.61 g 100 g−1 medium/mature Cheddar cheese and 4 g 100 g−1 of a liquid smoke. The product was tested acceptable by a trained sensory panel and a consumer panel (McIlveen & Vallely, 1996). Liquid smoke extract was shown to be superior to natural smoke regarding microbiological quality. The phenol compounds are better dispersed, because natural smoke may only penetrate to a depth of 1–1.5 cm (Ul’yanov et al., 1979).

5.4.3 Flavour changes Processed cheese is not a stable product with a very long shelf-life. During storage, the structure and flavour slowly change due to loss of moisture, protein hydrolysis, lipid oxidation and non-enzymatic browning. Enzymes in cheese are normally denatured and deactivated during the cooking step of processed cheese manufacture. However, heatstable proteases from psychrotrophic bacteria and denatured proteases that are rearranged may exhibit some degree of proteolytic activity. The proteolysis of caseins may result in texture and flavour changes (Sch¨ar & Bosset, 2002). Besides the proteolytic effects, several volatile organic compounds have been found to develop during storage of processed cheese depending on the following parameters: storage time, light and storage temperature conditions (Sunesen et al., 2002). All developments correlate positively with storage time. Processed cheese stored in the light results in a sharp rise in the concentration of octane, but also hexanal, heptanal, octanal and nonanal, compared with storage in the darkness. Raising the storage temperature, in particular, increases the concentrations of 2-propyl-1-pentanol, 2-hexanone, 2-octanone, 2-decanone, 2-tridecanone, octanal, nonanal and decanal. Very often the protein or fat ingredients either of dairy and non-dairy sources are used in processed cheese. They may not only improve the nutritive value, but also are applied for economic reasons. Nutritional and/or health benefits of processed cheese products may be increased by including high levels of soy protein; the resulting product possesses all the melt, firmness and flavour characteristics of regular processed cheese. With the correct levels, sensory properties may not be significantly impacted (Lindstrom et al., 2005).

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When whey protein concentrate (WPC) (0, 20 and 40 g 100 g−1 ) was used to replace skimmed milk protein in the manufacture of processed cheese, and the amounts of emulsifying salts adapted concurrently to 3 g 100 g−1 to avoid the occurrence of free oil, effects on flavour were noted. Sensory properties were acceptable (Abd El-Salam et al., 1996). However, it was reported that hardness, cohesiveness and springiness of the processed cheese decreased and flavour deteriorated when WPC was used (Thapa & Gupta, 1992). Kaminarides & Stachtiaris (2000) included WPC and soybean oil in processed cheese. A control processed cheese (A) made mainly from Kasseri cheese (60 g 100 g−1 ) without WPC or soybean oil, and three other cheese products (B, C and D) containing increasing amounts of WPC (i.e. by UF) and soybean oil, were manufactured simultaneously. The cheeses were subjected to sensory analysis and showed differences in flavour, texture and spreadability on day 1 and, moreover, in appearance after 90 days. Protein isolates from chickpea, peanut and sesame were used to replace dried skimmed milk protein in the manufacture of processed cheeses. Emulsion stability, water absorption capacity and water oil absorption index changed and flavour score decreased with addition (El Sayed, 1997). The packaging material used may also play a role in changes of flavour. Migration of packaging material components, such as vinyl monomers and butylhydroxytoluene and Irganox 1010 (Schwope et al., 1987; Gallmann et al., 1997), and corrosion of aluminium foil may affect flavour (Berger et al. 1998; Sch¨ar & Bosset, 2002). Permeation of oxygen through packaging material leads to oxidation flavours (Sch¨ar & Bosset, 2002). Moreover, the packaging should also provide sufficient protection from light as, depending on composition and manufacturing conditions, processed cheese may exhibit some photosentitivity (Alves et al., 2007).

5.5 Colours Normally, only yellow to orange colours are found in cheese. Naturally, these pigments are of the carotene type, and are carried over from the plant material consumed by the cow. When Cheddar, Gouda or Edam cheeses are used as base for processed cheese, the colour will stay in the yellow to orange range. However, with the use of green and blue mould ripened cheeses such as Roquefort, Gorgonzola, Blue and surface ripened cheeses such as Cammembert, a dirty grey colour is obtained that cannot be removed (Berger et al., 1998). Off-colours were also reported in blends of Cheddar cheese with up to 50 g 100 g−1 direct acidified Kashkaval, Kefalotyri and Ras cheeses (Zeidan, 1993).

5.5.1 Natural colours Normally, only colours within the yellow to orange band of the spectrum are used. The major colour pigments are trans-β-apo−8 -carotenal and trans-β-carotene. Total β-carotene of processed cheese is 18.5 ± 0.98 mg kg−1 (Scotter et al., 2003). A blend containing β-carotene, β-apo-carotenal and α-tocopherol as stabiliser, with fractionated coconut oil triglycerides, was developed for processed cheese uses (Johnson et al., 1979). Annatto, a carotenoid substance extracted from the fruit of the indigenous South American plant Bixa orellana, is most commonly used. The pigment itself is called cis-bixin,

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which upon alkali extraction is changed to norbixin (Orange 3) (Todd, 1991). A decisive factor in determining the quality of a colouring is its heat stability. Lack of resistance to heat leads to a defect known as ‘pinking’. Other carotenes are not suitable because they are less stable to heat and may also be destroyed by oxidation due to light exposure (Berger et al., 1998). Furthermore, annatto suspensions have been reported to be more stable than annatto solutions (Shumaker & Wendorff, 1998).

5.5.2 Colour decay and changes Colour changes in processed cheese have been noted as a problem since the 1930s. Pink, yellow and white types of discoloration were noted. Early studies on the yellow discoloration of processed cheese was ascribed to the types of natural cheese used in manufacture of processed cheese, the amount of re-work cheese added, the time taken to reach the emulsification temperature, and interactions between natural cheese and neutraliser and added annatto (Niki et al., 1959). Pink discoloration of processed cheese has been ascribed to the norbixin pigment in annatto colorant used in cheese (Zehren & Nusbaum, 1992). The norbixin is oxidised and can react with protein or carbohydrates to result in a red colour. In processed cheese, this shift towards a red colour is observed as pink. The cooking temperature, type and concentration of emulsifying salts, and amounts of coloured cheese in the processed cheese blends affect the extent of pinking (Shumaker & Wendorff, 1998). Processed cheese was also observed to lose colour. Whiteness of processed cheese was found to increase with increasing concentration of emulsifier and WPC, and the cheese becomes darker during storage due to Maillard browning (Abd El-Salam et al., 1998).

5.5.3 Process colours The storage for processed cheese may cause non-enzymic browning, which may shorten the shelf-life (Kristensen & Skibsted, 1999), and also cause off-flavours (Berger et al., 1998). Both lactose and glycerol contribute to browning of the final product (KombilaMounduounga & Lacroix, 1991). Brown colour intensity of processed cheese was highly correlated (r = 0.020) with galactose content of the Cheddar cheese from which it was made (Johnson et al., 1984). It was found that high storage temperatures (37◦ C) may cause browning, which is absent at low temperatures (5◦ C) (Kristensen et al., 2001). According to the L∗ a ∗ b∗ colour scale, the L∗ -value (lightness) decreased under these conditions, while the a ∗ -value (red-green) and b∗ -value (yellow-blue) increased. These changes were ascribed to reactions coupled to lipid oxidation. Exposure to light does not affect the colour, as β-carotene was found to be stable; however, riboflavin and α-tocopherol are degraded, which is also coupled to lipid oxidation, due to the formation of 7-keto-cholesterol from cholesterol (Kristensen et al., 2001).

5.6 Sensory attributes of processed cheese In general, the perception of cheese flavour is a complex process (Auvray & Spence 2008). Gustatory, olfactory, trigeminal, textural and also visual perceptions contribute to

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the overall evaluation of food and there are several interactions between the different perception systems. • • •

Colours influence our flavour perception. Acoustic perceptions modulate our textural perception. Textural perceptions modify taste perceptions and so on.

Colourants can even function as flavour enhancers, as the intensity of taste perceptions can be enhanced by a colour which fits into our sensory experience (Koza et al., 2005; Luisa et al., 2006). Consumers often expect yellow or green food products to have a sour taste and pink food products to taste sweet. Intense yellow to orange colour may also work as a visual clue for cheese made of milk full of natural carotenoids from flowers in the cow’s meadow. Tastants can influence the perception intensity of odorants or even other tastants (Frank & Byram 1988). Sodium chloride, for example, can reduce bitterness, and extracts of yeast work as aroma enhancers in processed cheeses. Many additives to processed cheeses function as flavour modulators. Under certain conditions, emulsifying agents used in the production process influence the flavour of the processed cheese (Mayer, 2001). Which flavourant or colourant should be used largely depends on the consumer target group and the intended eating situation. Products for children normally contain lower amounts of herbs and spices, as they should not be too intense in cheese flavour. Conversely, processed cheese for children may be enriched with different kinds of sweeteners, colourants, and kid-friendly flavours like strawberry, watermelon, green apple, banana and even bubblegum. For those adults who like it hot, cheeses spiced with peppers, jalapeno and Serrano chiles, even horseradish and wasabi, may be an option. On the savoury side, there are cheeses studded or rolled in cumin, dill, garlic, fennel, rosemary, tarragon, thyme and others. According to different eating habits, processed cheeses with fruit flavours are often intended to be used in breakfast situations, whereas cheeses with wine or beer aromas fit into lunch or dinner. For chocolate and sweet lovers, there are also flavoured cheeses containing chocolate, cocoa and cinnamon on the market.

5.7 Conclusion Processed cheese is made from a variety of cheeses, and the raw material that is selected may be linked to the culture of the consumer. Emmental, Kashkaval and Cheddar cheeses are representative examples of central and eastern European and British cultural influence. Processed cheese is not a dairy product that is formed directly by natural processes, such as soft and hard cheeses. A secondary technological step has to be employed. Nevertheless, processed cheese is perceived and utilised by the consumer as cheese. The acceptable quality parameters therefore depend on the appearance, texture, mouth-feel and taste being very similar to those of cheese. The quality of the cheese to be used as raw material is therefore important. The fact that processed cheese is perceived and utilised as cheese seems to restrict expansion in utilisation of processed cheese. To illustrate this, it has been shown in this chapter that colour is the main quality trait for appearance, and that only the yellow-orange spectrum is acceptable. Pinking is not acceptable, although taste and texture are not affected.

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It therefore seems as if the consumer’s mind is conservatively fixed on this important parameter. The opposite is observed for chocolate, where not only different brown colours are acceptable, but also white and even pink and green with respectively strawberry and mint flavours. At least for the children’s market, some shifts have been made. In contrast to colour, the flavour of processed cheese has been expanded by the introduction of vegetable, fruit, meat and seafood flavours and, when these are not perceived as strong enough, the flavours are enhanced by means of chemical additives. Processed cheese has undoubtedly become a high convenience product and this special property is appreciated by consumers. However, to ensure a sustainable long-term hedonic acceptance of processed cheese varieties, research and product development should be focused on a higher degree of flavour complexity.

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Burkhalter, G. (1973) Frozen storage of Emmental cheese for processed cheese manufacture. Schweizerische Milchzeitung, 33, 41–42. Callahan, K.C. & Metzger, V.L. (1992). Product and process of making a firm-textured Mozzarella/Cheddar product. United States Patent Application No. 5 104 675. Collins, Y.F., McSweeney, P.L.H. & Wilkinson, M.G. (2003) Lipolysis and free fatty acid catabolism in cheese: a review of current knowledge. International Dairy Journal , 13, 841–866. De Wit, M., Osthoff, G., Viljoen, B.C. & Hugo, A. (2005) A comparative study of proteolysis in Cheddar cheese and yeast-inoculated Cheddar cheese during ripening. Enzyme and Microbial Technology, 37, 606–616. Drake, M.A., Mcingvale, S.C., Cadwallader, K.R. & Civille, G.V. (2001) Development of a descriptive sensory language for Cheddar cheese. Journal of Food Science, 66, 1422–1427. El Abassy, M., Abd el Gaffar, E. & Okasha, A.I. (1998) Using smoked Mozzarella cheese in the manufacture of processed cheese spread. Annals of Agricultural Science Moshotor, 36, 2395–2403. El Sayed, M. (1997) Use of plant protein isolates in processed cheese. Nahrung, 41, 91–95. Fathi, F.A., Hussein, G.A.M. & Mohamed, A.G. (2005) Fortification of processed cheese spread with accustomed edible mushroom. Arab University Journal of Agricultural Science, 13, 825–839. Frank, R.A. & Byram, J. (1988) Taste–smell interactions are tastant and odorant dependent. Chemical Senses, 13, 445–455. Gallmann, P.U., Bosset, J.O. & Sieber, R. (1997) Lebensmittel, Verpackung und Stoffmigration. Lebensmittel-Technologie, 30, 326–336. Groux, M.J.A. & Moinas, M. (1975) Cheese flavouring. United States Patent Application No. 3 911 158. Gutierrez, S., Gonzalez, A. & Chang, L. (1997) Obtaining a pork meat flavour. Alimentaria, 35, 33–35. Heisserer, D.M. & Chambers, E., IV (1993) Determination of the sensory flavour attributes of aged natural cheese. Journal of Sensory Studies, 8, 121–132. Hofman, H.J. & Sloot, D. (1976) Cheese flavouring. British Patent Application No. 1 428 374. Holsinger, V.H., Flanagan, J.F., Konstance, R.P., Smith, P.W. & Kwoczak, R. (1987) Properties of process cheese manufactured from previously frozen Cheddar. Journal of Dairy Science, 70 (suppl. 1), 77–79. Jang, E.K., Lee, K.W., Shin, Y.K., Chee, G.H. & Kwak, H.A. (1991) The characteristics of sliced Cheddar processed cheese made from UF cheese base and Cheddar cheese. II. Sensory characteristics. Korean Journal of Dairy Science, 13, 271–281. Jha, Y.K. & Gupta, S. (1994) Development of processed cheese spread from cow’s milk using enzymes and additives. In: Cheese Yield and Factors Affecting its Control , pp. 513–519, International Dairy Federation, Brussels. Johnson, J.R., Saddler, W. & Andres, C. (1979) Nutrition and color added to cheese substitute with same ingredient. Food Processing, 40, 74–75. Johnson, M.E., Bley, M.E. & Olson, N.F. (1984) Browning of natural and processed cheeses. Journal of Dairy Science, 67 (suppl. 1), 82–83. Jung, J.H. & Yu, J.H. (1988) Studies on the flavour intensity and quality in processed cheese made from different amounts of Cheddar cheese. Korean Journal of Dairy Science, 10, 34–43. Kalle, G.P. & Deshpande, S.Y. (1977) Production of processed cheese using a flavour concentrate prepared by cream fermentation. Journal of Food Science and Technology India, 14, 207–212. Kaminarides, S. & Stachtiaris, S. (2000) Production of processed cheese using kasseri cheese and processed cheese analogues incorporating whey protein concentrate and soybean oil. International Journal of Dairy Technology, 53, 69–74. Kilcawley, K.N., Wilkinson, M.G. & Fox, P.F. (2006) A novel two-stage process for the production of enzyme-modified cheese. Food Research International , 39, 619–627. Kim, K.S., Ha, W.K. & Lee, J.Y. (1990) Studies on the development of processed cheese made with Cheddar cheese and Gouda cheese. I. Determination of ripening properties of the natural cheese. Korean Journal of Dairy Science, 12, 164–171.

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Kombila-Mounduounga, E. & Lacroix, C. (1991) The effect of combinations of sodium chloride, lactose and glycerol on rheological properties and colour of processed cheese spreads. Canadian Institute of Food Science and Technology Journal , 24, 239–251. Koza, B.J., Cilmi, A., Dolese, M. & Zellner, D.A. (2005) Color enhances orthonasal olfactory intensity and reduces retronasal olfactory intensity. Chemical Senses, 30, 643–649. Kristensen, D. & Skibsted, L.H. (1999) Comparison of three methods based on electron spin resonance spectrometry for evaluation of oxidative stability of processed cheese. Journal of Agriculture and Food Chemistry, 47, 3099–3104. Kristensen, D., Hansen, E., Arndal, A., Appelgren Trinderup, R. & Skibsted, L.H. (2001) Influence of light and temperature on the colour and oxidative stability of processed cheese. International Dairy Journal , 11, 837–843. Kulic, L. & Cari´c, M. (1990) Processed cheese production blend modification using natural cheese flavours. Mljekarstvo, 40, 91–104. Lee, C.R., Lin, C.F. & Melachouris, N. (1986) Process for preparing intensified cheese flavor product. United States Patent Application No. 4 595 594. Lindstrom, T.R., Laye, I., MacBlane, G. & Mei, F. (2005) Processed cheese made with soy. United States Patent Application No. 6893674. Lubbers, S., Cayot, N. & Taisant, C. (1997) Blue cheese taste intensification in processed cheese products. Sciences des Aliments, 17, 393–402. Luisa Dematte, M., Sanabria, D. & Spence, C. (2006) Cross-modal associations between odors and colors. Chemical Senses, 31, 531–538. Mariaca, R., Gauch, R., Berger, T., Bosser, J.O. & Schar, W. (1998) Volatile compounds of Swiss processed cheeses. Mitteilungen aus dem Gebiete der Lebensmitteluntersuchung und Hygiene, 89, 625–638. Mayer, H.K. (2001) Bitterness in processed cheese caused by an overdose of a specific emulsifying agent? International Dairy Journal , 11, 533–542. McIlveen, H. & Vallely, C. (1996) The development and acceptability of a smoked processed cheese. British Food Journal , 98, 17–23. McSweeney, P.L.H. (2007) Cheese Problems Solved , Woodhead Publishing, Cambridge. Muir, D.D. & Hunter, E.A. (1991/2) Sensory evaluation of Cheddar cheese: order of tasting and carryover effects. Food Quality and Preference, 3, 141–145. Muir, D.D., Hunter, E.A., Banks, J.M. & Horne, D.S. (1995) Sensory properties of hard cheese: identification of key attributes. International Dairy Journal , 5, 157–177. Murray, J.M. & Delahunty, C.M. (2000) Selection of standards to reference terms in a Cheddar cheese flavour language. Journal of Sensory Studies, 15, 179–199. Ney, K.H., Wirotama, P.G. & Freytag, W.G. (1973) Method for manufacturing a food product having a Provolone cheese flavour and cheese flavour composition suitable for this method. Netherlands Patent Application No. 7 213 536. Niki, T., Sukegawa, K., Taneya, S. & Suenaga, Y. (1959) Study on the discoloration of processed cheese. I. Extraction of factors on change of colour and influence of characteristic values (pH-value, acidity, moisture content, viscosity, elasticity and melting quality). Reports of the Research Laboratory, Snow Brand Milk Products, 59, 22. Nikolaev, A.M., Kuleshova, M.F., Vetrova, I.V. & Belinka, T.I. (1978) New types of processed cheese. Molochnaya Promyshlennost , 3, 10–13. Noronha, N., Cronin, D.A., O’Riordan, E.D. & O’Sullivan, M. (2008a) Flavouring reduced fat high fibre cheese products with enzyme modified cheeses (EMCs). Food Chemistry, 110, 973–978. Noronha, N., Cronin, D.A., O’Riordan, E.D. & O’Sullivan, M. (2008b) Flavouring of imitation cheese with enzyme-modified cheeses (EMCs): sensory impact and measurement of aroma active short chain fatty acids (SCFAs). Food Chemistry, 106, 905–913. Piggott, J.R. & Mowat, R.G. (1991) Sensory aspects of maturation of Cheddar cheese by descriptive analysis. Journal of Sensory Studies, 6, 49–62.

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Rozehnal, Z., Bezdeka, Z., Brezina, P., Bartosek, V. & Bohac, V. (1987) Effect of age of natural cheese on processed cheese quality. Prumysl Potravin, 38, 533–535. Saleem, R.M., Habeeb, W.H., Ghaleb, A.A. & Al Shibani, M. (2003) The use of Taiz cheese in processed cheese spread. Egyptian Journal of Dairy Science, 31, 139–145. Saluja, J.M. & Singh, S. (1989) Development of processed cheese spread using accelerated Cheddar curd slurries. Journal of Food Science and Technology India, 26, 29–31. Sch¨ar, W. & Bosset, J.O. (2002) Chemical and physico-chemical changes in processed cheese and ready-made fundue during storage. A review. Lebensmittel-Wissenschaft und- Technologie, 35, 15–20. Schwope, A.D., Till, D.E., Ehntholt, D.J., Sidman, K.R., Whelan, R.H., Schwartz, P.S. & Reid, R.C. (1987) Migration of BHT and Irganox 1010 from low-density polyethylene (LDPE) to foods and food-simulating liquids. Food Chemistry and Toxicology, 25, 317–326. Scotter, M.J., Castle, L., Croucher, J.M. & Olivier, L. (2003) Method development and analysis of retail foods and beverages for carotenoid food colouring materials. Food Additives and Contaminants, 20, 115–126. Shumaker, E.K. & Wendorff, W.L. (1998) Factors affecting pink discoloration in annatto-colored pasteurized process cheese. Journal of Food Science, 63, 828–831. Sloot, D. (1976) Cheese flavouring. British Patent Application No. 1 427 702. Suneeta, P., Rathour, A.K., Prajapati, J.P., Jana, A.H. & Solanky, M.J. (2007) Utilization of whey protein concentrate in processed cheese spread. Natural Product Radiance, 6, 398–401. Sunesen, L.O., Lund, P., Sorensen, J. & Holmer, G. (2002) Development of volatile compounds in processed cheese during storage. Lebensmittel-Wissenschaft und-Technologie, 35, 128–134. Sutherland, B.J. (1975) Rapidly ripened cheese curd slurries in processed cheese manufacture. Australian Journal of Dairy Technology, 30, 138–142. Tewari, B.D. & Sachdeva, S. (1991) Effect of processing variables on quality of spread prepared from Chhana. Indian Journal of Dairy Science, 44, 375–379. Tewari, B.D., Kumar, V. & Singh, S. (1992) Spray drying process for accelerated ripened Cheddar cheese. Indian Dairyman, 44, 244–248. Thapa, T.B. & Gupta, V.K. (1992) Changes in sensoric and rheological characteristics during storage of processed cheese foods prepared with added whey protein concentrates. Indian Journal of Dairy Science, 45, 140–145. Todd, P.H. (1991) Norbixin adducts with water-soluble or water-dispersible proteins or branchedchain or cyclic polysaccharides. United States Patent Application No. 5053240. Ul’yanov, S.D., Shilyaev, V.V. & Gavrilova, N.B. (1979) Effect of the smoking method on the quality of salami shaped processed cheese. Molochnaya Promyshlennost , 12, 36–37. Varghese, S. & Sachdeva, S. (2002) Development of rennet casein based processed cheese preparations. Indian Journal of Dairy Science, 55, 1–6. Wilster, G.H. (1980) Practical Cheesemaking, 13th edn, pp. 348–349, Oregon State University Bookstores, Corvallis. Zehren, V.L. & Nusbaum, D.D. (1992) Process Cheese, Cheese Reporter Publishing Co., Madison. Zeidan, I.A. (1993) Properties of processed cheese made from Ras and Kashkaval cheese manufactured by direct acidification. Egyptian Journal of Food Science, 21, 1–10.

6 Manufacturing Practices of Processed Cheese M. Nogueira de Oliveira, Z. Ustunol and A.Y. Tamime

6.1 Introduction Processed cheese is made from natural cheeses that may vary in degree of sharpness of flavour. Natural cheeses are shredded and heated. The protein, water and oil phase is emulsified during heating with suitable emulsifying salts to produce a stable oil in water emulsion. The melted mixture is then reformed and packaged into blocks, or as slices, into tubs or jars, depending on the specific desired end product. Processed cheeses typically cost less than natural cheeses; they have longer shelf-life, and provide for an unlimited variety of products (Oliveira, 1986). Until now, the literature on processed cheese has been somewhat limited because earlier research was done in companies and held as trade secrets or was protected by patents in the USA. Today almost all initial patents on process cheese have expired, providing opportunities for new developments. There has been renewed interest in processed cheese due to the food industry’s need for tailor-made cheeses with consistent quality and functionality, as well as consumer needs for cheese products beyond natural cheeses. Processed cheese provides an opportunity to meet these needs. Today processed cheese is one of the leading cheese varieties worldwide (Sorensen, 2001; Henning et al., 2006) and, in this chapter, the scientific aspects of the manufacturing stages of processed cheese are reviewed; in addition, some aspects of reduced-fat/energy cheeses and related products are also discussed.

6.2 Some historical background Although somewhat uncertain, the origins of processed cheese are thought to date back to Swiss cheese fondue, German Kochk¨ase (cooked cheese), French Cancoillotte or Canquillote and Welsh rabbit. Kochk¨ase and Cancoillote are made with coagulated sour milk or skimmed milk; fondue is made from Swiss cheese, which is a rennet cheese. Soda is added in the preparation of Kochk¨ase and eggs are used to make Cancoilotte. In addition, wine and/or beer are used to prepare fondue. Commercially, the first processed cheese was developed by Walter Gerber and Fritz Stettler in Switzerland in 1911. In this process, natural Emmentaler cheese was shredded Processed Cheese and Analogues, First Edition. Edited by A.Y. Tamime. © 2011 Blackwell Publishing Ltd. Published 2011 by Blackwell Publishing Ltd.

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and heated with sodium citrate to produce a homogeneous product which firmed up on cooling. The initial intent of this product was to improve shelf-life of cheese shipped to warmer climates. About this time, James Lewis Kraft in the USA was working independently on blending and heating of natural cheeses. The first patent, which was issued to him in 1916, describes melting pieces of Cheddar cheese and stirring it while heating to form a homogeneous warm cheese which was then transferred into glass jars or cans, and was sealed (Kraft, 1916). This first patent did not describe addition of emulsifying salts and/or other ingredients during processing. The use of emulsifying salts (sodium phosphate) was described later for the first time in 1921 in a patent issued to George Herbert Garstin of the Phoenix Cheese Company (Garstin, 1921). In another patent issued to Kraft in 1921, packaging of a 2.27-kg loaf was described, which was a significant breakthrough for the distribution of process cheese (Kraft, 1921). It is believed that the 2.27-kg loaf was responsible for the popularity and for nearly doubling processed cheese consumption in the USA during this time period. Later, several other patents were issued describing processing and packaging methods and equipment. In 1927, Wheeler & Scott (1927) were issued a patent in which they described a lay-down cooker that they claimed produced rapid and uniform heating of the cheese during manufacturing. This equipment later evolved to the jacketed kettle and, in 1935, Norman Kraft was issued a patent for a lay-down cooker that heated the cheese by direct injection of steam into the product (Kraft, 1935). However, direct injection of steam for cooking added moisture, which then needed additional monitoring to ensure that the cheese did not exceed its legal moisture limits. Over the years, other gradual improvements have included modifications to cookers for improved and more uniform heating, and changes to mixing configurations for more uniform mixing of the ingredients and enhanced emulsification. Improvements in process control resulted in more uniform quality product. During this time, there was also concurrent development in the manufacture of cheese slices and other convenient forms of process cheese and related products. In the 1940s and early 1950s, methods and equipment for continuous forming of processed cheese slices were developed. Norman Kraft filed a patent in 1940, issued in 1944, that described the production of process cheese slices. In this process, hot processed cheese was transferred onto a pair of cooling drum rolls. The thin sheet of cheese that was produced was then transferred onto a conveyor where it was cut into ribbons and then cross cut again to form the processed cheese slices (Kraft, 1944). These cheese slices were flexible, and had a glossy smooth finish. The process prevented the slices from sticking together as well as sealing in the flavour of freshly produced cheese. This was a significant breakthrough in terms of convenience because until this time the cheese loaf was the only type available to consumers. At present, processed cheese slices account for 74% of total sales at the supermarket in the USA (IDFA, 2007). By 1950s, several other procedures were developed to fill the demand for sliced cheese. The most significant one was the invention of individually wrapped slices for processed cheese food. Other developments included type and quality of the ingredients used for process cheese manufacturing. In 1950, standards of identity for processed cheese were established in the USA by the Food and Drug Administration (FDA) (see also Chapter 2). At this time it was also required that the optional ingredients be declared on the label. In 1974, enzyme-modified cheese (EMC) was approved as an optional ingredient in the

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manufacture of processed cheese. EMC allowed accelerated ripening of natural cheeses in order to enhance flavour levels in processed cheese. They reduced storage time, including costs associated with storage, and investment of natural cheese inventory. They also allowed cheese with specific flavours, flavour intensities and uniformity to meet specific processing needs. In 1973, standards of identity for cheese analogues and imitation cheeses were established by the FDA (Zehren & Nusbaum 2000).

6.3 Processed cheese and products Standards of identity that define the product, its composition and the types and levels of ingredients allowed for processed cheese products and analogues vary depending on the country. In the USA, they are found in the Code of Federal Regulations (CFR) Title 21 (FDA, 2006). There are also International Codex Alimentarius Standards for processed cheese varieties (for more details refer to Chapter 2). In the USA, three main categories of processed cheese and products are defined, and Table 6.1 summarises the characteristics of these different categories of processed cheese and related products. They differ based on requirement of minimum fat content, maximum moisture content, minimal final pH, and the optional ingredients that can be used. Pasteurized Process Cheese is a dairy product that is produced by mixing and heating of natural cheeses with emulsifying salts to produce a homogeneous plastic mass. This product is cooked at about 70–80◦ C, and the final product has the same fat content as the corresponding natural cheese and not more than 1 g 100 g−1 greater than the maximum moisture content. A good processed cheese is smooth and uniform in colour; it melts uniformly, slices smoothly and has a compact body. Pasteurized Process Cheese Food has the same specifications and ingredients as Pasteurized Process Table 6.1

Standards of identity for processed cheese and related products in the USA. Chemical composition (g 100 g−1 )

Product

Ingredients (g 100 g−1 )

Pasteurized Process Cheese

Contains natural cheeses or enzyme modified cheeses, emulsifying agents (≤3), acidulants (vinegar, lactic acid, citric acid, acetic acid, phosphoric acid), milk fat (from cream, anhydrous milk fat or dehydrated cream; ≤5), water, salt, colours, spices, flavourings, mould inhibitorsa (sorbic acid, potassium sorbate, sodium sorbate; ≤0.3), anti-sticking agenta (lecithin ≤ 0.03)

Moisture (≤40), fat (≥30) and pH ≥ 5.3

Pasteurized Process Cheese Food

Natural cheeses and enzyme modified cheeses (>5 of the final products), all the ingredients allowed in processed cheese, also milk, skimmed milk, buttermilk and cheese whey

Moisture (≤44), fat (≥23) and pH ≥ 5.0

Pasteurized Process Cheese Spread

Natural cheeses and enzyme modified cheeses (> 51% w/w of the final products), all the ingredients allowed in processed cheese food, also food gums, sweeteners, nisin (≤250 ppm)

Moisture (44–60), fat (≥20) and pH > 4.0

Source: after FDA (2006) and Kapoor & Metzger (2008). a Slices, or cut in consumer-size packages.

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Cheese, but the product contains more moisture and less fat; the cooking temperatures are higher and this product has a lower pH. The standard of identity allows for additional optional ingredients, which are not permitted in Pasteurized Process Cheese. The final product is softer in body and milder in flavour than processed cheese. Cooking temperatures for this product are around 82◦ C, and organic acids, such as citric, lactic, acetic and phosphoric, are added to decrease the pH in the product. The final pH of processed cheese could range from 5.2 to 5.6 (Kosikowski & Mistry, 1997). ‘Process Cheese Spread’ is manufactured in a similar way to processed cheese and processed cheese food; however, the incorporation of excess moisture is permitted for better spreadability of the product. This product is cooked to about 88◦ C. Again, organic acids are use to acidify the product during processing. Same optional ingredients as processed cheese food are allowed. In addition, sweetening agents, starches and gums/hydrocolloids at a maximum level of 0.8 g 100 g−1 of the finished product may be used (Kosikowski & Mistry, 1997). Gums/hydrocolloids provide for additional water binding for this higher moisture product. There are also a variety of additional products and low-fat versions of the above products that do not fit into the above standardised categories. Pasteurized Process Cheese Product is an undefined category for products that do not meet the standards of identity as defined in the CFR. In the Pasteurized Process Cheese Product category there are no limits on the fat and moisture content. This allows for different and innovative milk-derived ingredients, and provides more readily for new product development opportunities. Additional ingredients included in the above products include vegetables, meats, fruits, herbs, flavours, colours and spices. As mentioned elsewhere, the market share of these products in the USA in 2007 is as follows: 74% of processed cheese is sold as slices, 20% as loaves of various sizes, 4.5% as spreads, and the remaining 1.5% as cubed, shredded and grated (IDFA, 2007). In Brazil, the gross compositional content of processed cheeses should contain roughly the same proportions of cheese nutrients that were used in the formulation of the cheese blend. The percentage (g 100 g−1 ) of fat and protein contents range from 9 to 31 and 8 to 24, respectively. Loss of vitamins B1 and B2 , niacin, pantothenic acid, and vitamin B12 occurs during the manufacturing of processed cheese (Fox, 1993). According to Mercosur (1997), processed cheese should contain maximum 70 g moisture 100 g−1 and a minimum of 35 g fat 100 g−1 dry matter (i.e. fat-in-dry matter, FDM), and the Brazilian legislation defines processed cheese as ‘the product made by grinding, mixing, melting and emulsion through heat, and emulsifiers of one or more varieties of cheese, with or without the addition of other dairy products and/or source of milk solids, spices, condiments or other substances in which the cheese is the main ingredient’ (Anonymous, 1997a). Requeij˜ao is a typical Brazilian processed cheese that is very popular, but in the market the consistency of the product varies considerably. In 2000, the national production of Requeij˜ao was 96 900 tonnes, increasing to 121 627 tonnes in 2004, an increase of 25%. This product ranks second after Mozzarella, and among the various varieties of Requeij˜ao produced in Brazil, the cream variety has the most significant popularity in the domestic market. In 2004, 30 900 tonnes of creamy Requeij˜ao was produced, which corresponds to 7% of total cheese production (Anonymous, 2006); in 2007, 113 400 tonnes of creamy Requeij˜ao was produced (ABIQ, 2008). As mentioned above, processed cheese products are obtained by grinding, mixing, melting and heat by means of emulsion of one or more varieties of cheese, with or without

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the addition of other milk products and/or solids of milk origin and spices, condiments or other food substances in which the cheese is the main milk ingredient used (Anonymous, 1997a). Requeij˜ao, on the other hand, is generally defined as the product made from the fusion of the curd mass of cheeses (cooked or not), which is obtained by acid or enzymatic coagulation of milk; optionally, cream, butter, anhydrous milk fat (AMF) or butteroil can be added to the curd after whey drainage and wash. The product can be manufactured with added condiments (spices and/or other food substances), but the milk ‘base ingredients’ may not contain fat and/or protein of non-milk origin (Anonymous, 1997b). It is evident from the above Brazilian legislation that Requeij˜ao can be made from cheese or dairy ingredients. Furthermore, there are products on the Brazilian market sold under the name Requeij˜ao that differ in level of moisture and fat content (Table 6.2). Thus it is possible to find products that are very creamy with an unctuous consistency, but there is also a very firm type. The latter type of Requeij˜ao, called ‘butter’ Requeij˜ao or ‘Requeij˜ao from North’, can be sliced. According to the Brazilian Statutory Legislation, the Technical Regulation for the Establishment of Identity and Quality of Requeij˜ao classifies the product into three categories: (a) Requeij˜ao, (b) creamy Requeij˜ao, and (c) buttery Requeij˜ao (Anonymous, 1997b) (Fig. 6.1). However, the manufacturing stages of ‘Requeij˜ao from North’ can be briefly described as follows. • • • • • • • • •

Fresh raw milk is skimmed and stored in open tanks at room temperature (i.e. normally high); the following day the skimmed milk coagulates to form a curd. The whey is removed using a cloth bag; the concentrated curd is placed in a specially designed jacketed tank (i.e. it has a very large diameter) for heating with steam. The curd is heated indirectly by injecting steam into the jacket of the tank, and the curd is washed with milk and water (clotting of the milk proteins continues). The free whey and water are removed from the curd mass by using a sieve made out of straw and a ‘basin’. The curd is repeatedly washed and the whey is drained as often as necessary until the milk stops clotting. The temperature of the curd mass is raised and citrate is added, and curd is stirred continuously using a wood utensil until it is completely melted. Local butter or ‘butter from the land’ is added until the melted curd mass stops absorbing it, and the steam is switched off. The product is placed in plastic moulds of the desired size, and cooled at room temperature. The product is packaged in plastic containers (see Fig. 6.1) and dispatched.

Table 6.2

˜ Physicochemical specification (g 100 g−1 ) of different types of Requeijao.

Constituent

Normal

Creamy

Buttery

Fat-in-dry matter (FDM)

45.0– 54.9

55 minimum

25.0– 59.9

Moisture

60 maximum

65 maximum

58 maximum

Source: after Anonymous (1997b).

Manufacturing Practices of Processed Cheese

a

a

b

153

a

b

˜ variety and (b) ‘butter’ Requeijao ˜ made in the north of Brazil, sometimes Fig. 6.1 (a) Creamy Requeijao ˜ from the North. known locally as Requeijao

In contrast, commercial production uses a typical formulation (g 100 g−1 ) of Requeij˜ao as follows: curd (35; milk is acidified by using lactic acid or alternatively Mozzarella cheese could be used), high-fat cream ∼40 g 100 g−1 (47), salt (0.8), emulsifying salt (0.7 consisting of trisodium citrate, tetrasodium pyrophosphate and sodium tripolyphosphate) and water (16.55). According to Murilo Hadad Pires (personal communication), the processing conditions for Requeij˜ao can be described as follows. • •

Mix the curd and the emulsifying salt in a processing kettle and heat to 80–90◦ C (i.e. direct heating) under shear (1500 rpm) until the curd is melted. Afterwards, add the remaining ingredients (e.g. salt, cream and water), mix the melted blend at 3000 rpm, heat to 85–95◦ C (i.e. direct heating), fill the product into glass jars at 70–80◦ C, and cool to 10◦ C before dispatching the product.

6.4 Key steps in processing Manufacturing of high-quality processed cheese involves the key steps described in this section. Figure 6.2 provides a schematic diagram of the typical steps involved in the manufacturing of processed cheese.

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Raw materials

Grinding/shredding and mixing of natural cheeses

Addition of emulsifying salts, water and other ingredients

Heating (85-90°C for 3-4 min) under continuous agitation

Homogenisation

Hot packaging

Cooling

Storage and dispatch Fig. 6.2

Flow diagram showing the stages of manufacturing processed cheese.

6.4.1 Selection of ingredients Natural cheeses Appropriate selection of natural cheeses is essential for the production of processed cheese and related products. Age of the cheese, pH, flavour, calcium and intact casein content are important criteria in selection of natural cheeses for manufacture of processed cheeses since they impact the functional properties of the final processed cheese produced from them (see Chapter 3). In the USA, Cheddar cheese is the main ingredient used in the manufacture of processed cheese (FDA, 2006). Cheddar cheese may be manufactured the traditional way or in barrels (Turner, 2003). Barrel-type Cheddar cheese manufacture is similar to Cheddar cheese except that it is not pressed after salting. The salted curds are instead ripened

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in polyethylene-lined large drums or barrels for faster development of flavour and body. Barrel-type Cheddar cheese is less expansive to manufacture, and meets the specific needs of the processed cheese industry. Depending on the country and their availability, other natural cheeses such as Swiss, Colby, Gouda, Mozzarella and Monterey Jack are also used as starting materials in processed cheese production. Selection of natural cheeses require some experience in identifying the specific flavour and texture characteristics that will be desirable in the final processed cheese and related product that is being manufactured. Processed cheese manufacturers typically rely on past experience to make their selections. For example, young cheeses are desirable for textural attributes whereas aged cheeses provide flavour. Block processed cheese with good sliceability and elasticity requires mostly young cheese (75–90% intact casein). Spreads require primarily cheeses of medium ripeness (60–75% intact casein) (Kosikowski & Mistry, 1997; Fox et al., 2000; Kapoor & Metzger, 2008). In addition to the contribution to flavour (due to age), as cheese ages the protein and fat contents are broken down by the action of the enzymes present in the product. Ageing decreases the intact casein content of the natural cheese and thus their emulsifying capacity during processing (Garimella et al., 2006). Furthermore, the age and type of natural cheese used in the manufacturing also have a marked influence on the final pH of the resulting processed cheese. A pH of 5.4–5.8 in the natural cheese is reported to be optimum for maximising the structure and the final functional properties of processed cheese and related products. The stability of processed cheese emulsion is decreased when the pH of the product is reduced below 5.4 or increases above 5.8 (Upreti & Metzger, 2007). The emulsification of the proteins, and thus the properties of the final processed cheese, is also influenced by the calcium content of the natural cheese. Natural cheese is the main ingredient that contributes to variation in the calcium content of a formulation. High calcium content in the starting (natural) cheese may result in poor functionality of processed cheese, and therefore it is crucial that appropriate emulsifying salts are selected to sequester the calcium (for further details refer to Chapter 4). Typically, natural cheese that is high in initial calcium results in processed cheese that is firm and which has reduced meltability (Kapoor et al., 2007). Because of the above discussed variations in natural cheeses, it is challenging to produce a processed cheese of consistent quality. Kapoor et al. (2007) reported that natural cheese calcium and phosphorus content, as well as salt to moisture ratio, significantly increased the total calcium and phosphorus, pH and intact casein in the processed cheese and thus significantly impacted the final functional properties of the product (Brickley et al., 2007). With the increase in natural cheese calcium and phosphorus contents and salt to moisture ratio, there was a significant increase in the texture profile analysis (TPA) hardness and the viscous properties of processed cheese, whereas the meltability of the product decreased. These authors concluded that it was not only important to balance for moisture, fat, salt and total protein contents, but also control the calcium and phosphate contents, pH and intact casein in order to manufacture a processed cheese with targeted functionality (see also Mizuno & Ichihashi, 2008). The importance of the pH of the natural cheese used on the functional properties of the processed cheese manufactured was reported as early as 1958 by Olson et al. They also reported that even after the final pH of the processed cheese was adjusted to 5.4–5.5, the product, which was made with Cheddar cheese that had higher pH values, resulted in

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processed cheese that was harder with lower meltability, even if the natural cheese was aged up to 150 days compared with control cheeses. Upreti & Metzger (2006) reported that changes in the manufacturing protocol (set and drain pH, level of salting) of the natural cheese altered the calcium and phosphate levels, the salt to moisture ratio, and the amount of residual lactose in the natural cheese. These changes then affected the physicochemical properties of natural cheese, such as final pH, the state and amount of calcium as well as the rate and extent of protein hydrolysis (and thus the amount of intact casein present in the final cheese). These alterations significantly impacted the functionality of the processed cheese being manufactured from these natural cheeses. EMC (Drake et al., 1999) and cheeses made from concentrated milk (Acharya & Mistry, 2004, 2005) have also been used in processed cheesemaking. EMC is derived by adding ripening enzymes (typically proteases and lipases) during production or after maturation. Incubation under controlled conditions is needed for proper flavour development. EMC may have a texture similar to, or slightly modified from, the texture from the cheese it represents, or it may be in a paste form (Moskowitz & Noelck, 1987). Low flavour intensity and flavour stability has been a limitation of natural cheeses, whilst EMC may provide natural cheeses for processed cheese manufacturing that have more diverse flavour range. Also, a long maturation period is needed for flavour development in natural cheeses, which adds to the high cost of the cheese and extended investment in inventory. EMC provides low production costs, consistency, low storage costs and increased functionality. When EMCs are blended with young natural cheeses, a high-quality and economical product may be manufactured (Moskowitz & Noelck, 1987; Kilcawley et al., 1998, 2000). Cheeses manufactured from concentrated milk also provide an alternative to natural cheeses. However, these cheeses have altered calcium and phosphorus content, salt to moisture ratio and residual lactose content (Anderson et al., 1993; Acharya & Mistry 2004, 2005; Nair et al., 2004). As the concentration factor of the milk is increased, calcium, lactose and salt to moisture ratio of the resulting cheese is also increased. These factors in turn influence the intact casein and pH and thus influence the functionality of processed cheese and related products. More recently, exopolysaccharide (EPS)-producing cultures have been investigated for the manufacture of natural cheeses to be used in the production of processed cheese (Awad et al., 2005a,b; Hassan et al., 2005, 2007). The intent was to overcome textural problems, such as excessive firmness, rubbery texture and decreased melting properties, which are typically associated with young and reduced-fat natural cheeses. It has been reported that Cheddar cheese manufactured with EPS cultures were softer, smoother and less rubbery compared with the non-EPS-producing control cheeses (Awad et al., 2005a,b; Hassan et al., 2005). Hassan et al. (2007) evaluated the characteristics of reduced-fat processed cheese made from young reduced-fat Cheddar cheese that was manufactured with EPS cultures, and compared it with cheese manufactured using a 50/50 blend of young and aged that acted as a control. Processed cheeses made with reduced-fat natural cheeses produced with EPS cultures were softer, less chewy and gummy, and exhibited lower viscoelastic moduli than the control cheeses. Sensory scores for texture were higher for the EPS-positive reduced-fat processed cheese compared with the EPS-negative cheeses. No correlation was reported between the physical and melting properties of the initial cheese and processed cheese.

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Re-work cheese Re-work cheese (also referred to as ‘pre-cooked’ cheese in Europe) is cheese that has already been processed once. Re-work cheese may be cheese from line changeover, edge trimmings or perhaps processed cheese that does not pass quality control. It could also be residual processed cheese removed from the cooker or packaging machine, sometimes referred to as ‘hot melt’ (Kapoor & Metzger 2008). Re-work cheese may be added back into processing of processed cheese. However, use of re-work cheese in processed cheese formulations is limited because this cheese may upset the formulation by introducing additional emulsifiers and proteins with altered functionalities due to prior processing. Kalab et al. (1987) reported that addition of re-work cheese increases the viscosity of the emulsified cheese coming out of the cooker, decreased meltability and increased firmness of the final processed cheese. Their microstructure analysis showed that samples containing re-work cheese had a tighter protein matrix and were over-emulsified. Generally, 4% of the total cheese blend has been specified as the maximum amount that can be added to a processed cheese formulation without contributing to undesirable properties of the final product (Scharpf & Kichline, 1969). Cheese base Cheese base is increasingly being used instead of natural cheeses in formulations of processed cheese and related products. The main reason is that it is lower in cost and has a more consistent quality (Turner, 2003). It is typically manufactured by culturing milk that has been concentrated by ultrafiltration and diafiltration. Processing of cheese base has a significant effect on the functional properties of the final processed cheese and related products. Cheese bases generally result in processed cheese that is firmer in texture and less flowable when melted. Acidifying the milk prior to ultrafiltration gives a lower calcium content in the cheese base and thus better meltability of the manufactured processed cheese. Rennet coagulation of ultrafiltrated milk provides poor flowability of the melted processed cheese. The use of proteases for accelerated ripening leads to higher levels of proteolysis in the cheese base and thus softer and more flowable final products (Ernstrom et al., 1980; Savello & Ernstrom, 1989; Tamime et al., 1990, 1991; Tamime & Younis, 1991; Younis et al., 1991a–c; Zehren & Nusbaum, 2000). Other dairy ingredients In addition to the natural cheeses, standards of identity for processed cheese and spreads allow other dairy ingredients, for example skimmed milk powder, dried whey products such as whey, whey protein concentrate (WPC) or whey protein isolate, to be used in formulations (FDA, 2006). These products are significant sources of whey proteins and lactose. Therefore, formulations will need to be adjusted by taking this into account. However, the addition of WPC at higher levels imparts a milder flavour to the product. Processed cheese spread with good meltability and improved spreadability can be prepared by using dried WPC at levels up to 4.5 g 100 g−1 of the cheese solids (Pinto et al., 2007). Proteins, such as α-lactalbumin and β-lactoglobulin, are most abundant in whey protein products. These proteins denature under the temperature conditions of processed cheese

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manufacturing. As β-lactoglobulin denatures, it can then interact with other proteins in the mixture, specifically κ-casein and other whey proteins through disulphide bridges (Wong et al., 1996). These covalent protein–protein interactions are fairly strong, and tend to increase firmness and decrease meltability of the final processed cheese products. Sensory properties are also affected (Everard et al., 2007; Kapoor & Metzger, 2008). Mleko & Foegeding (2001) reported that up to 2% casein may be replaced by whey protein, even though they observed a slight increase in firmness and decrease in meltability. These changes were still in the acceptable range. Additional lactose may also be introduced into the formulation through these dairy ingredients. Lactose is a reducing sugar and it participates in Maillard reactions, a browning reaction that also results in flavour compounds. The presence of lactose at high concentrations in a formulation could lead to undesirable colour and flavours in the final product. Furthermore, when present at high concentrations in a formulation, lactose crystallisation is also a concern. At 20◦ C the solubility of lactose is 17 g 100 g−1 in water (Harper, 1992). Therefore, concentrations of lactose higher than 17 g 100 g−1 in the water phase of a product will lead to crystallisation. Kapoor & Metzger (2008) reported that in a formulation of processed cheese (44 g moisture 100 g−1 ) and spreads (60 g moisture 100 g−1 ) lactose content should not exceed 7.48 g 100 g−1 and 10.20 g 100 g−1 , respectively. Hydrocolloids Standards of identity for processed cheese spread allow the use of hydrocolloids (or gums) up to 0.8 g 100 g−1 of the finished product. The primary function of the hydrocolloids is to provide additional water binding and viscosity to the product, and they also provide enhanced meltability. They are most extensively used in the formulation of reduced-fat, low-fat and imitation cheeses where additional water binding is needed to allow the reduction of fat in the formulation (Swenson et al., 2000). A wide variety of hydrocolloids are available to processed cheese manufacturers, and are available as general blends as well as tailored to meet the specific formulation needs of the manufacturer. The use of hydrocolloids as ingredients in processed cheesemaking has been reviewed extensively elsewhere (Fox et al., 2000; Kapoor & Metzger, 2008; AiQian et al., 2009). Pectin may be added and acts as a linkage with other ingredients in the cheese blend; it also assists in making the product(s) more compact and with fewer cavities compared with products without added pectin. Scanning electron microscopy (SEM) revealed differences in the microstructure of processed cheese analogues (Liu et al., 2008 and Macku et al., 2008) reported that the addition of pectin affected the firmness of processed cheese spread but not the appearance and flavour of the product. Polysaccharides (e.g. starches) have the potential to be used to partially replace ingredients and reduce cost (Bennet et al., 2006; Gampala & Brennan, 2008; Trivedi et al., 2008a,b). The addition of whey products (demineralised whey powder and WPC) added to the processed cheese analogues exerted higher hardness compared with similar products containing acid casein (Solowiej et al., 2008).

6.4.2 Emulsifying salts The function of emulsifying salts in processed cheese manufacturing is to produce a homogeneous cheese emulsion on heating and agitation of the cheese mixture in the presence

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Table 6.3

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Thirteen emulsifying salts approved for processed cheese manufacture in the USA.

Phosphates Monosodium phosphate Disodium phosphate Dipotassium phosphate Trisodium phosphate Sodium metaphosphate (sodium hexametaphosphate) Sodium acid pyrophosphate Tetrasodium pyrophosphate Sodium aluminium phosphate Citrates Sodium citrate Potassium citrate Calcium citrate Other Sodium tartrate Sodium potassium tartrate Source: FDA (2006).

of water (see Chapter 4). The emulsifying ability of these salts prevents the oiling-off that is seen typically in natural cheeses upon heating. In the USA, there are 13 emulsifying salts that are approved for use in the manufacture of processed cheese. Table 6.3 provides a list of these salts. Emulsifying salts are typically phosphate and citrate; they are sold individually or may also be supplied as blends to target specific functionalities of the final products, such as desired texture, firmness, spreadability and meltability. Potassium salts of phosphates typically are more soluble; however, sodium salts are preferred because they do not give a bitter taste especially at high concentrations. Trisodium citrate and disodium phosphate or mixtures of both are the most widely used emulsifying salts in processed cheese production in the USA (Kosikowski & Mistry, 1997; Kapoor & Metzger, 2008). Disodium phosphate is used primarily in loafs whereas trisodium citrate is used in processed cheese slices (Kapoor & Metzger, 2008). Processed cheese slices are cooled with a chill belt, and typically use slice-on-slice applications (Garimella Purna et al., 2006; Kapoor & Metzger, 2008). Trisodium citrate provides better flexibility, more desirable gloss and reduced adhesiveness to the slices. Disodium citrate and sodium orthophosphate are used for softer, more spreadable processed cheese. Other ingredients, such as gluconates, lactates, malates, ammonium salts, gluconic acid, lactones and tartarates, have been used in the past for their emulsification ability, but most are no longer used in the USA for a variety of reasons including technical issues and economical aspects. Aluminium phosphate (another type of emulsifying salt) is primarily used in rennet-casein-based imitation pizza cheese or analogue pizza cheese. Aluminium phosphate has been reported to enhance cheese flavour. A disadvantage is that

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Ser

Ser

O

O

P O − OH O Ca+2 +2 − Ca O O OH P

+ Na2 HPO4 + H2O

P O − OH O Na+

+ Ca HPO4

+ − Na O O OH P

O

O

Ser

Ser

Fig. 6.3 Simple model showing the effect of emulsifying salt in processed cheese. The salt reaches the calcium agglomerate and there is substitution of Ca2+ by Na+ .

it provides excessive thickening when re-work cheese is used (Kosikowski & Mistry, 1997; Fox et al., 2000). An important function of emulsifying salts is to enhance the emulsification capacity of caseins; however, caseins in their natural state are good emulsifiers. Emulsifying salts are not emulsifiers in the strict definition in that they are not surface-active compounds. Their function in process cheese is to chelate calcium and adjust pH. Emulsifying salts can chelate calcium and disrupt the calcium phosphate-linked casein matrix of natural cheeses through their ion exchange properties; the divalent calcium of the para-casein matrix is exchanged with the monovalent sodium of the emulsifying salt (Fig. 6.3). This removal of calcium from the casein matrix is referred to as calcium chelation or sequestration. Chelation of calcium then results in partial breakdown of the para-casein matrix due to disruption of the intra- and inter-protein interactions. Conversion of the calcium para-casein gel network into sodium phosphate para-caseinate dispersion is significantly influenced by processing conditions and the emulsifying salt that has been used in the formulation (Caric & Kalab, 1996; Fox et al., 2000; Kapoor & Metzger, 2008). Peptisation (or swelling of proteins) is the dispersion of para-casein, which involves conversion of the calcium para-casein into sodium phosphate para-caseinate. The change in the charge of the proteins during emulsification and their hydration during mixing has an impact on their water-binding capacity. Furthermore, there is an inverse relationship between the extent of calcium bound to casein and the hydration of that casein. The dispersed and hydrated para-casein then contributes to the emulsification of the fat and stability of the emulsion by immobilising free water (Fox et al., 2000). So, once the caseins are solubilised they are able to interact with the lipid and water phase in the mixture thus creating a true emulsion (Caric et al., 1985; Caric & Kalab, 1996). In addition, Dimitreli et al. (2005) reported that by increasing the moisture content or reducing the pH of the cheese blend increases the flow behaviour index, whilst the consistency index, and thus the apparent viscosity, of processed cheese samples was increased when the moisture content was reduced, and when pH and the soluble casein content were increased.

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Emulsifying salts vary in their calcium-chelating ability and thus ion-exchange properties and therefore their emulsification ability. Final emulsion properties and functionality of the processed cheese will greatly depend on the emulsifying salts used in the formulation of the specific product (Gupta et al., 1984). Guinee et al. (2004) summarised the chelating properties of common emulsifying salts as follows: polyphosphate > pyrophosphate > orthophosphate > citrate. The calcium-chelating properties, especially of the shorter-chain phosphates, is reported to be strongly influenced by pH. At higher pH, a more complete dissociation of the phosphate molecules provides better ion exchange. For the shorter-chain phosphates, calcium-chelating ability increases in the following order: sodium hydrogen orthophosphate (NaH2 PO4 ) < disodium hydrogen orthophosphate (Na2 HPO4 ) < disodium diphosphate (Na2 H2 P2 O7 ) < trisodium diphosphate (Na3 HP2 O7 ) < tetrasodium diphosphate (Na4 P2 O7 ). Emulsifying salts and their blends can shift the pH of the cheese upwards and provide stability to the emulsion through their buffering capacity. Typical pH values of natural cheese range from 5.0 to 5.5, and this is shifted to 5.6–5.9 during the manufacture of process cheese. The extent of this shift is related to buffering of the natural cheese used in the formulation, pH of the emulsifying salt solution and the buffering ability of the emulsifying salts (Fox et al., 2000). As a result, the functional properties of the final processed cheese are also controlled by the extent of pH buffering provided by the emulsifying salts. The buffering capacity of sodium phosphate in the pH range 5.5–6.0 decreases with increasing chain length, and becomes ineffective at chain lengths greater than 10. Orthophosphate and pyrophosphate provide high buffering capacities in a wide pH range; therefore they function not only as buffering agents, but also as pH correction agents. In the case of citrates, only trisodium citrate has buffering capacity in the pH range 5.3–6.0. The final pH of processed cheeses is determined by the pH of the solution of emulsifying salts and by their buffering capacity. The pH of cheese made with trisodium citrate or different sodium citrate emulsifying salts, at equal concentrations, decreases in the following order: tetrasodium pyrophosphate = trisodium citrate = pentasodium tripolyphosphate > disodium hydrogen phosphate > sodium polyphosphate. The pH of processed cheese generally increases linearly with the emulsifying salt concentration used in the formulation, in the range 0–30 g kg−1 for trisodium citrate, tetrasodium pyrophosphate, sodium tripolyphosphate and disodium hydrogen phosphate (Kosikowski & Mistry, 1997; Fox et al., 2000; Guinee et al., 2004). As previously stated, the functional properties of processed cheese are significantly influenced by the pH of the final product imparted by the emulsifying salts. At low pH (≤5.2), the texture of processed cheese was mealy, dry, crumbly and had lower hardness, whereas at higher pH (>6.4) the manufactured products were excessively soft (Caric et al., 1985; Marchesseau et al., 1997). Stampanoni & Noble (1991a,b) reported that there was an increase in the hardness and elasticity of cheese analogues with decrease in pH of cheese from 6.2 to 5.0. Marchesseau et al. (1997) studied the influence of pH on protein interactions and microstructure of processed cheese, and found that variation in pH substantially affected the structure. Recently, Mulsow et al. (2007) reviewed the impact of pH on the texture and rheological properties of different types of processed cheese. Lu et al. (2008) studied the functional properties of processed cheese made with different types of emulsifying salts (trisodium citrate, disodium phosphate, sodium

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hexametaphosphate and tetrasodium pyrophosphate) at 2 g 100 g−1 level as a function of different pH values (5.3–5.9). All processed cheese samples exhibited an increase in degree of flow determined at 45◦ C when the pH was increased from 5.3 to 5.6. It was suggested that this was due to greater calcium binding by the emulsifying salt, increased charge repulsion and therefore greater casein dispersion. When the pH of the processed cheese was increased from 5.6 to 5.9, the cheeses emulsified with disodium phosphate and sodium hexametaphosphate exhibited no further increase in their degree of flow at 45◦ C. However, the degree of flow did increase in processed cheese emulsified with trisodium citrate, and decreased in cheese made with tetrasodium pyrophosphate. It was hypothesised that tetrasodium pyrophosphate was able to form cross-links with casein around pH 6, which then restricted the melt of the cheese; in contrast, trisodium citrate did not cross-link the caseins and the increase in pH helped with a greater casein dispersion. Samples with low pH (5.3) were not harder than samples with higher pH for all emulsifying salts investigated, but they did show fracture. The processed cheeses that had the highest hardness scores at pH 5.3 and 5.6 were made with tetrasodium pyrophosphate and trisodium citrate, respectively. It was concluded that the pH-dependent functional behaviour of processed cheese was strongly influenced by the type of emulsifying salt. In addition to the ability of the emulsifying salt to bind calcium and thus the ability to create cross-links with casein, the casein dispersion during cooking is also significant in the final functional properties of the processed cheese. Emulsifying salts have also been reported to reduce the size of the fat globule and contribute to its emulsification and thus control firmness and oiling-off (ability of the fat to become free when processed cheese is subsequently cooked). Some oiling-off is desirable upon baking or grilling as it limits drying out of the cheese, and it contributes to a desirable flow, surface sheen and succulence of the melted product (Fox et al., 2000; Kapoor & Metzger, 2008). However, excessive oiling-off could be unattractive, and result in a greasy and soggy product. All conditions being equal, it has been reported that the fat globule diameter is generally smallest when tetrasodium pyrophosphate is used as the emulsifying salt in a formulation, largest with basic sodium aluminium phosphate, and somewhere in between when trisodium citrate or disodium phosphate is used as the emulsifying agent. Increasing the concentration of emulsifying salts and processing temperature result in progressive decrease in milk fat globule size and increase in firmness of the process cheeses. Increasing the processing time for a given formulation results in final products that are firmer, more elastic and less flowable (Rayan et al., 1980). The same researchers also suggested that the decrease in fat globule diameter was accompanied by para-casein hydration on prolonged holding or shearing of the hot molten blends at a high temperature. More recently, Shirashoji et al. (2005) studied the effect of trisodium citrate concentration (0.25–2.75 g 100 g−1 ) and cooking time (0–20 min) on the physicochemical properties of processed cheese. Meltability of the product decreased with increased concentration of trisodium citrate, and holding time led to a slight reduction in meltability. Hardness increased as the concentration of trisodium citrate increased. Using fluorescence microscopy, the authors were able to show that the size of the fat droplets decreased with increase in concentration of trisodium citrate and with longer cooking times. The buffering capacity peaked at pH 4.8 due to the residual colloidal calcium phosphate, but decreased as the concentration of trisodium citrate was increased. The soluble phosphate

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content increased as the concentration of trisodium citrate increased. However, the insoluble calcium decreased with increasing concentration of trisodium citrate. The results of this study suggest that trisodium citrate chelates calcium from colloidal calcium phosphate and disperses the casein; the citrate–calcium complex remains trapped within the processed cheese matrix. Increasing the concentration of trisodium citrate helps to improve fat emulsification and casein dispersion during cooking, both of which probably helps to reinforce the structure of processed cheese. In another study with no-fat cheeses, Brickley et al. (2008) reported on the influence of emulsifying salts on the textural properties of non-fat processed cheese made from direct acid cheese bases. Non-fat cheeses tend to be sticky, have insufficient or excessive melt, have an undesirable pale colour on cooling, and form dry skin often leading to dark blistering and chewy texture. The results indicate that these problems in processed cheese may be overcome by using cheese bases manufactured to have specific textural characteristics with the use of appropriate emulsifying salts during the manufacture of processed cheese. Over the years, the effectiveness of emulsifying salts in promoting various physicochemical changes that occur during processing has been studied extensively in both processed cheese products and cheese analogues. However, there are many discrepancies between studies reporting the role of emulsifying salts in changing different physicochemical parameters, probably due to differences in product formulation, the amount of emulsifying salt added and varying processing conditions. What have been discussed here are merely trends that have been reported and confirmed by others.

6.4.3 Preservatives The preservation of food has always been of great importance to humans, since they evolved/changed their way of life from food-gathering to food-producing and storage. Compounds such as salt, sugar, acid and smoke have been used as food preservatives for centuries. Currently, food is conserved mainly with chemical substances, which act as antimicrobial agents, protecting food from contamination by moulds, yeast and bacteria. In Brazil, preservatives are defined as ‘substances that prevent or delay the change of food caused by microorganisms or enzymes’ (Anonymous, 1996), and the existing legislation allows the use of different substances in foods, but sorbates and its salts are the most popularly used preservatives (Tfouni & Toledo, 2001). In addition, nisin and lysozyme are widely used in the manufacture of processed cheese (Moreno et al., 2001). The occurrence and proliferation of microorganisms in the environment is common, and the chemical and enzymatic reactions associated with them result in decomposition of materials, including food. This decomposition causes changes in appearance, taste, texture, colour and nutritional quality of the product. Moreover, certain microorganisms are toxic to humans and can cause infections or poisoning when proliferated in food. Except for specific microbiological fermentation, the growth of microorganisms in food is undesirable, so it is necessary to avoid or inhibit it through methods of conservation. Preservatives may be effective in conserving foods by controlling the growth of microorganisms directly or by destroying all or part of them. Selection of a preservative compound(s) for a specific application is based on the following factors: (a) physical and

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chemical properties (solubility, pKa , reactivity, toxicity), (b) the microorganisms whose growth needs to be controlled/inhibited, and (c) type and properties of the product to be retained. In some cases, combinations of more than one substance are most effective for a given product (Tfouni & Toledo, 2001). Some examples follow in the subsequent sections, and the types of preservative widely used during the manufacture of processed cheese are shown in Table 6.1. Potassium sorbate, or sorbic acid, is naturally present in nature and was first isolated in 1859 by the German chemist A.W. von Hohmann from the fruit of Sorbus aucuparia L. However, it was only around 1939 that its antimicrobial activity was discovered simultaneously by E. Muller in Germany and by C.M. Gooding in the USA. Its role as a food preservative is quite extensive worldwide, due to the fact that it does not interfere with the taste and because it is physiologically harmless. Sorbic acid can be used pure or as sodium, calcium or potassium salts (Tfouni & Toledo, 2001). The sorbates were first used as food preservatives in the early 1950s because they are effective at inhibiting the growth of yeasts and moulds in food, but are less effective at inhibiting bacteria. The sorbates are therefore tideal for use in cheese and pickles because the action of fermentative lactic acid bacteria is vital to the production of these types of food, and because sorbates tend to prevent the growth of moulds and yeasts. Temperature and low pH can affect the action of the sorbates, causing a change in their effectiveness; however, they are employed more frequently in foods with pH ∼ 6.5 (Frazier & Westhoff, 1993). The antimicrobial activity of sorbates is related to the undissociated molecule, which determines their greater effectiveness in acid or acidified foods. Sorbic acid has a pKa of 4.8 and has increased activity at pH < 6.0; it is ineffective at pH > 6.5. Between pH 4.0 and 6.0, sorbic acid and its salts are more efficient than the benzoates. As for benzoic acid, the minimum concentration of sorbic acid needed to inhibit microorganisms varies depending on the substrate, pH of the medium and specific microorganisms. The minimum inhibitory concentration (in μg g−1 ) ranges from 10 to 10 000 (bacteria), from 25 to 400 (yeast), and from 10 to 1000 (moulds). The antimicrobial activity of sorbic acid is synergistic with that of sodium chloride, sucrose, propionic acid, carbon dioxide and sulphur dioxide. Otherwise, it has antagonistic effects similar to those of the main anionic surfactants. The main disadvantage of sorbates is that they are more expensive than benzoates or propionates. However, in products with high pH, they are generally used in smaller quantities than the benzoates and propionates in order to attain their desired effect (Tfouni & Toledo, 2001). Nisin is a bacteriocin produced by Lactococcus lactis subsp. lactis that occurs naturally in milk, and inhibits the majority of Gram-positive bacteria especially the spore-formers. Bacteriocins are proteins with different molecular weights that have usually, but not necessarily, bacteriostatic or bactericidal action. All substances that inhibit pathogenic bacteria and sporulation are potentially usable, but only nisin produced by L. lactis subsp. lactis is used commercially. It is used in processed cheese to inhibit the growth of Gram-positive microorganisms including Listeria monocytogenes (Cogan & Hill, 1993; Zottola & Smith, 1993; Gujarathi et al., 2008; see also Chapter 1). The production of bacteriocins by lactic acid bacteria, especially Lactococcus spp., has been known for about six decades (i.e. first reported in 1928) after observing the failure of dairy starter cultures during the production of yoghurt and cheese (Eapen et al., 1983; Daeschel, 1990). In New Zealand, Whitehead

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(1983) first reported that the prolonged storage of raw milk caused the inhibition of lactic acid bacteria, which influenced the production of lactic acid during the manufacture of Cheddar cheese. These antagonistic effects were initially attributed to the presence of some sort of inhibitory substance, which showed resistance to heating to 100◦ C, produced by certain strains of L. lactis subsp. lactis. Whitehead also showed the ability of a strain of Lactococcus lactis subsp. cremoris to inhibit the development of other lactic acid bacteria, when added to milk. Studies to elucidate the cause of such inhibition showed the presence of a substance produced by this strain, that had antimicrobial activity only against other strains of the same species. Nisin is widely used in processed cheese to inhibit the activity of spore-forming bacteria; however, its action is limited due to the presence of bacteria in natural cheeses that destroy or inhibit its activity (Robinson & Wilbey, 1998). Nisin has a molecular mass of 3.5 kDa and contains a number of unusual amino acids, including lantionina; sometimes it is referred to as a lantibiotic. Its potential mechanism of action involves disruption of the cell membrane leading to its collapse and release of low-molecular-weight compounds (Cogan & Hill, 1993; Zottola & Smith, 1993). It is suitable for use in the food industry as it is quickly digested in the stomach and cannot therefore cause resistance to endogenous selective microorganisms as happens when antibiotics are administered as medicine (www.grupobv.com.br/Nisaplin_txt.htm). Nisin was first isolated and purified by Mattick and Hirsch in 1947, and the name was derived as follows: N from group N of Streptococcus (currently known as Lactococcus); I for inhibitory; S for substance; and IN as the suffix of most antibiotics. Nisin was purified and began to be produced commercially by Aplin-Barret by the end of 1950s under the name Nisaplin. The early studies with nisin showed that this bacteriocin is degraded by the action of the digestive enzyme α-chymotrypsin and pancreatic proteolytic enzymes. Normally, sensitivity to proteolytic enzymes has been used by different researchers to characterise new bacteriocins. In the case of nisin, many studies have shown different profiles of sensitivity and resistance to different enzymes and, sometimes, even for the same production strain. The stability, solubility and biological activity of nisin are dependent on the pH of the solution. It is stable at 100◦ C for 10 min and at 115.6◦ C in a solution of 5.0N HCl and pH 2.0. A 40% loss of activity was detected at autoclave temperatures in a pH 5.0 buffer solution. Under the same conditions but at pH 6.8, loss of activity is greater than 90%. In alkaline pH (11), its activity is completely destroyed after 30 min at 63◦ C. Some substrates, such as milk solids, offer a protective effect at high temperatures. Due to the nature of its acidic molecule, nisin has maximum stability under acidic conditions. It is completely stable in solutions at pH 2.0, which can be stored for an extended period at temperatures of 2–7◦ C without loss of activity. Above pH 7.0, inactivation occurs even at room temperature (www.grupobv.com.br/Nisaplin_txt.htm). Nisin shows bactericidal activity against a wide range of microorganisms including Gram-positive spore-forming bacteria belonging to the genera Bacillus and Clostridium. Nisin is not only active against the spores of microorganisms, but also against the development of post-germination spores. Nisin shows no activity against moulds and yeasts or Gram-negative organisms. Characterisation of the basic molecule of nisin suggests its connection to negatively charged membranes; this has been proven in studies showing that nisin prefers membranes that contain relatively high amounts of fat, mainly anionic.

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In general, the Gram-positive bacteria have high concentrations of lipids compared with Gram-negative organisms, which may partly explain the activity of nisin against the former (Breukink & Kruijff, 1999). Nisin targets the membrane of the bacteria, and the pores formed after its insertion lead to cell death (Breukink & Kruijff, 1999). Streptococcus thermophilus produces nisinase, an enzyme that destroys nisin. However, nisin is active in several bacteria of the genera Staphylococcus, Bacillus and Clostridium. Certain bacteria found in milk such as Enterococcus faecalis and Lactococcus spp. also destroy the activity of nisin (Robinson & Wilbey, 1998). Nisaplin is a commercial product and is obtained from the fermentation of L. lactis subsp. lactis in a medium without lactose. The resulting nisin is subject to concentration, followed by milling and processing into small particles, which are then standardised by the addition of sodium chloride solution. As well as the lack of hygiene in its production, the application of Nisaplin does not allow the use of deteriorated raw materials since it has no effect on moulds and yeasts, Escherichia coli and a whole range of Gram-negative bacteria (i.e. failure in the conduct of good manufacturing practice) (www.grupobv.com.br/Nisaplin_txt.htm). In 1969, nisin was accepted by the World Health Organisation (WHO) as a food additive, and has been used extensively for this purpose in Europe. In 1988, FDA in the USA approved the use of nisin in limited quantity in pasteurised spreadable cheese, where the high humidity and low levels of sodium increase the risk of formation of botulinum toxin in the product (Cogan & Hill, 1993; Zottola & Smith, 1993). The amount of nisin needed depends on the number of spores of Clostridium spp. present in the cheese, the shelf-life expected or required, and the desirable storage temperature. The recommended dosage level is ∼200 industrial units (IU) nisin 500 g−1 cheese. Higher levels are recommended when the formulation of processed cheese includes the addition of flavours, low-fat and high moisture contents (Cogan & Hill, 1993; Zottola & Smith, 1993). Another preservative that can be used during the manufacture of processed cheese is lysozyme (N -acetyl-hexosaminidase). Lysozyme breaks the cell wall of certain species of bacteria by hydrolysis of the β-(1 → 4) glucosidic bonds of peptidoglycan. However, the antibacterial activity of lysozyme is attributed not only to its enzymatic activity, as the irreversibly inactivated enzyme also shows antibacterial effects. It has been suggested that the alkaline nature of lysozyme contributes to its antibacterial activity. Lysozyme from different sources differs with regard to the spectrum of antibacterial activity and specificity concerning different types of peptidoglycan, in particular its ability to hydrolyse the O-acetylate component or other components for replacing peptidoglycan. Lysozyme is active mainly on Gram-positive bacteria because they possess an outer membrane. However, Gram-negative bacteria are more sensitive to lysozyme in combination with ethylenediaminetetra-acetic acid (EDTA). The interaction of lysozyme with perillaldehyde (4-isopropenyl-1-cyclohexene-1-carboxaldehyde) or combination of lysozyme with galactomannan increases the power of the enzyme with respect to Gram-negative bacteria by enabling dissemination of the enzyme through the outer membrane of the target cell. Usually, the dosage rate is 2.5 g lysozyme 100 L−1 of milk (250–300 mg kg−1 of cheese) and the enzyme is safe to human health (Walstra et al., 2006). In the case of Clostridium tyrobutyricum, lysis begins as the spores germinate. Lysozyme is not active in high concentrations of NaCl solution (e.g. 5 g NaCl 100 g−1 water). In moderate concentrations

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of the enzyme, lactic acid bacteria are only slightly or not affected; the propionic acid bacteria are inaccessible to the enzyme, so lysozyme can be used during the manufacture of Emmental cheese (Walstra et al., 2006). In some instances, the recommended dosage rate of lysozyme may not be sufficient for wide varieties of natural cheeses to prevent butyric acid fermentation because some types of butyric acid bacteria are not sensitive to lysozyme and the addition of nitrate is required (Walstra et al., 2006). In order to obtain the antibacterial benefits of the enzyme, it is clear that it is necessary to preserve enzyme activity. Like all other enzyme systems, activity is dependent on the pH, temperature and the presence of salts.

6.4.4 Formulation of the cheese blend Cheese ingredients that will be used during the manufacture of processed cheese products should be analysed for fat and moisture content. Careful computation of all ingredients is essential to meet legal standards of identity for the different products being manufactured. Traditionally, processors relied on past history and experience in formulation of their products. Today, several computer programs are available to assist the processor to select ingredients based on composition and desired properties of the final end product (Kapoor & Metzger, 2008). Formulation adjustments need to be made when incorporating re-work cheese as mentioned earlier. Formulation of processed cheese depends on the variety of product being manufactured and the final functional properties desired in the final cheese product. Because the availability and properties of natural cheeses vary (due to the type and age of natural cheese), and because the amount of re-work cheese to be added may also vary, the processed cheese manufacturer may have to reformulate the processed cheese procedure regularly in order to achieve a product with consistent quality.

6.4.5 Grinding/shredding Initially cheeses selected will be trimmed to remove wax, packaging material(s) and other defects. Cheese wheels or blocks are ground using large-capacity grinders to form part of a new blend (for further details see Chapter 7). High-power shredders are able to grind cheese at roughly 454.5 kg min−1 . A colloidal mill may be used to further reduce particle size. At this point a cheese pre-mix is prepared where the formulation is standardised and other ingredients (i.e. emulsifiers) are blended and transferred to the cookers; alternatively they could be added directly to the cookers in the next phase of processing (Kosikowski & Mistry, 1997; Fox et al., 2000).

6.4.6 Heating/cooking After addition of the ground cheese to the cooker, water, colour, salt, condiments and emulsifiers are also added if they were not incorporated during earlier stages of processing. Emulsifiers may also be added after dissolving in potable water. CFR specifies the minimum

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Fig. 6.4

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Pilot-scale batch cooker used in processed cheese manufacture.

cook temperature and time for processed cheese: 65.5◦ C for 30 s (FDA, 2006). However, cook temperatures can vary between 70 and over 100◦ C depending on the cheese processor, the type of cooker being used and the variety of product being manufactured. Heating may be by indirect or direct steam injection. Figure 6.4 illustrates a batch cooker used in processed cheese manufacturing. The application of a partial vacuum during processing is practised, but is optional. The application of vacuum may regulate moisture level as well as remove some of the air that may have been incorporated during mixing, thus preventing an open structure in the product. Upon heating, the natural cheese is melted, and the fat and serum phases separate. Emulsifying salts then aid in the emulsification process. During cooking and emulsification steps, the pH becomes more alkaline (which solubilises the proteins), the diameter of the milk fat globule is reduced, and a smooth homogeneous mass is obtained. Freshly made cheese pre-mixes may be sterilised by passing through a continuous cooker, where the mix temperatures could reach 130–145◦ C for 2–3 s. In horizontal batch cookers, 70–75◦ C may be attained in 4–6 min. During a batch process, close control of temperature and time in the cooker is essential to minimise browning and thickening of the cheese emulsion. Direct culinary steam injection (69–550 kPa) may also be employed in batch operations. Agitation during batch cooking is typically slow

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(50–150 rpm) (Kosikowski & Mistry 1997; see also Guinee et al., 2004; Walstra et al., 2006). In manufacturing of dips and sauces, where typically continuous cookers are used, the blends are mixed and heated to 80–90◦ C in a vacuum mixer then pumped into tubular heat exchangers and heated to 130–145◦ C for a few seconds and then flash cooled to 90◦ C. The final product is pumped to a surge tank, which then feeds the packaging machine. Cheese slices are manufactured by pumping the hot emulsified molten cheese mixture through a manifold that extrudes the cheese ribbons onto counter-rotating chilled rollers, which cool the cheese to ∼30◦ C. Next, the ribbons are sliced automatically and stacked. Cook temperature, cook time, mixing speed during manufacture and the rate of cooling once the cheese is processed are key factors in controlling the formation of the emulsion and the functional properties of the final product. Therefore it is important to have close control of these parameters. It has been demonstrated that fat particle size and its distribution are affected by mixing speed and temperature during processed cheese manufacture (Rayan et al., 1980; Glenn et al., 2003; Lee et al., 2003). The latter researchers reported that at high mixing speed under constant cooking temperature and time conditions, emulsified processed cheese mixtures had a larger number of small, evenly distributed fat globules compared with processed cheese mixtures that were mixed at low speeds. The authors theorised that a large number of small, evenly distributed fat globules enhance fat–protein and protein–water interactions and thus facilitate the formation of a stronger network. However, increasing the mixing speed beyond its optimum may enhance protein–fat and protein–protein interactions to an extent that the casein molecules coagulate into a pudding-like structure. This phenomenon is referred to as over-creaming as it is characterised by an increase in viscosity and reduction in meltability (Berger et al., 1998; Glenn et al., 2003). Lee et al. (1981) reported that an increase in cooking temperature during the manufacture of processed cheese increased the strength of the cheese emulsion and thus the firmness of the final product. Increases in cooking time have been reported to increase firmness and degree of elasticity and decrease meltability of the final processed cheese (Rayan et al., 1980). These reported observations were independent of the type of emulsifying salt used. The microstructure of the processed cheeses revealed stronger emulsification of the product at longer process times. Garimella Purna et al. (2006) studied the effect of mixing speed during the manufacture of processed cheese and reported increased viscosity immediately after manufacture, and increase in firmness and decrease in flow properties and meltability with increased mixing speed. Cryo-SEM images of processed cheese has revealed that products manufactured at higher speeds have smaller milk fat globules that are more uniformly distributed compared with processed cheese manufactured at lower mixing speeds. It should be noted that the studies summarised in this section, although very valuable for our understanding, are somewhat limited in scope. Much research has been conducted on the effects of processing parameters on the properties and quality of processed cheese and related products. However, these studies have been somewhat limited and have typically evaluated one to two parameters. It is difficult to compare results from different studies due to differences in manufacturing techniques, raw materials and ingredients used, and other processing variables. In addition, different studies have used different types of cookers. It is difficult to choose a particular cooker design to simulate the effect of all potential manufacturing parameters (Berger et al., 1998).

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6.4.7 Miscellaneous processing steps Homogenisation is an optional step in processed cheese manufacturing, although it provides for better emulsification of the fat. Homogenisation is recommended for high-fat formulations and when high-fat natural cheeses are used.

6.4.8 Packaging Hot processed cheese can be transported through pumps to the filling/packaging machine or may be transferred in mobile containers; the latter system is not safe when considering the risk of contamination. The product is usually packed in collapsible tubes, glass, cans or cardboard (see Chapter 8 for detailed information). In general, packaging (primary and secondary) should be impermeable and should protect the product against the following. •

• •

•

• •

Dehydration is the loss of moisture through evaporation of water; the surface of the product will be particularly affected and this should be avoided. Dehydration can cause changes in the texture and appearance of the product, and also weight loss. Contamination of the product with microorganisms must be avoided because the contaminating microflora could be pathogenic or spoilage in nature. Loss of flavour/aroma may occur due to the absorption off-flavours from the environment during the storage period, or by the migration of these components and interaction with the packaging material. Permeation of oxygen causes oxidation of fat content leading to the development of rancid taste or aroma; also the presence of oxygen enhances the growth of aerobic microorganisms, which may cause spoilage of the product. Permeation of light accelerates the reaction(s) of fat oxidation. Mechanical damage of the product during storage, transportation and marketing may occur, and the packaging material used should protect the processed cheese (Sarant´opoulos et al., 2001).

Of the processed cheeses, the creamy curd has a short shelf-life, and this is mainly a factor of its development process. The thermoduric microbiota is generally composed of microorganisms that produce proteolytic or lipolytic enzymes. The proteolytic enzymes hydrolyse the proteins, making the product more liquid and producing a bitter taste. Lipolytic enzymes cause rancidity (Alves et al., 1994; Sarant´opoulos et al., 2001). In Brazil, Requeij˜ao is mainly packed in glass containers. However, some brands are packed in flexible containers made of plastic laminates of polyethylene tetraphthalate/polyethylene (PET/PE) or polyethylene tetraphthalate/polypropylene (PET/PP) (Sarant´opoulos et al., 2001).

6.4.9 Rate of cooling and storage The creamy-type processed cheeses (i.e. spreadable) must be cooled as soon as possible and relatively at a slower rate than for processed cheese in blocks because cooling softens the

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product. However, slow cooling may intensify the Maillard reaction and promote growth of spores (Fox, 1993). The final products must be stored at temperatures below 10◦ C, even though low temperatures can induce the formation of crystals. Once the cheese is processed, the rate of cooling has also been reported to impact the functional properties of the cheese. During cooling, the molten viscous mass of processed cheese sets to form a characteristic body, depending on the blend formulation, processing conditions and the cooling rate. These parameters vary depending on the final desired product (sliceable, semi-soft, spreadable processed cheese). Solidification (or crystallisation) of fat within the new matrix that is formed by protein–protein interaction contributes to the structure formation (setting) during cooling. It is thought that on cooling the newly formed emulsified fat globules become an integral part of the protein matrix through a variety of molecular interactions with the para-caseinate matrix. Microstructure studies of processed cheese show that protein exists as relatively short strands, but with a high degree of continuity depending on the specific product. The protein strands are much finer than that seen in natural cheeses, and the fat globule size is smaller in diameter and more uniformly distributed compared with natural cheeses. Piska and Stetina (2003) investigated processed cheese products manufactured using Dutch-style semi-hard and hard cheese blends and which were cooled at different rates. They reported that cheeses that were cooled to 20◦ C in 50 h were significantly firmer, more adhesive and gummy compared with the cheeses that reached 20◦ C in less than 1 h and 5◦ C in 2 h. Zhong et al. (2004) reported the storage modulus (G ) of processed cheese that was cooled 0.025, 0.05, 0.1 and 0.5◦ C min−1 .G increased with decrease in cooling rate, confirming earlier studies that slow cooling of processed cheese results in firmer cheese. These authors also investigated the sliceability and meltability of 2.5-kg processed cheese loaves that were cooled in free convection and forced convection coolers. They reported that cheeses cooled in the forced convection cooler had higher meltability and were softer than the cheeses cooled in the free convection cooler, probably because of more rapid cooling by the forced convection cooler (Zhong et al., 2004).

6.5 Changes in processed cheese during its shelf-life The firmness of processed cheese is influenced by many factors, such as the composition/formulation of the cheese blend, level of moisture content, type of emulsifying salt used, processing conditions and temperature of storage. In a study reported by Tamime and Younis (1991), Tamime et al. (1990, 1991) and Younis et al. (1991a–c), processed cheeses (i.e. block-type ∼2 kg in weight) were made from different types of cheese base, and mature and young Cheddar cheeses. The products were cooled for 3 days at 5◦ C and later stored for 6 months at 10, 20 and 30◦ C. It was observed that processed cheeses made from cheese base blends stored at 30◦ C were the firmest, which was possibly attributed to the more extensive hydrolysis of polyphosphate emulsifying salts (JOHA SE, C and T; the former two types are special emulsifying salts for the manufacture of block type processed cheese, whilst T is a strongly alkaline correcting emulsifying salt) at this temperature compared with product stored at 10◦ C, and products stored at 30◦ C contained slightly higher concentrations of soluble nitrogen than the freshly made processed cheese. Incidentally, condensed polyphosphate emulsifying salts partially hydrolyse during melting of the

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cheese, and the hydrolysis continues during the storage period (Guinee et al., 2004). Lee et al. (1979, 1986) reported that other aspects that can influence the firmness of processed cheese are the level of non-sedimentable nitrogen (possibly soluble nitrogen) and increased amount of emulsifying salt. In addition, the microstructure of processed cheese products stored at 30◦ C reported by Tamime et al. (1990) developed irregularly shaped fat particles, but the differences in their dimensions were not statistically significant (for further details see Chapter 10). The temperature of processing (e.g. 117◦ C for 20 min) and storage temperature (23◦ C) for 24 months caused colour change, which was more significant (P < 0.05) than for products stored at 8◦ C for the same duration. Also, the firmness of stored processed cheeses increased, and the rise was higher at 23◦ C, but decreased in the second year of storage (Bunka et al., 2008). These reported changes during shelf-life can affect the desired functional properties and end-use functionality of the processed cheese for which it is intended (i.e. meltability, spreadability). Other changes that may occur in processed cheese during its shelf-life include crystal development, colour changes and gas production. Sommer (1930) and Leather (1947) identified calcium tartrate crystals in processed cheese. However, this would not be common today in the USA since tartrate salts are no longer used as emulsifying salts in the manufacture of processed cheese. Other researchers have identified calcium citrate crystals (Morris et al., 1969; Scharpf & Kichline, 1969) and tertiary complexes of sodium and calcium citrate crystals in processed cheese (Klostermeyer et al., 1984). Crystals of sodium and calcium phosphate (Scharpf & Kichline, 1968; Pommert et al., 1988) and calcium salts of free fatty acids, lactose (Kapoor & Metzger, 2008) and tyrosine (Kosikowski & Mistry, 1997) have also been reported. Although some level of crystal formation may be tolerated, when crystals become too large and produce white specks the cheese is rejected. Crystals also produce undesirable ‘gritty’ or ‘sandy’ texture and weak spots in the processed cheese and may therefore impact its sliceability and other textural properties. Colour changes during the shelf-life of processed cheese include browning or pink discoloration. Browning may initiate due to lactose, particularly in formulations which contain ingredients with high lactose content (Thomas, 1969, 1973). A final pH > 5.9 (Thomas, 1969) and storage temperature of 35–37◦ C (Thomas, 1969; Kristensen et al., 2001) accelerate the browning reaction in processed cheese. Chemical composition of the natural cheeses has also been reported to contribute to the browning process (Kapoor & Metzger, 2008). On the other hand, the pink discoloration that may occur during storage is due to annatto, particularly the alkaline extracts of this colouring (Shumaker & Wendorff, 1998; Zehren & Nusbaum, 2000). Gas production may occur several weeks into storage or on the grocery store shelf. Gas formation in processed cheese is typically due to microbial spores of Clostridium tyrobutyricum and Clostridium sporogenes. Spores of these organisms are not destroyed by the heating process during manufacturing. Under favourable conditions during storage, the spores germinate and ferment available sugars, producing gas that will swell the cheese and also the packaging (Kosikowski & Mistry, 1997). However, addition of mould inhibitor/preservative is allowed in processed cheese at levels of 0.2% or less of the final product. Nisin is an approved additive in processed cheese spread at levels below 250 μg g−1 (Kapoor & Metzger, 2008).

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Some properties of stored processed cheese, such as firmness, heat stability and addition of re-worked cheese, gradually change. The tendency of these changes seems to be similar to the changes caused by creaming of processed cheese (Kawasaki, 2008). In addition, some of the defects of the product may have been caused by mechanical action during processing or biological activity of residual microorganisms. These faults could be attributed to the natural cheeses used during the maturation period or present in the finished product (Frazier & Westhoff, 1993). Overall, the quality of cheese is related to several factors, such as the microbiological quality of milk and other raw materials, and the technological and sanitary conditions during the manufacture of processed cheese (Sarant´opoulos et al., 2001).

6.6 Conclusions With a variety of end-use applications, processed cheese is by far the most versatile of all dairy products. Today numerous processed cheese and related products can be found in the marketplace, including slices, loaves, toppings, spreads, dips, sauces, reduced-fat and reduced-sodium counterparts. Processed cheese has come a long way over the past 100 years. However, the literature on processed cheese and peer-reviewed published studies has been limited because much of this information was patented, and today some still remain ‘trade secrets’. Nevertheless, despite the fact that the manufacturing steps are well known, the mechanism of emulsification and how the variables influence the process are still not fully understood. There are many blends of ‘ready to use’ emulsifying salts available in the market for processed cheese manufacturers; the use of dried ingredients tends to facilitate technological studies, which allows the product to be treated as a model system where the variables are limited and well known. Also, it is difficult to compare published studies due to differences in experimental conditions, formulations, processing conditions and equipment used. Furthermore, it is difficult to extrapolate studies done with model systems directly to processed cheese products since the products have specific standards of identity. Since standards of identity are lacking for sauces and dips, there is even less information on the formulation, processing and functionality of these products. Today, there is still much need for scientifically sound published literature on processing, functional aspects and methods to study the functional properties of processed cheese and products to fill the information gap. Processed cheese is a product that fits the modern way of life and consumer needs, and the accessibility of a quality product with low prices could be advantageous for industry and consumers worldwide.

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7 Processed Cheese Plants and Equipment: A Practical Overview S. Dixon

7.1 Introduction The type of product and the attributes required in processed cheese products would normally determine the design and type of processing line for installation. Choosing the correct equipment is essential to achieving an optimum product that will deliver the desired customer approval. The old definition in the UK for processed cheese was ‘natural cheese that had been subjected to a process of melting and mixing, with or without the addition of emulsifying salts’. Some of the actual methods for melting and mixing are covered in this chapter. As an example, if we consider the types of cooking or melting and mixing systems available they can generally be split into two categories, batch cookers and continuous cookers, both of which either pasteurise or sterilise the cheese blend with direct steam injection. Indirect heating of processed cheese products has virtually disappeared from the industry now and the negatives of using this method are discussed later. Batch cooking systems can be divided further into ‘low shear’ and ‘high shear’ equipment. The type of mechanical action can have a critical impact in terms of product mouth-feel, flavour ‘getaway’ and, of course, customer liking for a product. Continuous cooking systems, by their very design, have to raise the temperature of a product to either pasteurisation or sterilisation level in a very short time. This is achieved by steam injection with a wide range of injector possibilities but, in order to achieve the temperature in a short time, the shear created by the steam injection provides a similar result to a ‘high mechanical action’ in batch cookers. Continuously cooked products are further compromised from a consumer approval perspective because of the vacuum flash cooling system. This produces a dense close-knit structure that significantly impacts flavour release from the product. The result of ‘high mechanical action’ cooking is a product with small fat droplets in the continuous hydrated protein phase of the emulsion versus the larger fat droplets and open structure of the ‘low mechanical action’ cooking systems. It is this difference in structure that can influence customer preference and therefore careful consideration should be given to the type of equipment required before commitment to capital investment. Processed Cheese and Analogues, First Edition. Edited by A.Y. Tamime. © 2011 Blackwell Publishing Ltd. Published 2011 by Blackwell Publishing Ltd.

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Processed cheese manufacturing lines can range from a simple batch cooking operation carrying out a range of functions to a complete line with many specific unit operations carried out by specialist equipment. The selection of equipment is obviously very important but the ability to add on compatible equipment to expand the line, increase output to meet consumer demand, and to continue to produce an acceptable product is equally important. However, this chapter is based on my 39 years of personal experience in the cheese processing industry and therefore based mainly on opinion.

7.2 Unit operations A typical processed cheese manufacturing line may consist of the following unit operations: (a) weighing the cheese, butter and other ingredients, (b) initial size reduction of the cheese for grinding, (c) grinding of the cheese for further size reduction, (d) blending the cheese and other ingredients to target moisture and fat contents, (e) transferring the standardised blended cheese to a cooking system, (f) direct steam injection cooking, and (g) filtering the molten cheese mass before packaging or further handling. These unit operations are briefly reviewed below.

7.2.1 Weighing the ingredients to be processed It is obvious, however, that an important step during the manufacture of any processed cheese product is the accurate weighing of ingredients to enable the finished product to be consistent in its chemical composition to comply with existing or proposed legal standards for processed cheese products, and to exercise good raw material control thereby avoiding variances. Most product development personnel will have been trained to consider blender or cooker batch sizes when formulating processed cheese products. It is quite often possible to formulate products in terms of whole numbers of units of cheese or butter, which reduces the potential for operator error. The same is true for many powder ingredients, especially materials such as casein, where one bag of casein can typically cost as much as one pallet of salt. Consideration has to be given to the point at which secondary and primary packaging materials are removed from natural cheeses to maintain good manufacturing practice (GMP). Generally, the primary packaging should be removed in a high-care environment and not in the presence of the wooden pallets on which cheese is most often supplied. Weighing of materials can be carried out on simple but accurate scales or on motorised conveyor belt load cell systems that deliver the cheese to the next unit operation, which is typically initial size reduction (Fig. 7.1). Load cell conveyors can perform two very important functions. They can of course control and record the exact weight of natural cheese and butter ingredients being put through the system, but they can also provide a means of transferring raw materials in primary packaging from a low- or reduced-care environment into a high-care environment before the packaging material is removed. All secondary packaging, such as cardboard boxes, would have been removed in the low- or reduced-care area of the operation. Depending on the size of the load cell conveyor, it can also perform a staging operation for the next batch of cheese blend.

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¨ Fig. 7.1 Typical load cell conveyor. (Reproduced by courtesy of Karl Schnell GmbH & Co. KG, Muhlstrasse 30, D-73650 Winterbach, Germany.)

7.2.2 Initial size reduction The general term given to the piece of equipment that carries out the initial size reduction on the blocks or barrels of cheese is a ‘curd breaker’ (Fig. 7.2). This piece of equipment utilises revolving shafts with claws that break pieces as large as a fist from the blocks or barrels, and deposits them either directly into a grinder or onto a conveyor that feeds a grinder for the final size reduction of the cheese. Butter is also passed through the same equipment. Whilst there are alternatives to a curd breaker and grinder (i.e. modified meat mincing machine), the two-stage operation provides the greatest flexibility. Normally, curd breakers are fed from the load cell conveying system where the previously weighed natural cheese and butter is transferred into a dump hopper, which typically holds up to 400 kg of different ingredients. The dump hopper is raised and emptied into the curd breaker via a mechanical hoist. Without the use of a curd breaker, the type of cheese grinder design would be limited and the initial size reduction through an appropriately geared curd breaker significantly reduces the strain on the final size reduction through the grinder. There are numerous designs for cheese grinders available on the market, but the modified design meat grinder offers the most interesting range of options in terms of extrusion plate sizes. Small extrusion hole plates can be especially useful when producing sterilised high moisture cheese spread products. They ensure that small curd particles are broken down prior to sterilisation, which could create spoilage problems due to inefficient heat transfer into the centre of the particle. Large extrusion hole plates, apart from increasing throughput of any cheese line, can also be useful for producing products that need to mimic pasta filata type cheeses in which the natural cheese structure has not been overworked. Although there are combined curd breakers and grinders, the downside of these types of equipment is difficulty in cleaning.

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(a)

(b) Fig. 7.2 Overall views of the breaker equipment (a) and the auger assembly in the breaker unit (b). ¨ (Reproduced by courtesy of Karl Schnell GmbH & Co. KG, Muhlstrasse 30, D-73650 Winterbach, Germany.)

7.2.3 Grinding Cheese grinding into paste is essential for accurate moisture and fat standardisation in the next stage, the blending operation. Considerable success has been achieved in initially converting large meat grinders for grinding cheese but, in recent years, design changes have resulted in an optimum piece of equipment in its own right as a cheese grinder. The size of the extrusion hole plates in a grinder, through which augers extrude the natural cheeses and butter, may range from 2 to 20 mm depending on the type of product to be

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manufactured, but switching the hole plates is a relatively easy task and can be carried out in minutes. Lumps or chunks of cheese and butter are fed from the curd breaker into the grinder and, on more modern production lines, photoelectric cells control the level in the grinder by stop/starting the curd breaker and conveyor in-feed. The paste extruded from the grinder is normally fed into bins for tipping directly into a cooking system or blender, or alternatively on automated lines the cheese would be fed directly onto an inclined conveyor that feeds one or more ribbon blenders. Grinders (Fig. 7.3) can be fed via bins and lifting devices, but the shape of typical 20-kg blocks can cause bridging in the grinder. The pre-breaking of the cheese in the curd breaker results in less downtime and frustration in production. However, ground product(s) can be transferred from the outlet of the grinder into mobile bins for tipping directly into batch cookers or blenders via a lifting device or onto an inclined conveyor (Fig. 7.4) for feeding one or more blenders.

Fig. 7.3 Modern cheese grinder fed by bins and/or lifting device. (Reproduced by courtesy of Karl Schnell ¨ GmbH & Co. KG, Muhlstrasse 30, D-73650 Winterbach, Germany.)

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Fig. 7.4 An inclined conveyor for transferring ground cheese into one or more blenders. Note the open style to facilitate cleaning; the belt rests on stainless steel bars rather than a flat bed making cleaning much ¨ easier. (Reproduced by courtesy of Karl Schnell GmbH & Co. KG, Muhlstrasse 30, D-73650 Winterbach, Germany.)

7.2.4 Blending the ingredients to form a standardised cheese mix or blend After natural cheeses have been size reduced, it is necessary to combine them with the balance of the formulation ingredients to form a homogeneous mass which can be standardised to target moisture and fat contents with added butter and water. A target percentage of fat-in-dry matter (FDM) is established in the cheese blend, and this ratio of fat to dry matter is adjusted first. Once the FDM is correct, then the cheese blend can be adjusted to the target moisture content, which will be calculated minus the condensate from the steam injection system used to heat the cheese blend. Modern rapid analytical techniques used to determine the moisture and fat contents, such as the CEM Smartrac system (Fig. 7.5), employing variable power microwave for moisture and nuclear magnetic resonance (NMR) for fat analysis have assisted significantly in making the process far more accurate, resulting in more consistent finished products. The word ‘nuclear’ in the analytical technique refers to the instruments ability to analyse the nuclei of the sample. NMR technology from CEM does not generate or use ionising radiation. Results for moisture analysis typically take around 3 min, and fat analysis of the dry sample is available in 30 s. The CEM SmartTrac is configured to detect hydrogen atoms that are in the liquid state. By first removing water from the sample in the microwave to determine the product moisture, the NMR is configured to only see hydrogen protons that are held in the liquid state and from this the fat content of the sample is calculated. The analytical equipment, for example CEM Smatrac system, combined with the introduction of the computer in the 1980s together with spreadsheet programs that use standard compositional assumptions for all raw materials, has dramatically improved the accuracy in formulating cheese blends.

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Fig. 7.5 A typical analyser for measuring the moisture and fat contents. (Reproduced by courtesy of CEM Microwave Technology Ltd, 2 Middle Slade, Buckingham Industrial Park, Buckingham MK18 1WA, UK.)

It is now generally acknowledged that the optimum method of blending cheese and other ingredients is in a twin ribbon blender (Fig. 7.6). The blending ribbons are helix shaped and travel in opposite directions when the materials are being blended. More modern blenders have an alternating direction function which prevents build-up of product in the upper corners of the blenders, and some are positioned on load cells for more accurate management of the cheese blend. Dry ingredients, such as a range of dairy powders, starch, emulsifying salts and sodium chloride, are fed into the blender whilst the cheese and butter are blending. Powders can be transferred to the blender by many different techniques, but vacuum systems (e.g. stainless steel spirals in plastic tubes and aeromechanical systems) are the most popular. Some companies use water as the method of feeding the powders into the blenders, but this method is limited by the amount of water available in the formulation. The size of blenders available on the market may range from 500 to 6000 kg capacity, and are generally installed in pairs and in parallel. The process involves filling and standardising one blend, while the second blend would be discharging standardised blend into an auger for transfer to a cooking system, whether batch or continuous cooker. The process would then involve alternating the filling, standardising and discharging of the blenders.

7.2.5 Transferring the standardised cheese blend to a cooking system The most common and arguably the best method of transferring product from the blender unit to the cooker would be via an auger dump hopper system. Typically, the outlets of the two blenders would be positioned directly over the dump hopper, which would be sized to hold at least one full blend of standardised cheese. Modern dump hoppers contain three shafts, two of which run in parallel at the bottom of the hopper as screw augers and the third shaft would normally be used to level out the cheese blend in the hopper preventing build-up at the pump end of the hopper (Fig. 7.7). The quality of the dump hopper can

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Fig. 7.6 Illustration of a twin ribbon blender with the typical helix-shaped mixing shafts. (Reproduced by ¨ courtesy of Karl Schnell GmbH & Co. KG, Muhlstrasse 30, D-73650 Winterbach, Germany.)

Fig. 7.7 The auger in the transfer hopper for transferring standardised cheese blend from the blending unit ¨ to the cooker system. (Reproduced by courtesy of Karl Schnell GmbH & Co. KG, Muhlstrasse 30, D-73650 Winterbach, Germany.)

often be determined by the ability of the constructor to engineer the screw augers to mesh together resulting in less cheese sticking to the augers. The augers force feed the cheese blend into a positive displacement pump, which in turn transfers the product to the cooking system. The amount of cheese blend pumped from the dump hopper into the cooker can be controlled by the use of load cells on the dump hopper or by using load cells on the cooker(s).

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The blenders and auger pump system are normally linked in modern systems for cleaning-in-place (CIP) with revolving spray balls and centrifugal pumps. CIP validation trials should always be carried out to determine the effectiveness of the cleaning system.

7.2.6 Direct steam injection into the cooking systems As mentioned elsewhere, direct steam injection cookers (batch and continuous) are widely used during the manufacture of processed cheese, and hence it would seem logical to review the available systems. Batch cookers As previously described, batch cookers falls into two main categories: (a) low mechanical action/low shear, and (b) high mechanical action/high shear. Most batch cookers result in pasteurised products being produced, but it is possible to produce a sterilised product in a pressurised cooker at around 125◦ C with a long holding time (e.g. few minutes depending on the initial load). This technique restricts the formulation in that the product would not have any lactose-containing ingredients, which are a significant part of the cost-focused modern processing industry. Low mechanical action batch cookers, such as twin alternating direction auger (Fig. 7.8), produce an emulsion, when hot, of large butterfat droplets in the continuous hydrated protein phase of the system. When these products cool to form a suspension they will generally have much better melting characteristics and flavour release than a high shear cooker. This comment is of course influenced by the composition of the product but, if a

Fig. 7.8 A low mechanical action batch cooker with eight direct steam injection nozzles and the in-feed valve, which can be seen on the left-hand side of the picture in the fully closed position. (Reproduced by ¨ courtesy of Karl Schnell GmbH & Co. KG, Muhlstrasse 30, D-73650 Winterbach, Germany.)

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cheese blend was split into two halves and one half processed in a low shear cooker and the other in a high shear cooker, the end-result would be two completely different products. This is less of an issue in processed cheese spreads (i.e. containing high moisture content), but generally as the dry matter of the product increases so the difference becomes more pronounced. Most batch cookers can be charged with cheese blend without opening the lid and through cut-off valves that ensure no product falls from the in-feed into the cooker during the cooking process. Smaller and simpler operations can be based on feeding the cooker with product in a ‘eurobin’ on wheels via a lifting device. These simple operations can be very cost-effective, especially when starting up a new operation. Careful planning would allow the integration of this simple operation into a more automated complete line as volumes increase over time. The basic principle during the manufacture of processed cheese is the conversion of insoluble calcium para-casein to soluble sodium caseinate through a process of ion exchange with the emulsifying salts. This ion exchange process is much more effective at higher pH, typically above pH 6.0, and therefore pH correction of product is always best made at the end of a cooking cycle. A typical pH range for most processed cheese products is 5.7 ± 0.2; this can be achieved easily and in a controlled way by adding the organic acidulants, such as lactic or citric acid, at the end of the cooking cycle. The acid can be added either manually or in the more modern systems automatically through a peristaltic pump directly into the cooker near the end of the cooking cycle. Heating of batch cookers should always be by means of direct steam injection, and the number of steam injectors will always be adjusted to the size of the equipment. Typically, steam pressure would be reduced from the boiler to ∼0.3 MPa at the cooker for optimum cooking cycle time and to avoid energy losses. The latest cooker systems utilise dynamic steam regulating techniques in which the steam valves can be programmed to gradually close as the product temperature rises to avoid unnecessary energy loss. Typical processing temperature would be 75–90◦ C on this type of system, but the important point is that an appropriate holding time related to the formulation composition is observed. The lower the final cooking temperature, the more risk of filling the product into packaging below pasteurisation temperature, which is very poor practice, defeating the object of the process. High mechanical batch cookers (Figs 7.9, 7.10 and 7.11) are generally based on a system of sharp high rotation speed blades in the cooker that not only mix the product but can also cut blocks of cheese and replace the grinding or size reduction operations. The high-speed blades are sometimes also assisted by recirculation systems through emulsifying heads containing additional knives. This type of mechanical action works well for processed cheese spreads (i.e. high moisture products) as the high shear simulates homogenisation, and the fat droplets become extremely small within the hydrated protein phase. This type of emulsion, produced with high moisture and sometimes high lactose processed cheese spreads, does not necessarily negatively impact the flavour release of the product compared with low mechanical action cookers. The high moisture/lactose generally supports a rapid flavour release or flavour ‘getaway’ in the mouth. The high shear on these products tends to result in a high gloss product. If a higher dry matter product was produced in the same way then there would be a significant impact on the flavour ‘getaway’ in the mouth.

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Fig. 7.9 An example of a high mechanical action cooker. (Reproduced by courtesy of Karl Schnell ¨ GmbH & Co. KG, Muhlstrasse 30, D-73650 Winterbach, Germany.)

Fig. 7.10 An example of a high mechanical action cooker. (Reproduced by courtesy of Karl Schnell ¨ GmbH & Co. KG, Muhlstrasse 30, D-73650 Winterbach, Germany.)

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Fig. 7.11 An example of a high mechanical action cooker. (Reproduced by courtesy of Karl Schnell GmbH & ¨ Co. KG, Muhlstrasse 30, D-73650 Winterbach, Germany.)

In general, high shear cookers are supported with the addition of vacuum during and after the cooking process. High shear systems have a tendency to incorporate air into the product, and the application of vacuum is a good way to control the residual air present in the product. Batch cookers that are used for preparing a complete batch can also be used to pull powders (casein, skimmed milk powder, whey powder, emulsifying salts, etc.) via a conical-shaped hopper and valve arrangement into the cooker while the batch is being blended. This technique is very useful in ensuring that no lumps are created in the product. Good manufacturing practice would dictate that the powder hopper would be in a different room to the cooker; this may create a problem due to the headspace in the cooker and therefore the distance that the powders can be drawn into the cooker. Continuous cookers: pasteurisation and sterilisation The basic principle of continuous cookers is to pump product at a constant throughput into one end of the cooker whilst it emerges continuously as a pasteurised or sterilised product at the other end. There are, of course, positive and negative aspects to continuously processed product, and generally only the positives are extolled. When using continuous cookers for the manufacture of processed cheese products, the ingredients are prepared as normal in a blender and standardised to target moisture and fat contents. The resulting standardised cheese blend is pumped through a non-return valve

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to a steam injection nozzle of which there are many different designs. The role of the steam injector is to as efficiently as possible collapse the steam into the product while at the same time creating the agitation to form a homogeneous mass. Some cookers have static mixers or mechanical devices after the injector to provide additional support to the mixing operation, but a well-designed injector will be sufficient to provide more than adequate mixing. The shear at the injector should not be underestimated. Some cookers have in excess of 4 tonnes h−1 passing the injector, and in a very short space of time the product temperature must be raised from the blend temperature of about 12◦ C to the desired pasteurisation temperature of typically 85–97◦ C. The injection process simulates homogenisation of the product and the fat droplets are very small, typically similar in size to those produced by high mechanical action cookers. The injector is the start of the continuous cooking process, and the next stage of the process is the product holding section (e.g. stainless steel pipe of specified capacity). At the other end of the holding section is a back-pressure valve which controls the pressure, thus enabling the product temperature to rapidly rise to the desired temperature set point. The pressure in the holding section is a function of the product pump and the steam pressure. The length of the holding pipe will determine the holding time that the product resides at the pasteurisation temperature. The length of the holding pipe should be calculated to ensure that at maximum throughput the product will have been held at that temperature for the required time. This is even more critical when carrying out a sterilisation process. However, it should be noted that it is a false assumption that the holding pipe is always full of product and an allowance should be made for this fact when calculating product hold time based on pipe length. Trials carried out in the past using clear pharmaceuticalgrade plastic piping have revealed a pulsing movement of product linked to the type of feed pump and the holding pipe to be less than 50% full. Typically, there are at least two platinum thermometers in the holding pipe that measure the resistance of the platinum element and this is converted to temperature; the two platinum thermometers are placed at opposite ends of the holding pipe. In a well-controlled system, there should be no more than 1◦ C difference in temperature between the two devices. After the back-pressure valve, there will be a product-diverting valve to direct product away from the vacuum flash cooling unit until the product has achieved and maintained the correct temperature. The diverting valve will continue to divert product away from the vacuum flash tank for ∼30 s after the target temperature has been achieved. This process ensures that the short section of pipe between the back-pressure valve and the diverting valve will be completely purged of product prior to the diverting valve redirecting product to the next stage of the process, the vacuum flash tank. The vacuum flash tank serves as both a major benefit and a negative of a continuous cooking system. The positive point is that it is an extremely efficient means of reducing product temperature, both on the pasteurised and sterilised products. If the pasteurised product has been processed to within the temperature range (85–97◦ C), then the flash tank would be capable of reducing the product temperature to about 74–75◦ C. This can be a major advantage on some product lines, such as on ‘slice on slice’ production on a chill roller or chill belt system. The cooler the product emanating from the cooker, then generally speaking the greater the line output due to the lower demand at the next stage of cooling on the roller or belt. This vacuum stage also produces a constant density product,

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which results in excellent weight control. However, there is also a major negative aspect with vacuum flash cooling of the product. This cooling technique, combined with the high shear from the steam injector, produces a dense close-knit structure in the product that not only negatively impairs flavour release from the product but also produces a major negative with ‘slice on slice’ products. The dense close-knit structure can be likened to placing two pieces of glass, one on top of the other, and trying to separate them without sliding them. The suction created by the ultra-smooth surfaces has a tendency to make the slices stick together and the use of anti-sticking compounds becomes a must. This product texture can be compared with a low mechanical action batch cooker product of identical composition that has a more open structure with large butterfat droplets in the continuous hydrated protein phase. Not only is the texture more open, lending itself to excellent ‘separability’ with ‘slice on slice’ processed cheese, but the mouth-feel and flavour release from the product is far superior to continuously cooked product with the same composition. Rather than similar to separating two pieces of glass, as with the continuously cooked product, the batch cooked product can be compared to separating two sponges placed one on top of the other. The production of individually wrapped slices (IWS) of processed cheese works well with continuously cooked product. Whereas with ‘slice on slice’ products the composition of the formulation, especially the age of the natural cheese component, is critical for providing the elasticity required for the slices to support themselves, the composition of IWS is not so critical due to the fact that it is the wrapper that is actually supporting the product through the machine. The continuous cooker plays an important role in supplying constant density product to the IWS machine and providing excellent weight control. In addition, IWS products will support the inclusion of a range of lactose-containing ingredients without a detrimental effect on the performance of the product during slice forming. Processing temperature can vary between 85 and 140◦ C, but typically any processing temperature greater than 120◦ C will require a creaming step to adjust the viscosity of the final texture of the product. Continuous cookers with direct steam injection (Fig. 7.12) are used during the manufacture of sterilised processed cheese and cheese spread products. Indirect heating systems are totally inappropriate for these types of products. Typical sterilisation temperatures are between 140 and 143◦ C with a holding time of 10 s. Modern continuous cookers utilising digital recording systems not only record processing temperature and throughput, but are also capable of continuously calculating and recording the Fo value. It should also be remembered that the product holding pipe will not be full and calculations for product sterility should take this into account. The purpose of sterilising processed cheese and cheese spread products is generally not to produce an aseptic product because typically processed cheese filling equipment does not allow for this. The objective is to eliminate mainly clostridial spores that may be present in the natural cheese or other dairy ingredients. The water activity (aw ) of most cheese spreads is such that they would support the germination and outgrowth of spores leading to product spoilage and in some cases potential health risks. Generally, retail conditions in many parts of the world have improved dramatically, and refrigeration is the main barrier to product spoilage. There are, however, exceptions and the sterilisation process, whilst not providing an aseptic solution, has gone a long way to eradicating spoilage problems.

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Fig. 7.12 View of a continuous cooker system for both pasteurisation and sterilisation of processed cheese ¨ products. (Reproduced by courtesy of Karl Schnell GmbH & Co. KG, Muhlstrasse 30, D-73650 Winterbach, Germany.)

Sterilisation for cheese spread products has improved dramatically during the last 15 years, and some well-designed equipment is able to run continuously for 3 to 4 days before it becomes necessary to clean the equipment. This fact is of course determined by the composition of the product and, generally, the higher the lactose content of a product, the shorter the continuous production run. In general, sterilisation equipment has two steam injection and holding pipelines, allowing for switching between the lines to facilitate ‘in process’ cleaning of these sections without line stoppages and a full clean down. Product that has been sterilised on a continuous cooker at typically 140◦ C and then vacuum flash cooled to within the temperature range 85–95◦ C will experience a significant reduction in viscosity versus an equivalent batch cooked product. There are numerous techniques for building viscosity in the product after sterilisation to facilitate filling triangular foil portions, IWS or even plastic tubs. The term generally used for this operation is the ‘creaming’ step. This is a controlled stirring or agitation of the product to build viscosity to a point that will provide for a suitable finished product texture. The most common method

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for initiating the ‘creaming’ step is through the use of sterilised re-work from a previous production run. This re-work has very little impact if added before sterilisation, and the technique involves the addition of the re-work after vacuum flash cooling when melted cheese blend is in the creaming tank. The re-work is prepared in a high mechanical action batch cooker, and typically combined with some product coming from the vacuum flash tank at the start of production. This small batch of product is normally heated to 85◦ C, and then added directly to the creaming tank at the start of production. The re-work has a type of catalytic influence on the sterilised product in the creaming tank, and builds viscosity in the product. The creaming action on the product is controlled by maintaining a level in the creaming tank and, as fresh product enters the creaming tank from the sterilisation unit, a similar quantity of creamed product flows out of the tank from the base. The method of initiating the creaming action through the addition of re-work may be considered poor practice in terms of potentially recontaminating the sterilised product, but the potential for spore contamination is very low, especially if good control and selection of re-work is exercised. Continuous sterilisation cookers can and are also used for cooking and sterilising other similar products, such as starch-based cheese sauces, which are also emulsions where the fat (i.e. vegetable or dairy) forms the discontinuous phase of the emulsion. In this type of product, cheese can typically represent 1–35% of the formulation, and starch or blends of starch tend to be more important in determining the finished product texture and viscosity. Evaluation of potential new or optimised products through the preparation of samples on pilot plant equipment has always been very important to the acceptance of products by the consumer. Small-scale cooking systems not only allow significant raw material savings by enabling sensible batch sizes to be produced but they also provide the possibility of simple experimental designs to be developed for the optimisation of products. The design of pilot plant cookers and their ability to mimic the larger-scale equipment that the new or optimised product will be produced on is critical to the product development scientist. The type of mechanical action, whether high or low, will determine key attributes such as texture and flavour release from the product. Pilot-scale equipment is available from numerous companies around the world, and the best approach is to link the design of the unit as closely as possible to the production scale unit thereby increasing the potential for realistic scale-up (Fig. 7.13).

7.2.7 Filtering the molten cheese An important step during the manufacture of processed cheese, which is often considered a critical control point in hazard analysis critical control (HACCP), is the filtration of the molten cheese (Fig. 7.14). This is usually carried out after the cooking/heat treatment of the cheese blend and filling/packaging of the product. The molten homogeneous cheese mass, typically in the temperature range 75–90◦ C, is pumped through a 200–800 μm filter to remove any cheese lumps and/or foreign bodies, which are quite often an inevitable part of a processing operation. The most common contaminant is often small pieces of plastic wrapper from the natural cheese that have found their way into the blend, i.e. attached to the blocks of natural cheese or butter. Other natural materials, such as calcium lactate crystals typically found in over-mature cheese, would also be removed by the filter.

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Fig. 7.13 An example of a 20–30 kg low-mechanical action pilot plant cooker for the preparation of ¨ processed cheese. (Reproduced by courtesy of Karl Schnell GmbH & Co. KG, Muhlstrasse 30, D-73650 Winterbach, Germany.)

The size of the filter would normally be determined by the viscosity of the product and the pressure created by pumping the molten cheese through the filter. The better filter systems are based on disposable plastic filter bags placed inside a stainless steel mesh retainer and housed in a stainless steel pressure unit. The time at which the filters are replaced during a production day is often determined by the pressure reading from the filter. Examination of the filter after use and recording the contents of every filter will assist in determining the source of foreign bodies. Prior to the filter and directly after the steam injection cooking operation there would normally be a dump hopper (Fig. 7.15), which would receive the batch of molten cheese from the batch cooker or would be fed from the continuous cooker. The dump hopper can be constructed from either stainless steel or food-grade plastic. The advantage of plastic for many products is that the molten cheese blend has a lower tendency to stick to the sides of the hopper, which can be a problem in processed cheese products containing high levels of lactose. A build-up of product on the side of the hopper can, over a production day, result in a problem with the Maillard reaction and pieces of the build-up on the sides of the hopper can break off and fall into the product.

7.3 Processing plant for the manufacture of processed cheese slices The early ‘type’ of processed cheese slices started with manufacturers producing block products of specific dimensions, allowing the block to cool, and then cutting the block into numerous slices using rotating blade slicers. The problems encountered with this technique were many and included (a) post-process contamination, (b) poor and inconsistent texture, (c) poor melt characteristics due to slow rate of cooling, and (d) impossible weight control.

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Fig. 7.14 A twin filtration system that allows switching between filters without stopping the production ¨ line for a filter change. (Reproduced by courtesy of Karl Schnell GmbH & Co. KG, Muhlstrasse 30, D-73650 Winterbach, Germany.)

The introduction of chill roll technology, which is based on a large-diameter stainless steel roll and two smaller diameter rolls, had a major impact on the cheese market, with functional processed cheese products that had excellent shelf-life being made available to consumers. Hot molten cheese that has been heat treated is pumped to a spreader pipe above the larger of the three rolls. All three rolls are chilled by means of ammonia or freon and are rotating. The hot molten cheese is formed into a sheet between the larger roll and the first of the smaller rolls, which is used to form the thickness of the sheet for individual slice weight control. The continuous sheet of cheese adheres to the large roll and travels through approximately 270◦ before being removed from the large roll by a scraper and then passed over the second of the smaller rolls, which is typically named the ‘take-off’ roll. The thin sheet of cheese would have cooled (typically below 15◦ C) by the time it passes over the ‘take-off’ roll. At this point, the sheet of cheese passes through slitter blades to

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Fig. 7.15 An example of a plastic dump hopper for receiving the molten batch of processed cheese. ¨ (Reproduced by courtesy of Karl Schnell GmbH & Co. KG, Muhlstrasse 30, D-73650 Winterbach, Germany.)

form vertical continuous bands of cheese that are then twisted to enable them to be passed under bobbins and be layered on top of each other as ‘slice on slice’. The continuous band of ‘slice on slice’, ranging from four layers to 30 layers, then passes via a conveyor and under a wire, which makes a vertical cut to produce a stack of slices. The stacks of slices are then passed through an overwrap machine and sealed under modified atmosphere. Processed cheeses produced on chill rolls are generally very high in cheese content (typically >75%), and the type and age of the cheese is critical to the performance of the product on the equipment. This method is still used today for the manufacture of foodservice slices providing convenience for the operators in burger chains. In addition to the chill roll method of producing ‘slice on slice’ products, there are other similar methods, such as horizontal stainless steel belts and, more recently, the introduction of a vertical stainless steel belt system, which cools both sides of the slices extremely efficiently and is housed in a laminar airflow unit for improved microbiological control. This unit is manufactured by the company Natec based in Heimenkirch, Germany, and has taken ‘slice on slice’ manufacture to a completely new level. Increased consumer acceptance of processed cheese slices led to the introduction of individually wrapped slices in which the hot molten cheese is fed into a continuous band of clear plastic film. The continuous band of film is cooled through a water bath or over a cold surface, similar to a chill roll, before being sealed, cut and stacked for overwrapping. The ‘hot pack’ formation of slices has many benefits for the manufacturer and the consumer over the ‘slice on slice’ method of slice production. The manufacturer enjoys almost total formulation flexibility with this type of equipment because it is the film material that supports the product through the cooling process rather than the cheese supporting itself in the ‘slice on slice’ methods. Lower cost ingredients, such as lactose-containing products like skimmed milk powder and whey powder, can and are included in the formula. Starch

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and hydrocolloids are also used but, with the incorporation of these ingredients, the sole purpose is cheese reduction in the product. There are in fact some products on the world market that do not even contain cheese in the product but the familiar packaging and appearance provides the impression of cheese. Generally, the consumer benefits from more consistent and longer shelf-life products with individually wrapped products.

7.4 Conclusions The processed cheese industry has experienced major changes over the last 30 years, with products meeting the true standard of identity for ‘processed cheese’ being virtually eliminated. Cheese food, cheese spread and, in the USA, cheese product, which are products containing dairy ingredients other than cheese, have become dominant and driven mainly by cost. Arguably the consumer is the one losing out as the competitive battle continues. Sadly, some ingredient declarations, when examined closely, do not even contain the word ‘cheese’, as some manufacturers take advantage of brand name recognition to confuse the consumer. The quality of engineering in cheese manufacturing technology improves significantly every year, but the bottom line is that these products are simple emulsions of fat as the discontinuous phase, in a continuous hydrated protein phase that becomes more clouded every year with alternative ingredients. For the most part these alternative ingredients tend to degrade products for the sake of competitive product cost. Selection of the correct processing technology will determine the success of most companies in the future as the key point of difference will be process technology delivering improved efficiencies through reduced labour cost and more consistent compositional control.

8 Packaging Materials and Equipment E.M. Buys and J.F. Mostert

8.1 Introduction The primary purpose of packaging is to ensure that a food product reaches the ultimate consumer in a safe, sound and convenient condition. Packaging is in fact an integral part of modern production processing, and is usually considered to be the key to successful plant operations. Modern packaging technologies have made tremendous strides in improving the hygienic quality and shelf-life of the product. Packaging equipment requires special attention since the product reaching this equipment will no longer be treated to reduce its microbial content. Ideally, equipment design should not contribute any contamination to either the product or the package (Mostert & Jooste, 2002). The aesthetic appearance of a package is usually one of the decisive factors for the consumer in deciding whether to buy a product. Basically, the same standard of hygiene requirements that apply to dairy plants and the preparation of the product itself should apply to the manufacturers of packaging materials, containers and closures. The package or packaging material must firstly be free from pathogens and as free as possible from other microorganisms able to grow under normal storage conditions. Thus, it is obvious that it is essential to apply microbiological safeguards to all parts of production and distribution of the packaging material including the containers (Mostert & Jooste, 2002). The equipment and machinery used for processing and packaging must be designed and constructed so as to avoid microbiological, chemical and physical contamination and, ultimately, health risks (Wainess, 1995a). The packaging area is a high-risk area, which is a physically segregated area designed to a high standard of hygiene where practices relating to personnel, ingredients, equipment, packaging and environment aim to prevent contamination by pathogens, spoilage or other microorganisms. Comprehensive reviews in this regard are given by Holah (2003), Lelieveld et al . (2003), Wierenga & Holah (2003) and Mostert & Buys (2008). Special attention has to be paid to the selection of packaging materials, for example those used to pack processed cheese products (Berger et al ., 1989). The packaging should be properly hermetically sealed, not only to meet the consumer’s expectations, but also to prevent drying out and the growth of moulds. The issue of environmentalism

Processed Cheese and Analogues, First Edition. Edited by A.Y. Tamime. © 2011 Blackwell Publishing Ltd. Published 2011 by Blackwell Publishing Ltd.

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is rapidly moving up the packaging industry’s agenda, as consumers demand more ‘green’ from their packages. Price, functionality and convenience are still other key issues (Christiansen, 2008).

8.2 Packaging materials 8.2.1 General specifications In general, the specifications of any food packaging material should include information on the following (Tamime & Robinson, 2007): • • • • • • • •

toxicity of the materials; levels of contamination; moisture resistance and/or permeability to water vapour; gas permeability for nitrogen (N2 ), carbon dioxide (CO2 ) and oxygen (O2 ) (important in modified atmosphere packaging); permeability to volatile flavour and aroma compounds and/or chemicals in the environment; transparency to visible or ultraviolet (UV) light; permeability to dirt and/or to microorganisms; migration of molecules from the packaging material to the product.

It is evident that most, if not all, of the above-mentioned specifications for packaging material are applicable to processed cheese packaging. There are various types of packaging materials and publications on the theory and practice of food packaging in the literature. The International Dairy Federation (IDF) also publishes periodically monographs and documents on technical information on the packaging of milk and milk products (Odet & Zachrison, 1982; Ronkilde Poulsen, 1995; Floros et al ., 2000).

8.2.2 Functions of a package Packaging plays an important role to ensure that the product reaches the consumer in a sound condition. The retail package should be designed to meet a broad range of requirements including functionality and cost-effectiveness. Specific technical information on the functions of packages has been reported by various authors (Bull & Grønborg, 1995; Fl¨uckiger, 1995; Gallmann, 1995; Hall, 1995; Kooi & Van den Berg, 1995; Skibsted, 2000; Yam et al ., 2005; Tamime & Robinson, 2007). Some of the important aspects are as follows. •

•

Protection of the environment: (a) dirt or other foreign bodies, (b) microorganisms which can affect the keeping quality, (c) gases and (d) light. The package must also prevent the loss of flavour volatiles or the absorption of undesirable odours and taints. The retail package should also provide a convenient means of handling the product in the factory during storage and transport, and throughout the sale period in shop outlets.

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•

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The printing and graphic work on the package must provide a ‘message’ to persuade the consumer to buy the product and should contain food labelling information, such as identity of the product, name and address of the manufacturer, approximate composition or nutritional data of the product or ingredients, best before date, and suggestions of recipes or other instructions for use. Other functions: the packaging material, which is in direct contact with the product, must be non-toxic and no chemical reactions should take place between the material and the product.

8.2.3 Types of packaging materials Packaging materials for processed cheese and analogues are basically divided into two main categories: (a) the unit container/package which is in direct contact with the product, and (b) the outer or shipping packaging to assist handling of the unit containers along the retail chain. It is evident that the material which is in direct contact with the product should have certain specific characteristics to ensure a safe, wholesome, high-quality product with the longest possible shelf-life. The outer packaging should not only provide mechanical strength (Bull & Grønborg, 1995), but also convenience. Some of these aspects are discussed in more detail in section 8.3.

8.2.4 Hygiene of packaging material As mentioned elsewhere, the same general hygiene requirements that apply to dairy plants should apply to plants manufacturing packaging materials, also those in which containers are formed and filled. Requirements for the hygienic manufacture of packaging materials, containers and closures, especially for single-service containers, have been suggested by Wainess (1995b). Uncoated paper stock, prior to lamination, should meet a microbiological standard of not more than 250 colony-forming units (cfu) g−1 as determined by a disintegration test (Hickey et al ., 1993). Where a rinse test can be used, the residual microbial count should not exceed 50 cfu per package, except in packages of less than 100 mL where the count should not exceed 10 cfu. Where the swab test technique is used (e.g. laminated board, sheet, wrapping) the microbial count should not exceed 1 cfu cm−2 of product contact surface. These contact surfaces should be free from coliform organisms. It is evident that package or packaging material must arrive at the dairy plant with an ‘acceptable’ low microbial count and be formed, filled and sealed employing the proper hygienic measures to preclude additional contamination. For retail packaging, the container can be made of glass, polycarbonate or polyethylene and sealed by single-service aluminium, paper or plastic caps or lids. With the advent of plastic-coated packages and closures and the development of vacuum-formed and blow-moulded plastic packages, plastic bags, extruded and fabricated sheets of plastic for packaging, hygienic problems that could not be solved by treatment after forming the package have become evident. It is obvious that physical impurities, such as dust or particles released from the packaging material, should not gain access to the product. The influence of packaging on the contamination of processed cheese products may be direct,

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due to the presence of microorganisms on the material, or indirect due to the permeability of the material to bacteria. Special attention should be devoted to the microbial content of air in packaging and filling areas. Radmore (1986) found that a correlation (r = 0.93) existed between the number of airborne organisms present in a packaging environment and the number of organisms contaminating the final product. He calculated that, during a 60-s exposure period, 2.2% of the organisms in 1 m3 of air would be able to contaminate 1 L of a product that is being packed in a container with an opening of 100 cm2 . Detailed information on the sampling of packaging material, containers and closures for microbiological examination is outlined by Grace et al . (1993). Methods for the assessment of microorganisms on packaging material must reliably detect bacteria, moulds and yeasts. Various methods, i.e. the disintegration test, rinse test, coating technique, membrane filter and direct plating techniques, are used for this purpose and have been comprehensively outlined by Hickey et al . (1993), Wainess (1995b), Tacker & Hametner (1999) and Mostert & Jooste (2002). New developments using high-intensity pulsed light technology to sterilise packaging materials without chemicals provide new possibilities in terms of quality, monitoring and controlling the destruction of microorganisms (Harrysson, 1998). The innovative development of bioactive packaging material to inhibit the growth of pathogens, mycotoxinproducing moulds and spoilage organisms is also very promising, although further work is necessary to evaluate the performance of these materials in food systems (Scannell et al ., 1999; Floros et al ., 2000; Han, 2000). The wrapping of retail portions of cheese in coated paper, aluminium, plastic and many combinations has changed very little in recent years. Nevertheless, the development of new materials, laminates, cups and pots has widened the choice, improved hygiene, and provided better protection for various products.

8.2.5 Shelf-life and interactions with packaging materials Processed cheese packaged in laminated plastic foil should have a shelf-life of at least 3–4 months, 8 weeks for slices, 20 weeks for small portions and over 1 year for products packed in collapsible tubes or metal cans (Sturm, 1998). Packaging technology used for processed cheese products requires low oxygen permeability to avoid oxidation and microbial growth. Products should be protected against light-induced oxidation – which causes, for example, discoloration, flavour formation and nutrient loss – and against water evaporation (Petersen et al ., 1999; Alves et al ., 2007). Processed cheese is often expected to be a stable product with a very long shelf-life. However, even products without any bacteriological contamination retain their high quality only for few months at room temperature. During storage, various factors may be responsible for the structure and flavour changes, as reviewed by Sch¨ar & Bosset (2002). Relevant to this section are changes that are affected by the packaging process and packaging material selection. Loss of water vapour, causing a firmer texture, occurs if the packaging is not completely airtight. The incidence depends on the packaging’s properties and can be overcome with tighter packaging. Reactions induced by light and oxygen, which causes oxidation flavours, are due to traces of oxygen in the packaging, as well as permeation of oxygen through the packaging material. Selection of packaging material with low oxygen permeability and good light barrier as well as tighter packaging will reduce the incidence of these reactions (Sch¨ar &

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Bosset, 2002; Alves et al ., 2007). Active packaging technology where oxygen scavengers are included in the packaging laminate can also be applied (Oyugi & Buys, 2007). Toxicological effects of interactions between the food and packaging materials, and the effect of such interactions on the shelf-life and sensory quality of food, are extremely complex (Fellows, 2000). Interaction with packaging materials may cause migration of the packaging components or corrosion of the aluminium foil (Sch¨ar & Bosset, 2002). This can be prevented by selection of optimal packaging material produced according to the relevant legislation. No constituents of the packaging materials should be transferred to the processed cheese product that could cause deterioration in the sensory properties (ILSI, 2000). Important aspects of the interaction between the package and food include lacquers and coating material(s) for metal containers to prevent interaction of food acids with steel, tin or aluminium, as well as the migration of plasticisers, pigments, metal ions and other components of plastic packaging into food (Fellows, 2000). Schwope et al . (1987) reported that the migration of butylhydroxytoluene (BHT) and Irganox 1010 into processed cheese slices depended on the molecular weight. BHT with a low molecular weight migrated faster than Irganox 1010. Tin foil (97% tin, 3% antimony with traces of lead, copper and iron), which is supported by a cardboard carton, was the preferred retail pack for processed cheese before the Second World War. However, thereafter it became an extremely expensive packaging material, and another constraint was that the tin foil discoloured. The alternative, aluminium foil, corroded quickly and initially was not compatible with automatic packaging machines (Templeton & Sommer, 1937; Robertson, 2006). It was also found to be somewhat more rigid than the tin foil, and did not cling to the cheese mass closely. This resulted in air pockets, which contributed to mould growth and loss of moisture from the processed cheese mass (Templeton & Sommer, 1937). Although Kraft developed a technology for the packaging of processed cheese in a flexible film in 1951–2, it was only used when appropriate lacquers were developed. Metal foil has remained the preferred packaging material for processed cheese in cartons and plastics, either in flexible film or rigid containers that present a range of various opportunities for the marketing/presentation of processed cheese products. Aluminium foils, whether used with the two foil process, shell and lid, or the single sheet process for packaging of processed cheese provide a hermetic seal for a long shelflife. A protective polymer and a polyvinyl copolymer coating protect the aluminium foil used for processed cheese from corrosion; otherwise the cheese will decompose, give off free hydrogen and cause pitholes on the cheese surface (Kosikowski & Mistry, 1997; Sturm, 1998). The corrosion is due to salts and acids present in the cheese matrix and, subsequently, also prevent the undesirable migration of aluminium into the body of the cheese. Foils are available in silver, gold and a wide variety of colours and shades, and are made with an approved heat sealable lacquer designed to be compatible with the packaging equipment. From the standpoint of modified atmosphere packaging (MAP) and active packaging (AP), one can classify processed cheese as a ‘stabilised’ cheese with no active lactic acid bacteria and, to achieve sufficient shelf-life, it must be packed in low O2 and high CO2 levels (Floros et al ., 2000). MAP, AP and/or good barrier materials should be used for

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packaging of processed cheese. Examples of MAP films currently used include laminates of polyethylene terephthalate (PET)/polyvinylidene chloride (PVdC)/polyethylene (PE), PE/nylon/PE or PE/EVOH/PE. MAP packs for processed cheese require high oxygen barriers, and they have only been possible at a reasonable cost using either PVdC or aluminium foil. Aluminium oxide-based co-extrusions and nylon-based coatings have an oxygen permeability of 0.48 mL m−2 24 h−1 atmosphere−1 (Fellows, 2000). Antimicrobial releasing films or other active systems may also be used. A wide range of processed cheese products are nowadays available in the market and may, according to Berger et al . (1989), for practical purposes broadly be classified as processed cheese in: • • • • • • • •

portions (spreadable and sliceable); blocks; sausage shape; metal cans; tubs and jars; collapsible tubes; slices; and processed cheese externally decorated.

8.3 Packaging equipment 8.3.1 Background Modern processing technologies make it possible to produce bacteriologically stable processed cheese (Sch¨ar & Bosset, 2002). Although the manufacturing procedure(s) is the most important aspect, packaging of the heated or sterilised product should be controlled, and the packaging methods, machines and packaging material must not adversely affect the quality and subsequent shelf-life of the product (Meyer, 1973; Mostert & Jooste, 2002). Processed cheese effectively packaged should achieve a shelf-life of 6 months to 1 year (Sch¨ar & Bosset, 2002). All processed cheese products are filled and packaged by semi-automatic or automatic machines. According to Meyer (1973), small rectangular, triangular or round portions and block cheese were made during the 1960s; the packs changed during the next decade with packs of multiple sizes and shapes. This introduced new machine applications. In the past, processed cheese was only available in limited format, i.e. rectangular, triangular or round portions. Due to developments in packaging technology many different forms of packaging, as per consumer demand for convenience and shelf-life, are available worldwide. In the European market, the triangular portions (e.g. 20–30 g), wrapped in aluminium foil and sold in round cardboard cartons, are the most common. In North America, however, processed cheese blocks are packed in laminated plastic foil in the form of slices for fast food restaurants (Caric, 1999). In South Africa, processed cheese packaged in glass as a spread, triangular portions and slices in resealable packs are the most popular types of packages.

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Liquid or melted processed cheese can be packed in almost any format, but once solidified it must not be pressed and shaped (Berger et al ., 1989). Currently, processed cheese is available in many markets as portions (spreadable or sliceable), slices, blocks, sausage form, shredded cheeses, in cans, tubs, glass jars and collapsible tubes, and decorated on the surface where a special packaging machine is used for each packaging application (Berger et al ., 1989; Mayer, 2001). Considerable attention has always been paid to the packaging itself – its outer appearance, whether it is airtight – as this affects the consumer’s purchase decision. Packaging machines used are also important, and there is a trend to automation of filling and packaging; a new development is the continuous formation, cutting and packing of cheese slices (Berger et al ., 1989; Caric, 1999; Mayer, 2001). A wide range of machines for various types of processed cheese packaging applications are supplied by a number of companies; although not an exhaustive list, some examples include: • • • • • •

Benz & Hilgers GmbH (www.oystar.benhil.de); Corazza (www.sympak.com); FASA (www.fasa.lt); Kustner Industries S.A. (www.kustner.com); PFM packaging machinery (www.pfmusa.com); ULMA packaging (www.ulmapackaging.com).

8.3.2 Portions/wedges Current packaging machines use double-coated aluminium foil with plastic laminate, and all aspects of foil packaging are automated. This includes cutting and punching of the parts of the foil, shaping of the body foil, filling of the processed cheese, laying on of the lid foil, folding, sealing, ejection of package and insertion into the outer packaging (Berger et al ., 1989). The foil is produced by a cold reduction process in which pure aluminium (purity >99.4%) is passed through rollers to reduce the thickness to less than 0.152 mm, and then annealed and heated to control its ductility to achieve dead-folding properties. According to Fellows (2000) and Robertson (2006), the advantages of using aluminium foil, for example, to package processed cheese include: • • • • • • • • • • • •

good appearance; odourless and tasteless; good dead-folding properties; ability to reflect radiant energy; excellent barrier to moisture and gases, when thicker than 25.4 μm; good weight to strength ratio; impermeable to light, moisture, odours and microorganisms; high-quality surface for decorating or printing; lacquers not needed because a protective thin layer of oxide forms on the surface as soon as it is exposed to air; can be laminated with paper or plastics; compatible with a wide range of sealing resins and coating for different closure systems; good value as scrap.

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Both sliceable and spreadable processed cheeses can be found in portion packs. The slices must separate from the foil easily and must cut well. Since the dry matter content of the spreadable and sliceable processed cheese will differ, this places different requirements on the filling machine. The spreadable type must also be easy to fill. Since the consistency of the sliceable product is more viscous in the molten state, it requires more pressure during the filling process and is inclined to tail. A scraper, cutter, return stroke or a jet of compressed air are suitable devices to ‘cut-off’ the cheese (Berger et al ., 1989). Most machines are designed to permit a change of packaging format, since the processed cheese comes in a wide variety of shapes and sizes, through incorporation of different folding or moulding systems. However, the sequence of operations is similar for all these machines. The processed cheese mass is fed into the stirred hopper and the filling machine, hot processed cheese is then pumped via the dosing and filling station into the aluminium foil wrapper, which has already been cut from a roll, folded and shaped. Then the lid foil is then laid on top of the portion. The overlapping edges of the body foil are folded, and the two foils are sealed together (Berger et al ., 1989). To facilitate the opening of the portions of cheese, an opening device is provided, which consists of narrow strips of PE film sealed onto the inner side of the aluminium foil before it is formed. The tear-off strip is extended several millimetres beyond the packaging material so that they can be gripped between two fingers. Their point of exit from the packaging must itself be sealed to avoid any possible leakage or contamination of the product. The strips are normally coloured red to attract the consumer’s attention (Robertson, 2006). In the case of triangle portions, the process ends with the ejection of portions onto a collecting plate, where six or eight individual packs can be collected into a circular paperboard carton or plastic container complete with lid (Berger et al ., 1989; Robertson, 2006). Filling machines for this purpose are made and supplied by FASA. The machine has an output of up to 65 portions min−1 , varying in size from 30 g (50 × 50 × 12 mm) to 100 g (71 × 52 × 26 mm). The packaging material used is aluminium foil with a thickness of 0.014 mm. Corazza has a double, four or six head automatic dosing/wrapping machines designed for the packaging of square and triangular portions of processed cheese. In the dosing station, the wrapping shells from the reel-fed heat sealing aluminium foil is formed for subsequent filling of processed cheese. A lid of heat-sealing aluminium foil is placed inside the filled shell, which is then folded over the lid, and sealed by heated pressure pads. Each portion includes an internal ‘consumer-friendly’ easy opening tear strip and an external paper brand label. The portions (output 220, 380 or 560 min−1 , the weight 10 or 40 g to 40 or 62.5 g) are gathered in the required bundle configuration and carried onto a conveyor on a single lane (Fig. 8.1). The MULTIFORME YH from Kustner Industries S.A. produces different shapes and weights of packages; the weights range from 5 to 50 g with heights between 3 and 27 mm. Wrapping of the packs is by means of two sheets of aluminium foil, shell and lid, possibly hot sealable from two reels. Labelling is on the opposite of the folded side, and is applied before cutting the aluminium foil. Square, rectangular or round packages are carried onto the conveyor belts. Triangular portions are assembled on a small revolving table, which facilitates packing of these portions. All these machines are fabricated with stainless steel, and the design should be hygienic and the machines easy to clean (Mostert & Buys, 2008).

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(a)

(b) Fig. 8.1 Automatic dosing/wrapping machines designed for the packaging of triangular portions of processed cheese. (Reproduced by permission of M. Messori, www.sympak.com.)

Cheese portions arrive from the packaging machines alternately onto periodically moving collection plates where they are formed into a circular shape (Meyer, 1973). The removing mechanism clears first one of the collecting plates and then the other, transporting the rounded collection of portions to a periodically moving conveyor and brings them to a boxing machine. Here they are packed into boxes at the rate of 200, 400 or even 800 portions min−1 (Berger et al ., 1989). The collapsed boxes are taken automatically from the magazine, opened and the lids separated from the bottoms. The bottom is placed over the formed bundle of portions, capsized and fed to the outfeed belt where it receives the lid for closing. A band-wrapping machine is used for wrapping the side of a round box containing wedges of processed cheese. The machine can also apply a label to the top face of the box, print the band and

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insert a tearstring between the band and the box so as to make the latter easier to open. Each stage is monitored by mechanical sensors or photoelectric cells at all four corners so that it cannot be touched by humans, to eliminate human errors. The machines stop if they run out of foil, labels or lid foils. Before the box leaves the filling and boxing machine, there is check-weight station and a counter registers the output of packages per minute, hour or shift. Boxes are also labelled, banded and resorted, if necessary automatically. Depending on the operation, a conveyor belt will take the boxes to a banding and labelling machine, or they may first be cooled in a chill tunnel, compartment or chamber (Berger et al ., 1989).

8.3.3 Blocks Bulk processed cheese is packed hot and requires thermostable materials. Box-bulk products, up to 2.5 kg, are usually packed in wax-coated cellophane material, which is relatively inexpensive. More costly, durable materials (i.e. multilayer) are made of aluminium foil, polypropylene (PP), PE, PVdC and cellophane combinations (Fig. 8.2) (Kosikowski & Mistry, 1997). To fill block processed cheese – the oldest form of packaging type, weighing 200 g to 2.5 kg – semi-automatic or automatic machines are used. The popularity of sliced processed

(a)

(b)

(c)

(d)

Fig. 8.2 Block and portioned processed cheese. (a, Courtesy of Friesland Campina Cheese Specialities; b, c and d, courtesy of Parmalat/Melrose.)

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cheese affected the production of processed cheese blocks. Fully automated packaging machines could be developed for processed cheese when the processing technique for blocks was changed so that the desired consistency could be obtained without cooling (Berger et al ., 1989). Packaging takes place in the absence of oxygen to inhibit the growth of mould. Mostly, the cheese is wrapped in lacquered aluminium foil or in aluminium foil-lined cardboard or plastic boxes (EPA, 1997). The Multipack 8345 K, from Benz & Hilgers GmbH, is a rotary machine equipped with an integrated cartoning unit, with an output of 60 packs min−1 , and is capable of handling 100 g to 400 g brick-shaped portions (Fig. 8.3). Parchment or aluminium foil laminated packaging material can be used with this machine. The machine functions on the following principles. The wrapping material is fed from the reel, cut laterally and placed into a cell in the turntable, where it forms an open wrapper bag. The hot melted processed cheese (i.e. of pumpable consistency) is volumetrically dosed and filled into the wrapper bag. Finally, the product is closed and calibrated, thus ensuring sharp edges. With the

(a)

(b)

(c)

(d)

Fig. 8.3 Dosing and wrapping machine designed for the packaging of large square, rectangular or round portions of processed cheese. (a, Reproduced by permission of M. Messori, www.sympak.com; b, reproduced by permission of M. Aberle, www.oystar.benhil.de; c, courtesy of Friesland Campina Cheese Specialities; d, courtesy of Clover.)

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integrated cartoning, the carton blank is withdrawn from the magazine, erected and placed into the cell at an additional station in the turntable prior to the wrapper bag forming station. On the discharge conveyor, the cover flap of the carton is closed and glued by hot melt. Corazza has complete dosing–wrapping–cartoning lines for 100–250 g or 250–500 g portions of large square, rectangular or round portions of processed cheese, wrapped with aluminium foil and packed into single cartons. The dosing–wrapping–cartoning line is formed by a dosing–wrapping machine with capacities of 50–300 portions min−1 depending on the size of the portion, with a double-lane conveyor system to enable smooth transfer to the double-head cartoning machine for packaging the portions into single glued cartons (Fig. 8.3).

8.3.4 Sausage shape Smoked cheese in sausage form can be filled with a semi-automatic block filling machine into artificial casings, and come in units between 10 g and 5 kg in weight (Fig. 8.4) (Meyer, 1973; Berger et al ., 1989). The broad filling connection normally used for block cheese (long filling tube) is used. Sausage skin, previously dipped in water and bound at one end, is pulled over the nozzle and, after filling with the hot cheese mass, is twisted by

(a)

(b)

Fig. 8.4 Smoked processed cheese sausage shape and sliced. (Courtesy of Friesland Campina Cheese Specialities.)

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hand and tied (Meyer, 1973). Large units are cut up and pre-packaged in units containing 5–10 slices. Smaller sizes are filled by using sausage filling machines, and are ready for sale (Fig. 8.4). They are packed with automated machines with an output of about 60 pack units min−1 , and closed by a double metal clip machine (Berger et al ., 1989).

8.3.5 Metal cans Sometimes processed cheese products are packaged either in tinplate or aluminium cans. These metal containers must be adequately enamelled/lacquered from the inside to prevent corrosion from occurring (Robertson, 2006). Canned processed cheese, which consist of round cans of tinplate with a capacity of 100–1000 g of cheese, is expected to attain a shelf-life of over 1 year (Meyer, 1973; Berger et al ., 1989). The advantages of hermetically sealed metal cans compared with other types of packaging containers are as follows: (a) they can withstand high temperature processing and storage at low temperatures; (b) they are impermeable to light, moisture, odours and microorganisms to provide total protection of the contents; and (c) they are inherently tamperproof and the metal can be recycled by extraction from solid wastes. However, they are expensive due to the high metal cost and relatively high manufacturing costs and incur higher transport costs because, except for glass, they are heavier than other packaging materials (Fellows, 2000). Further information on the manufacture and lacquer coating of cans used for foods has been reported by Fellows (2000). If the processed cheese is manufactured at 90–95◦ C, the cans are filled with the product, sealed and transferred to the steriliser, while still hot. The second heating is at <117◦ C for less than 20 min. To ensure effective heat penetration, metal cans weighing 200 g or less are used for sterilisation and then aseptically filled at high temperature (Berger et al ., 1989). The cans are usually filled by semi-automatic and automatic filling machines as supplied by Benz & Hilgers GmbH and Kustner. Fully automated machines are used for canning, placing the lid and sealing. These machines are specific for processed cheese packaging, and have a double-walled hopper with a stirring mechanism, adjustable to different quantities. There is a ‘cut-off’ at the filling station with a sealing system incorporated, which suits the hot liquid cheese. The can must not be subjected to strong rotation when it is sealed. Packaging material can be loaded into the machine in large quantities. Cooled cans, tunnels or compartments, are boxed automatically at the final packing station (Berger et al ., 1989).

8.3.6 Tubs, jars, cups and plastic containers Processed cheese packed in glass is still very popular, and maintains a firm share of the market. Glass is completely impermeable to gases and vapours, which is not the case for plastic packaging materials (Fig. 8.5) (Alves et al ., 2007). Glass containers are also inert, and do not react with or migrate into the food product. They have filling speeds comparable to those of metal cans, and are suitable for heat processing when hermetically sealed. Furthermore, glass containers can be reused, recycled and are resealable. In addition, they are perceived by the consumer to add value to the product, are transparent for displaying the contents, and can be decorated. The main disadvantages are the higher weight incurring

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(a) Fig. 8.5

(b)

Processed cheese packed in glass jars. (Courtesy of Parmalat/Melrose.)

higher transportation costs, and lower resistance than other materials to fracturing and thermal shock; glass is potentially a serious hazard as splinters or fragments may end up in the product (Fellows, 2000). Folded aluminium tubs in 100 and 200 g sizes have gained market share in recent years. Moulded packs, now also more common, were made of plastic initially and later of strong aluminium foil (Berger et al ., 1989). The plastic packs are permeable to oxygen through the cap, seal or closure system (Alves et al ., 2007). These rigid and semi-rigid plastic containers are made from single or co-extruded polymers (Fellows, 2000). Polyvinyl chloride (PVC) is used for containers where processed cheese is filled below 80◦ C; it is co-extruded or laminated in combination with other plastic materials, such as PVC (450 μm)/PVdC or PVC/EVOH copolymer (20 μm)/low-density PE (LDPE, 50–90 μm); however, PP is used when the cheese melt ranges between 165 and 170◦ C and PET can be used as a laminate material (Robertson, 2006). According to Fellows (2000), the main advantages of plastic containers compared with glass and metal are as follows: • • • • •

Lower weight, resulting in savings of up to 40% in transportation and distribution costs compared with glass and metal. Precisely moulded into a wider range of shapes than glass. Tough and unbreakable, with impact and pressure resistance, and easy to seal. Easily coloured, offer UV light protection and are produced at relatively low cost. Greater chemical resistance than metals.

However, they are not reusable, have lower heat resistance and are less rigid than glass or metal. The methods of manufacture of these containers are detailed by Fellows (2000). The plastic packs range from 20 to 300 g in weight and due to the wide choice of machines available, there has been a considerable increase in filling processed cheese in

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pre-formed packaging units. FASA supplies an automatic packaging machine designed for packaging processed cheese in cups that are made from biodegradable polymers (Guilbert, 2000), with ring-shaped edges over the cup with diameter of 75 or 95 mm and polymer lids from laminated foil thermally welded layer. The dose of cheese mass is between 100 and 500 mL, with a maximum output capacity of 40 packs min−1 . Corazza supplies a continuous motion, updated manifold design (without a hopper), glass jar filling machine that incorporates the latest technology in product supply and facilitates cleaning-in-place (see Fig. 8.3). The volume that can be filled ranges from 100 to 1000 mL, with a maximum speed of 20 000 bottles h−1 .

8.3.7 Collapsible tubes A small quantity of processed cheese spread is packaged in collapsible tubes, which used to be made from aluminium but which are now made from five-layer laminates containing aluminium foil as the central core. The collapsible aluminium tube is a unique food packaging system that allows the user to apply the product directly and in precise amounts when required. Currently, the aluminium tube is relatively rare, with most food tubes being made of plastic. Although early plastic tubes contained aluminium foil as a barrier layer, it is now common to co-extrude LDPE with EVOH to obtain a tube that provides an excellent barrier to air and moisture. Plastic tubes are also printed by a dry offset process (Robertson, 2006). Collapsible tube filling and closing/sealing machines are fully automated, and are filled with 75–200 g of processed cheese. An example of such machine is available from Benz & Hilgers GmbH where the collapsible tubes are not inserted individually, but a whole batch of tubes is placed in the machine at any one time. The aluminium tube is formed by the cold impact extrusion of an aluminium slug using a plunger. To relieve the hardness, the tube is annealed in an oven at 600◦ C after which the inside is coated with an epoxy-phenolic or acrylic lacquer (Robertson 2006). Collapsible tubes are supplied pre-formed, with an open end ready for filling (Fellows, 2000). Filling is through the unsealed base opening of the collapsible tube and ‘tailing’ is prevented by making the filling piston perform a return stroke, which ensures that the processed cheese mass breaks off; therefore, the fold at the end of the collapsible tube is not contaminated with cheese. Aluminium tubes are printed by a dry offset process using either thermal or UV-cured ink. The collapsible tubes are closed by folding after application of latex or heat-sealable lacquer inside the foil area, and heat is applied, which ensures a hermetic seal (Robertson, 2006). The tube is sealed with rubber or plastic material (Berger et al ., 1989) or welded by high-frequency current (Robertson, 2006). This type of packaging is mostly available in Scandinavia (Berger et al ., 1989).

8.3.8 Packs with external decoration Processed cheese decorated with nuts or black pepper, with a limited shelf-life, is packed by fully automatic machines. The molten cheese mass is poured into tubes of 1–1.5 m in length and cooled. The cheese is then pressed out of the pipe the next day with a piston,

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after insertion in an appropriate machine. At the end of the pipe is a cutting wire, which cuts the strip of processed cheese, pressed out of the pipe, to the desired length. The unit is then decorated, wrapped in plastic foil and vacuum sealed using standard commercially available equipment (Berger et al ., 1989).

8.3.9 Slices In 1950, the first pack of sliced processed cheese went on sale in the USA. It was then introduced in Europe and continued to spread rapidly throughout the world, and has been replacing block processed cheese. Sliced processed cheese was first manufactured by solidifying a ribbon of cheese on chilled rollers, followed by slitting and cutting. Slices were also manufactured by moulding the cheese in the form of a tube around which a web of plastic was wrapped. The whole assembly was then flattened and cooled (Robertson, 2006). Individually wrapped slices have been increasingly replacing packs containing six, eight or twelve or more slices (Fig. 8.6). The films most often used are laminates of PET/LDPE or, for a more permeable package, PET/PVdC/copolymer-LDPE or oriented polypropylene (OPP)/EVOH/copolymer-LDPE (Robertson, 2006). The production of slices can be subdivided into four production processes: block, roller, band or strip and injection methods (Berger et al ., 1989). The block method is used to avoid the expense of investing in special packaging equipment. Slices of processed cheese are vacuum packed or gas flushed with an inert gas. The roller method of processed cheese production (the oldest method) underwent development to produce individually wrapped slices. With the band or strip method , a wide cooled moving belt of stainless steel is used instead of a cooling roller. The molten cheese is poured onto the band, and the thin layer of processed cheese is divided into strips. After the underside of the strips of processed cheese has been cooled on the first belt, they are turned over and transferred to a second lower belt on which the other side of the processed cheese is cooled. The strips are subsequently removed from the second belt, sliced and taken to the final packing station. With this method, liquid coolants are used to cool the belts from below. Cooling can also be achieved by fans, and the steel belt only serves as a means to convey the cheese. The injection method was developed to produce slices with a low dry matter and

(a) Fig. 8.6 Clover.)

(b)

(c)

Individually wrapped processed cheese slices. (a and b, Courtesy of DairyBelle; c, courtesy of

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to solve both the risk of mould growth and the problem of slices sticking together; this led to the adaptation of the standard packaging machine used for processed cheese triangles to the production of slices. A normal twin foil, with different folding devices and formats, is used to produce sliced processed cheese. As with processed cheese triangles, the product is injected into the pre-shaped body foil. Then the lid foil is laid on top and, after the folding station, the processed cheese is shaped into a slice when the pack is sealed and pressed (Berger et al ., 1989). Individually wrapped slices can be packaged with machines available from Kustner. Essentially two machines are built into a common frame, with each lane producing 800 individually wrapped processed cheese slices per minute (Newcorn, 1997). The processed cheese is extruded, while still hot, directly into a tube of film which is then cross-sealed and chilled in a water bath. On other machines the product is chilled prior to wrapping by passing over a series of chill rollers. The Kustner machine starts out with two rolls of flat film (1.5 mm PP/ethylene vinyl acetate (EVA) co-extrusion) with one roll running while the other is on standby. This film has excellent release properties, enhancing easy unwrapping of the cheese. The packaged slices are hermetically sealed and submerged in a water bath to cool. Other wrapped slices have fold-over lap seams without seals. The plastic tube is filled with processed cheese, and passes between synchronised forming belts. Voiding bars flatten the filled tube and squeezes the molten processed cheese out the intended seal area between each slice. The plastic film is heat-sealed, but not cut, resulting in a continuous ribbon of individually sealed slices of the product, which is chilled with water. Excess moisture is then blown off with hot air (Newcorn, 1997). Maximum packaging throughput is 1600 slices min−1 , with slice size of 86 × 86 mm, thickness 2.3–5.2 mm and weight 18–40 g. The web of slices then passes over a rotary drum that meshes with a three-bladed rotating knife assembly that cuts the ribbon into individual slices. Both lanes of production are held onto the drum by vacuum cups, which drop the slices onto a flat takeaway conveyor, resulting in six lanes of cheese slices. Photo eyes over each lane count the slices before entering a stacking assembly (EPA, 1997; Newcorn, 1997). A recent development is resealable packs for processed cheese, PFM packaging machinery and Multivac supply machines for this purpose (Anonymous, 2001). The ability to reseal the package ensures the product’s freshness.

8.4 Conclusion The packaging industry is noted for a reasonably high research and development investment and for continuing innovations in food packaging. Some of the novel technologies being pursued include antimicrobial packaging, oxygen scavenging, packaging that notifies the consumer when the shelf-life has ended, and the extension of MAP to products, such as sliced cheese. These active food packaging technologies offer new opportunities in the preservation of foods (Ozdemir & Floros, 2004). Another technology that is rapidly developing is the use of innovative packages with multiple compartments, which has many potential applications for dairy foods (Munro, 2002). The key to success in processed cheese packaging is to recognise that these products, as well as other cheeses, are complex ecosystems with complicated interactions between specific packaging applications/systems,

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storage conditions and the cheese (Floros et al ., 2000). Understanding these parameters will help us to develop proper packaging systems in order to ensure total quality of the product.

References Alves, R.M.V., van Dender, A.G.F., Jaime, S.B.M., Moreno, I. & Pereira, B.C. (2007) Effect of light and packages on stability of spreadable processed cheese. International Dairy Journal , 17, 365–373. Anonymous (2001) Keeping one step ahead. Machinery Update, May/June, 27–32. Berger, W., Klostermeyer, H., Merkenich, K. & Uhlmann, G. (1989) Packaging, cooling, storage. Processed Cheese Manufacture: A JOHA® Guide (ed. H. Klostermeyer), pp. 131–144, BK Ladenburg, GmbH, Germany. Bull, M.F. & Grønborg, H. (1995) Outer packaging. Technical Guide for the Packaging of Milk and Milk Products, Bulletin 300, 3rd edn, pp. 65–70, International Dairy Federation, Brussels. Caric, M. (1999) Processed cheese. Encyclopedia of Food Science and Technology (ed. J.F. Francis), 2nd edn, pp. 1973–1987, John Wiley & Sons, New York. Christiansen, S. (2008) The green revolution. Dairy Industries International , 73, 22–23. EPA (1997) Natural and Processed Cheese, EPA contract 68-D2-0159, Final report (July 1997), pp. 1–9, US Environmental Protection Agency, Research Triangle Park, North Carolina. Fellows, P.J. (2000) Packaging. Food Processing Technology: Principles and Practice, 2nd edn, pp. 462–510, Woodhead Publishing, Cambridge. Floros, J.D., Nielsen, P.V. & Farkas, J.K. (2000) Advances in modified atmosphere and active packaging with applications in the dairy industry. Packaging of Milk Products, Document No. 346, pp. 22–28, International Dairy Federation, Brussels. Fl¨uckiger, E. (1995) Odour and taste. Technical Guide for the Packaging of Milk and Milk Products, Bulletin 300, 3rd edn, pp. 12–16, International Dairy Federation, Brussels. Gallmann, P. (1995) Migration. Technical Guide for the Packaging of Milk and Milk Products, Document No. 300, 3rd edn, pp. 8–11, International Dairy Federation, Brussels. Grace, V., Houghtby, G.A., Rudnick, H., Whaley, K. & Lindamood, J. (1993) Sampling dairy and related products. Standard Methods for the Examination of Dairy Products (ed. R.T. Marshall), 17th edn, pp. 59–83, American Public Health Association, Washington, DC. Guilbert, S. (2000) Edible films and coatings and biodegradable packaging. Packaging of Milk Products, Document No. 346, pp. 10–16, International Dairy Federation, Brussels. Hall, H.S. (1995) Mechanical strength. Technical Guide for the Packaging of Milk and Milk Products, Document No. 300, 3rd edn, pp. 17–18, International Dairy Federation, Brussels. Han, J.H. (2000) Antimicrobial food packaging. Food Technology, 54, 56–65. Harrysson, G. (1998) New developments in packaging and processing. Proceedings of the 25th International Dairy Congress (ed. A. Rarn), pp. 249–264, The Danish National Committee of the IDF, Aarhus, Denmark. Hickey, P.J., Beckelheimer, C.E. & Parrow, T. (1993). Microbiological tests for equipment, containers, water, and air. Standard Methods for the Examination of Dairy Products (ed. R.T. Marshall), pp. 397–412, American Public Health Association, Washington, DC. Holah, J.T. (2003) Cleaning and disinfection. Hygiene in Food Processing (eds H.L.M. Lelieveld, M.A. Mostert, J. Holah & B. White), pp. 235–278, Woodhead Publishing, Cambridge. ILSI (2000) Packaging materials. ILSI Europe, Belgium. Kooi, J. & Van den Berg, M.G. (1995) Environmental constraints on packaging of dairy products. Technical Guide for the Packaging of Milk and Milk Products, Document No. 300, 3rd edn, pp. 71–77, International Dairy Federation, Brussels. Kosikowski, F.V. & Mistry, V.V. (1997) Packaging. Cheese and Fermented Milk Foods (ed. F.V. Kosikowski), 3rd edn, vol. 1, p. 618, F.V. Kosikowski LLC, Westport.

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Lelieveld, H.L.M., Mostert, M.A. & Curiel, G.J. (2003) Hygiene equipment design. Hygiene in Food Processing (eds H.L.M. Lelieveld, M.A. Mostert, J. Holah & B. White), pp. 122–166, Woodhead Publishing, Cambridge. Mayer, H.K. (2001) Bitterness in processed cheese caused by an overdose of a specific emulsifying agent. International Dairy Journal , 11, 533–532. Meyer, A. (1973) Processed Cheese Manufacture, 1st edn, pp. 164–184, Food Trade Press Ltd, London. Mostert, J.F. & Buys, E.M. (2008) Hygiene by design. Advanced Dairy Science and Technology (eds T.J. Britz & R.K. Robinson), pp. 75–120, Blackwell Publishing Ltd., Oxford. Mostert, J.F. & Jooste, P.J. (2002) Quality control in the dairy industry. Dairy Microbiology Handbook (ed. R.K. Robinson), 3rd edn, pp. 669–673, John Wiley & Sons, New York. Munro, P.A. (2002) New processing technologies to create the dairy products of the future. New Processing Technologies for the Future: Proceedings of the Emerging Technologies Conference, Document No. 374, pp. 4–7, International Dairy Federation, Brussels. Newcorn, D. (1997) Cheese wrapping on the double. Packaging World , July, 1–4. Odet, G. & Zachrison, C. (1982) Cheese. Technical Guide for the Packaging of Milk and Milk Products, Document No. 143, 2nd edn, pp. 102–109, International Dairy Federation, Brussels. Oyugi, E. & Buys, E.M. (2007) Microbiological quality of shredded Cheddar cheese packaged in modified atmospheres. International Journal of Dairy Technology, 60, 89–95. Ozdemir, M. & Floros, J.D. (2004) Active food packaging technologies. Critical Reviews in Food Science and Nutrition, 44, 185–193. Petersen, K., Nielsen, P.V., Bertelsen, G., Lawther, M., Olsen, M.B., Nilssonk, N.H. & Mortensen, G. (1999) Potential of biobased materials for food packaging. Trends in Food Science and Technology, 10, 52–68. Radmore, K. (1986) A microbiological study of air in dairy processing and packaging plants. MSc thesis, University of Pretoria, Republic of South Africa. Robertson, G.L. (2006) Packaging of dairy products. Food Packaging: Principles and Practice, 2nd edn, pp. 387–416, CRC Press, Boca Raton, FL. Ronkilde Poulsen, P. (1995) Selecting packaging systems. Technical Guide for the Packaging of Milk and Milk Products, Document No. 300, 3rd edn, pp. 3–4, International Dairy Federation, Brussels. Scannell, A.G.M., Hill, C., Ross, R.P., Marx, S., Hartmeier, W. & Arendt, E.K. (1999) Food Microbiology and Food Safety into the Next Millennium (eds A.C.J. Tuijtelaars, R.A. Samson, F.M. Rombouts & S. Notermans), pp. 303–307. Foundation Food Micro ’99, TNO Nutrition and Food Research Institute, A.J. Zeist, The Netherlands. Sch¨ar, W. & Bosset, J.O. (2002) Chemical and physico-chemical changes in processed cheese and ready-made fondue during storage: a review. Lebensmittel-Wissenschaft und Technologie, 35, 15–20. Schwope, A.D., Till, D.E., Ehntholt, D.J., Sidman, K.R., Whelan, R.H., Schwartz, P.S. & Reid, R.C. (1987) Migration of Irganox 1010 from ethylene-vinyl acetate films to foods and food-simulating liquids. Food and Chemical Toxicology, 25, 327–330. Skibsted, L.H. (2000) Light-induced changes in dairy products. Packaging of Milk Products, Document No. 346, pp. 4–16, International Dairy Federation, Brussels. Sturm, W. (1998) Verpackung Milchwirtschaftlicher Lebensmittel , Kempten: Edition IMQ, cited by Sch¨ar & Bosset (2002). Tacker, M. & Hametner, C. (1999) Methods of the assessment of the contamination rate of plastic cups for liquid milk products. Deutsche Lebensmittel Rundschau, 95, 176–180. Tamime, A.Y. & Robinson, R.K. (2007) Tamime and Robinson’s Yoghurt Science and Technology, 3rd edn, pp. 106–123, Woodhead Publishing, Cambridge. Templeton, H.L. & Sommer, H.H. (1937) Wrappers for processed cheese. Journal of Dairy Science, 20, 231–237.

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Wainess, H. (1995a) Design, construction and operation of packaging equipment. Technical Guide for the Packaging of Milk and Milk Products, Document No. 300, 3rd edn, pp. 47–51, International Dairy Federation, Brussels. Wainess, H. (1995b) Hygiene. Technical Guide for the Packaging of Milk and Milk Products, Document No. 300, 3rd edn, pp. 40–46, International Dairy Federation, Brussels. Wierenga, G. & Holah, J.T. (2003) Hygienic plant design. Hygiene in Food Processing, (eds H.L.M. Lelieveld, M.A. Mostert, J. Holah & B. White), pp. 76–105, Woodhead Publishing, Cambridge. Yam, K.L., Takhistov, P.T. & Miltz, J. (2005) Intelligent packaging: concepts and applications. Journal of Food Science, 70, R1–R10.

9 Production of Analogue Cheeses E.D. O’Riordan, E. Duggan, M. O’Sullivan and N. Noronha

9.1 Introduction Cheese consumption continues to rise with consumption in the USA reaching a record high of 14.2 kg per capita in 2005, a 0.6% increase over the record level set in 2004 (Dairy Facts, 2006). An increasing proportion of this cheese is consumed in the form of an ingredient in convenience foods, e.g. pizzas, sauces, cheeseburgers. Although cheese consumption and production levels are at an all-time high, cheese is nonetheless an expensive ingredient, with high production and storage costs. The high costs of natural cheese have prompted manufacturers to seek cost-effective replacement products that perform with equal or greater efficacy than the natural product. The search for this sort of substitute with similar taste, texture, colour and nutritional quality to cheese has culminated in the development of cheese analogues. This review discusses the legislation, main applications, and the advantages of cheese analogues over natural cheese products. The process of manufacturing analogue cheeses, the ingredients and the formulations typically used are also discussed. The usefulness of an analogue cheese is very dependent on how closely its functional attributes, both in a melted and unmelted state, can be matched to the requirements of its potential application, e.g. pizza topping or savoury pie. The chapter focuses particularly on the effects of the formulation on functional attributes including texture, microstructure, melt and flavour of analogue cheeses. Research in the area has developed considerably over the past decade, and there have been a number of innovations to increase the nutritional value of the end-products, e.g. low-fat cheeses, high-fibre cheeses. This review also examines these developments and explores the likely future for analogue cheeses.

9.2 Definition and legislation Analogue cheese products are described as products that look like cheese, but in which the milk fat has been partly or completely replaced by other fats (Codex Alimentarius Commission, 1995). Analogue cheeses can be categorised as either dairy, partial dairy or non-dairy. The category is determined by whether the fat and/or protein ingredients are from dairy or vegetable sources. In the USA, an ‘analogue cheese’ is defined as ‘a product which is a substitute for, and resembles, another cheese but is nutritionally inferior, where Processed Cheese and Analogues, First Edition. Edited by A.Y. Tamime. © 2011 Blackwell Publishing Ltd. Published 2011 by Blackwell Publishing Ltd.

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nutritional inferiority implies a reduction in the content of an essential nutrient(s) present in a measurable amount but does not include a reduction in the caloric or fat content’ (Food and Drugs Administration Regulation 101; FDA, 2003). The terms ‘analogue cheese’ and ‘cheese analogue’ are often used interchangeably. There appears to be little legislation covering analogue cheeses outside the USA, with few, if any, standards relating to permitted ingredients or manufacturing procedures. This provides food producers with the opportunity to manufacture products without much restriction on the type of ingredients or manufacturing procedures used. For the most part, analogue cheese is sold into the industrial sector, and the most common variety sold has functional properties designed to mimic those of natural Mozzarella cheese. However, analogue cheese is also available in the retail sector and accounted for 18 000 tonnes of supermarket sales in 2005, i.e. ∼7% of processed cheese sales, with a small proportion (∼2700 tonnes) accounting for the reduced- or low-fat market (Dairy Facts, 2006). Since analogue cheese products are increasingly used in consumer items, e.g. ready meals, clear and specific worldwide legislation is needed to ensure suitable labelling of these products.

9.3 Applications and advantages of analogue cheese products The principal application of analogue cheese in the USA is as a Mozzarella cheese substitute in frozen pizzas. Cheddar-type analogue cheeses are also very common, and are used predominantly as slices in cheeseburgers. In Europe, analogue cheese is increasingly used in the industrial sector, as an ingredient in formulated foods, such as processed meat products and combined cheese-filled co-extruded products (Guinee et al ., 2004). Other applications include salads, sandwiches, tacos, enchiladas, cheese dips, ready prepared meals and lasagne. Besides Mozzarella, other analogue cheese ‘varieties’ that have been reported in the trade literature include Parmigiano, Romano, Blue and Cream cheese. The use of enzyme-modified cheeses (EMCs) with flavour profiles close to those specific to individual varieties (e.g. Cheddar, Emmental) has greatly facilitated the development of different ‘varieties’ of analogue cheeses. Some advantages of analogue cheese over natural cheese include the following. •

• •

Lower production costs due to the replacement of milk fat with cheaper vegetable oils; no ripening required; the capital costs of the manufacturing equipment is lower than that required for natural cheese manufacture. Simplicity and speed of manufacture from readily available raw materials. Amenability of formulations to be easily altered to yield products with customised textural, melting and/or nutritional attributes (e.g. high melt, firm texture, low-fat, lowsalt).

9.4 Manufacture of analogue cheese 9.4.1 General principles and manufacturing protocol Manufacture of analogue cheese involves blending selected ingredients together and heating to produce a stable molten oil-in-water emulsion which sets on cooling. There are

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221

four key ingredients needed to manufacture analogue cheese, namely water, emulsifying salts, protein and fat. There are various ways to manufacture analogue cheese and the process may vary depending on the formulation and, in particular, the source of protein used. Irrespective of the formulation, the manufacturing process tends to be quick and uncomplicated. The procedure used to manufacture rennet casein-based products (Mounsey, 2000; Hennelly et al ., 2005; Montesinos et al ., 2006) will be the main focus of this discussion. Generally, the water and casein in the form of a dry powder are blended at ∼50◦ C in the presence of emulsifying salts (only required for rennet casein-based cheeses). The emulsifying salts promote, with the aid of heat and shear, a series of physicochemical changes within the cheese blend which result in the rehydration of the insoluble rennet casein and its conversion to an active emulsifying agent (Templeton & Sommer, 1936; Guinee et al ., 2004). The addition of emulsifying salts causes the pH of the mixture to increase (pH ∼8–9). A high pH during processing leads to greater sequestration of calcium by the sodium phosphate emulsifying salts and results in a higher degree of casein hydration. The lipid may be added at this stage but a number of workers add lipid at the protein hydration stage to help prevent over-hydration and ‘clumping’ of casein. When the hydrated casein and lipid are mixed, the temperature of the mixture is increased to ∼80◦ C (this can vary, but is usually in the range 70–95◦ C), using direct or indirect steam injection until the desired temperature is reached, which usually takes 4–6 min. Cooking and agitation continues until a homogeneous smooth plastic mass is obtained, with no free oil or water present in the cooker. At this stage acidulants, such as citric acid, can be added to adjust the pH of the analogue cheese to a final desired value. Once cooked the cheese product is discharged from the cooker, is cooled rapidly and stored at 4◦ C until required. Figure 9.1 captures the four key stages of matrix development during the manufacturing process and assists our understanding of the general process described above (Noronha et al ., 2008a). These researchers suggest that in the first stage the casein binds water, becomes swollen and develops a stiff particulate consistency. When heat (∼80◦ C) is applied to this matrix in stage 2, the casein particles become transformed into a translucent congealed mass and large quantities of free oil and water are evident in the cooker. As the heating and shearing action is continued, stage 3 marks the transformation of the translucent mass to an opaque cohesive matrix, but the surface remains quite oily in appearance. The volume of unimbibed liquid decreases, but it becomes milky in appearance reflecting the emulsification of the oil in the ‘free’ liquid by the hydrated proteins. Finally, stage 4 marks the incorporation of this emulsified lipid and the formation of a homogeneous cheese mass ready for discharge from the cooker. Light microscopy images of each of the four stages of analogue cheese manufacture (Noronha et al ., 2008a) help to further elucidate what is occurring during the process at a microscopic level (Fig. 9.2). In stage 1 the protein (stained blue) appears more or less evenly dispersed, although discrete particles are present (Fig. 9.2a). There is little fat (stained red) evident in the micrograph since only a small portion of the fat is incorporated at this stage. The protein matrix becomes more continuous during stages 2 and 3 with large but very few fat globules observed (Fig. 9.2b,c, respectively). The micrograph of stage 4 clearly indicates that the fat is now emulsified by the protein and an even distribution of fat globules ∼20 μm in diameter throughout the protein matrix is clearly evident. Presumably, this reflects the incorporation of the milky liquid containing the emulsified fat in the homogeneous matrix (Fig. 9.2d). A well-hydrated casein matrix with a stable fat phase is imperative for good end-product functionality.

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Processed Cheese and Analogues

(b)

(a)

Congealed matrix

Swollen particulates

Free oil & water

(c)

(d)

Cohesive matrix

Homogeneous cheese mass

Milky liquid

Fig. 9.1 Illustrations of the four main stages of matrix development during the manufacture of analogue cheese. (See Plate 9.1 for colour figure.)

(a)

(b)

P

F

F

P

(d)

(c)

F F

P

P

Fig. 9.2 Light microscopy images of the four main stages of matrix development during the manufacture of analogue cheese. (See Plate 9.2 for colour figure.)

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223

9.4.2 Key ingredients used in the production of analogue cheese products As shown above, analogue cheese is manufactured using a few key ingredients mixed and heated together to form a stable oil-in-water emulsion. Each ingredient has a specific role to play in the formation of a homogeneous cheese product. A brief description of the role of each key ingredient in analogue cheese is summarised in Table 9.1, and a brief overview of the range of ingredients typically used is presented. The impact of specific ingredients on the functionality of analogue cheese is discussed in greater depth in section 9.5. Protein sources The protein component in analogue cheese products forms the continuous hydrated matrix. It also stabilises the oil-in-water emulsion by reducing the interfacial tension at the aqueous phase–oil droplet interface and by increasing the viscosity of the aqueous phase during manufacture thereby decreasing the frequency of collisions between, and resultant Table 9.1 Summary of roles played by key ingredients commonly used in the production of analogue cheese products. Ingredient

Function

Examples

References

Milk proteins

Gives desired composition, texture with good shreddability, flow and stretch characteristics on heating

Rennet casein, caseinates, whey proteins

Hokes (1982), Zuber et al . (1987), Savello et al . (1989), Abou El Nour et al . (1996), Mounsey & O’Riordan (1999, 2001, 2008b), Hoffmann et al . (2005)

Vegetable proteins Gives desired composition, cheaper alternative to milk proteins

Soybean proteins, rice proteins

Yang & Taranto (1982a,b), Yang et al . (1983), Kim et al . (1992), Pereira et al . (1992), Murphy (1999)

Fat

Gives desired composition, texture and meltability characteristics; butteroil imparts dairy flavour

Anhydrous milk fat, rapeseed oil, native or partially hydrogenated soybean, corn or palm kernel oil

Eymery & Pangborn (1988), Lobato-Calleros et al . (1997), Lobato-Calleros & Vernon-Carter (1998), Hennelly et al . (2005), Jana et al . (2005), Montesinos et al . (2006)

Emulsifying salts

Chelate calcium and displace pH upwards, allowing the protein to hydrate, increasing protein’s emulsifying capability

Citrates, orthophosphates, pyrophosphates, polyphosphates, aluminium phosphates

Ennis et al . (1998, 2000), Ennis & Mulvihill (1999), Savello et al . (1989), Cavalier-Salou & Cheftel (1991)

Preservatives

Retard mould growth, prolong shelf-life

Potassium sorbate, nisin, calcium or sodium propionate

Guinee et al . (2004), Hennelly et al . (2006)

Acidulants

Assist in the control of the final pH of the product

Food-grade organic acids, e.g. lactic, acetic, citric, phosphoric

Shimp (1985), Stampanoni & Noble (1991), Aimutis (1995)

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coalescence of, oil droplets (Shimp, 1985; Ennis & Mulvihill, 1997). A number of proteins can be used in the manufacture of analogue cheese, such as rennet or acid casein, caseinates, whey proteins and/or vegetable proteins. Rennet casein is widely used as a source of protein in analogue cheese manufacture; however, it hydrates poorly and is effectively insoluble in water, so adequate hydration and solubility is achieved by the addition of emulsifying salts (e.g. disodium phosphate and trisodium citrate) with heat (80◦ C) and agitation. The emulsifying salts chelate and remove calcium from the rennet casein, allowing the casein to absorb water and hydrate. The addition of emulsifying salts causes the pH of the mixture to increase (pH ∼8–9) (Cavalier-Salou & Cheftel, 1991). A high pH during processing leads to better sequestration of calcium by the sodium phosphate emulsifying salts, and greater negative charge on the casein resulting in a higher degree of para-casein hydration. These changes enhance the conversion of the calcium para-casein to sodium para-caseinate, which binds water and emulsifies the fat (Guinee et al ., 2004). Acid casein can also be used as the protein source in the manufacture of analogue cheeses, but this protein must firstly be partially converted to a caseinate (sodium or calcium) using alkali, e.g. NaOH, Ca(OH)2 or KOH, to develop functionality (Aimutis, 1995). Cheeses in which acid casein is the main source of protein can leave an unsatisfactory gluey mouth-feel, leaving objectionable or undesirable musty flavours that are difficult to mask (Ennis & Mulvihill, 1997). Caseinates (sodium or calcium) can also be used as protein sources in analogue cheese products. Sodium caseinate solubilises in water without the aid of emulsifying salts, exhibiting excellent emulsification properties. Calcium caseinate forms a colloidal suspension when reconstituted in water and, unlike sodium caseinate, emulsifying salts are necessary to chelate the divalent calcium ions that were effectively cross-linking the proteins in order to convert calcium caseinate into a suitable emulsifier (Aimutis, 1995). Whey proteins (α-lactalbumin and β-lactoglobulin) have undergone limited study on their usefulness in processed or analogue cheese products (Savello et al ., 1989; Gupta & Reuter, 1992; Hill & Smith, 1992; Murphy, 1999). Generally, whey proteins exhibit emulsifying abilities inferior to caseins and caseinates, but they are less sensitive to changes in pH (Morr, 1982). Whey proteins can be used as partial substitutes (≤3.75 g 100 g−1 ) for caseins in Mozzarella cheese analogue (Murphy, 1999; Solowiej et al ., 2008). Vegetable proteins, such as soybean, rice protein, wheat gluten and peanut protein, have all been used successfully to partially replace milk-based proteins in analogue cheese (Chen et al ., 1979; Rule et al ., 1980; Yang & Taranto, 1982a,b; Kratochvil, 1987; Zwiercan et al ., 1987; Kim et al ., 1992; Murphy, 1999). However, vegetable proteins lack the specific functional properties of the caseins/caseinates as they tend to have larger molecular size, possess complex quaternary structures, and are subject to complex interactions with themselves and other components in the food matrix unlike milk proteins. Accordingly, vegetable proteins tend to be used in conjunction with caseinates for use in analogue cheeses. Lipid sources The lipid phase in analogue cheese can include a wide range of fats including butterfat and vegetable fats such as soybean, palm kernel, sunflower, rapeseed and corn oil

Production of Analogue Cheeses

225

(Caric & Kalab, 1993). Vegetable fats are most commonly used in analogue cheese products because they are much cheaper than milk fats. Fat in analogue cheese contributes to the cheese’s texture and influences meltability. Generally, harder fats strengthen analogue cheese products whereas liquid oils give rise to softer products (Zhou & Mulvaney, 1998). Emulsifying salts Emulsifying salts are the salts used in analogue cheese manufacture to promote, with the aid of heat and shear, the hydration of insoluble casein and its conversion to an active emulsifying agent, allowing adequate emulsification of the fat phase. A wide range of emulsifying salts is available. The most common emulsifying salts used in analogue cheese manufacture are sodium citrates and sodium orthophosphates (Caric & Kalab, 1993; see also Chapter 4). Acidulants Acidulants, such as citric, lactic, phosphoric or acetic acid, are generally added at the end of cheese manufacture, and are used to adjust the pH of analogue cheeses, from the relatively high values required during manufacture to a lower range which is better for stability. A pH range of 5.9–6.1 is optimal for good analogue cheese functionality, i.e. yields a good melting and stretching of analogue cheese (Aimutis, 1995). At pH values close to the isoelectric point of the proteins (pH <5.0), electrostatic repulsions are weakened, which can adversely affect cheese texture, making it excessively hard because of reduced waterbinding capacities. At pH values greater than 6.5, cheeses can become excessively soft and microbiologically unsafe (Shimp, 1985). Flavourings Analogue cheese is known to be bland in flavour, and is often associated with undesirable ‘casein’ off-flavours. There are a number of ingredients available to flavour analogue cheese products, including both butterfat and natural cheese, which when added in small amounts may contribute to a ‘dairy’ and ‘cheesy’ flavour to analogue cheeses. Concentrated flavour ingredients such as EMCs may also be added to give a matured flavour to processed and analogue cheese products (Caric & Kalab, 1993). EMCs are cheeses that have been treated enzymatically to enhance the flavour of that cheese, and they provide food manufacturers with a strong cheese note in a form that is cost-effective and natural (Kilcawley et al ., 1998). They can be used as the sole source of cheese flavour to intensify an existing cheese taste, or to impart a specific cheese character to an otherwise flavourless product. Kilcawley et al . (1998) have provided a review of EMCs and areas of interest in the production of EMC products. Noronha et al . (2008b,c) reported that the organoleptic quality of EMCflavoured analogue cheeses is affected by the level of flavour active hydrolysis products in the EMC (e.g. free fatty acids) as well as the pH and the composition (e.g. fat content) of the analogue cheese. These researchers reported a good correlation between the flavour intensity perceived by sensory panellists and the concentration of short-chain fatty acids in the EMCs. Decreasing the pH of analogue cheeses containing EMCs from 6.0 to 5.5 increased the intensity of flavours perceived by panellists and also changed the mouth-feel

226

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of the analogue cheeses. The lower pH cheeses were considered ‘smoother’, ‘creamier’ with ‘more balanced cheesy notes’ than the higher pH cheeses. This may provide a costcutting opportunity for cheese technologists to produce analogues with adequate flavour intensity using low-intensity EMCs. Analogue cheeses with high fat levels modulated a greater retention of fat-based flavour compounds in the EMCs and slowed flavour release during consumption compared to cheeses with low fat levels (2 g fat 100 g−1 ). Panellists described the EMC-flavoured low-fat analogue cheeses as ‘too intense’ with ‘short bursts of off-flavours’.

9.4.3 Formulation Formulation involves selecting the correct levels and types of ingredients to give the desired composition and optimal textural and melting properties to analogue cheese products. Each cheese producer has their own specific cheese recipe, usually closely guarded secrets not released in the public domain. In Table 9.2 the range/limits of some key ingredients that have been used in published work are presented. Table 9.3 shows a selection of specific cheese formulations that have been published by researchers working in the area.

9.4.4 Processing equipment The most common type of cooker used to manufacture analogue cheese has twin-screw augers (Fig. 9.3). The twin-screw auger cookers can operate at low mixing speeds, ranging from 50 to 200 rpm, manufacturing the product at temperatures ranging from 70 to 90◦ C for typical holding times of 3–7 min. Twin-screw cookers mimic the kneading and stretching action in traditional Mozzarella cheese manufacture (Ennis & Mulvihill, 1999; Mounsey & O’Riordan, 1999; O’Malley et al ., 2000). Table 9.2 A range of ingredients used to formulate analogue cheese. Ingredient Water (including condensate) Casein and caseinates Vegetable oil

Addition level (g 100 g−1 ) 43.5– 60 11–28 0–28

Starch

0–25.8

Emulsifying salts

0.5–4

Acidifying agents

0.1–1.6

Sodium chloride Preservatives

0.7–2 0.09– 1.1

Stabilisers

0.35–5

Colour

0.2–2

Flavour or flavour enhancers

0.2–5

Production of Analogue Cheeses

Table 9.3

227

Examples of specific formulations for various analogue cheeses. Formulations by different researchers

Ingredients Water

Jana & Upaghyay Rule & Werstak Mounsey & O’Riordan O’Malley Noronha (2001) (1978) (2008a) et al . (2000) et al . (2007) 56.40

50.76

48.80

46.50

60.00

–

19.40

–

–

–

Calcium caseinate

–

4.85

–

–

–

Rennet casein

–

–

15.50

–

19.70

Acid casein

21.00

–

–

–

–

Vegetable oil

–

–

26.00

23.00

1.80

Soybean oil

12.50

–

–

–

–

–

22.63

–

–

–

Sodium caseinate

Hydrogenated cottonseed oil Starch

5.00

–

9.00

0.79

15.60

Guar gum

–

–

–

0.06

–

Starter distillate

–

–

–

0.04

–

Trisodium citrate

1.00

–

1.08

–

0.78

Disodium phosphate

1.75

–

0.48

0.65

0.36

Tween 80

0.15

–

–

–

–

Na salt of carrageenan

0.42

–

–

–

–

NaCl

1.10

–

1.67

1.83

1.24

Flavouring

0.30

0.3

–

–

–

Calcium chloride

0.36

0.87

–

–

–

Lactic acid

0.27

–

–

0.3

–

Citirc acid

–

–

0.62

–

0.45

Sorbic acid

–

0.13

0.10

0.09

0.07

Colouring matter

–

–

–

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Extruders have also been reported to be an effective means of processing analogue cheeses (Cavalier-Salou et al ., 1990). Batch-produced analogues containing calcium caseinate and butteroil processed in a twin-screw cooker were compared with cheeses of the same composition processed using an extrusion cooker. Results showed that the extruded cheese had a similar texture to that prepared using a batch system, but displayed a lower degree of fat emulsification and a higher degree of casein dissociation. Some literature has shown that processing conditions, such as temperature, cook time and shear rate, can be manipulated to control the functional properties of processed cheese (Rayan et al ., 1980; Berger et al ., 1998; Glenn et al ., 2003). Recently, Noronha et al .

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(a)

(b)

Fig. 9.3 The interior of a pilot-scale twin-auger cooker that is typically used to manufacture analogue cheese (a) and a single-blade cooker (b).

(2008d) compared the physical properties of cheese analogues with identical formulations but which had been manufactured at a range of speeds in either a twin-screw Blentech cooker or a single-blade Stephan cooker. In the case of the single-blade cooker, they reported that increasing the blade speed from 750 to 1500 rpm increased the hardness, decreased the meltability and whitened the colour of the cheese. Micrographs of the cheese indicated a substantial decrease in fat globule size with increasing blade speed (Fig. 9.4). Increasing the auger speed in the twin-screw cooker (100 to 200 rpm) had little influence on the physical properties of the analogue. Micrographs of the analogue cheeses manufactured in the single-blade cooker indicated that fat globules were of a smaller, more uniform size compared with those from cheeses made in the twin-screw cooker. Although the cooker type and agitation speed influenced the physicochemical properties of the cheese, the study concluded that it was possible to manufacture comparable cheese analogues using both cookers.

9.5 Factors influencing analogue cheese functionality Cheese functionality can be generally defined as ‘its behaviour during all stages in the preparation and consumption of the food in which it is incorporated’ (Guinee, 2002). The properties that contribute to cheese functionality may be grouped into three main types: (a) the texture-related properties, (b) the melting properties, and (c) the flavour/aromarelated properties. Texture is seen to be one of the primary quality attributes of cheese. Lawrence et al . (1987) suggested that the overall appearance and mouth-feel of cheeses are appreciated before their flavour. Analogue cheese is predominantly used as an ingredient in ready meals and is used in both unmelted and melted states. In the unmelted state, cheese is exposed to operations involving a combination of shear and compressive stresses (e.g. cutting and shredding) that are generally of a magnitude which results in large deformation and fracture into smaller pieces.

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(a)

(b) Fig. 9.4 Electron micrographs of analogue cheese containing 48 g moisture 100 g−1 made in a Stephan cooker at (a) 750 or (b) 1500 rpm.

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As an ingredient, analogue cheese is also used extensively in cooking applications, e.g. on pizzas, cheeseburgers, and in pasta dishes and sauces. A key aspect of cooking performance of cheese is its heat-induced functionality, which is a composite of different attributes, including melting (softening), stretchability, flowability and tendency to brown to varying degrees. Melting cheese is viscoelastic in nature in that it exhibits both solidand liquid-like properties. Dynamic rheology can be applied to measure the rheological properties of cheese during heating (Nolan et al ., 1989), and a number of researchers have employed this technique in recent years (Mounsey & O’Riordan, 1999; Hennelly et al ., 2006; Montesinos et al ., 2006). The functionality of analogue cheese can be substantially affected by formulation changes. Therefore, in the following section the effect of changing the composition on the functional attributes of analogue cheese is discussed. However, before beginning this discussion, the hydration of the protein, arguably the most important stage in analogue cheese manufacture, and its effect on functionality is addressed.

9.5.1 Hydration of protein: impact on cheese functionality As discussed in section 9.4.2, rennet casein is widely used as the source of protein for analogue cheese manufacture, and this protein requires the use of emulsifying salts to render it soluble and act as an effective fat emulsifier. The extent and nature of the hydration of the protein are critical factors in determining the functional performance of the rennet casein during the manufacture of analogue cheese and in influencing analogue cheese end-product functionality. Insufficient hydration of the protein component leads to unsatisfactory incorporation of the oil phase (under-emulsification), and the analogue cheese produced may exhibit unacceptable functional characteristics such as poor stretchability and excessive release of free oil on heating. In extreme cases, hard glassy lumps of poorly hydrated rennet casein (referred to as ‘fish-eyes’) are evident in the analogue cheese (Aimutis, 1995). On the other hand, if rennet casein hydration is too extensive, the phenomenon of overcreaming or over-emulsification is reported (Meyer, 1973). Neville & Mulvihill (1995) reported that when the oil-phase in analogue cheeses was over-emulsified the cheese product had poor meltability characteristics. These characteristics are undesirable in analogue Mozzarella cheese intended for use as a pizza topping. Few researchers have investigated the hydration of rennet casein and its possible effect on cheese functionality in detail. Ennis et al . (1998) used a model system to show that the hydration of casein occurred in a number of stages (particle swelling, clumping, network formation and subsequent breakdown of the network), with the degree of hydration being dependent on the concentration of the emulsifying salt solution. They also observed that there was wide batch-to-batch variation in the functional performance of rennet casein used. In a subsequent study these researchers assessed the hydration characteristics of 44 different batches of rennet caseins, and identified possible indicators of the performance of rennet casein in the manufacture of Mozzarella analogue cheeses (Ennis & Mulvihill, 1999). They established from this study that the maximum viscosity index in combination with the time taken to reach this maximum viscosity was a useful indicator of the performance of different batches of rennet casein in pilot-scale analogue cheese manufacture. More recently,

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400

Tough

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Low waterbinding capacity starch Medium waterbinding capacity starch High waterbinding capacity starch

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0 15

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Fig. 9.5 Water mobility as determined by NMR T2 relaxation time (left) and texture map as determined by torsion gelometry (right) for analogue cheeses containing different starches. (Adapted from Noronha et al., 2008e.)

Noronha et al . (2008a) used a combination of viscosity measurement, microscopy and low-field nuclear magnetic resonance (NMR) to study the hydration and subsequent emulsification occurring during analogue cheese manufacture. NMR is a phenomenon which occurs when nuclei of certain atoms are immersed in a static magnetic field and exposed to a second oscillating magnetic field. The most commonly measured nuclei are hydrogen 1 H and carbon 13 C. Noronha et al . (2008a) reported that initially casein absorbs water rapidly, after which protein–protein interactions occur to the detriment of protein–water interactions. However, after this stage a cohesive hydrated casein matrix was formed, which then allowed the emulsification of the fat phase into the cheese matrix. These researchers found 1 H NMR relaxometry useful in analysing the water and fat fractions of analogue cheese products. In heterogeneous systems, NMR relaxation times differ for lipids and water, and can also be used to distinguish between different states of water. Noronha et al . (2008e) reported that the spin-lattice relaxation time (T1 ) of water in analogue cheese was considerably lower than reported by Kuo et al . (2001) for natural Mozzarella cheese, indicating that water in analogue cheese is less mobile (i.e. more bound) than in natural Mozzarella. Noronha et al . (2008e) also added starches to selectively alter the mobility of water in analogue cheese, and the textural properties of the ensuing cheese were determined using torsion gelometry. Analogue matrices with high water mobility tended to have a soft texture and good meltability. However, cheeses in which the water was more tightly bound were brittle and non-melting (Fig. 9.5). Clearly, water mobility has a major influence on the functional attributes of analogue cheese.

9.5.2 Effect of compositional change on analogue cheese functionality Formulation has a major impact on the properties of analogue cheese. This section focuses on the effect of water, fat, protein and emulsifying salts on cheese functionality.

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Water A study by Marshall (1990) showed that moisture in cheese acted as a plasticiser, making the cheese more elastic and less likely to fracture. Recently, Hennelly et al . (2005) investigated the impact of increasing the moisture content of analogue cheeses from 46 to 54 g 100 g−1 on cheese functionality. Increasing the moisture content decreased cheese hardness and the rheological dynamic moduli of analogue cheese samples. The same authors proposed that the observed decreases in cheese hardness with increasing moisture levels were most likely due to increased hydration of the protein matrix, whereby increased hydration attenuated the protein–protein interactions, thus softening the matrix. Similar observations have been made by others on the effects of increasing moisture content on the hardness of natural Mozzarella cheeses (McMahon et al ., 1996; McMahon & Oberg, 1998) and model processed analogue cheeses (Pereira et al ., 2001). Increasing the ratio of water to protein also helps to increase the meltability of analogue cheeses, with the excess ‘unbound’ water facilitating cheese particles to flow when heated. Lee et al . (2004) and Dimitreli and Thomareis (2008) observed that increasing the moisture content of processed cheese spreads changed the rheological behaviour of the spreads from being solid-like to more liquid-like. Noronha et al . (2007) reported that increasing the moisture content of analogue cheese (containing a resistant starch) from 52 to 60 g 100 g−1 decreased the hardness and the melting point (G = G ) of the cheeses. Sensory panellists considered the lower moisture cheeses preferable; cheeses with 58 or 60 g moisture 100 g−1 were considered ‘sticky’, ‘clingy’, ‘soft’ and ‘unpleasant’. Fat The fat phase in cheese analogues can include a wide range of fats including butterfat and vegetable fats such as coconut, sesame, soybean, palm kernel, sunflower, canola (rapeseed), peanut, corn, safflower, cottonseed and olive oils, as well as hardened oils and blends (Caric & Kalab, 1993). Fat in analogue cheeses can have dual functionality depending on the intended temperature use. At lower temperatures, i.e. less than the melting point of the fat phase (<10◦ C), the fat acts as a rigid filler within the casein water matrix. At higher temperatures, i.e. temperatures greater than the melting point (>40◦ C), the liquid fat acts as a plasticiser and aids the flow of cheese (Zhou & Mulvaney, 1998). Vegetable fats are most commonly used in analogue cheese formulation because they are much cheaper than milk fats. Recently, Jana et al . (2005) examined the suitability of fats like soybean oil and hydrogenated vegetable oil (HVO) blend, corn oil and HVO blend, and HVO alone in the manufacture of Mozzarella cheese analogues. All the cheeses had similar texture profiles, organoleptic attributes, baking qualities and pizza-related characteristics, except for the cheese containing the HVO, which was harder and gummier than the other cheeses and was least preferred for pizza topping in terms of flavour and chewiness. Many researchers have shown the influence of fat distribution on cheese texture, although some of these findings are conflicting. Marshall (1990) proposed that the way fat is distributed contributes to the fracturability of analogue processed cheeses, by forming weak points, through which fractures propagate if sufficient strain is applied to the cheese. His findings were in agreement with previous work reported by Chen et al . (1979).

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Lobato-Calleros & Vernon-Carter (1998) also observed that small well-distributed fat globules caused ‘weak spots’ within the matrix. These authors suggested that fat interfered with the linkage formation between protein chains, decreasing the opportunity for protein–protein interactions, thus weakening the matrix. The weakening of the cheese matrix as influenced by fat distribution was also reported by Metzger & Mistry (1995) and Hassan & Frank (1997). While the above findings suggest that well-distributed fat globules contribute to a weakening of the cheese matrix, Lelievre et al . (1990) reported that smaller fat globules may result in less disruption of the casein matrix, contributing to a firmer protein structure. This is supported by work completed by Sharma & Dalgleish (1993), in which these authors suggested that smaller-sized globules are coated with caseins to stabilise the expanded fat globule surface area, with these stabilising proteins being available for interaction with each other (protein–protein) and with the protein matrix per se, which could increase the firmness of the cheese. The level of fat, or more particularly the fat to protein ratio, exerts a powerful influence on the functional properties of cheese analogues. Stampanoni & Noble (1991) showed that a higher fat content in cheeses results in softer, less springy and more cohesive analogue cheeses, possibly due to the fat droplets disrupting the continuity of the protein matrix. Recently, Dimitreli & Thomareis (2008) showed how increasing the fat content reduces elastic and viscous moduli, complex modulus and complex viscosity of spreadable processed cheese. These authors also observed that the cheeses containing higher levels of fat tended to melt more (longer flow) than cheeses of normal fat content, with these higher fat cheese samples exhibiting a more liquid-like behaviour. They attributed this softening to fat and its ability to act as a lubricant. The softening effect of fat on the texture of processed cheese has also been shown by other authors (Green et al ., 1986; Stampanoni & Noble, 1991; Dimitreli & Thomareis, 2007). Gwartney et al . (2002) reported that when the fat content of commercial natural and processed cheeses was reduced, all reduced-fat cheeses were harder, less melting and perceived to be waxier, chewier and stickier than cheeses containing higher levels of fat. Similarly, Hennelly et al . (2006) reported that the replacement of fat (up to 63% fat replacement) with a soluble dietary fibre increased the hardness of the cheese, although this effect was overcome by simultaneously increasing the moisture content. Noronha et al . (2007) formulated a fat-free analogue using a resistant starch to replace the fat. As the fat content was decreased from 10 to 0 g 100 g−1 , the cheeses became harder; this effect was only partly attributed to the reduction in fat as the concomitant increase in resistant starch would also have increased hardness. Protein The concentration and type of protein employed in formulation have a major influence on the physical properties of analogue cheese. Analogue cheese has been manufactured successfully using a range of protein types: rennet casein (Mounsey & O’Riordan, 1999; O’Malley et al ., 2000; Hennelly et al ., 2005, 2006; Montesinos et al ., 2006), acid casein (Savello et al ., 1989), caseinates (Vernon, 1972; Song & Park, 1986; Cavalier-Salou & Cheftel, 1991), whey protein (Mleko & Foegeding, 2000, 2001) and vegetable proteins (Yang & Taranto, 1982a,b; Pereira et al ., 1992). Increasing the proportion of casein in the cheese matrix has been reported to increase the inter-strand linkages, resulting in a matrix with greater elasticity (Ma et al ., 1997) that

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is more difficult to deform (de Jong 1976, 1978; Chen et al ., 1979; Prentice et al ., 1993; Fox et al ., 2000). Joshi et al . (2004) and Dimitreli & Thomareis (2007) both reported that increasing the protein content of processed cheese samples resulted in an increase in the magnitude of the storage and loss moduli of the cheeses. Generally, it has been found that substitution of rennet casein with whey proteins in analogue or processed cheese products results in reduced flowability, which makes these products more suitable for food applications where a high melt is not desirable (Zuber et al ., 1987; Savello et al ., 1989; Murphy, 1999). Gupta & Reuter (1992) ultrafiltrated whey to produce a concentrate with 20 g 100 g−1 whey proteins and 5.8 g 100 g−1 lactose, which was utilised as an ingredient to replace 20 g 100 g−1 of the cheese solids in a processed cheese formula. They determined that the addition of approximately 2.2 g 100 g−1 whey protein in the final processed cheese with an average moisture content of 45 g 100 g−1 did not adversely affect the quality of the product. Whey protein isolate (WPI) and whey protein polymers, produced by a single or double heating (80◦ C) process (with the latter, the first heating was at pH 8.0, followed by a second heating at pH 7.0), were used by Mleko & Foegeding (2000, 2001) to investigate the function of whey proteins as partial casein replacers in analogue cheeses. These studies showed that the fracture stress of the processed cheese analogue increased and meltability decreased with increasing levels of addition of WPI and whey protein polymers. Savello et al . (1989) and Gupta & Reuter (1992) also reported that processed cheese meltability decreased due to addition of WPI. Mleko & Foegeding (2000) suggested that the whey proteins interacted with the casein network as active filler, or that a mixed gel was formed, in either case strengthening and reinforcing the structure. In addition, Mleko & Foegeding (2001) also reported that analogue cheeses containing 13 g protein 100 g−1 from casein and 2 g 100 g−1 double-heated whey protein polymers had rheological properties similar to analogues containing 17 g protein 100 g−1 from casein. Some workers reported that analogue Mozzarella cheese containing soy protein (up to 25 g 100 g−1 ) exhibited textural characteristics in the solid state and stretching properties in the melted state that were comparable to those of natural Mozzarella cheese (Yang & Taranto, 1982a,b). It was also reported that heat-denatured soy proteins could be used to replace up to 60 g 100 g−1 of the caseinate in an analogue cheese without adversely affecting its melting characteristics (Lehnhardt et al ., 1984). In marked contrast to these findings, other authors have reported that soy proteins result in a softer, less cohesive and mealy analogue cheese compared with that of a control cheese based on casein (Lee & Marshall, 1981; Ahmed et al ., 1995). These discrepancies may have arisen due to differences in the functionalities of the proteins used. Emulsifying salts The effects of emulsifying salts on the properties of processed cheese are well reported in the literature (see also Chapter 4); however, their effects in analogue cheeses are less clearly understood (Caric et al ., 1985), with little literature available. As discussed previously, in order to utilise rennet casein in the manufacture of analogue cheese, emulsifying salts are needed to disrupt the calcium-mediated cross-bridges within the casein and thereby allow it to hydrate and adequately stabilise the fat phase of the

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cheese. While there is a range of emulsifying salts suitable for use in the manufacture of processed cheese (Caric & Kalab, 1993; Cavalier-Salou & Cheftel, 1991), the emulsifying salts used in the manufacture of rennet-based cheese analogues are largely, if not exclusively, sodium salts, and include sodium phosphates, sodium polyphosphates, trisodium citrate (TSC) and basic sodium aluminium phosphates. A study by Ennis et al . (2000) compared the effects of disodium phosphate (DSP), dipotassium orthophosphate (DPP) or diammonium orthophosphate (DAP) on the hydration characteristics of rennet casein in a dilute model system. The results showed that rennet casein exhibited similar hydration behaviour on dispersion in DPP solutions, producing rheological profiles very similar to those obtained in DSP, indicating that DPP could be a suitable alternative for DSP. However, the hydration behaviour of the DAP dispersion was markedly different to those of both DSP and DPP, with the liquid phase in the DAPbased solution appearing grey, with a white curd-like mass forming, suggesting that DAP was not a suitable alternative for DSP. The authors did acknowledge that their work only reflected the ability of these substitutes in a model system, and future work should perhaps be undertaken to address whether the results reported in their study are in agreement with a real analogue cheese system. Comparative studies in processed cheese products have shown that the potassium salts of orthophosphates, pyrophosphates and citrates yield products with similar textural properties to those made with the equivalent sodium salts at similar concentrations (Gupta et al ., 1984; Karahadian & Lindsay, 1984); however, the use of the potassium salts reduced the flowability slightly. While potassium emulsifying salts may have potential in the preparation of reduced-sodium processed and analogue cheeses, they are rarely used in practice as they impart a bitter taste to the finished product, which becomes more pronounced with storage (Templeton & Sommer, 1936); they are also more expensive than the sodium equivalents. While there is little literature available on varying the emulsifying salts type and/or concentration on the functionality of analogue cheeses per se, such variables have been examined in the context of processed cheese (Templeton & Sommer, 1936; Gupta et al ., 1984; Cavalier-Salou & Cheftel, 1991; Swenson et al ., 2000). In general, these studies showed that orthophosphates, citrates and sodium aluminium phosphates give relatively soft processed cheeses, which generally undergo slight oiling-off on heating and have desirable melting properties, i.e. good flowability and surface sheen. In contrast, pyrophosphates and polyphosphates generally give harder processed cheeses, showing little oiling-off on heating and have poor melting properties. Overall, the flowability of processed and analogue cheeses made with different emulsifying salts shows the following trend: sodium aluminium phosphate ≈ trisodium citrate (slightly) > disodium phosphate sodium tripolyphosphates ≈ tetrasodium pyrophosphates > higher-chain sodium polyphosphates. Generally, the opposite effect is observed for firmness (Guinee et al ., 2004). pH An appropriate pH value (∼8) during cheese processing is important as it affects protein conformation and hydration, solubility and calcium sequestration by the emulsifying salts and ultimately the degree of emulsification. It also affects the textural and melting properties

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of the final analogue cheese. There is limited work on the effect of pH on analogue cheese functionality per se; however, its effects on processed cheese are better understood. As early as 1932, the texture of processed cheese was reported to vary with the pH (Templeton & Sommer, 1932). In general, low-pH processed cheeses (<5.0) were dry and crumbly whereas high-pH (>6.0) processed cheeses were moist and elastic (Templeton & Sommer, 1932; Gupta et al ., 1984; Caric et al ., 1985; Shimp 1985). Lee and Klostermeyer (2001) also found that the processed cheese spread samples changed from a solid-like character to a liquid-like character with an increase in cheese pH. Stampanoni and Noble (1991) reported that decreasing the pH from 6.2 to 5.0 resulted in increased hardness and elasticity in analogue cheeses. Similarly, Noronha et al . (2008b) reported a decrease in analogue cheese hardness and cohesiveness when the pH was decreased from 6.0 to 5.5. This was attributed to a decrease in calcium-mediated protein interactions. The meltability of the cheese also decreased with decreasing pH. It was postulated that the pH-induced calcium solubilisation would decrease protein–protein interactions at room temperature, but the lower pH may have promoted the proportion of hydrophobic interactions at the higher temperature used to assess cheese melting.

9.6 Developments in analogue cheese 9.6.1 Protein replacement The high costs of casein and caseinates have forced processors to search for readily available low-cost substitutes to partially or totally replace these types of milk proteins in analogue cheeses. Plant-derived ingredients, such as soy protein isolates, cottonseed protein, peanut protein, wheat gluten, rice proteins, hydrocolloids, starches and mixtures thereof, have been used in the past as casein substitutes (Yang & Taranto, 1982a,b; Lee & Son, 1985; Zwiercan et al ., 1987; Nishiya et al ., 1989; Zallie & Chiu, 1989; Mounsey & O’Riordan, 1999, 2008a,b; Murphy, 1999). There are a number of patents describing the use of alternatives to replace casein and/or caseinate in analogue cheese. The work of Zwiercan et al . (1986, 1987) and Zallie & Chiu (1989) documented numerous caseinate replacers for use in analogue cheese, and disclosed the use of pre-gelatinised high amylose starches for partial or total replacement of caseinates. These patents conclude that total replacement of caseinate requires the use of pre-gelatinised high amylose starches, as these starches provide the texture and melt characteristics in cheese similar to those obtained using the caseinates. Yoder et al . (1996) disclosed the use of granular, hydroxypropylated, high amylose starch as a possible ingredient to replace all the caseinate in analogue cheese. According to the patent, gelatine and a gum, such as pectin or carrageenan, are also needed to improve the overall texture of the ‘cheese’. Although the above patents have approached either partial or total replacement of the caseinate fraction in analogue cheese as a cost-saving venture, these patents required that the starches used had extensive pretreatment processes, such as pre-gelatinisation or hydroxypropylation, which inevitably added to their purchase cost. Thus, even with all this work, there is still a need for a casein replacer that is low in cost. Within the last decade, Carpenter et al . (1998) and Duenas et al . (2007) have successfully used cheaper

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native granular starches to replace part of the caseinate fraction in analogue cheeses. These products are reported to be firm, providing good shreddability and melt, probably due to the large amounts of moisture present (up to 60 g 100 g−1 ) in these products. Murphy (1999) investigated the use of a number of protein alternatives – soy protein isolate, whey protein concentrate (WPC) with 75 g protein 100 g−1 , rice protein and wheat gluten – as partial replacers of rennet casein in analogue cheese. Replacement of up to 3 g 100 g−1 of the casein with the protein alternatives did not significantly affect the texture of cheeses; however, increasing casein replacement to 15 g 100 g−1 significantly decreased the meltability of cheeses, making these low-melt products ideal for deep-frying applications, but of limited use for most other applications. Furthermore, the same author concluded that cheeses containing rice protein best mimicked the melt and texture properties of rennet casein-based analogue cheeses, making this protein type a good possible alternative to casein at substitution levels of 1.25–3.75 g 100 g−1 . In another study by the same author, the effect of increasing the amounts of WPC and rice protein from 1.25 to 11.25 g 100 g−1 on the physical properties of analogue cheeses was also investigated. This study showed that increasing the concentration of either WPC or rice protein decreased the meltability and hardness of cheeses. Sensory panellists described these cheeses as acceptable but having a softer, crumblier mouth-feel than the full casein-based cheeses. This author concluded that rice protein was a more suitable casein replacer than WPC from both a cost and functionality perspective. The effectiveness of a number of native starches (3 g 100 g−1 ; maize, potato, waxymaize, wheat or rice) as possible casein replacer was investigated by Mounsey & O’Riordan (2001). One of the main findings from this study was that the amylose content of the starches used was important in determining the hardness properties of these cheeses, with high hardness values being associated with cheeses containing starches with higher levels of amylose. These authors concluded that rice starch appears to have the most potential as a partial casein substitute in analogue cheese, possibly because of its low water-holding capacity, which helped to yield a cheese product with good hardness and meltability. As the amylose content of starches proved to be important in determining whether starch was a good partial casein replacer, the same authors sought to assess whether varying the amylose content of rice starch would impact negatively on cheese functionality (Mounsey & O’Riordan, 2008a). Results from this study showed that replacement of casein with high amylose or chemically cross-linked rice starches strengthened the analogue cheese structure at the expense of melt properties. Of all the rice starch-containing products, the analogue cheese containing waxy rice starch most closely resembled the cheese containing no starch in terms of meltability. The authors attributed this similarity to the low amylose levels of this starch (∼2.5 g 100 g−1 ) and the fact that the fat globules were large and poorly emulsified. The use of different pre-gelatinised starches (maize, waxy-maize, wheat, potato and rice) as casein replacers in analogue cheese was investigated by Mounsey & O’Riordan (2008b). This study showed that the microstructure of cheeses containing all starch types contained poorly emulsified fat globules which resulted in a softer cheese texture; these cheeses also had poorer meltability than cheeses containing no starch. The authors ascribed these effects to the ability of the pre-gelatinised starches to compete with casein for water during the cooking stage, resulting in poorly hydrated casein with impaired emulsifying properties.

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9.6.2 Fat replacement Consumers are increasingly demanding reduced- and low-fat cheeses and, as a result, manufacturers are trying to replace fat with ingredients that mimic its properties. This is quite a challenge for low-fat cheese manufacturers, and there is much interest in the area; over 50 patents in the area of low-fat cheese have been issued worldwide over the past 20 years (Mistry, 2001). Fat substitutes (which possess the physical and functional properties of fat), such as sucrose polyesters, esterified propoxlated glycerol, dialkyl dihexadecylmalonate and many structured lipids, have been used as fat replacers by different food companies (Drake & Swanson, 1995). Fat mimictants (natural protein or carbohydrate derivatives), such as Dairy-Lo®, Simplesse® and Novagel®, have also been used (Drake & Swanson, 1995). These fat mimics have a polar nature, can bind more water, and improve the texture and yield of the cheese. Recently, researchers have found a way to possibly improve the nutritional status of analogue cheese by partially replacing the fat content with ingredients that provide certain health benefits, e.g. inulin and resistant starch (Hennelly et al ., 2006; Montesinos et al ., 2006). Hennelly et al . (2006) used inulin gels to partially replace the fat in analogue cheese. Although meltability was found to be unaffected by the inclusion of inulin, cheese hardness increased. The authors suggested increasing the moisture content to offset the hardness. They concluded that inulin, added as a 25 g 100 mL−1 aqueous gel, could be used to replace up to 63 g 100 g−1 of the fat in analogue cheese, without negatively impacting the melting properties. Montesinos et al . (2006) used resistant starch, such as Novelose 240® (RS2 - resistant granular) or Novelose 330® (RS3-resistant retrograded), to replace up to 50 g fat 100 g−1 in analogue cheese. Cheese hardness increased linearly with starch content. The dynamic rheological cross-over temperature (G = G ), an indicator of cheese meltability, was unaffected by Novelose 240®, but was increased by the inclusion of Novelose 330®. The authors concluded that over 50 g 100 g−1 of the fat content of analogue cheese could be successfully replaced with the resistant starches without impacting negatively on cheese meltability. In a recent study, Noronha et al . (2007) used resistant starch (Novelose 240®) to replace 90 g 100 g−1 of the fat in a typical analogue cheese, to yield a product with just 2 g fat 100 g−1 . The low-fat product was amenable to slicing and shredding, and had excellent meltability. Thus, the crucial role played by fat as a plasticiser in full-fat analogue cheese may be fulfilled by water in low-fat, high-moisture content products. Duggan et al . (2008) showed that in these low-fat analogue cheeses, the resistant starch does not compete with protein for water molecules. Rather, the starch entraps the water, and allows it to remain available for the plasticisation of the cheese. This enables the analogue cheese to maintain good functionality despite the very low fat levels.

9.6.3 Microwave expansion of analogue cheese Today’s consumers tend to eat on the move and seek snack foods that are not only convenient but also healthy. This trend has helped make microwaved snacks a popular option as they require minimal fat and are lower in fat than fried snacks (Ernoult et al . 2002). Recent research in our laboratory (O’Riordan et al ., 2008) has shown that it is possible to microwave heat an analogue cheese matrix, which expands to form an aerated crispy

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A microwave heated analogue cheese matrix to form aerated crispy snack.

snack (Fig. 9.6). The resultant product is high in both protein (∼40 g 100 g−1 ) and fibre (∼30 g 100 g−1 ) but low in fat (0–2 g 100 g−1 ), making it nutritionally superior to most snack foods currently on the market. By manipulating the composition of the analogue cheese in terms of protein, fibre, fat and water content, the degree of expansion in the microwave and ultimately the texture and particularly the crispiness of the final product can be controlled. The water content of the analogue cheese is a key parameter controlling the expansion. Water vapour acts as a plasticiser, and creates the pressure to induce expansion. On continued microwave heating, moisture is evaporated and the matrix sets, maintaining its expanded structure (Arimi et al ., 2008).

9.7 Future of analogue cheese The major role of analogue cheeses at present is undoubtedly in providing low-cost alternatives to natural Mozzarella for pizza manufacturers. Industry often sees these substitute products as being inferior to natural cheese. Because manufacturers of analogue cheese are less subject to compositional constraints than apply to producers of natural cheese, they are free to reformulate the product to confer novel desirable attributes that can improve the appeal of the product to consumers, for example the replacement of saturated fat with polyunsaturated fat, inclusion of prebiotic fibres and other functional nutraceutical ingredients. Analogue cheese is a versatile product, and there are opportunities to reposition the status of the analogue products from an ‘inferior’ product to a functional food with health benefits.

References Abou El Nour, A., Scheurer, G.J., Omar, M.M. & Buchheim, W. (1996) Physicochemical and rheological properties of block-type processed cheese analogue made from rennet casein and total milk protein. Milchwissenschaft , 51, 684–687.

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Ahmed, N.S., Hassan, F.A.M., Salama, F.M.M. & Enb, A.K.M. (1995) Utilization of plant proteins in manufacture of cheese analogs. Egyptian Journal of Food Science, 23, 37–45. Aimutis, W.R. (1995) Dairy protein usage in processed and imitation cheeses. Food Technology Europe, 2, 30–34. Arimi, J.M., Duggan E., O’Riordan, E.D., O’Sullivan, M. & Lyng, J.G. (2008) Microwave expansion of imitation cheese containing resistant starch. Journal of Food Engineering, 88, 254–262. Berger, W., Klostermeyer, H., Merkenich, K. & Uhlmann, G. (1998) Processed Cheese Manufacture: JOHA Guide, B.K. Guilini Chemie, Ladenburg, Germany. Caric, M. & Kalab, M. (1993) Processed cheese products. Cheese: Chemistry, Physics and Microbiology (ed. P.F. Fox), 2nd edn, vol. 2, pp. 467–505, Chapman & Hall, London. Caric, M., Gantar, M. & Kalab, M. (1985) Effects of emulsifying agents on the microstructure and other characteristics of process cheese: a review. Food Microstructure, 4, 297–312. Carpenter, R.N., Finnie, K.J. & Olsen, R.L. (1998) Imitation cheese composition and products containing starch. United States Patent Application 5 807 601. Cavalier-Salou, C. & Cheftel, J.C. (1991) Emulsifying salts influence on characteristics of cheese analogs from calcium caseinate. Journal of Food Science, 56, 1542–1547. Cavalier-Salou, C., Queguiner, C. & Cheftel, J.C. (1990) Preparation of cheese analogues by extrusion cooking. Processing and Quality of Foods (eds P. Zeuthen, J.C. Cheftel, C. Eriksson, R. Gormley & P. Linko), vol. 1, pp. 373–383, Elsevier Applied Science Publishers, London. Chen, S.L., Wan, P.J., Lusas, E.W. & Rhee, K.C., (1979) Utilization of peanut protein and oil in cheese analogs. Food Technology, 33(7), 88–93. Codex Alimentarius Commission (1995) Codex General Standard for Food Additives (192–195), Food and Agriculture Organization of the United Nations, Rome. Dairy Facts (2006) International Dairy Foods Association, Washington, DC. Dimitreli, G. & Thomareis, A.S. (2007) Texture evaluation of block-type processed cheese as a function of chemical composition and in relation to its apparent viscosity. Journal of Food Engineering, 79, 1364–1373. Dimitreli, G. & Thomareis, A.S. (2008) Effect of chemical composition on the linear viscoelastic properties of spreadable-type processed cheese. Journal of Food Engineering, 84, 368–374. Drake, M.A. & Swanson, B.G. (1995) Reduced and low fat cheese technology: a review. Trends in Food Science and Technology, 6, 366–369. Duenas, J.M.E., Rodriguez, G.A. & Morfin, O.I. (2007) Dairy product and process. Worldwide Patent Application WO2007049981. Duggan, E., Noronha, N., O’Riordan, E.D. & O’Sullivan, M. (2008) Effect of resistant starch on the water binding properties of imitation cheese. Journal of Food Engineering, 84, 108–115. Ennis, M.P. & Mulvihill, D.M. (1997) Cheese analogues. 5th Cheese Symposium (eds T.M. Cogan, P.F. Fox & R.P. Ross), pp. 1–14, Organised by the Dairy Products Research Centre, Moorepark, Fermoy, Co. Cork and the Faculty of Food Science, University College Cork, 11–13th March, 1997, Teagsac, Dublin. Ennis, M.P. & Mulvihill, D.M. (1999) Compositional characteristics of rennet caseins and hydration characteristics of the caseins in a model system as indicators of performance in Mozzarella cheese analogue manufacture. Food Hydrocolloids, 13, 325–337. Ennis, M.P., O’Sullivan, M.M. & Mulvihill, D.M. (1998) The hydration behaviour of rennet casein in calcium chelating salt solution as determined using a rheological approach. Food Hydrocolloids, 12, 451–457. Ennis, M.P., O’Dowd, J.J., Thornton, A. & Mulvihill, D.M. (2000) The effect of varying the calcium sequestering salt cation on the hydration behaviour of rennet caseins in a simple model system. International Journal of Dairy Technology, 53, 41–44. Ernoult, V., Moraru, C.I. & Kokini, J.L. (2002) Influence of fat on glassy amylopectin extrudates by microwave heating. Cereal Chemistry, 79, 265–273. Eymery, O. & Pangborn, R.M. (1988) Influence of fat, citric acid and sodium chloride on texture and taste of a cheese analog. Science des Aliments, 8, 15–32.

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FDA (2003) Code of Federal Regulations, Title 21 Regulation 101: Food Labelling, US Government Printing Office via GPO Access. www.cfsan.fda.gov/∼lrd/FCF101.html Fox, P.F., Guinee, T.P., Cogan, T.M. & McSweeney, P.L.H. (2000) Processed cheese and substitute or imitation cheese. Fundamentals of Cheese Science, pp. 429–451, Aspen Publishers, Gaithersburg. Glenn, T.A., Daubert, C.R. & Farkas, B.E. (2003) A statistical analysis of creaming variables impacting process cheese melt quality. Journal of Food Quality, 26, 299–321. Green, M.L., Langley, K.R., Marshall, R.J., Brooker, B.E., Willis, A. & Vincent, J.F.V. (1986) Mechanical properties of cheese, cheese analogues and proteins gels in relation to composition and microstructure, Food Microstructure, 5, 169–180. Guinee, T.P. (2002) The functionality of cheese as an ingredient: a review. Australian Journal of Dairy Technology, 57, 79–91. Guinee, T.P., Caric, M. & Kalab, M (2004) Pasteurized processed cheese and substitute/imitation cheese products. Cheese: Chemistry, Physics and Microbiology (eds P.F. Fox, P.L.H. McSweeney, T.M. Cogan & T.P. Guinee), 3rd edn, vol. 2, pp. 349–394, Elsevier Academic Press, London. Gupta, V.K. & Reuter, H. (1992) Processed cheese foods with added whey-protein concentrates. Lait , 72, 201–212. Gupta, V.K., Karahadian, C. & Lindsay, R.C. (1984) Effect of emulsifier salts on textural and flavour properties of processed cheeses. Journal of Dairy Science, 67, 764–778. Gwartney, E., Foegeding, E.A. & Larick, D.K. (2002) The texture of commercial full-fat and reducedfat cheese. Journal of Food Science, 67, 812–816. Hassan, A.N. & Frank, J.F. (1997) Modification of microstructure and texture of rennet curd by using a capsule-forming non-ropy lactic culture. Journal of Dairy Research, 64, 115–121. Hennelly, P.J., Dunne, P.G., O’Riordan, E.D. & O’Sullivan, M. (2005) Increasing the moisture content of imitation cheese: effects on texture, rheology and microstructure. European Food Research and Technology, 220, 415–420. Hennelly, P.J., Dunne, P.G., O’Riordan, E.D. & O’Sullivan, M. (2006) Textural, rheological and microstructural properties of imitation cheese containing inulin. Journal of Food Engineering, 75, 388–395. Hill, A.R. & Smith, A.K. (1992) Texture and ultrastructure of process cheese spreads made from heat precipitated why proteins. Milchwissenscaft , 47, 69–74. Hoffmann, W., Hinrichs, M., Johannsen, N., Scheurer, G. & Maurer-Rothmann, A. (2005) Use of different acid caseins in analogue low-moisture Mozzarella. Milchwissenschaft , 60, 395–398. Hokes, J.C. (1982) An analysis of the functional properties of calcium caseinate as related to imitation processed cheese. PhD thesis, Ohio State University, Columbus. Jana, A.H. & Upaghyay, K.G. (2001) Development of a formulation and process standardization for Mozzarella cheese analogue. Indian Journal of Dairy Science, 54, 1–7. Jana, A.H., Upaghyay, K.G. & Solanky, M.J. (2005) Quality of Mozzarella cheese analogue made using different fats. Journal of Food Science and Technology Mysore, 42, 497–500. de Jong, L. (1976) Protein breakdown in soft cheese and its relation to consistency. 1. Proteolysis and consistency of ‘Noorhollandse Meshanger’ cheese. Netherlands Milk Dairy Journal , 30, 242–253. de Jong, L. (1978) The influence of moisture content on the consistency and protein breakdown of cheese. Netherlands Milk Dairy Journal , 32, 1–14. Joshi, N.S., Jhala, R.P., Muthukumarappan, K., Acharya, M.R. & Mistry, V.V. (2004) Textural and rheological properties of processed cheese. International Journal of Food Properties, 7, 519–530. Karahadian, C. & Lindsay, R.C. (1984) Flavor and textural properties of reduced sodium process American cheeses. Journal of Dairy Science, 67, 1892–1904. Kilcawley, K.N, Wilkinson, M.G. & Fox, P.F (1998) Enzyme modified cheese. International Dairy Journal , 8, 1–10. Kim, S.Y., Park, P.S.W. & Rhee, K. C. (1992) Textural properties of cheese analogs containing proteolytic enzyme-modified soy protein isolates. Journal of the American Oil Chemists’ Society, 69, 755–759. Kratochvil, J.F. (1987) Imitation cheese products. United States Patent Application 4 684 533.

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Kuo, M.I., Gunasekaran, S., Johnson, M. & Chen, C. (2001) Nuclear magnetic resonance study of water mobility in pasta filata and non-pasta filata Mozzarella. Journal of Dairy Science, 84, 1950–1958. Lawrence, R.C., Creamer, L.K. & Gilles, J. (1987) Texture development during cheese ripening. Journal of Dairy Science, 70, 1748–1760. Lee, C.H. & Son, H.S. (1985) The textural properties of imitation cheese by response surface analysis. Korean Journal of Food Science and Technology, 17, 361–370. Lee, S.K. & Klostermeyer, H. (2001) The effect of pH on the rheological properties of reduced-fat model processed cheese spreads. Lebensmittel-Wissenschaft und Technologie, 43, 288–292. Lee, S.K., Anema, K. & Klostermeyer, H. (2004) The influence of moisture content on the rheological properties of processed cheese spreads. International Journal of Food Science and Technology, 39, 763–771. Lee, Y.H. & Marshall, R.T. (1981) Microstructure and texture of processed cheese, milk curd and caseinate curds containing native or boiled soy proteins. Journal of Dairy Science, 64, 2311–2317. Lehnhardt, W.F., Streaty, C.E., Yackel, W.C., Yang, H.S. & Tang, D.K. (1984) Soy isolate suitable for use in imitation cheese. United States Patent Application 4 435 438. Lelievre, J., Shaker, R.R. & Taylor, M.W. (1990) The role of homogenization in the manufacture of Halloumi and Mozzarella cheese from recombined milk. Journal of the Society of Dairy Technology, 43, 21–24. Lobato-Calleros, C. & Vernon-Carter, E.J. (1998) Microstructure and texture of cheese analogs containing different types of fat. Journal of Texture Studies, 29, 569–586. Lobato-Calleros, C., Vernon-Carter, E.J., Guerrero-Legarreta, I., Soriano-Santos, J. & EscalonaBeundia, H. (1997) Use of fat blends in cheese analogs: influence on sensory and instrumental textural characteristics. Journal of Texture Studies, 28, 619–632. Ma, L., Drake, M.A., Barbosa-Canovas, G.V. & Swanson, B.G. (1997) Rheology of full-fat and low-fat Cheddar cheeses as related to type of fat mimetic. Journal of Food Science, 62, 748–752. Marshall, R.J. (1990) Composition, structure, rheological properties and sensory texture of processed cheese analogues. Journal of the Science of Food and Agriculture, 50, 237–252. McMahon, D.J. & Oberg, C.J. (1998) Influence of fat, moisture and salt on functional properties of mozzarella cheese. Australian Journal of Dairy Technology, 53, 98–101. McMahon, D.J., Alleyne, M.C., Fife, R.L. & Oberg, C.J. (1996) Use of fat replacers in low fat Mozzarella cheese. Journal of Dairy Science, 79, 1911–1921. Metzger, L.E. & Mistry, V.V. (1995) A new approach using homogenization of cream in the manufacture of reduced fat cheddar cheese. 2. Microstructure, fat globule distribution and free oil. Journal of Dairy Science, 78, 1883–1895. Meyer, A. (1973) Processed Cheese Manufacture, Food Trade Press, London. Mistry, V.V. (2001) Low fat cheese technology. International Dairy Journal , 11, 413–422. Mleko, S. & Foegeding, E.A. (2000) Physical properties of rennet casein gels and processed cheese analogs containing whey proteins. Milchwissenschaft , 55, 513–516. Mleko, S. & Foegeding, E.A. (2001) Incorporation of polymerized whey proteins into processed cheese analogs. Milchwissenschaft , 56, 612–615. Montesinos, C., Cottell, D.C., O’Riordan, E.D. & O’Sullivan, M. (2006) Partial replacement of fat by functional fibre in imitation cheese: effects on rheology and microstructure. International Dairy Journal , 16, 910–919. Morr, C.V. (1982) Functional properties of milk proteins and their use as food ingredients. Developments in Dairy Chemistry (ed. P.F. Fox), vol. 1, pp. 375–399, Applied Science Publishers, London. Mounsey, J.S. (2000) Characteristics of imitation cheese containing starch. PhD thesis, University College Dublin, National University of Ireland, Dublin. Mounsey, J.S. & O’Riordan, E.D. (1999) Empirical and dynamic rheological data correlation to characterize melt characteristics of imitation cheese. Journal of Food Science, 64, 701–703. Mounsey, J.S. & O’Riordan, E.D. (2001) Characteristics of imitation cheese containing native starches. Journal of Food Science, 66, 586–591.

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10 Quality Control in Processed Cheese Manufacture A.Y. Tamime, D.D. Muir, M. Wszolek, J. Domagala, ¨ L. Metzger, W. Kneifel, K. Durrschmid, K.J. Domig, A. Hill, A. Smith, T.P. Guinee and M.A.E. Auty

10.1 Introduction Tamime & Robinson (2007) reported that ‘the quality of any food product can be defined against a wide range of criteria, including, for example the chemical, physical, microbiological and nutritional characteristics, or simply in relation to its overall appeal to potential consumers. As a result, quality has to be judged by a range of tests with varying degrees of objectivity, and yet all of them can be useful in ensuring that a product: • • • •

is safe for human consumption with respect to both chemical or microbial contamination; conforms to any regulations enshrined in law, or advisory/statutory requirements laid down by public health or other local authorities/agencies; is capable of achieving a specified shelf-life without spoilage; has as high an organoleptic standard as can be achieved within the existing constraints of manufacture or marketing.’

Nevertheless, the main goal of any food processing industry is to supply clients and consumers with products of good healthy quality that have attractive sensory features. This goal can be reached by implementation of the good manufacturing practice (GMP) and the hazard analysis critical control points (HACCP) system. The international legislative activity is performed by Codex Alimentarius Commission, which is established by the Food and Agriculture Organisation (FAO) and the World Health Organisation (WHO) of the United Nations. One of the main aims of this Commission is the protection of consumer’s health by ensuring that good practice is applied during all stages of food production and distribution. GMP combines production procedures with quality control and supervision, which guarantees that manufactured products meet all quality specifications. GMP is a set of principles of safe food product manufacturing. It consists of full descriptions of all basic specifications about the main constructional, technical, technological, equipment, operational and manufacturing requirements necessary for the production of good-quality food. In addition, good hygienic practice (GHP) plays the main role in this system in ensuring good product Processed Cheese and Analogues, First Edition. Edited by A.Y. Tamime. © 2011 Blackwell Publishing Ltd. Published 2011 by Blackwell Publishing Ltd.

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quality including all the hygiene requirements of the manufacturing process. The combined rules of GHP and GMP are mostly about the staff, organisation of processing plants, plants’ grounds and surroundings, buildings and workrooms, manufacturing process, production hygiene, quality control, labelling, storage and dispatch, training, documentation, autocontrol and validation (Sperber et al., 1998; Arvanitoyannis et al. 2005). These principles are established by the official government bodies in many countries, such as the Food and Drug Administration (FDA) in the USA or other professional organisations, for example the Institute of Food Science and Technology (IFST) and Food Standards Agency in the UK. In addition, the starting point has to be the current legislative controls in the country in question. In the UK, the Statutory Instruments (SIs) for England, Scotland, Wales and Northern Ireland are known as SIs, SSIs, WSIs and SRNIs, respectively, including different Acts. For example, a dairy product has to conform to the following. • •

• •

•

Food Safety Act (Anonymous, 1990; FSA, 2009). The Food Hygiene Regulations (SI, 2000a, 2005, 2006, 2010; SSI, 2006; WSI, 2006, 2007a; SRNI, 2006; see also EU, 2004a,b, 2007a, 2009a). Note that the new English and Scottish hygiene regulations are implementing regulations of all the new European Union (EU) hygiene ‘package’ of regulations, which is in the form of Regulations that are binding in their entirety on all Member States without the need for incorporation into the laws of the Member States, as would have been the case with the earlier hygiene directives. The SSIs, WSIs and SRNIs may slightly differ from the SIs, but they come into operation at different times in Scotland, Wales and Northern Ireland. Miscellaneous Food Additives Regulations (SI, 1995a, 1997, 1999a, 2001a,b). Colours in Foods Regulations (SI, 1995b, 2000b, 2001c; WSI, 2000a, 2001, 2007b; EU, 2007b). Note that in 2006, the European Commission adopted a package of legislative proposals that aimed to upgrade rules for additives, flavourings and to introduce harmonised legislation on food enzymes. It also proposed the creation of a common authorisation procedure for food additives, flavourings and enzymes, based on scientific opinions from the European Food Safety Authority (EFSA). Following inputs from the European Parliament, four new regulations were adopted: (a) on common authorisation procedures for food additives (EU, 2008a), (b) on enzymes (EU, 2008b), (c) on food additives (EU, 2008c), and (d) on flavourings and certain food ingredients with flavouring properties for use in foods (EU, 2008d). In Article 30, Regulation 1333/2008 (EU, 2008c) refers to the creation of ‘Community lists of food additives’, but Article 31, headed Transitional Measures, states that ‘until the establishment of Community lists of food additives, the Annexes to Directives 94/35, 94/36 and 95/2 (EU, 1994a, 1994b, 1995, respectively) shall be amended, where necessary, by measures designed to amend non-essential elements of those Directives, adopted by the Commission in accordance with the regulatory procedure with scrutiny referred to in Article 28 (4)’. In Article 34, entitled Transitional Provisions, it is indicated that the provisions in certain articles and annexes of the three Directives referred to in Article 31, Food Additives already permitted therein shall continue to apply until transfer to this regulation has been completed. The above will in due course be incorporated in the UK legislation. Food Labelling Regulations (SI, 1996, 1998, 1999b,c, 2000c,d, 2003, 2004, 2008; WSI, 2000b, 2008; EU, 2009b).

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• •

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Weights and Measures Act (Anonymous, 1985). Weights and Measures Regulations (SI, 1987).

At the end of January 2008, the European Commission adopted a proposal for a draft regulation on the provision of food information to consumers. This proposal marked the first step in a process intended to negotiate new regulations to replace the current rules on food labelling. The proposal is claimed to simplify the existing legislation. It applies to all stages of the food chain, where the activities of food businesses concern the provision of food information to consumers. At present, the majority of the provisions laid down in Directive 2000/13/EC date back to 1978 (EU, 2000), and the Directive has been amended a number of times in recent years and therefore needs to be updated. While the original introduction of this piece of legislation was to provide rules for the labelling of foods as an aid to free circulation of food in the Community, over time the protection of consumers’ rights has emerged as a specific objective of European Community law. The new proposed Regulation aims to consolidate and update both the general labelling and nutritional labelling legislation. It aims to simplify the existing rules and to protect consumers’ interests by providing accurate, necessary information required to enable them to make informed choices about the food they purchase. At this time they are being considered by the European Parliament and the report of the Parliamentary Rapporteur has tabled 143 amendments. Among these are that on the front of a product should be mandatory nutritional labelling for eight nutrients and energy, with seven others labelled on the back. Other amendments seek more rigorous country of origin provisions and traceability of foods. Adoption of the revised text is likely during 2009 (EU, 2009c). In theory, neither the food product nor the packaging material(s) used should contravene any statutory regulation, and the manufacturer must then be able to demonstrate that compliance with the regulation is being achieved in practice. However, while it is anticipated that any manufacturer, for example, of processed cheese can produce a faulty batch of product, what the same manufacturer must be able to show is that the fault arose despite ‘due diligence’ being shown by all concerned. This blanket responsibility informs the HACCP concept and its basic principles, and these are now widely accepted as the basis for responsible food operations in a factory.

10.2 HACCP 10.2.1 Background HACCP is a scientifically based and internationally recognised process control system for the identification of hazards, i.e. critical control points (CCPs), for preventive measures and for implementation of a monitoring system. Compared with GHP and GMP, HACCP includes detailed analysis of the potential hazards of the whole manufacturing process, storage, transport and distribution. Areas at high risk of undesirable changes or events are particularly well monitored. While the system is being implemented, particular concern should be paid to eliminating any situations and events that could contaminate the product

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with any foreign substances, chemicals or pathogenic microorganisms, and corrective procedures should be established. The HACCP system identifies seven aspects of production that merit constant attention, and these aspects are enshrined in seven principles. The system is a 12-step process incorporating the seven HACCP principles. • • • • • •

• • •

• •

•

Assemble a multidisciplinary, facility-based HACCP team. Describe the final product and the method of its distribution, e.g. formulation and processing requirements. Identify the intended use of the food and the targeted consumer group or groups. Develop a flow diagram that describes the production and distribution process. Verify the flow diagram in the place of production. Implement principle 1: conduct a hazard analysis by preparing a list of steps in the production process where significant chemical and microbial hazards occur and begin to describe preventive measures. Apply principle 2: identify the CCPs in the production process, usually via decision-tree analysis. Employ principle 3: establish critical limits for triggering the implementation of preventive measures associated with each CCP that has been identified. Implement principle 4: establish a monitoring system for each CCP and organise the procedures for using the results of the monitoring programme; the goal is to use results of the monitoring programme to adjust the procedures and maintain control of the production process. Organise principle 5: create corrective action to be initiated when the monitoring programme indicates a deviation from an established critical limit. Maintain principle 6: establish effective procedures for record keeping that document implementation of the HACCP system (e.g. the HACCP plan, records obtained during production). Institute principle 7: establish procedures for verification that the HACCP system is working correctly, e.g. internal and external verification; periodic revalidation of the system (Corlett, 1992; Pierson & Corlett, 1992; WHO, 1993, 2003; Mortimore & Wallace, 1994; FAO, 1995, 1997, 1998; Loken, 1995; Cullor, 1997; Ingham et al., 1997; Kvenberg, 1998; NACMCF, 1998; Mauropoulos & Arvanitoyannis, 1999; Sandrou & Arvanitoyannis, 2000a,b; FAO/WHO, 2001; Heggum, 2001; Mayes & Mortimore, 2001; Mortimore, 2001; Jervis, 2002; Jones, 2003; Surak, 2003a,b; EU, 2004a,b, 2005a; Arvanitoyannis, 2009; Sayler, 2009).

10.2.2 Implementation (theoretical approach) Definition, types and sources of hazards According to the Codex Alimentarius Commission, the definition of ‘hazard’ is a biological, chemical or physical factor in the food or food processing conditions which is potentially health-threatening (FAO, 1997, 2001). During the manufacture of dairy products including processed cheese and cheese analogues, the final products are exposed to various factors

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that may make them a risk for consumer health. These factors are known as ‘health hazards’ and are divided into three groups: microbiological, chemical and physical. According to the International Commission on Microbiological Specifications for Foods (ICMSF), a microbiological hazard is defined as an unacceptable contamination of the food with microorganisms, their proliferation or occurrence potentially causing decay of the food, production and presence of toxins, enzymes, biogenic amines or products of metabolism. Among microbiological hazards, it is possible to distinguish between bacterial, viral, mould and parasitic types of hazards. The main sources of microbiological hazards are humans (staff, visitors), animals (rodents, flying or crawling insects, birds) and surroundings (tools, work clothes, waste bins, flowers, drains, toilets, etc.). Microbiological hazards may also result from primary and auxiliary materials used for the production of processed cheese (natural cheeses, butter, dairy powders, flavouring and colouring additives, stabilisers, etc.), machines and devices (i.e. result of insufficient cleaning and disinfection) and auxiliary materials (packaging). However, chemical hazards are divided into groups according to their origin. • •

• • •

Natural chemical food contamination, i.e. biogenic amines, mould toxins, mollusc toxins. Substances of environmental origin (heavy metals, polychlorinated biphenyls, chloroorganic or polynuclear insecticides, aromatic hydrocarbons, nitrates, nitrites, nitrous oxides, sulphur oxides, radioactive substances), mineral fertilisers, pesticides, substances used in the production and feed fortification, veterinary medicines and other substances used in animal husbandry. Food supplements, for example preservatives (nitrates), flavour additives (sodium glutamate), nutritive supplements (nisin), colouring matter. Substances migrating from equipment, tools and packaging machines (grease, cleaners, disinfectants, tiles, paints). Substances added to disguise the raw product quality. Physical hazard may be divided as follows:

• • • •

naturally occurring in food (seeds, fish bones, bones, peels); originating from the factory (strings, screws); resulting from technical errors (pebbles, metal pieces, bones); caused by the consumer’s actions (pieces of the packaging left after improper opening).

Penetration of foreign elements into the food often directly correlates with the concurrent microbiological hazard. It means that sources of physical hazard are the same as those of microbiological hazard (humans, insects, rodents, birds, machines, devices, tools, raw materials). Factors determining the implementation of HACCP These are sociological, technical, economical and organisational, but the most important aspects for a successful implementation of HACCP are:

250

• • • • • •

Processed Cheese and Analogues

manufacturing conditions (location and surroundings of the processing plant, technology, production rooms and social background, raw materials, machines and devices); qualifications of the HACCP team and the staff; uncomplicated system organisation; easily accessible and understandable system of documentation; building of staff awareness about their impact on the final product health safety (Fig. 10.1); regular and effective staff training (Khandke & Mayes, 1998; Kumar & Budin, 2006).

Hygienic requirements with regards to buildings Walls, floors and ceilings in all rooms should be made of materials resistant to mechanical damage, water, and cleaning solutions such as detergents and disinfectants. Any crevices, splinters and other damaged surfaces are unacceptable. Rounded (not square) wall-to-wall, wall-to-floor and wall-to-ceiling junctions help to prevent mechanical damage, and make cleaning processes easier as well. Walls should be covered with material resistant to all cleaning and disinfectant materials. Floors in the production area should be uniform, smooth and inclined towards any drain holes to prevent water collecting on the surface. Antifungal prevention by the use of proper ventilation is necessary together with the use of anti-mould treatments and sufficient thermal insulation of the building and systems to prevent water vapour condensation. Ventilation should not allow any contamination of the ventilated space with dust, fines and especially microbiological contamination. Fan ventilation is recommended or a combination of fan and suction with a minimum of 15% of air suction in the system. The air, which is pumped into the system, should be cleaned with appropriate mechanical and antibacterial filters and heated to the correct temperature. Air cleanness in

Fig. 10.1 Wash hand basins located before entering the production area. (Reproduced with courtesy of SEROTP Ltd., Tychy, Poland.)

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the production area is particularly important during the manufacture of processed cheese and analogues when using traditional methods (i.e. batch process or cooking kettles) and not the continuous method of processing (IDF, 1997a; Cichosz, 2000). Hygienic zones According to the recommendations by the International Dairy Federation (IDF), the production area should be divided into special zones depending on the hazard of the raw products, materials, intermediates and product contamination (IDF, 1997a, 2004i). This division depends on the product type, machines and devices used in automation of the procedure and staff awareness. The main aim of this division is maximum prevention of microbial cross-contamination by: • • • • •

limited free movements of the staff during manufacture; limited inter-zone staff movements; hygienic barriers setting (Fig. 10.2); setting the technical barriers between zones in the form of the walls, locks, staff rooms; visual marking of each zone.

Zone division should be planned to reflect the various stages of manufacture of the product. The staff working in a zone should not have access to the staff rooms in other zones without special hygienic precautions. The final zone pattern in the processing plant should be verified by HACCP analysis. Three hazard zones can be distinguished: (a) green, which are the work zones without risk of contamination of the final products or the heattreated intermediates or zones where contamination is of minor concern; (b) yellow, which are zones of limited risk for the product caused by the contaminated surroundings; and

Fig. 10.2 Poland.)

Disposable protective cloths for visitors. (Reproduced with courtesy of SEROTP Ltd., Tychy,

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Processed Cheese and Analogues

Fig. 10.3 Visual marking of the yellow and green hygienic zones in the factory. (Reproduced with courtesy of SEROTP Ltd., Tychy, Poland.) (See Plate 10.1 for colour figure.)

(c) red zones, which have the highest hygienic requirements. Most CCPs (according to the HACCP system) appear during the processing stage and in red zone areas. The green and yellow zones are often positioned at the borders, with high-hazard zones acting as hygienic barriers. However, in all the zones good hygienic practice should be maintained. In processed cheese and analogues factories, the products are manufactured from pre-processed ingredients, and it is safe to recommend that the production area(s) should be divided into only two hygienic zones: the green and the yellow one (IDF, 1997a; Fig. 10.3). Pest control Good production practices include the prevention and control of pests such as rodents, insects and birds. They may be a cause of various dangerous infections and physical hazards (faeces, hair, insect body parts, and feathers) in the product. Pest prevention and control should correlate with monitoring of their presence. Negative results of monitoring prove that preventive actions are effective. Of the rodents, rats and mice are the most hazardous species for plants involved in manufacturing processed cheese and analogues. To protect buildings and rooms from these rodents, all holes, gaps and slits in foundations, walls, doors, windows, ceilings and floors should be eliminated. All ventilation openings and drain ends should be protected with metal grates. Rodents should also be controlled in all the surroundings. Mice can be controlled with mechanical and chemical methods. Mechanical methods are based on the use of various traps, whilst chemical methods use food poisons containing rodenticides. To control rodents in food processing plants, rodenticides containing cholecalciferol (vitamin D3 ) should be used. These chemical preparations should be applied mostly in production areas

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Fig. 10.4 Poland.)

253

Feeding tray for trapping rats and mice. (Reproduced with courtesy of SEROTP Ltd., Tychy,

and their surrounding areas, e.g. storage rooms, to eliminate the hazard of contamination by dead animals. Rodenticides should be placed in special poison stations (Fig. 10.4), and each station should be numbered. It is recommended that these stations are placed every 20–50 m inside and every 10–15 m outside the building’s walls. Stations should be placed appropriately to decrease or eliminate the risk of access by other animals or unauthorised people. The most hazardous insects in food processing areas are running insects, such as German cockroach (Blatella germanica) (Fig. 10.5a), oriental cockroach (Blatta orientalis), ants (Monomorium pharaonis), and flying insects such as the housefly (Musca domestica), lesser housefly (Fannia canicularis), common green bottle fly (Lucilia sericata), cheese fly (Piophila casei ) and others. All buildings and production rooms should be protected from insect penetration from outside. Windows, ventilation inlet, drainage and other openings must be netted. Physical means of insect control include sticky traps placed in places at risk of running insects (i.e. around washbasins; Fig. 10.5b) and electrically operated insecticidal lamps (Fig. 10.6).

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Processed Cheese and Analogues

(a)

(b)

Fig. 10.5 Detector trapping for (a) cockroaches and (b) sticky traps. (Reproduced with courtesy of SEROTP Ltd., Tychy, Poland.)

Fig. 10.6 Poland.)

Electrical (insecto-cutor) lamp to kill flies. (Reproduced with courtesy of SEROTP Ltd., Tychy,

Protection of processing areas from birds is based on preventing them from entering the rooms using automatically closing doors, nets in the windows and ventilation openings, and preventing them from sitting close to the windows with slanted outer windowsills and ledges. Because of the hazard of food contamination with glass pieces in the processing areas, all light fittings should be protected. Cleaning and disinfection procedures Correct production hygiene strongly depends on properly performed cleaning and disinfection procedures of the rooms and processing equipment. Cleaning efficacy depends on factors, such as:

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• • • • •

255

type of contamination and circumstance of its appearance; porosity and type of cleaned surface; water hardness; type of detergents and sterilisers; proper cleaning procedures.

Basic parameters of the cleaning process include time and temperature, type of detergent and steriliser, and mechanical impact (Cichosz, 2000; Tamime, 2008). Each room and equipment/processing line should have cleaning programmes installed, including documented record sheets. After cleaning the equipment and production areas, the efficiency of cleaning should be examined every day with adenosine triphosphate (ATP) tests (i.e. swabs of individual equipment, for example, using HY-LiTE®). The cleanness of storage areas should be examined once weekly.

10.2.3 Implementation (practical approach) A flow chart illustrating the manufacturing stages of processed cheese is shown in Fig. 10.7, and the identification of CCPs can be completed only after the full HACCP system is detailed in relation to a specific processing line. Identified CCPs may be described as follows. • • • • •

Type of hazard, stage of the production process and CCP number. Critical limit and how it is to be controlled. Type of analytical test, frequency of its application, who is responsible and relevant documentations (forms to fill). Corrective actions to follow in case of deviations. Frequency of calibration or control procedures for measurement equipment, with detailed descriptions of materials and size of analysed samples in case of metal detectors, X-rays and test documentation.

During the manufacture of processed cheese, heat treatment during melting and cooking of the natural cheeses is a CCP. Heat treatment aims both to control the microbiological safety and to achieve specific physical properties of the product, especially its structure and texture. Temperature parameters used during the heat treatment stage depend on the type of processed cheese produced (e.g. blocks, sliced or cheese spread), and are also influenced by the type of equipment used. For example, when using periodic melting in batch cookers during the manufacture of processed cheese spread, the target temperature is usually 90 ± 1◦ C (i.e. CCP1; Fig. 10.8), albeit an actual temperature of 80 ± 1◦ C in the ‘creaming’ tank when using a continuous cooking process (i.e. CCP1; Fig. 10.9). Lower temperatures are used during the manufacture of block-type processed cheese. Alternatively, ultra-high temperature is used for the production of sterilised processed cheese and, according to the GMP code, it is recommended that the melted cheese (i.e. with no added flavouring ingredients) is heated at 135 ± 1◦ C for 5 s; however, the residence time is extended to 8 s when the product is flavoured with ham (ASSIFONTE, 2007). Incidentally,

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Processed Cheese and Analogues

Start

Natural cheeses

Storage

De-rinding

Cleaning

Rind, foil

Cutting

Fat (milk fat, butter, vegetable oils)

Shredding

Protein (milk powder, whey powder, casein)

Preparation of the blend

Emulsifiers

Mixing Miscellaneous additives

Melting

Metal cans

CCP1

CCP1

Filling metal cans

Filling (blocks, slices, spread, sauces, tubs)

Sterilisation

Carton boxes

CCP2 CP1

Cooling

Cardboard boxes

Storage

Dispatch

Fig. 10.7 Generalised scheme illustrating the manufacturing stages for the production of processed cheese and a typical HACCP system.

Quality Control in Processed Cheese Manufacture

Fig. 10.8 Poland.)

257

Critical control point (CCP1) in batch cooker. (Reproduced with courtesy of SEROTP Ltd., Tychy,

Fig. 10.9 Critical control point (CCP1) in a creaming tank when using a continuous cooking method. (Reproduced with courtesy of SEROTP Ltd., Tychy, Poland.)

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Processed Cheese and Analogues

the temperature of heat treatment used during the manufacture of processed cheese should be recorded continuously using a computerised system. The second identified CCP is usually filtering the hot melted cheese before packaging to protect the final product from external or foreign matter contamination. The diameter of holes in the filtering sieve is <5 mm in cheeses without added flavour ingredients, and larger than 5 mm if the product contains added herbs or pieces of ham. Monitoring this CCP involves checking the sieve(s) before starting the filtering stage, and inspection of the sieve(s) at the end of the process to check if anything was retained in them. If a sieve is damaged the whole batch of product should be discarded. The use of metal and X-ray detectors is recommended only if the product is not packed in aluminium foil or metal cans. Some manufacturers set a control point (CP) at the buffer tank before packing the product (Fig. 10.10) to ensure the temperature of cheese does not drop below 75 ± 1◦ C; this is a safeguard to inhibit the growth of microorganisms originating from the packaging material as contaminant(s).

Fig. 10.10 Control point (CP) in at the buffer tank before packaging the processed cheese. (Reproduced with courtesy of SEROTP Ltd., Tychy, Poland.)

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10.2.4 Verification of HACCP HACCP system verification is intended to prove that in practice the system works according to the HACCP plan, and that this plan effectively ensures that the food is of good and healthy quality. Verification of an HACCP system can be realised by using the following methods: • • • •

internal audit, performed by HACCP team members; external audit, performed by independent organisation; tests (mostly microbiological) of the randomly taken samples; surveys among the system’s users. The verification procedures are:

• • • • • • • • •

overview and revision of HACCP plan; overview of all records documenting HACCP functioning; revision of CCPs set; overview and analysis of the most frequent irregularities of the production process; revision of the critical limits against their adequacy for health quality of the final product; visual observation to determine whether CCPs are under control; random sampling and sample analyses; evaluation of the efficacy of the corrective actions set for the occurring deviations; overview of the HACCP plan modifications. Verification of an HACCP system should be performed for the following aspects:

• • • • •

preventively at regular time intervals; every time new information about the health safety of any food product or its component appears; when the food product was the cause of food poisoning; when the critical limits were not observed; after HACCP plan modifications to check whether the changes undertaken are correct and effective. However, verification of HACCP should also be performed in any case of:

• • • • • • • •

change of the product or the introduction of a new product; any change in the process parameters; installation or modification of new equipment; change of packaging material or dealing with the final product; change in the way the client deals with the product; change of instruction to consumers on the package regarding the preparation of the product; change of awareness about potential pathogens or environmental contamination; targeting the product to an ‘increased risk’ population (Ingham et al., 1997, 1998; Khandke & Mayes, 1998; Sperber et al., 1998; Koło˙zyn-Krajewska, 2003).

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10.2.5 Monitoring the processing plant Reception and storage of raw material While developing and implementing HACCP, the specifications of the raw materials should be included on the label if they were not beforehand. For example, there should be a requirement that hard cheeses, Quark, milk powder and whey powder used for processed cheesemaking should be free of bacterial spores 0.1 g−1 . In addition, hard cheeses graded as second class should not have any spores 0.01 g−1 . Other processing plants require a maximum most probable number (MPN) of spores allowed as <5 g−1 . However, it is recommended that the proportion of ‘low’ graded cheeses in the formulation of the blend should be relatively small. Raw materials used in the manufacture of processed cheese and analogues should originate only from well-established suppliers, and have all necessary certificates. Examination of all raw materials at reception at the factory is based on sensory, physicochemical and microbiological tests. Raw material contaminated with moulds or bacterial spores should not be accepted. The main parameter of materials controlled in warehouses is temperature (≤8◦ C), and sometimes the humidity level in the store is controlled. In the case of materials stored in moisture-impermeable packaging, humidity control is not so important, and the installation of air ‘screens’ ensures that the temperature in the storage area is maintained at the desired level. Warehouses should have proper anti-rodent protection, and should be kept clean. Stored raw materials should be properly marked (e.g. ‘allowed for production’, ‘tested’, ‘questionable’, ‘rejected’; Fig. 10.11), and sorted according to the production date declared by the producers. It is necessary to control stock levels to prevent raw material storage longer than 3 months.

Fig. 10.11 Some examples of properly marked raw materials intended for processed cheesemaking. (Reproduced with courtesy of SEROTP Ltd., Tychy, Poland.)

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Preparation of main ingredients This includes careful removal of the cheese, for example from the packaging material, and removal from the product of any contaminated part, such as mould growth or bacterial spoilage. Processes of washing and disinfection of all devices used in raw material preparation (knives, guillotines, transporter bins) should be performed correctly. A physical hazard at this production stage is penetration by the metal parts of the machines and other devices of parts of the packaging material. The possibility of contamination of the raw material with chemical hazards, such as detergents and disinfectants as a result of poor after-washing rinsing, should be monitored and not overlooked. Composition of the cheese mix for processing While preparing the formulation of a balanced mix, attention should be paid to component quality, especially the degree of ripeness of the cheeses, including the final calculations of fat and moisture contents of the final product. Devices used for preparing the mix should be carefully washed, rinsed and disinfected to eliminate any possibility of contamination of the mix with various contaminants including residues of detergents and disinfectants. Milling/shredding/grinding of natural cheeses Hazards at his stage of processing include the possibility of some metal parts of the grinder being left in the product or residues of detergents and sanitation agents (Fig. 10.12). To control the milling grade, 5 mm metal sieves are used, and this particular hazard should be visually monitored by assessing the assembly of the grinding unit (knives, sieves) in any of the milling devices used (i.e. pressure grinders, blenders). Preparation of additives Natural flavouring ingredients, such as ham, salami, smoked chicken, salmon, tomatoes, paprika, dill, caraway, celery, pepper, marjoram, garlic, mushrooms, sunflower, peanuts, caraway seed, leeks and mustard, are added to enrich the product with specific flavours. Attention should be paid to quality, freshness (shelf-life), amount to be used and to the possibility of contamination with physical contaminants such as bones, stones and peels. Sometimes the properties and components of the additives can be used to control the quality of processed cheese. A good example is the pungency of Jalapeno pepper caused by capsaicin (Marshall & Doperalski, 1981). Cooking (mixing and blending) Procedures of washing, disinfecting and rinsing should be controlled to eliminate the possibility that these cleaning compounds remain on the surfaces of the processing equipment (see IDF, 2004i). Mixing devices and seals should be controlled to eliminate physical contamination of mixing units with fragments. During cooking/melting of the cheese blend, the main parameter to be monitored is temperature, which in the creaming tank should not be lower than 90◦ C (batch cooker) or 80◦ C (continuous process). In a continuous processing

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Processed Cheese and Analogues

Fig. 10.12 Schematic illustration of milling/shredding/grinding of natural cheese. courtesy of SEROTP Ltd., Tychy, Poland.)

(Reproduced with

line (Fig. 10.13), a special cheese mass filter is installed after the heat treatment stage, where it is controlled, but it is not considered a CCP (Figs 10.14 and 10.15). If direct steam injection is used to heat/melt the cheese blend, the steam should be of food-grade quality. Re-work cheese or cheese from opened packages and all other additives added after processing should be under special quality control. The quality of the processed cheese mass should be evaluated directly after the end of processing; the product mass should be shining and of semi-fluid consistency, and homogeneous without any visible sign of unprocessed material(s). On the surface of processed cheese thin creamy peel should form (Cichosz, 2000). Homogenisation (optional) Microbiological hazards at this stage of processing include secondary contamination as a result of leakage at the piston rings of the homogeniser or of poor cleaning and disinfection of the equipment, especially if the homogenisation is performed downstream. Physical hazard contamination could be associated with metal fragments from the homogeniser, whilst chemical hazards are mainly residues of detergents and disinfectants as a result of

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(a)

263

(b)

Fig. 10.13 (a) Melted cheese continuous heating equipment and (b) the head of the heating unit. (Reproduced with courtesy of SEROTP Ltd., Tychy, Poland.)

Fig. 10.14 Open filter of the cheese mass. (Reproduced with courtesy of SEROTP Ltd., Tychy, Poland.)

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Fig. 10.15

Fine mesh filter screen. (Reproduced with courtesy of SEROTP Ltd., Tychy, Poland.)

careless or poor final rinsing. These hazards can be prevented by (a) proper maintenance of the homogeniser, and (b) controlling the efficiency of cleaning and disinfection of the equipment using microbiological swabs. Packaging Processed cheese should be packed at a temperature of 75◦ C or above, which prevents the development of any potential microbiological contaminants, i.e. from the air or packaging material. Microbiological hazards at this stage of processing may be caused by secondary contamination, for example from the environment, and filtered air should be used to operate different parts of the packaging. Packaging materials should be sterilised and microbiologically controlled to prevent the presence of yeasts and moulds. Physical hazards in processed cheese at this stage of production are the result of fragments from the packaging materials used (e.g. foil, glue, labels, cardboard, clips) or metal fragments from the packaging machine. The CCP of the packing process depends on the packaging machine(s) used, and metal sieves (e.g. 5.2-mm diameter holes; large pieces of flavouring additives in the product eliminate the possibility of using small perforations) are fitted at the outlet of the filling nozzle of the packaging machine. However, chemical hazards are

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Fig. 10.16 Cooling of multi-pack processed cheeses. (Reproduced with courtesy of SEROTP Ltd., Tychy, Poland.)

similar to those mentioned earlier, and the product could be contaminated with residues of detergents and disinfectants. Cooling area Control at this stage of processing is mostly limited to monitoring the temperature as the product is being cooled (usually to 10◦ C); this includes monitoring the airflow in the cooling chamber. The rate of cooling of the processed cheese affects the rheological properties of the final product (Piska & Stetina, 2004) (Fig. 10.16). In addition, control of cooling chambers, such as cleanness and appropriate pest control, should not be overlooked. Storage and dispatch In product storage rooms, temperature (≤10◦ C) and air relative humidity (85%) should be controlled. As in the cooling rooms, the product store should be kept clean and free from pests. Quality control of final product Each batch of processed cheese is sampled for chemical analysis (i.e. water, fat and NaCl contents), pH measurement, bacteriological examination, rheological measurements and sensory evaluation. The International Standards Organisation (ISO) method and the IDF methods (IDF, 1992, 1995, 2004h, 2008d) of sampling are used to sample the product and raw ingredients for analysis. Moreover, the net weight of the product is assessed, together with packaging and labelling quality. Sensory evaluation includes profiling the colour, structure, consistency, taste and flavour of the product (see section 10.8; IDF,

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1997b). Periodically (once every 6 months), microbiological examination for the presence of Salmonella spp. and staphylococcal enterotoxin (analytical reference method: European Screening Method of the Community Reference Laboratories for Milk; Hennekinne et al., 2003) should be carried out. These analytical measures are criteria for product safety. Process hygiene is controlled by confirming that there is no Escherichia coli present during the manufacturing process when the count is expected to be highest (EU, 2005b; see also section 10.5). In arbitration cases, such as after starting a new manufacturing process and/or after changing the processing equipment, and at the request of government agencies, additional tests for the presence of harmful metals (lead, copper, zinc, cadmium, mercury and arsenic) and phosphate have to be made. Each batch of processed cheese that complies with the norm used can obtain the quality certificate (see Appendix).

10.3 Examination of raw materials Processed cheese is obtained by mixing natural cheeses with salts and water under the influence of heat and mixing, whereas analogue cheeses are produced with partial or whole replacement of natural cheeses by milk or other proteins (Gustaw & Mleko 2007; Kapoor et al., 2007). Typical ingredients that can be used during the manufacture of processed cheese include natural cheeses (hard cheese, Quark, sheep’s milk cheese), dairy powders (whole or skimmed milk, buttermilk, whey, whey protein concentrates, rennet and acid casein and caseinates), butter, natural flavouring ingredients, emulsifying salts, NaCl, water and salty whey from Cheddar cheesemaking. The extent of any chemical analysis will depend on the scale of operation, but may include as a minimum some of the tests shown in Table 10.1. Polysaccharides can be used during the manufacture of processed cheese to improve the mouth-feel, flavour, texture and shelf-life of the product, and to reduce the cost of production (Gupta & Reuter, 1992; Lee & Klostermeyer, 2001; Kapoor & Metzger, 2004). Typical ingredients and types of analogue cheese are (a) non-dairy (soya oil, soya protein, artificial flavour), (b) part-dairy (casein and/or caseinates, soya oil, enzyme-modified cheese and/or flavour), and (c) all-dairy (casein and/or caseinates, butteroil, enzymemodified cheese, natural cheeses); salt, colouring matter, stabilisers and emulsifying salts are used in all types of analogue cheeses (Varnam & Sutherland, 1994; Bachmann, 2001). In some instances, polysaccharides (e.g. xanthan gum κ-carrageenan, locust bean gum and their mixtures) are used in the manufacture of analogue cheeses (Gustaw & Mleko, 2007). Rennet casein is often used as the main source of protein in the production of analogue cheese (Ennis et al., 1998) but, recently, acid casein has been used (Glibowski et al., 2002). Whey protein and whey protein polymers are often used in the production of processed cheese and analogues (Mleko & Foegeding, 2000, 2001).

10.3.1 Natural cheeses High-quality processed cheese can be produced only from high-quality raw materials. Thus, natural cheeses used for processing should be of as excellent a quality as those for direct

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Table 10.1 Some International Dairy Federation (IDF) tests that may be applied to different dairy ingredients used in the production of processed cheese including the final product.

a

Product

Examination

Reference

Butter

Fat, solid-not fat (SNF), moisture, acidity, salt

IDF (2001a,b, 2002a, 2003a,b, 2004c,d,k,l,m,n, 2006e,f, 2008b)

Butteroil

Fat, moisture

IDF (1964a, 2002a, 2003b, 2004d, 2006e,f, 2008b)

Cream

Fat, moisture

IDF (1987b, 2002a, 2004d, 2006e,f, 2008b)

Casein and caseinates

Protein, lactose, fat, moisture, calcium, sodium, potassium, magnesium, ‘fixed’ ash, free acidity, ash

IDF (1979, 2002c,d, 2004g,j, 2006c,e,f, 2007a,d, 2008e,f,g)

Dairy powders

Titratable acidity, fat, lactose, protein, moisture, lactic acid, calcium, sodium, potassium, magnesium

IDF (1981a,b, 1987a, 2002b,c,d, 2004e, 2005a, 2006e,f, 2007a, 2008a,b)

Processed cheese

Ash, phosphorus, fat, lactose, protein, total solids, citric acid, sodium chloride, calcium, sodium, potassium, magnesium, natamycina , nitratea , aflatoxina

IDF (1964b, 1987c, 1997c, 2002b,c,d, 2004a,b, 2005f, 2006a,d,e,f, 2007a,b,c, 2008b,c,h,i,j), ISO (2005f, 2007b,c)

Tests to be performed on natural cheeses to detect such residues.

consumption. However, cheeses with minor defects, such as some mould growth on the surface, discoloration, open texture, deformed shape and products with limited shelf-life, can also be used for processing provided that they are free from off-flavours. The use of cheeses with butyric acid fermentation can cause problems in processed cheese, as these bacteria may survive the heat treatment of the cheese blend, and can cause fermentation in the product (Anonymous, 2003). In addition, it is recommended that natural cheeses intended for processing should be of moderate ripeness, i.e. contain 20–30 mg 100 g−1 of nitrogen in the form of soluble nitrogen. Appropriate selection of natural cheese is important for achieving a product with the desired chemical and functional characteristics. The important physicochemical characteristics of a natural cheese that influence the functional properties of processed cheese include type, flavour, pH, calcium content, consistency, maturity, and age or amount of intact casein micelles present in natural cheeses (Piska & Stetina, 2004; Kapoor et al., 2007). Cheeses which are blown, over-matured, bitter, soapy, of unclean taste or with other defects that cannot be removed during processing should not be used in production. Blown cheeses, which are caused by butyric acid fermentation bacteria and which cannot be inactivated during processing, can cause defects in processed cheese. Defects in structure or consistency, mechanical damage and sour flavour are not major issues warranting rejection of the cheese during the manufacture of processed cheese. The use of mouldy cheeses may cause the occurrence of toxins, such as aflatoxin, sterigmatocystin or ochratoxin, in processed cheese. Matured cheeses contain significant amounts of amines because of favourable conditions and because of microorganisms performing aminoacidic decarboxylation. Amines can be produced by Propionibacterium spp., Micrococcus luteus, Clostridium perfringens, Clostridium butyricum and, most of all, by enterococci, which may be present

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in natural cheeses. In general, cheese with microbiological defects, particularly the presence of dangerous microorganisms such as pathogens, spore-formers and gas-producing bacteria (El Sayed, 1996; Cichosz, 2000), should not be used to make processed cheese. Furthermore, approved cheeses for processing have been tested in-house for (a) sensory evaluation (appearance, consistency, taste and flavour; the degree of cheese maturation is assessed organoleptically and according to the production date), (b) physicochemical analysis, such as water and fat content, and pH level, and (c) microbiological examination, including anaerobic spore-forming bacteria assay. According to Su & Ingham (2000), the presence of more than 5 spores L−1 of milk may cause late blowing of the cheese, and yield more than 1.4 spores g−1 of natural cheese. In many countries, the common practice by processed cheese manufacturers is to demand from natural cheese producers that the product is free from spore-formers. This can be achieved using different treatments of the cheese milk, such as microfiltration and twostage bactofugation (Anonymous, 2003). The spore count in natural cheese should be taken into account to predict the MPN of spores in processed cheese. To limit the possibility of spore development in processed cheese, it is recommended that very old matured cheeses are not used because the spore population increases; additives with high lactose content also can stimulate the growth of spore-forming bacteria.

10.3.2 Butter and fat of plant origin Dairy and non-dairy fatty products are used to standardise the fat content of processed cheese and analogues, and they must be of good quality without any flavour defects. These raw materials are allowed to be used during the manufacture of processed cheese and analogues, and their application in most countries is governed by regulation (see Chapter 2). Organoleptic evaluation of these raw materials and determination of the moisture content are important during formulation of the cheese blend prior to processing.

10.3.3 Dairy powders Powders, such as whole milk, skimmed milk, buttermilk, whey, whey concentrates, whey isolates casein and caseinates, are widely used in the formulation of the cheese blend, and their acceptability for production of processed cheese is based on the following criteria: (a) supplier’s certificates, (b) organoleptic evaluation, and (c) microbiological analyses, including assay of spores content and the presence of sulphite-reducing bacteria.

10.3.4 Natural flavouring ingredients These ingredients may be a potential source of contamination by bacterial spores and mechanical fragments, such as animal and fish bones, stones and fruit peels. Ingredients of plant origin may cause chemical contamination with residues of pesticides or herbicides, and for this reason all ingredients used must be certified by the supplier to be free from these chemical compounds. In addition, the flavouring ingredients are tested for their water content (i.e. to ensure proper balance of the cheese blend) and microbiological quality, particularly for the presence of moulds and spore-forming bacteria.

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10.3.5 Emulsifying salts Appropriate choice of these salts ensures the production of good processed cheese without any undesirable features at a detectable level. For example, the IDF method (IDF, 2006b) can be used to calculate the amount of added citrate emulsifying agents and acidifiers (i.e. for pH control/adjustment level) expressed as citric acid. In particular, the selection of emulsifying salts is influenced by the pH of the product. For example, if the pH is >6.0, it is easier to process, but this affects the cheese flavour negatively because of fatty acid reactions, and the shelf-life of the product could be reduced because it promotes the growth of harmful bacteria in processed cheese (Cichosz, 2000). The pH level of the emulsifying salts is tested in 10 g 100 g−1 solution, and in some instances certain blends of emulsifying salts are used to adjust the pH level in the cheese blend.

10.3.6 Miscellaneous additives Salt, water, nisin, pigments, colouring matter and artificial flavours are widely used in processed cheesemaking. Non-dairy components used in mixes during the manufacture of analogue cheeses must be sterile and of good quality; the organoleptic features (taste and flavour) should mimic the original, and must be certified by suppliers.

10.3.7 Water/steam Water/steam used in the production of processed cheese should comply with requirements for potable water as described in various countries relating to the quality of water intended for human consumption and national law regulations (EU, 1980, 1998; SI, 2000e,f, 2001d,e, 2007a,b; WSI 2000c; WHO, 2004, 2008; ISI, 2007). In addition, water vapour in contact with food and ice water used for food cooling must be produced from good potable water. Non-processing water should be used in a separate flow system, and the pipeline should be clearly marked or identified. Sources and water installations should be protected from contamination, with the protective zones setting according to water regulations. Water used in production should be tested monthly by the supplier’s laboratory for the presence of coliform bacteria, yeasts and moulds. Once every year, the water should be tested by the government department, for example the Sanitary and Epidemiological Station in Poland, for physicochemical analysis and bacteriological quality. All components of the cheese blend should fulfil valid quality requirements described in the standards and quality specifications of the country where it is produced. The list of permitted additives of chemicals, flavours and preservatives should be approved for use in the food industry according to the appropriate national laws (Cichosz, 2000).

10.3.8 Sampling for quality appraisal of the retail product Every batch of processed cheese should be separated and identified with an appropriate label showing the production date, and a sample is taken for organoleptic, chemical and microbiological analyses. The protocols of sampling each batch of the product are established

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by international standards organisations (IDF, 1992, 1995, 2004h, 2008d; ICMSF, 2006) but, in every case, it is essential that the sample truly reflects the quality of the bulk (i.e. raw materials and product). Equally important is that the samples are (a) collected in a manner that avoids contamination (Mostert & Joost, 2002), (b) handled correctly en route to the laboratory (e.g. for microbiological examination, the sample is held at <5◦ C), and (c) that the initial preparation of any subsamples is completed in accordance with standard procedures with respect to microbiological examination (Harrigan & McCance, 1976; Harrigan & Park, 1991; APHA, 2004; ICMSF, 2006). Although it is advisable to insist that the raw materials used in processed cheesemaking meet agreed specifications, or to monitor standards of plant hygiene, it is the end-product that must pass the final test. Does it meet the specified legal requirements in the countries where it is produced and marketed, and is the quality of processed cheese acceptable to the consumer? It is evident that in every country the imposition of chemical compositional standards for processed cheese aims to encourage the maintenance of quality but, for the most part, the nature of the product in terms of consistency and related features ensures that the proposed standards are met with little difficulty. Nevertheless, analysis of the end-product is an essential feature of quality control, because problems in manufacture are almost certain to manifest themselves as faults in the product. Consequently, the main aims for examinations at this stage are: • • •

to protect the consumer from poor-quality products or, in extreme cases, products that might constitute a health hazard; to protect the manufacturer from the inconvenience and expense of a barrage of returned goods; to assist in the smooth operation of a plant by identifying variations in product quality at an early stage, so that any necessary corrective actions can be taken before the onset of serious problems (Tamime & Robinson, 2007).

The appraisal of product quality has therefore become a vital function of factory operation, and the gamut of examinations that may be performed can be considered under the headings that follow.

10.4 Analysis of chemical composition The crucial factor in processed cheese production is the proper choice of raw materials and melting salts. Thorough knowledge of the composition of the materials is necessary, and gross compositional analysis of processed cheese (fat – dairy or plant origin, moisture, protein, pH and salt) is determined according to the methods published by the IDF, Association of Official Analytical Chemists (AOAC, 2007) and ISO (see Table 10.1). However, many countries have legal standards covering the composition of processed cheese, and a selection of some existing proposals is detailed in Chapter 2. The requirements for fat and moisture content are stipulated in relation to the type of processed cheese, i.e. block, slices, spread or sauces. In reality, the moisture content, including the level of protein, emulsifying salt used and processing conditions can influence the rheological characteristic(s) and can have a major impact on the sensory attributes of the product. However, determination

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of flavour substances in processed cheese is optional, and GuoNong et al. (2007) suggested that the flavour substances of the product could be profiled using solid-phase micro extraction (SPEM) gas chromatography and mass spectrometry.

10.5 Microbiological quality and safety of the product 10.5.1 Introduction and microbiological techniques For any food-borne microorganism, the range of analytical methods available seems almost as diverse as the number of food microbiologists. However, the dairy industry is fortunate in having standardised microbiological methods through the work of two international organisations, the ISO and IDF, and Table 10.2 summarises the analytical methods used to examine the raw material used in the manufacture of processed cheese and analogues including the final products.

10.5.2 Microbiological safety of the product The reviews by Glass & Doyle (2005) and Kapoor & Metzger (2008) reported that the microbiology and safety of processed cheese necessitates particular attention. The microbiological safety concerns of the product are governed by many factors, including (a) the undesirable microbial load of ‘natural’ cheeses used during the manufacture of processed cheese, (b) various formulations employed, and (c) physicochemical factors that help to control the proliferation of pathogenic microorganisms in the product. However, a generalised scheme regarding the multitude of factors that influences the microbiological quality of processed cheese and analogues is shown in Fig. 10.17. In general, processed cheese products have excellent historical safety (Glass & Doyle, 2005), and good hygienic quality as these products tend to be less susceptible to microbial spoilage (Warburton et al., 1986; Glass et al., 1998; Muir et al., 1999). According to Meyer (1973), defective packaging and storage conditions of processed cheese can lead to mould growth in the product, whilst the fault could be controlled by adding mould inhibitors, such as sorbates and propionates, to the cheese blend. However, only a few outbreaks have been reported, which were associated with cheese products of high pH or high water activity, highlighting the importance of tailored formulation(s), packaging and storage for processed cheese products. Critical and well-known spoilage microorganisms, such as pathogenic spore-formers (Clostridium spp., Bacillus spp.) and post-heat treatment pathogenic contaminants (Listeria monocytogenes, Salmonella spp., Staphylococcus aureus and Escherichia coli 0157:H7), can lead to microbiological safety concerns in processed cheese products (Glass & Doyle, 2005). The genus Clostridium has been identified as the most common microorganism associated with spoilage of processed cheese (Kautter et al., 1979, Sinha & Sinha, 1988). However, very few outbreaks of botulism from the consumption of canned processed cheese products have been reported (Glass & Doyle, 2005). The products associated with these outbreaks had high water activity (aw ∼0.96–0.97) and also high pH levels (∼5.7 to 5.8); under these conditions, the microbial contaminant promoted the production of toxins

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Table 10.2 International microbiological standard methods published by the International Dairy Federation (IDF) and International Standards Organisation (ISO) for the microbiological analysis of different dairy and other ingredients used in the production of processed cheese including the final product. Product

Examination of test organism

Reference

Part 1: General requirements, guidance and quality control Microbiology of food and animal feeding stuffs

General requirements and guidance for microbiological examinations

ISO (2007a)

Preparation of test samples, initial suspension and decimal dilutions for microbiological examination

ISO (1999a)

Guidelines for the estimation of measurement uncertainty for quantitative determinations

ISO (2006a, 2009a)

Protocol for the validation of alternative methods

ISO (2003a)

Preparation of test samples, initial suspension and ISO (2010a) decimal dilutions for microbiological examination – Part 5: Specific rules for the preparation of milk and milk products Milk and milk products

Guidance on sampling

ISO (2008c), IDF (2008k)

Quality control in microbiological laboratories

ISO (2005a,b), IDF (2001e, 2005b,c)

Part 2: Hygiene-, spoilage- and starter culture-related methods Microbiology of food and animal feeding stuffs

Enumeration of microorganisms (colony count technique ISO (2003b) at 30◦ C) Enumeration of yeasts and moulds (colony count technique in products with water activity >0.95 and ≤0.95)

ISO (2008a,b)

Enumeration of psychrotrophic microorganisms

ISO (2001a,b)

Enumeration of mesophilic lactic acid bacteria (colony count technique at 30◦ C)

ISO (1998a)

Milk and milk products

Enumeration of yeasts and/or moulds (colony count technique at 25◦ C)

ISO (2004a), IDF (2004f)

Count of lipolytic organisms

IDF (1966)

Milk

Enumeration of microorganisms (plate loop technique at ISO (2004b), IDF (2004o) 30◦ C) Estimation and enumeration of psychrotrophic microorganisms (colony count technique at 21◦ C and 6.5◦ C)

ISO (2004c, 2005c), IDF (2004p, 2005d)

Butter, fermented milk and fresh cheese

Enumeration of contaminating microorganisms (colony count technique at 30◦ C)

ISO (2002a), IDF (2002e)

Milk, milk products and mesophilic starter cultures

Enumeration of citrate fermenting lactic acid bacteria: colony count technique at 25◦ C

ISO (2006b), IDF (2006g)

Yoghurt

Enumeration of characteristic microorganisms: colony count technique at 37◦ C

ISO (2003c), IDF (2003c)

Identification of characteristic microorganisms (Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus)

ISO (2003d), IDF (2003c)

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Table 10.2 (Continued) Product

Examination of test organism

Reference

Milk products

Enumeration of presumptive Lactobacillus acidophilus on a selective medium: colony count technique at 37◦ C

ISO (2006c), IDF (2006h)

Determination of the acidification activity of dairy cultures by continuous pH measurement (CpH)

ISO (2009b), IDF (2009a)

Bacterial starter culture – standard of identity

ISO (2010c), IDF (2010b)

Fermented milk products

Part 3: Potential pathogens and pathogenic microorganisms Microbiology of food and animal feeding stuffs

Enumeration of coagulase-positive Staphylococcus aureus and other species (techniques using Baird-Parker agar medium, rabbit plasma fibrinogen agar medium and most probable number, MPN)

ISO (1999b,c, 2003e,f,g) (testing for staphylococci toxin see Hennekinne et al., 2003)

Enumeration of presumptive Bacillus cereus (colony count at 30◦ C and MPN techniques)

ISO (2004d, 2006e)

Enumeration of β-glucuronidase positive Escherichia coli (colony-count technique at 44◦ C using membranes and 5-bromo-4-chloro-3-indolyl-β-d-glucuronide)

ISO (2001b,c)

Detection and enumeration of coliforms (MPN technique)

ISO (2006f)

Enumeration of coliforms (colony count technique)

ISO (2006g)

Detection and enumeration of Enterobacteriaceae (MPN with pre-enrichment and colony count techniques)

ISO (2004e,f)

Detection and enumeration methods of Listeria monocytogenes

ISO (1996, 1998b, 2004g,h)

Detection of Salmonella spp.

ISO (2002b, 2004i)

Detection of Escherichia coli 0157

ISO (2001e)

Detection of presumptive pathogenic Yersinia enterocolitica

ISO (2003h)

Enumeration of Clostridium perfringens (colony count technique)

ISO (2004j)

Enumeration of sulphite-reducing bacteria growing under anaerobic conditions

ISO (2003i)

Detection and enumeration of Campylobacter spp.

ISO (2006i,j)

Milk and milk-based products

Detection of thermonuclease produced by coagulase-positive staphylococci

ISO (2006d), IDF (2006i)

Milk and milk products

Enumeration of presumptive Escherichia coli (MPN and colony count techniques)

ISO (2005d,e), IDF (2005e,f)

Detection of Salmonella spp.

ISO (2001d), IDF (2001c)

Detection of Enterobacter sakazakii

ISO (2006h), IDF (2006j) (continued)

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Table 10.2

(Continued)

Product

Examination of test organism

Reference

Part 4: Examples for recently published standards or standards under revision or amalgamation Microbiology of food and animal feeding stuffs

Detection of Cronobacter spp. (E. sakazakii )

New draft standard based on ISO (2006h), IDF (2006j)

Enumeration of psychrotrophic microorganisms (colony count at 6.5◦ C)

Amalgamation of ISO (2001b, 2005c), IDF (2005d)

Dried milk

Enumeration of the spores of thermophilic bacteria

ISO (2009d), IDF (2009c)

Milk and milk products

Enumeration of Pseudomonas spp.

ISO (2009c), IDF (2009b)

Milk products

Enumeration of presumptive bifidobacteria (colony count technique at 37◦ C)

ISO (2010b), IDF (2010a)

• Milk quality • Production Environment • Hygiene aspects

Cheese quality

Initial cheese Composition, Formulation Intrinsic and extrinsic influencing factors

Additives, Preservatives, Ingredients

Manufacture, Processing, Technology

Intrinsic and extrinsic influencing factors

Processed cheese

• Quality • Hygiene aspects

Intrinsic and extrinsic influencing factors

Intrinsic and extrinsic influencing factors

Fig. 10.17 Generalised scheme regarding the multitude of factors that influence the microbiological quality of processed cheese and analogues.

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during storage (Briozzo et al., 1983; Glass & Doyle, 2005), and possible hazards related to microorganisms, their toxins and metabolites should be considered. Canned processed cheese products are classified as low-acid canned foods, and Clostridium spp. (i.e. anaerobic spore-formers) are a major concern. These products need to be subjected to a process to render them commercially sterile. According to Kapoor & Metzger (2008), the microbiological safety of canned processed cheese products can be achieved by (a) heat treatment (121◦ C for 2.5–3 min, which is the minimum heating to inactivate Clostridum botulinum) so that there is a 12-log10 reduction in the count of the botulinal spores, or (b) appropriate formulation changes as well as adjustments in pH and aw in these products in order to inhibit growth and toxin production. High heat treatment of canned processed cheese has a major undesirable effect on the microstructure and functional properties of the product (Glass & Doyle 2005). Furthermore, it is well established by many researchers that appropriate formulation adjustments, including pH and aw , during the manufacture of canned processed cheese have been found to inhibit the growth, survival and toxin production of Clostridium spp. in the product (Tanaka et al., 1979, 1986; Somers & Taylor, 1987; Roberts & Zottola, 1993; Eckner et al., 1994; ter Steeg et al., 1995; ter Steeg & Cuppers, 1995; Plockova et al., 1996; Loessner et al., 1997; Glass & Doyle, 2005). Quality problems and spoilage of processed cheese are mainly attributed to the presence and/or growth of microorganisms in the product. The possible origins of the microflora are (a) ingredients used, such as milk, natural cheeses, dried dairy products, butter and any other material(s), (b) microbiological contamination within the dairy, mainly post-heat treatment stage, and (c) improper packaging and storage temperature of processed cheese. Such contaminations constitute a major cause of microbial-induced damage to the product, and can lead to mould growth. Mould growth in processed cheese can be prevented by the addition of inhibitors, such as sorbates and propionates (Neaves & Williams, 1999). In addition, the level of salt and the aw value in processed cheese are the major factors influencing the development of spoilage microorganisms. Although sodium chloride is added to the cheese blend during the manufacture of processed cheese, emulsifying salts such as monophosphates, polyphosphates and citrates are normally used. All these salts tend to reduce the aw of the product and, as a consequence, reduce the capability of bacterial contaminants to survive and to develop. There is some unequivocal evidence that the nature of the salt largely affects the anti-botulinal properties. For example, emulsifying salts such as the orthophosphates and polyphosphates sequester certain metal ions (iron, magnesium and calcium) in processed cheese and, as a consequence, inhibit growth and toxin production by C. botulinum. Citrate-based emulsifying salts are less effective at inhibiting the growth of C. botulinum compared with phosphate-based emulsifiers (Tanaka et al., 1979; Karahadian et al., 1985; ter Steeg et al., 1995). The inhibitory potential of phosphate-based emulsifying salts on the growth of various microbes and their anti-botulinal effects in processed cheese (i.e. using model systems and products) has been studied by many researches (Tanaka et al., 1979; 1986, Karahadian et al., 1985; Eckner et al., 1994; ter Steeg et al., 1995; ter Steeg & Cuppers, 1995; Loessner et al., 1997; Borch & Lycken, 2007). Predictive models were established based on (a) pH value and total NaCl concentration, and (b) disodium phosphate content; these models take into account the different moisture levels. For example, the lower the pH and the higher the level

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of NaCl plus disodium phosphate, the safer the processed cheese. Loessner et al. (1997) varied the addition of long-chain phosphates at different levels in order to prevent the growth of Clostridium tyrobutyricum in the product, and they recommended the addition of 0.5–1.0 g 100 g−1 . However, trisodium citrate has been shown to be less effective than disodium phosphate in preventing bacterial spoilage (Tanaka et al., 1979; ter Steeg et al., 1995). In principle, osmotolerant microorganisms, such as moulds and yeasts, need to be considered as the primary spoilage-causing organisms. Since clostridia require critical limits of aw in food products in order to grow, most processed cheese varieties can be regarded as safe because their aw values are generally significantly lower than those required to prevent botulinal growth and toxin production (ter Steeg et al., 1995). Tanaka et al. (1986) reported that when the aw of processed cheese spreads was ≤0.944, no toxin was detected; in contrast, aw > 0.957 of formulations of the same product supported toxin production. It is evident that the aw level of processed cheese products ranges between 0.94 and 0.96, which is lower than the aw (∼0.97) that supports the growth of non-proteolytic C. botulinum. Although the level of aw in processed cheese is important for controlling growth and toxin production, the final pH level of the product is also important (Tanaka et al., 1986; ter Steeg et al., 1995; ter Steeg & Cuppers, 1995; Glass & Doyle, 2005). In addition, Tanaka et al. (1986) indicated that if the aw of processed cheese ranged between 0.944 and 0.957, toxin production in the product was dependent on the moisture, NaCl and disodium phosphate contents, and pH level. A lower pH has been found to prevent microbial spoilage and toxin production in processed cheese (ter Steeg & Cuppers, 1995; ter Steeg et al., 1995), and enhanced the inhibitory activity of mould preservative (e.g. sorbic acid) in the product (Glass & Doyle, 2005). During the manufacture of natural cheese, microbiological contamination usually occurs when the cheese curd is manually or mechanically handled, during the maturation phase, and finally during dispatch and transportation (Neaves & Williams 1999). The presence of pathogenic microorganisms in cheese and the production environments depends on several limiting and promoting factors appearing during manufacture, processing and ripening. Probably the most relevant pathogens in cheese production are L. monocytogenes, S. aureus, E. coli and Salmonella spp. (Neaves & Williams 1999; Kapoor & Metzger, 2008). Contamination with E. coli has been shown to possess some relevance for soft cheese varieties, but corresponding reports related to processed cheese are scare and mainly related to recontamination at the consumer stage. Since heat treatment of the cheese blend is an important stage during the manufacture of processed cheese, the processing conditions may exert selective enrichment of bacterial endospores, and the role of Clostridium and Bacillus endospores should be considered as a typical hazard related to product. For example, C. botulinum, which is a severe neurotoxin producer, may be of special concern. However, the fat content can be regarded as an important quality parameter of processed cheese, and the influence of this property on the growth of anaerobic bacteria was studied by few researchers. It was shown that reduced-fat processed cheeses are safer than high-fat products having the same moisture, salt and pH (ter Steeg et al., 1995). Different theories have been proposed to explain the relationship between fat content and reduced protection against Clostridium growth, and they are summarised as follows. •

The fat content may provide some protection for bacteria from antimicrobials in the water phase of a product.

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•

•

277

Reduced-fat processed cheeses often contain ingredients to enhance the flavour, and these additives may lower the aw value of the product or provide free fatty acids, aldehydes or peroxides with antimicrobial properties. Reduced anti-botulinal activity in processed cheeses with high-fat content may be due to the fact that the lipophilic portion of antimicrobials may interact with fat molecules rather than with the phospholipids in bacterial cell membranes, thereby decreasing their antimicrobial efficacy (McLay et al., 2002).

10.5.3 Preliminary treatment of natural cheese milk and effect of certain additives It could be argued, however, that the safety of processed cheese can be achieved by using spore-free natural cheeses, an approach that large-scale processed cheese manufactures in different parts of the world are demanding from the cheese producers. Preliminary treatments of the cheese milk before the pasteurisation stage at 72◦ C for 15 s that can be used to remove bacterial spores from the milk include (a) double bactofugation of the skimmed milk and the stream containing the fat content and the spores are subjected to high heat treatment, (b) microfiltration of the skimmed milk before standardising with the cream that has been treated at a high temperature (i.e. sterilised), and (c) the use of lysozyme in combination with either of the former two methods of milk handling (Anonymous,2003). Lysozyme, an enzyme present in milk, eggs, tears and other secretions, is most active against Gram-positive bacteria by degrading the cell wall. Certain strains of C. botulinum may retain their retractile properties when treated with lysozyme alone, but ethylenediaminetetra-acetic acid (EDTA) enhances its activity and lysed the bacteria. As with nitrate addition to cheese milk, lysozyme is used to prevent gas formation by C. tyrobutyricum in Gouda and Edam cheeses (Hughey & Johnson 1987; Hughey et al., 1989). However, reports that lysozyme enhanced the recovery of non-proteolytic C. botulinum in heated foods indicate that lysozyme should be used as an antimicrobial only after verifying safety (Graham et al., 1996, 1997). Sodium diacetate, commonly referred to as dry vinegar, has been shown to inhibit growth of L. monocytogenes in meats and has been approved for use at 0.3 g 100 g−1 in processed poultry and meat products (Glass et al., 2002); such additives may have potential use in the manufacture of processed cheese after being approved by local authorities. Processed cheeses formulations are usually near neutral pH value, and some types may be packaged in an anaerobic environment; the presence of anaerobic spore-formers (clostridia) is of particular relevance. Some reported cases of botulism due to the consumption of processed cheese have been described by Jarvis & Neaves (1977) and Neaves & Williams (1999), and they reported that the product needs to be sterilised in order to eliminate endospores. Alternative safeguards are cooler storage conditions of the product rather than the current practice of storing processed cheese at ambient temperature, and the use of preservatives against the target microorganisms. The latter safeguard approach involves the use of nisin (i.e. a natural bacteriocin produced by strains of Lactococcus lactis subsp. lactis) and has been demonstrated to be useful (Cleveland et al., 2001). Although bacterial spores seem to be much more resistant to bacteriocins than the vegetative bacterial cells, nisin is obviously capable of inhibiting endospore germination at

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the pre-emergent swelling stage. It also sensitises the endospores present to heat so that heat processing is more efficient (Delves-Broughton et al., 1996). Somers & Taylor (1987) have demonstrated that the application of 100–250 μg g−1 nisin preparation is required to prevent botulinal growth and toxin production in processed cheese spreads (chemical composition in g 100 g−1 : moisture 57, NaCl 1.2 and disodium phosphate 1.4). Neaves & Williams (1999) have reported that typical spoilage clostridia may even possess higher heat resistance than C. botulinum and therefore sporulation and bacterial growth may be facilitated if storage is not under well-controlled conditions in order to avoid spoilage and quality losses. The redox potential (Eh ) in natural cheeses has been identified as one of the relevant factors in determining the types of microorganisms that will be able to grow (Beresford et al., 2001). Usually, obligately aerobic microorganisms such as Pseudomonas spp., Brevibacterium spp., certain strains of Bacillus spp. and Micrococcus spp. can only grow on the cheese surface. However, in the inner core of the cheese block anaerobic condition occurs and, as a consequence, bacteria like clostridia will find suitable atmospheric conditions for survival and growth. Nitrate is sometimes added to the cheese milk during the manufacture of some Dutch-type cheeses used for processed cheese production; this method is practised to control the growth of C. tyrobutyricum, which can cause late blowing in the cheese, Hence, if cheese containing residual nitrate is utilised for processed cheese production, the nitrate is reduced to nitrite and this exerts some growth inhibition against clostridia in the product (Skovgaard, 1992; Beresford et al., 2001). Information about the development biogenic amines in processed cheese is limited, and reports by Brackett and Marth (1982), Fox et al. (1996), Pattono et al. (2000), Sarimehmetoglu et al. (2004), Komprda et al. (2005) and Yaroglu et al. (2005) have shown that certain levels of amines (e.g. tyramine) can be detected in commercial samples using currently available analytical techniques, albeit being without any hazardous significance (O’Brien et al., 2004). Turkish processed cheese samples collected from different markets and different manufactures contained aflatoxin M1 (∼79% of the samples tested); the detected levels were within the legal limits of the Turkish Regulations (Sarimehmetoglu et al., 2004). Although an earlier study by Brackett and Marth (1982) reported that processed cheese contained approximately the same concentration of aflatoxin M1 as that in the natural cheese used during the formulation of the product, current knowledge on the recovery of aflatoxin M1 from processed cheese suggests that the emulsifying salts used and heating applied at 90◦ C for 20 min increased the aflatoxin content in the product. These aspects need to be studied further in order to understand the mechanism(s) of aflatoxin increase in processed cheese to ensure the safety of the product.

10.5.4 Hygienic production/facility: HACCP As shown in section 10.2, the application of the HACCP system ensures the safety of the product through proper monitoring of the raw materials and final product, and provision of hygienic facility. Figure 10.7 shows the CCPs that require monitoring including the bacteriological examination (Palmas et al., 1999) and rheological measurements, and these aspects are reviewed in a subsequent section.

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10.5.5 Bacteriological examination Bacteriological analysis of processed cheese involves mostly tests for the presence of spore-forming Clostridium bacteria (see Table 10.2). Su & Ingham (2000) considered C. tyrobutyricum to be a primary cause, and Clostridium sporogenes, Clostridium beijerincki and C. butyricum to be possible secondary causes of gas production in Gouda cheese. Bacterial spores are usually estimated on reinforced clostridium medium. One approach for the presumptive enumeration of C. tyrobutyricum endospores involves heat-shocking the sample to destroy the vegetative cells, followed by MPN estimation based on gas production in anaerobically incubated medium containing lactate as the fermentable organic compound. The MPN value can be confirmed by verifying the lactate fermentation ability of cells as gas (+) tubes (Senyk et al., 1989; Jonsson, 1990; Klijn et al., 1995; Ingham et al., 1998; Su & Ingham, 2000). The choice of analytical method is very important regarding the presence of sporeforming bacteria in processed cheese because not every assay method will be appropriate for all types of bacteria. Recently, Lycken & Borch (2006) conducted studies on 42 spoiled samples of processed cheese spread products, and reported that the most harmful clostridia present in the product was C. sporogenes and the presence for the first time of Clostridium cochlearium, whilst C. tyrobutyricum was present in only 2% of the samples examined. Although the main cause of blowing in hard and semi-hard natural cheeses is C. tyrobutyricum, in processed cheese the blowing was mainly caused by C. sporogenes and C. cochlearium.

10.6 Assessment of physical characteristics Processed cheese has a wide range of end-use applications including as an ingredient in a variety of foods. In addition, processed cheese can be packaged in a variety of forms including (a) individually wrapped and bulk pack slices, (b) loafs of various sizes, (c) individually wrapped wedges and chunks, and (d) spreads (i.e. collapsible tubes or glass jars). The desired physical properties for a processed cheese are dependent on the end-use application as well as the packaging form. The physical properties of processed cheese can be broadly classified into two categories: firstly, unmelted texture and, secondly, melting characteristics. Table 10.3 provides an overall summary of the most commonly measured unmelted texture and melting characteristics of processed cheese along with the commonly used measurement techniques. As shown in Table 10.3, a variety of techniques have been developed to measure the physical properties of processed cheese. The preferred technique will be dependent on the type of processed cheese analysed as well as the availability of equipment, expertise of the analyst, and purpose of the analysis (i.e. rapid quality control testing or rheological characterisation).

10.6.1 Unmelted characteristics A variety of techniques has been utilised to characterise the unmelted texture of process cheese in a quality control setting. The physical characteristic that is primarily measured

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Table 10.3 Summary of commonly used testing methods of unmelted and melted processed cheese physical properties. Testing methods

Physical characteristics measured

Unmelted texture: instrumental based Texture profile analysis

Hardness/firmness, brittleness/fractureability, springiness/resilience and adhesiveness/stickiness

Pentrometry

Firmness: depth of penetration and force required for penetration

Melting characteristics a : empirical tests Arnott melt test

Change in height during heating

Schreiber melt test

Melt area during heating

Tube melt test

Extent of flow during heating

Melting characteristics: rheological and instrumental based Dynamic stress rheometry

G , G , tan δ

UW melt profiler

Softening point

Rapid Visco Analyzer

Melt time, melted viscosity, solidification time

a

Melt characteristics descriptor terms are: melt, viscosity/flow and stretching ability. For detailed information regarding the textural properties of processed cheese, the reader is referred to the review by Kapoor & Metzger (2008).

is consistency or hardness. The former descriptor is a general term used to describe the resistance of a material to a permanent change in shape (Gunasekaran & Ak, 2003), and consistency is typically measured with a cone pentrometer. Hardness is one of several texture parameters determined using an instrumental technique called texture profile analysis, which is defined as the force required to attain a given deformation of a process cheese sample. The pentrometry and texture profile analysis techniques typically used to evaluate processed cheese are described in the remainder of this section. Pentrometry One of the simplest and fastest techniques that can be used to measure the firmness of processed cheese is with a cone pentrometer. Three modes of operation can be used with cone pentrometry. In all modes, a cone assembly with specific dimensions and weight is used; however, the depth of penetration after a fixed time, depth of penetration when the cone comes to rest, or the force required to drive the cone into the sample is determined (Gunasekaran & Ak, 2003). Thomas et al. (1970) developed procedures for analysis of a wide range of processed cheeses. In their methods, the cheese sample is placed at the tip of a weighted (300 g) pentrometer and the depth of penetration in a fixed period of time (typically 15–60 s) is determined. Using this method they found a high correlation with firmness, i.e. results obtained from expert graders. The advantages of pentrometry are the relatively low cost and simple operation of the instrument. Its disadvantage is that it is an empirical test; the results obtained only serve as a relative measure of the firmness of processed cheese, and are dependent on the pentrometer and testing conditions used for the analysis.

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Texture profile analysis Texture profile analysis (TPA) is a technique that utilises a cross head with a flat plate to deform a sample that has been placed on a lower plate. In this test, the sample is typically compressed twice, and the data produced is plotted as a force versus time curve or a force versus distance curve. Various parameters are obtained from these curves, including hardness, fracturabilty, adhesiveness, springiness, cohesiveness and gumminess (Breene, 1975). However, the parameters primarily utilised for processed cheese are hardness and adhesiveness. Several different protocols have been reported for analysis of processed cheese using a variety of instruments (Harvey et al., 1982; Gupta et al., 1984; Acharya & Mistry, 2005; Everard et al., 2007; Kapoor et al., 2007; Dimitreli & Thomareis, 2009). A general protocol, which can be utilised for most processed cheese products, is two compressions of a cylindrical sample (20 mm height and 20 mm diameter) to 20% of the original height using a cross head speed of 0.8 mm s−1 (Kapoor et al., 2007). TPA is a valuable technique for determining the firmness of processed cheese, and provides data similar to pentrometry. In addition to firmness, TPA analysis also provides information on cheese adhesiveness, which is important for some processed cheese application. Relative to pentrometry, TPA analysis is less suitable for quality control purposes because it takes longer to perform, requires a more experienced analyst, and the equipment utilised is more expensive.

10.6.2 Melting characteristics There are numerous tests that can be used to evaluate the melting characteristics of processed cheese. Melt properties are difficult to define, and often encompass two aspects: (a) ease of melting, and (b) extent of flow (Gunasekaran & Ak, 2003). In a quality control setting, rapid low-cost empirical tests that provide an overall evaluation of melting characteristics, such as the Schreiber melt test, are preferred. However, several instrumental and rheological based tests including dynamic stress rheometry, modified squeeze flow rheometry and rapid visco analysis are also utilised in situations where a more in-depth analysis of the melting characteristics of a processed cheese is required. In the remainder of this section, the available empirical, rheological and instrumental methods for measuring the melt characteristics of processed cheese are discussed. Empirical melt tests Commonly utilised empirical melt tests include the Arnott melt test, Schreiber melt test and the tube melt test. In the Arnott melt test, a 17 mm height × 17 mm diameter cylinder of cheese is heated in an oven at 100◦ C for 15 min, and the percent decrease in height of the cylinder after heating is reported (Arnott et al., 1957). In the Schreiber melt test, a 5 mm height × 4 mm diameter cylinder of cheese is heated in an oven at 232◦ C for 5 min, and the diameter of the cheese spread is determined (Kosikowski & Mistry, 1997). Even though these two melt tests are similar, they have been reported to produce substantially different results for processed cheese products (Park & Rosenau, 1984). The different results obtained with the two melt tests are most likely caused by the different sample dimensions and heating conditions used in the two test. Several modifications to the Schreiber melt

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Processed Cheese and Analogues

test, including reducing the oven temperature to 90◦ C, placing the sample on an aluminium plate during heating and measuring the area of the melted cheese, have been suggested (Muthukumarappan et al., 1999a). An additional melt test, which was specifically developed for high moisture processed cheese, is called the tube melt test (Olson & Price, 1958). In this melt test a 20-g sample of processed cheese is placed in a 38 × 200 mm glass tube, the tube is sealed, placed horizontally on a tube rack, heated at 110◦ C for 10 min, and the extent of flow after cooling is determined. Among the empirical melt tests available, the Schreiber melt test is predominantly used in quality control testing. Rheological-based and instrumental-based melt tests From a rheological point of view, processed cheese is a viscoelastic material, and possesses both viscous and elastic properties. With the aid of dynamic stress rheometry the rheological properties of processed cheese can be determined at a range of temperatures (Gunasekaran & Ak, 2003). In this method of analysis, the storage modulus G (elastic properties), loss modulus (viscous properties) and the loss tangent or tan δ (ratio of G /G ) are determined at a range of temperatures (typically 25–90◦ C). The data collected in the analysis can be used to characterise the physical properties of unmelted and melted processed cheese. Additionally, tan δ = 1 can be used as a measure of the melting temperature of processed cheese (Sutheerawattananonda & Bastian, 1998). Consequently, dynamic stress rheometry can be used to rapidly characterise the physical properties of processed cheese. In the typical method, a cylindrical sample of processed cheese of approximately 2 mm height and 30 mm diameter is placed between two parallel plates in the rheometer. Serrated plates or gluing sandpaper to the upper plate is recommended to prevent sample slippage during testing. Prior to dynamic stress rheometry analysis, a stress sweep is performed at a frequency of ∼1.5 Hz and a stress ranging from 1 to 3000 Pa at 25◦ C to determine the maximum stress limit for the linear viscoelastic region (Biswas et al., 2008). Subsequently, dynamic rheological analysis is performed at a constant stress in the linear viscoelastic region while the sample is heated from 25 to 90◦ C. The temperature ramp used has been reported to range from 1 to 10◦ C (Sutheerawattananonda & Bastian, 1998; Bowland & Foegeding, 2001; Biswas et al., 2008). Since dynamic stress rheometry can rheologically characterise the physical properties of processed cheese over a wide range of temperatures in a short period of time, it can be a valuable tool for quality control purposes. However, this technique is not routinely used in quality control because of the relatively expensive rheometer and because analyst expertise is required to operate this instrument. UW melt profiler Muthukumarappan et al. (1999b) have developed a squeeze flow rheometry apparatus called the UW melt profiler that can determine the softening point of natural and processed cheeses. In this test, a 7 mm height × 30 mm diameter cheese cylinder is placed on a sample platform under a circular top plate that is attached to a linear variable differential transformer. The apparatus is then placed in a forced draft convection oven and the cheese temperature and cheese flow data are simultaneously collected. The total analysis time is

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approximately 15 min. From these data, the softening point of the cheese can be calculated. As compared to dynamic stress rheometry, this method also provides rheological-based data, but it utilises less expensive apparatus to conduct the melt test. Consequently, this method has the potential to be used in some quality control applications. Rapid visco analysis An additional instrumental-based method utilises a device called the Rapid Visco Analyzer (RVA) to determine the apparent viscosity of processed cheese during a controlled heating or cooling cycle (Prow & Metzger, 2005). This method has been reported to be correlated with results obtained from the tube melt test and dynamic stress rheometry. In this test, a 15-g sample of processed cheese is placed in a disposable RVA canister, a stirring paddle is inserted and the cheese is analysed using a 14-min test. During the test the temperature is raised from 25 to 90◦ C in 5 min, held for 3 min at 90◦ C, and then cooled from 90 to 25◦ C in 6 min. In the first 2 min of the test, the stirring speed is gradually increased from 0 to 300 rpm, and then maintained at 300 rpm for the remainder of the test. The apparent viscosity of the processed cheese is collected during the entire test. From these data, the melt time, hot viscosity, and solidification time are determined. The advantages of this test include simple instrument operation and the apparent viscosity data collected can be used to characterise the physical properties of the processed cheese over a range of temperatures. However, the cost of the RVA is relatively high compared with other empirical melt tests such as the Schreiber melt test or the tube melt test.

10.7 Assessment of the microstructure 10.7.1 Background It is widely accepted that electron microscopic techniques, such as scanning electron microscopy (SEM), cryo-SEM, transmission electron microscopy (TEM), confocal scanning laser microscopy (CSLM) and fluorescence microscopy, are used for observation and understanding the behaviour of foods. In general, these microscopic techniques have been used to study the microstructure of natural cheeses, processed cheese and related products, and cheese analogues. Recently, an overview of the application of these techniques for studying the microstructure of dairy products had been reported by Tamime (2007). The use of microscopy to study the structure characteristics of processed cheese and related products has been discussed in detail elsewhere and the reader is referred to these reviews for complete discussion (Kalab, 1981, 1983, 1984, 1992, 1993, 1995; Cari´c et al., 1985; Green et al., 1986; Kalab et al., 1987, 1995). This section reviews some of the applications used to study the microstructure of processed cheese and related products, and how microscopy is also applied in product development.

10.7.2 Some aspects affecting microstructure formation In general, SEM shows differences in the structure of Cheddar and processed cheeses (Fig. 10.18). The former product, which is made from full-fat unhomogenised milk, consists

284

Processed Cheese and Analogues

2 μm

(a)

1 μm

(b) Fig. 10.18 Scanning electron microscopy of Cheddar cheese and processed cheese. (a) Void spaces in the protein matrix indicating the locations of Lactococcus lactis spp. and of fat globules and their clusters. (b) Fat particles (as indicated by the void spaces) are relatively uniformly distributed in the protein matrix. (After Tamime et al., 1990. Reproduced by permission of M. Kalab, personal communication.)

of a protein matrix where the starter culture and large fat globules and their clusters (i.e. void spaces after the fat is extracted from the sample for preparation for SEM) are dispersed in agreement with the findings of many researchers. In contrast, the microstructure of processed cheese shows that the fat particles are uniformly distributed in the protein matrix. However, cryo-SEM of Cheddar cheese shows a drier microstructure and distorted fat globules because the milled cheddard curd was dry salted (Fig. 10.19a,b). The curd junctions would be visible at lower magnification but, at higher magnification of the Cheddar cheese, there are gaps around the fat globules because the water has been removed from the milk fat globule interface. The water-binding capacity of the Cheddar cheese is lower than the other cheeses that do not show this effect. In contrast, Gouda cheese (Fig. 10.19c,d) and America-type Swiss cheese (Fig. 10.19e,f) were pressed in the whey and do not experience the same amount of distortion. Their microstructure is smooth and regular and the fat globules and water are more uniformly distributed.

Quality Control in Processed Cheese Manufacture

(a)

(b)

(c)

(d)

(e)

(f)

285

Fig. 10.19 Cryo-scanning electron microscopy of commercial cheeses: (a, b) Cheddar; (c, d) Gouda; (e, f) American-type Swiss. Bar size = 30 μm for (a), (c) and (e); bar size = 6 μm for (b), (d) and (f).

286

Processed Cheese and Analogues

During cooking, changes in the rheology and microstructure of processed cheese (typical full-fat formulation and fat-free using a model system; the moisture contents of the products were 48.7 and 79.5 g 100 g−1 , respectively, whilst the level of solids in the products were 51.3 and 20.5 g 100 g−1 , respectively) were reported by Lee et al. (2003). They concluded the following. •

•

• •

•

Both products showed a similar trend in the change in their viscosity profiles during the cooking stage; the fat was not essential for the viscosity change, but its presence could influence some aspects of the viscosity curve. The proteins from the natural cheese and rennet casein dispersed during the initial stage of cooking (i.e. break-up of the calcium phosphate bridges), and then they reassociated to form a protein network matrix as cooking continued, which resulted in an increase in the viscosity (i.e. due to calcium chelation, ion exchange and action of the emulsifying salts); as cooking continued beyond the maximum viscosity, the protein matrix started to collapse, which resulted in a fall in viscosity (i.e. protein reassociation had become too ‘advanced’, resulting in large compacted protein structure). Changes in the viscosity of the melted cheese during cooking were associated with the phenomenon of ‘creaming’ reaction, a term used in the processed cheese industry. ‘Well creamed’ processed cheese contained protein particles that were optimally linked together as a strong protein network compared with closely compacted protein particles (‘over-creamed’) or dissociated protein particles (‘under-creamed’). The microstructure of the protein occurred as individual particles and in some areas of the melted cheese contained a tightly knit protein structure at the beginning of the cooking stage and formed a protein matrix when the viscosity peaked, whereas on further cooking (i.e. decline in viscosity continued) the protein structure was compacted with rough fractured surfaces; continued cooking resulted in a drop in viscosity, which signalled the collapse of protein matrix structure.

The changes in fat globule size during processing have been monioried using various types of microscopy. Fluorescence imaging and cryomicrotomy techniques, used to monitor the shape and size of the fat globule in processed cheese, showed that the diameter of the globule was influenced by heat and type of salts used (Sutheerawattananonda et al., 1997); batches made with trisodium citrate had fat particles in the product that were more circular than those in processed cheese made with sodium chloride. In addition, the diameter of the fat particle in processed cheese containing trisodium citrate decreased in size and stabilised after 5 min of cooking time, but no changes in size were observed in the product made with sodium chloride. During the cooling stage of processed cheese and related products, the homogeneous molten and viscous mass sets to form its body characteristic, which depending on the cheese blend formulation, processing conditions and cooling rate may vary from a firm sliceable product to a semi-soft spreadable consistency. Factors that probably contribute to structure formation (i.e. setting) during cooling include (a) fat crystallisation, (b) protein–protein interactions, and (c) incorporation of recombined fat globules. It is envisaged that the newly formed emulsified fat globules become an integral part of the fat matrix (Fig. 10.20) as a result of the interaction between the para-caseinate of the fat globule membrane with the para-caseinate of the protein matrix.

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1 μm (a)

1 μm (b) Fig. 10.20 Transmission electron microscopy of processed cheese analogues made from different ingredients. (a) Product made from ultrafiltered retentate and anhydrous milk fat (AMF) where darker images show outlines of fluffy material and newly formed globule membrane (arrow). (b) Product made with skimmed milk powder and AMF showing newly formed globule membrane (arrow) and fluffy electron-dense material. (c) Light areas (arrow) contain what appears to be some fluffy material, possibly Passelli® fat substitute. (d) Compact particles several micrometres in diameter (apparently Dairy-Lo™ fat substitute) interspersed with the fat globules; smaller compact particles (∼0.5 μm) are also noticeable. (e) Microparticulated whey protein Simpless® (arrow) is seen as dark particles. (After Tamime et al., 1999. Reproduced by permission of M. Kalab.)

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Processed Cheese and Analogues

1 μm (c)

1 μm (d)

1 μm (e) Fig. 10.20

(Continued)

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Microscopic studies on processed cheese products indicate that the microstructure represents an emulsion of discrete, round fat droplets of varying size, which are homogeneously distributed in a continuous protein matrix (Kimura et al., 1979; Rayan et al., 1980; Taneya et al., 1980; Lee et al., 1981, 1996; Tamime et al., 1990; Mistry et al., 2006) (see Figs 10.18 and 10.19). Compared with natural cheeses, there is less clumping or coalescence of fat globules, and the mean fat globule size is generally smaller that that of natural cheese. The actual size depends on formulation and processing conditions, such as type of emulsifying salts, milk protein additions, heating duration and extent of shear during heating and ‘creaming’ stages. The fat and the para-casein are more homogeneously distributed, and the matrix is less compact and fused than in natural rennet-curd cheeses. High-resolution TEM (× 60 000) with negative staining of the protein reveals that the matrix consists of strands that are finer than those of natural cheese and which appear to be composed of para-caseinate particles (20–30 nm diameter) joined end to end. It has been suggested that these particles may correspond to casein sub-micelles released from the cheese paracasein matrix as a result of calcium chelation by the emulsifying salts (Kimura et al., 1979; Taneya et al., 1980; Heertje et al., 1981). However, blends of different emulsifying salts (e.g. sodium diphosphate + sodium polyphosphate + sodium tripolyphosphate and/or sodium polyphosphate + sodium citrate + sodium orthophosphate + sodium diphosphate in a ratio of 40:40:30 and/or 40:10:20:30, respectively) had the best structure and texture characteristics of block-type processed cheese (Awad et al., 2002). In a different study, Abd Rabou et al. (2005) examined the properties of different blends of emulsifying salts during the manufacture of processed cheese spread and concluded the following: (a) the best blend consisting of potassium acetate and potassium citrate (with 1:1 or 2:1) gave the highest sensory scores, (b) the microstructure of the product showed better emulsification than when using a single emulsifying salt, and (c) product stored at room temperature affected the rheological properties of the product. The para-caseinate of the emulsified fat globule membrane appears to attach to the matrix strands and anchors the protein matrix, thereby contributing to the continuity of the matrix. The positive correlations between the degree of emulsification and firmness or elasticity and the inverse relationship between degree of emulsification and flowability of processed cheese products support this suggestion (Rayan et al., 1980; Cari´c et al., 1985; Savello et al., 1989). The incorporation of the emulsified para-caseinate-coated fat globules, which can be considered as pseudo-protein particles, into the new microstructural matrix may be considered as increasing the effective protein concentration (van Vliet & Dentener-Kikkert, 1982; Klostermeyer & Buchheim, 1990; Marchesseau et al., 1997). As mentioned earlier, in ‘hard’-type processed products, the strands of the protein matrix are longer, and inter-strand connections are more numerous than in ‘soft’ types (Taneya et al., 1980; Heertje et al., 1981; Cari´c et al., 1985; Tamime et al., 1990) (see Figs 10.18 and 10.19). Minute electron-dense areas in the strands of the protein phase may correspond to regions of strand overlap and/or reflect areas with relatively high degree of aggregation and fusion of the para-caseinate particles. The number and area of electron-dense zones in very firm processed cheese that had been cooked to 85◦ C and held for 5 h were markedly higher than in the control products that had been cooled after 3 min at 85◦ C (Kalab et al., 1987; see also Fig. 10.20). The microstructure of the protein matrix also appears to change during storage (i.e. formation of string-like structures), especially when the product is stored at high temperature

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Processed Cheese and Analogues

(a)

0.1μm

(b)

0.1μm

Fig. 10.21 High-magnification of transmission electron microscopy of processed cheese stored at 30◦ C for 3 months. which was made from a blend of matured Cheddar cheese, cheese base that had been treated with Savorase-A® and anhydrous milk fat. (a) String-like structures (large arrows) were present in the protein matrix similar to those reported by Taneya et al. (1980), Heertje et al. (1981) and Caric´ and Kalab (1987); however, the development of artefacts (small arrows) was difficult to avoid. (b) In addition to string-like structures in the protein matrices covering emulsified fat globule, membranes (large arrow) were evident at a higher magnification in different blends of processed cheese stored at 10◦ C and minute electron-dense particles (small arrow). (After Tamime et al., 1990. Reproduced by permission of M. Kalab.)

(Fig. 10.21). A study on age-related changes on processed cheese indicated that firmness and elasticity (i.e. force required to push a wire into the product) increased during storage over a 3-month period, with the extent of the increase being higher as the storage temperature was raised from 10 to 30◦ C (Tamime et al., 1990). The latter effect may be attributed to continued protein–protein interaction and/or interactions between the cheese proteins and the emulsifying salts, which may have affected the degree of protein interaction and the degree of emulsification of the fat (Tamime et al., 1990). The increase in firmness on raising the storage temperature form 10 to 30◦ C lends support to the suggestion that protein interactions probably occur during storage; an increase in temperature in this range is conducive to hydrophobic interactions. Similar protein fibrous structure was also

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reported by Tamime et al. (1999) in processed cheese analogues when visualised at higher magnification.

10.7.3 Cryo-SEM description of processed cheese microstructure The family of products in the general category of processed cheese is diverse, including both standardised and non-standardised products. Processed cheese products may have a wide range of fat and moisture contents, texture (ranging from pourable sauces to firm non-meltable slices) and retail packaging (ranging from 2-kg blocks to 50-mL tubes). In most jurisdictions where ingredients and composition are regulated, processed cheese is natural cheese that is comminuted and heated with phosphate and citrate salts to melt caseins and emulsify fat, perhaps including some additional salt, flavour, emulsifiers, stabilisers and antifungal agents, such as sorbate. During the last half of the 20th century, most processed cheese was replaced by standardised, but less restricted and less expensive versions of processed cheese. Typically called processed cheese foods, these products are standardised with respect to minimum content of natural cheese, minimum fat, maximum moisture and exclusion of non-dairy fats and non-dairy sources of protein. In the 1970s, unstandardised processed cheese type products were developed in the USA to mimic processed American and Mozzarella cheeses where ‘dried milk protein, hydrogenated vegetable oil, emulsifiers and other ingredients’ were used (Curtin, 1993; Hennelly et al., 2006). The trends to use alternative fats and less fat are also driven by dietary concerns about cholesterol and saturated fat (Bachmann, 2001). For reasons of functionality, most of the protein in non-standardised products is derived from milk powders and milk protein concentrates. Whey protein concentrates can also be used in small quantities depending on the required degree of meltability. Similarly, the amount of protein that can be derived directly from skimmed milk powder (SMP) and milk protein concentrates is limited by the amount of whey protein and, in some cases, lactose in these ingredients. These limitations encourage the use of some natural cheese in non-standardised cheese products because the cheesemaking process separates lactose and whey proteins from the casein. It is now possible to separate caseins from whey proteins by microfiltration of skimmed milk, so it is likely that ‘native’ casein will become a major ingredient in the manufacture of processed cheese and spreads, especially in non-standardised products. Processed cheese texture is strongly influenced by ingredients. Sodium caseinate binds water and builds a cohesive, firm texture. Processed young cheese leads to firmer more elastic product when compared with using processed old cheese. Including previously processed cheese leads to firmer texture. The ‘melting salts’ facilitate ion exchange by converting Ca- and H-caseinate to Na-caseinate, which enhances water binding and emulsification. However, undissolved salts may be visible, and the interaction between the salts and the calcium may leave inclusions of calcium phosphate (Kalab, 2005) (www.magma.ca). In addition to composition and ingredients, the microstructure of processed cheese and related products is affected by processing conditions, such as heating temperature and time. Possibly the best approach for studying the microstructure of cheese is cryo-SEM because the water and the fat can be retained in the sample (Hassan & Awad, 2005). The sample is frozen quickly in liquid nitrogen slush (–207◦ C) to minimise the size of

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Processed Cheese and Analogues

ice crystals, and then fractured to expose a fresh surface. When the cheese is sublimated (partially freeze dried) sufficient water is removed such that the underlying structure is possible to interpret. Through this method, the protein matrix is largely unchanged and the fat globules remain intact. The protein matrix and the size and distribution of the fat globules and the cavities vacated by sublimated water can be examined in the still frozen sample on the cold stage in the SEM. Some compositional parameters and other properties of the cheese samples examined by cyro-SEM are listed in Table 10.4. As shown in Fig. 10.22 the microstructure of processed cheese from two sources is quite different. Although both cheeses were made with Cheddar cheese, fat, protein and carbohydrate constituent levels are different (Table 10.4). The images of processed cheese, prepared in-house at the University of Guelph, are shown in Fig. 10.22(a,b). These images show clusters of milk fat globules that surround uniformly distributed areas of dense protein network. Because the product was homogenised after heating and before filling the jars, the fat globules are small and have a well-developed milk fat globule membrane (MFGM). Image analysis of the fat globule diameters indicates that 96% of the fat globules are less than 2 μm in diameter. The dense protein network may be attributed to the addition of SMP, which increases the spreadability and stability of the product (Mulsow et al., 2007.) The images of the commercially prepared sample (Fig. 10.22c,d) had larger fat globules, which suggest that these products were not homogenised. Most fat globules (i.e. 75%) are less than 2 μm, but substantial numbers range up to 6.5 μm and a few are 15 μm in diameter. Some size reduction, relative to native fat globules, is probably caused by shear during heat treatment. Relative to the homogenised product the fat globules are also more uniformly distributed (Fig. 10.22c), without clustering, although partial coalescence is evident. Coalescence is probably due to a combination of larger fat globules and native MFGM, which is less robust relative to the artificial membranes created during homogenisation. Coalescence is more evident in another image from the same sample (Fig. 10.23), and it also shows the presence of undissolved phosphate crystals and sodium citrate crystals based on their similarity to the inclusions identified from images provided by Cari´c et al. (1985) in their review of processed cheese structure (see also section 10.7.4). The processed cheese products chosen for cryo-SEM comparison with processed cheese were packaged in jars and recommended for melting or spreading. All products have a lower fat content than ‘regular’ processed cheese, and ranged from 16.5 and 20 g 100 g−1 for the ‘regular’ products down to 10 and 13 g 100 g−1 for the comparative ‘light’ products, as documented in Table 10.4. Cryo-SEM results (Figs 10.24 and 10.25) show differences in the microstructure of the processed cheese products compared with the processed cheeses illustrated in Fig. 10.22. The Cheez Whiz (Fig. 10.24a,b) contains milk fat globules that have a similar size distribution to those shown in processed cheese (Fig. 10.22c), although there are fewer. This is to be expected because the fat content is lower. In Fig. 10.25(a,b), the micrographs showing the microstructure of ‘regular’ Cheese-tastic!™, the fat globules (f) are small and dispersed in the protein matrix. They are difficult to identify because they are in the same size range as other particles on the surface. In Fig. 10.25(b), the microstructure appears to be highly hydrated, which suggests the addition of high-waterbinding polysaccharides to provide structural integrity and homogeneity to the matrix. From the ingredient lists (see Table 10.4), the differences between Cheez Whiz and Cheesetastic!™ are that modified milk ingredients are the first constituents followed by cheese and

13

13

55.2

59.2

20.0 12.0b 0.66c

13.0 8.3b 0.33c

Cheese-tastic™ (Original)

Cheese-tastic™ (Light) (30 g 100 g−1 less fat than the Original)

Saturated fatty acids.

Trans fatty acids.

Sugars.

b

c

d

Calculated by difference.

13

62.4

10.0 6.6b 0.33c

Cheez Whiz (Light) (36 g 100 g−1 less fat than the Original)

a

10

58.9

16.5 10.0b 0.3c

Cheez Whiz (Original)

15.0

19.8

31.0

Commercial

56.0

55.2

22.0

Guelph University

Fat

13 10.0d

10 6.64

13 9.3d

13 10.0d

4.8

1.0

Watera Protein Carbohydrates (g 100 g−1 ) (g 100 g−1 ) (g 100 g−1 )

1.8

1.8

1.6

1.6

233

264

200

250

Calorific Sodium value (kcal (g 100 g−1 ) 100 g−1 )

Table 10.4 Composition and description of commercial processed cheese spreads.

50

66

50

50

Cholesterol (mg 100 g−01 )

Cheese (milk, modified milk ingredients, bacterial culture, salt, rennet and/or microbial enzymes, calcium chloride, colour, lipase), water, modified milk ingredients, glucose, sodium phosphate, salt, lactic acid, sorbic acid, spice, colour

Cheese (milk, modified milk ingredients, bacterial culture, salt, rennet and/or microbial enzymes, calcium chloride, colour, lipase), water, modified milk ingredients, glucose, sodium phosphate, salt, lactic acid, spice, sorbic acid, colour

Modified milk ingredients, cheese (modified milk ingredients, bacterial culture, salt, calcium chloride, colour, rennet and/or microbial enzymes, lipase), water, sodium phosphates, maltodextrin, salt, lactic acid, sodium alginate, spice, colour, sorbic acid, ground mustard

Modified milk ingredients, cheese (modified milk ingredients, bacterial culture, salt, calcium chloride, colour, rennet and/or microbial enzymes), water, maltodextrin, sodium phosphates, salt, sodium alginate, ground mustard, spice, colour sorbic acid, lactic acid.

Cheddar cheese, water, cream, sodium citrate, sorbic acid, citric acid, artificial colour, soy lecithin

Cheddar cheese (milk, modified milk ingredients, bacterial culture, salt, calcium chloride, rennet and/or microbial enzyme), butter, skimmed milk powder, sodium phosphates, salt, citric acid, colour (annatto)

Ingredients

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(a)

(b)

(c)

(d)

Fig. 10.22 Cryo-scanning electron microscopy of processed cheese: (a) and (b) were prepared in the pilot plant (Guelph Food Technology Centre; (c) and (d) are from a second commercial process. f, fat globules (note that they are much larger and more uniformly distributed in the commercially prepared samples); C, cavity left from the removal of a fat globule during the fracturing step; cf, coalesced fat globules. Bar size = 30 μm for (a) and (c); bar size = 6 μm for (b) and (d).

water in Cheez Whiz, whereas the order of ingredients is cheese, water and modified milk ingredients in Cheese-tastic!™. Cheez Whiz contains maltodextrin and sodium alginate, whereas Cheese-tastic!™ contains glucose as a source of polysaccharide. In order to assess the significance of the contribution of each ingredient and the effect of its concentration on the microstructure, it would be necessary to conduct a controlled study. The ‘light’ processed cheese foods shown in Fig. 10.24(c,d) and Fig. 10.25(c,d) are dense and amorphous. The higher magnification of the Cheez Whiz Light (Fig. 10.24d)

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Fig. 10.23 Cryo-scanning electron micrograph of processed cheese from a commercial source showing the presence of coalesced fat globules (f), phosphate crystals (P) and sodium citrate crystals (S). Bar size = 6 μm.

appears to have a globular appearance, whereas the higher magnification of Cheese-tastic!™ appears striated (Fig. 10.25d). These two products have a similar functionality, but look very different when viewed by cryo-SEM. The Cheez Whiz types (regular and light) have similar lists of constituents except that the reduction in fat is coupled with an increase in the protein. The Cheese-tastic!™ light has a lower fat content coupled with an increase in carbohydrates accounted for by the addition of lactose and glucose (Table 10.4). It would seem from the comparison of two products and their ‘light’ versions that there are many possible approaches to managing the composition of the processed cheese food and processing conditions to mimic typical processed cheese products. The result is a product that is similar in functionality, but with a lower fat content for the health conscious consumer.

10.7.4 Faults in processed cheese products Microscopy has been used in trouble-shooting and the reader is referred to Meyer (1973) and Berger et al. (1998) for example to view some microscopic images regarding crystal/sandiness formation (mainly due to excessive amount of lactose in the cheese blend) as a fault in processed cheese. However, Modler et al. (1989) attributed grittiness

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(a)

(b)

(c)

(d)

Fig. 10.24 Cryo-scanning electron microscopy of Cheez Whiz processed cheese food. (a, b) Regular Cheez Whiz; (c, d) Cheez Whiz Lite. f, fat globule in the regular Cheez Whiz. Bar size = 30 μm for (a) and (c); bar size = 6 μm for (b) and (d).

in pasteurised cheese spread to compacted protein, and the fault was minimised by using coagulated raw milk in the cheese blend, or using coagulated heat treated milk (90◦ C for 10 min), but the product should be hot-packed. Evidence of crystal formation by various salts in the protein matrix of processed cheese products has been reported by many researchers (Rayan et al., 1980; Kalab, 1981; Uhlmann et al., 1984; Cari´c et al., 1985; Bester & Venter, 1986; Cari´c & Kalab, 1987; Kalab et al., 1987; Pommert et al., 1988; Savello et al., 1989; Tamime et al., 1990). As most emulsifying salts are phosphates-based salts, it would be safe to assume that the nature of the crystals is phosphate and citrate complexes, possibly calcium phosphate and/or calcium citrates.

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(a)

(b)

(c)

(d)

297

Fig. 10.25 Cryo-scanning electron microscopy of Cheese-tastic!™ processed cheese food. (a, b) Cheesetastic!™ regular; (c, d) Cheese-tastic!™ light. f with arrow points to a fat globule. Bar size = 30 μm for (a) and (c); bar size = 6 μm for (b) and (d).

Figure 10.26 shows illustrations of salt crystal formation in processed cheese; it is worth noting that the size or the shape of these crystals do not cause any grittiness in the product.

10.7.5 Product development Electron microscopy and other techniques are widely used in product development as supplementary analytical method to minimise processing defects, and some of the reported work follows.

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(a)

(b) Fig. 10.26 Crystal salt (mainly calcium phosphate and sodium citrate, and other types) formation in the protein matrix of processed cheese. (a) Calcium phosphate crystals (ph) in processed cheese (scanning electron microscopy, SEM) cooked for 10 min; void spaces (ci) are the imprints of sodium citrate crystals which had been dissolved in aqueous glutaraldehyde during fixation for SEM; fat (f) is in the process of emulsification, and bacterium (b). (b) Calcium phosphate crystal (ph) in processed cheese (light microscopy) specifically stained for calcium with Alizarin red. (c) Disodium phosphate crystals (i.e. needle-shaped; outgrowth shown by arrows) in processed cheese. (d) Cystallisation takes place when using tetrasodium pyrophosphate (arrows); bacterium (b). (e) Sodium citrate crystals (and a bacterium) in processed cheese spread which also contained degraded protein (dark areas); this image also shows the aqueous phase (light areas) and emulsified fat (left upper corner and the round area below it); a bacterium is found in the aqueous area surrounded by protein above the left end of the micrometre bar. (f and g) Calcium phosphate crystals developing in processed cheese from emulsifying salt sodium phosphate. (h and i) Examples of crystal formation in commercial Cheddar processed cheese: the sheet-like crystal (arrows) are noticeable in (j); (j) SEM of tetrasodium pyrophosphate (TSPP) crystal in the processed cheese protein matrix. (k) Transmission electron microscopy detailing TSPP crystals in processed cheese. (l) Detail of fat particle (F), osmophilic lining (arrow) and calcium salt crystal (C). (m) Electron-dense area (t) developed in processed cheese heated to 82◦ C and using TSPP emulsifying salt; melting salt crystal (C), lactic acid bacteria (m) and dark arrow points to fat particle (f) lining. (After Rayan et al., 1980, Caric´ et al., 1985 and Kalab et al., 1987. Reproduced by permission of Scanning Electron Microscopy, Food Microstructure and M. Kalab.)

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(c)

(d)

(e) Fig. 10.26 (Continued)

299

300

Processed Cheese and Analogues

(f)

(g) Fig. 10.26

(Continued)

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(h)

(i)

(j) Fig. 10.26 (Continued)

301

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Processed Cheese and Analogues

(k)

(l)

(m) Fig. 10.26

(Continued)

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Fat substitutes Fat substitutes (e.g. modified starches and microparticulated whey protein) have been used in dairy and other food products to simulate the functional and organoleptic properties of fat, with substantial reductions in calorific value. Singer (1990) reported the use of Simplesse® as a fat substitute in processed cheese, but comparatively little is known of the effects of different types of fat substitutes on the microstructure of processed cheese. Tamime et al. (1999) reported the use of three types of fat substitutes (Simplesse®, DairyLo™ and Paselli®; the former two types are microparticulated whey protein base, whereas Paselli® is modified starch) for the development of a processed cheese analogue. These ingredients were evident in the microstructure of the analogue products (see Fig. 10.20), but had no influence on acceptability except that the control processed cheese analogue made with anhydrous milk fat (AMF) was highly rated compared with products containing low-fat and fat-substitutes (Muir et al., 1999). White cheese White cheese (i.e. made by coagulating heated milk at 90◦ C with citric acid solution to pH 5.5) is sometimes used as an ingredient during the formulation of the cheese blend. Kalab et al. (1991) studied the effect of using White cheese on the structure, meltability and firmness of processed cheese. In general, White cheese does not melt alone when heated but, when used at a rate of 16 g 100 g−1 to replace natural cheese in the blend with sodium citrate as an emulsifying salt, the product was firmer and the meltability value was similar to the control processed cheese. However, this variety of cheese consists of casein particles, which have a characteristic core-and-shell structure; based on such a characteristic, TEM detected the presence of White cheese in processed cheese (Fig. 10.27). Disruption of the core-and-shell structure was less noticeable in product formulation made with trisodium phosphate than with product made with sodium citrate.

10.7.6 Application of confocal scanning laser microscopy as a quality control tool in processed cheese manufacture Whilst electron microscopy is useful for characterising the morphology of processed cheese products (PCPs) at high resolution, discriminating between ingredients can be difficult. Optical microscopy techniques can be very useful for identifying specific components and their distribution in food products using various stains or fluorescent probes (Heertje et al., 1987; Flint, 1994; Blonk & van Aalst, 1993). Sometimes starch is used in processed cheese formulations and particularly in analogue cheese products (ACPs). Light microscopy can be used to confirm the presence of starch, its distribution and degree of gelatinisation (Figs 10.28 and 10.29). CSLM has become a useful technique for characterising the microstructure of food products including a variety of cheese types (Auty et al., 2001). Fluorescent probes are used to localise the main components of fat and protein. Lasers provide a coherent high-intensity excitation illumination, whilst confocal optics enables imaging of undisturbed regions of the sample ∼10 μm below the cut surface. By using a combination of fluorescent probes and

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Processed Cheese and Analogues

(a)

(b) Fig. 10.27 Processed cheese made with American White cheese. (a) The core-and-shell structure of the casein particles is marked with an asterisk and this structure is very stable. (b) Similar microstructure as in (a) but at higher magnification. Bar size = 1 μm for (a); bar size = 0.5 μm for (b). (After Kalab et al., 1991. Reproduced by permission of M. Kalab personal communication).

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Fig. 10.28 Confocal scanning laser micrograph of processed cheese showing fat droplets (green), continuous protein phase (red) and crystalline inclusions of (a) calcium lactate and (b) calcium phosphate shown by negative contrast. (Source: Moorepark data.) (See Plate 10.2 for colour figure.)

Fig. 10.29 Bright field light micrograph of analogue cheese stained with iodine/potassium iodide solution to reveal gelatinised starch inclusions (black). (Source: Moorepark data.) (See Plate 10.3 for colour figure.)

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Processed Cheese and Analogues

Fig. 10.30 Confocal scanning laser micrograph of analogue cheese showing fat droplets (green), protein phase (red) and presumptive starch inclusions shown by negative contrast. (Source: Moorepark data.) (See Plate 10.4 for colour figure.)

appropriate excitation and emission wavelengths, it is possible to simultaneously localise the distributions of fat and protein in a processed cheese (Figs 10.29 and 10.30). At commercial level, CSLM has been applied to PCPs as a quality control tool for monitoring: • • • •

the degree of emulsification over time, how it is affected by various factors (e.g. formulation ingredients) and how it correlates with corresponding textural changes; the structural changes in fat and protein phases that occur during creaming/overcreaming in PCPs; the presence of non-dairy bioloymers, such as starch; and the presence of crystalline inclusions. These aspects are discussed briefly below.

Degree of fat emulsification During the heating and shearing applied on processing of natural cheese, free oil is released, continually re-dispersed, and emulsified by the casein/para-casein. Compared to natural cheese, the emulsified fat particles (globules) in PCPs are generally smaller and more discrete (with less evidence of clumping/coalescence). The emulsified fat particles are enrobed and stabilised by hydrated casein, which may be considered as a blend of sodium para-caseinate (NaPC) and calcium-phosphate para-caseinate (CPPC), with the ratio of

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NaPC/CPPC increasing with extent of calcium sequestration as affected inter alia by the type and level of emulsifying salt and pH of the PCP/ACP. The size of the fat globules has generally been found to be strongly correlated with the meltability, and inversely with the firmness/rigidity of the resultant processed cheese products (Guinee et al., 2004). This effect has been attributed to an increase in the effective surface area of the protein phase, as the number of emulsified protein-covered fat particles increase. Consequently, changes in degree of fat emulsification using CSLM have been used to assist commercial manufacturers in elucidating the effects of changes in process conditions (e.g. time, temperature) or formulation on textural characteristics of the resultant PCPs. CSLM has shown that increase in processing time at 80◦ C of a typical processed cheese formulation (comprising Cheddar cheese, water, and emulsifying salts) coincided with a progressive reduction in fat globule size (Fig. 10.31) and, as discussed in Chapter 3, a

(a)

(b)

(c)

(d)

Fig. 10.31 Microstructure of experimental processed cheese products after heating to 80◦ C and holding for (a) 1, (b) 16, (c) 24 or (d) 32 min; the cheese were formulated from Cheddar cheese, water and emulsifying salts. (Source: Moorepark data.) (See Plate 10.5 for colour figure.)

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Processed Cheese and Analogues

Flowability-Schreiber method ( %)

350 300 250 200 150 100 50 0

0

5

10

15 20 25 Processing time (min)

30

35

Fig. 10.32 Changes in experimental processed cheeses (as described in Fig. 10.31) with processing time at 80◦ C: flowability on heating the formed product at 180◦ C for 7.5 min, according to modified version of Price-Olson method. (Source: Moorepark data.)

marked increase in the firmness of the resultant cheese but a decrease in the extent of flow on reheating at 280◦ C (Fig. 10.32). Similar trends were observed on increasing the degree of process shear for a standard processing time. The fat globule size changed little on increasing processing temperature from 70 to 80◦ C, but then increased on raising the temperature to 85–90◦ C (Fig. 10.33). However, the heat-induced flow of the resultant processed cheese decreased significantly with processing temperature in the range 70–80◦ C and thereafter changed little; in contrast, the firmness increased gradually with processing temperature (see Chapter 3; Gliguem et al., 2009). Identification of starch Starch is frequently used in PCPs, and particularly in ACPs at typical levels of 1–4 g 100 g−1 . While it is primarily included as a low-cost substitute for rennet-casein or fresh cheese curd, it also imparts certain structuring (e.g. starch structure, phase separation) and texturising functions (e.g. viscosity, controlled melt), depending on the type (e.g. gelatinisation temperature, amylose-to-amylopectin ratio, type/level of modification) and level of starch used, and processing conditions (e.g. temperature, shear). In model cheese analogue systems where the casein is partially replaced by starch on a weight basis, while maintaining a fixed starch plus protein level (e.g. at 22 g 100 g−1 ), increasing starch content is paralleled by an increase in fat globule size and a decrease in heat-induced meltability of the resultant ACPs, as indicated by reductions in tan δ at 80–90◦ C (as measured using low-ampltitude oscillation rheometry) and heat-induced flowability (as measured using the Schreiber-based melt tests) (Mounsey & O’Riordan, 1999, 2001). These effects become more pronounced as the ratio of starch to casein is increased (e.g. from 20:0 to 10:10), especially at total starch concentrations >4 g 100 g−1

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(a)

(b)

(c)

(d)

(e)

(f)

309

Fig. 10.33 Microstructure of experimental pasteurised processed cheese products after holding for 4 min at different temperatures (◦ C): (a) 70, (b) 75, (c) 80, (d) 85, (e) 90 or (f) 95. (Source: Moorepark data.) (See Plate 10.6 for colour figure.)

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Processed Cheese and Analogues

(AiQian & Hewitt, 2009; AiQian et al., 2009). The increase in fat globule size may reflect the dilution in the concentration of casein, and also poorer emulsifying properties of the casein as a consequence of a lower degree of hydration owing to greater competition for water at the higher starch levels. The inverse relationship between fat globule size and meltability or tan δ at increasing starch levels (Mounsey & O’Riordan, 1999; Ye et al., 2009) is opposite to the positive correlation between fat globule size and meltability in ACP without added starch (Guinee et al., 2004; Figs 10.31 and 10.33). The adverse effect of starch on meltability, despite the increase in fat globule size, has been attributed to the formation of thermo-irreversible amylose gel structures in the ACP, via hydrogen bonding-induced reassociation (retrogradation) of amylose molecules, that leach from starch granules into the moisture phase during gelatinisation on cooking/shearing, during cold storage of the formed product (Guinee et al., 1999). Consequently, the degree of melt reduction is generally higher on using starches with a higher amylose-to-amylopectin ratio (Mounsey & O’Riordan, 2008). Ye et al. (2009) suggested that the deterioration in meltability as the starch-to-protein ratio was increased is rooted in phase separation of the starch and casein, which is driven by the thermodynamic incompatibility of the biopolymers (Tolstoguzov, 1995), and leads to a concentration effect of both casein and starch in the binary aqueous phases (casein rich, starch rich). At low starch concentrations (e.g. <3 g 100 g−1 , starch-to-protein ratio 3:17), phase separation resulted in starch forming small inclusions (∼10 μm) uniformly dispersed as a filler within the continuous casein matrix, leading to a relatively small reduction in meltability of the ACP (Ye et al., 2009). However, on raising the starch levels (to >3 g 100 g−1 , starch-to-casein ratio >3:17), the starch occurred increasingly in the form of larger clusters and strands, eventually leading to the formation of a separate continuous starch network (at 7 g 100 g−1 starch). These changes were paralleled by marked increases in the rigidity of the unheated ACP, as indicated by the increase in storage modulus (G ), and significant reductions in fluidity/meltability of the heated product (as measured by tan δ) at temperatures in the range 70–90◦ C. Owing to the impact of starch on the structure–function relationships of PCPs/ACPs, it is important for commercial manufacturers to have an objective method to identify the presence and structure of starch in products. This facilitates the replication of a competitor product and also enables a more systematic approach in optimising the type and level of starch that can be included in formulations subjected to different processing conditions to minimise formulation costs while retaining product functionality. Various types of microscopy have been used to study the changes in microstructure associated with addition of starch, including light microscopy (Noronha et al., 2008), SEM (Mounsey & O’Riordan, 2008), and CSLM using fluorescent dyes excited at differ wavelengths for specific staining of fat (e.g. Nile Blue at 488 nm), protein (Fast Green FCF at 488 nm) and starch (iodine–potassium iodide) (Guinee et al., 1999; Trivedi et al., 2008). Identification of crystalline inclusions A common defect in PCPs and APCs is occurence of crystalline deposits on the surface and interior of processed cheese. Such deposits are visible to the naked eye as a delicate white powdery covering on the surface of the cheese, and sometimes referred to as a haze or bloom. A coating of crystals imparts a dull, grainy, uneven and/or striated appearance to the surface, especially in slices, which is otherwise normally smooth and shiny; hence, products

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containing crystal deposits are not aesthetically pleasing and can sometimes lead to product rejection by the retailer/consumer who may confuse them with mould contamination. Crystalline inclusions are frequently observed by SEM, TEM and CSLM in PCPs (see Fig. 10.28; Pommert et al., 1988; Cari´c & Kal´ab, 1993; Kal´ab, 1995). Analysis using various techniques such as X-ray diffraction analysis, infrared spectroscopy and energy dispersive X-ray spectrometry analysis indicates the presence of several types, including calcium pyrophosphate dihydrate, disodium phosphate dodecahydrate, unreacted melting salts, tyrosine, calcium citrate, lactose and complexes of various materials, such as calcium, fatty acids, protein and lactose (Guinee et al., 2004).

10.8 Sensory profiling of processed cheese The decision to purchase any food product is influenced by many factors, including perceived healthiness, packaging and value for money. Nevertheless, if the sensory profile (appearance, smell, flavour and mouth-feel) do not match, or exceed, the customer’s expectations, the product will fail in the marketplace. Sensory profiling of food can be a powerful tool in other ways. It allows products to be classed into type. For example, cheese spreads may be differentiated from one another. Profiling can be useful in establishing brand identity and in positioning new products. Moreover, it is essential for matching existing products. The objectives of this section are to provide practical guidance on methods for profiling the sensory properties of processed cheese. Although the methodology refers to processed cheese, it is directly transferable to other foodstuffs. Theoretical considerations of sensory profiling will not be discussed in depth, but can be probed further by reference to Stone and Sidel (1993).

10.8.1 Elements of sensory assessment Sensory profiling is an objective technique. Although it uses human assessors as the measuring instruments, when implemented in a rigorous and structured way the end-results have confidence limits comparable with physicochemical measurements of comparable complexity. There are four key elements common to any analytical procedure: •

• •

•

The property of the object being assessed must be defined. This may be a comparatively simple measurement, such as salt content or a more complex characteristic like rheological profile. In sensory terms, the properties to be assessed are the sensory attributes and together they comprise a sensory vocabulary. Sample preparation and presentation to the measuring instrument are a key element of any analytical procedure. This is the protocol for sensory assessment. The measuring instrument must be calibrated. Assessors must be selected and trained. In addition, the ‘calibration factor’ of the measuring instrument, irrespective of type, must be monitored. The unadjusted output of the analytical device is converted into an index or indices, which have practical utility. In sensory terms, data might take the form of ratings for a series of attributes or an overall picture in the form of a sensory space map.

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10.8.2 Assessor selection Internal versus external panels Assessor selection poses an important dilemma. Ideally, a sensory panel should be made up of independent specialists, chosen for their sensory acuity and with no competing duties. However, the direct costs of employing an external panel may preclude this course of action and the panel may have to be drawn from staff of the organisation. This course of action has two disadvantages. First, it is inevitable that other duties within the organisation will deny the employee freedom to attend the panel sessions when required. Second, a smaller pool of prospective candidates will be available from which to make a selection. Nevertheless, irrespective of whether the panel is selected from outside or within the organisation, certain basic selection should be used to optimise performance. Pre-selection The initial selection should be based on a questionnaire. The following details should be ascertained. • •

•

• •

The age and sex of the prospective assessor should be established. This information is used to attain the required balance of sex and age distribution. The general health of the applicant should be gently probed. These questions are necessary to ensure that medication does not interfere with the assessor’s performance, or prejudice an existing medical condition. Smokers of tobacco should be excluded because there is conclusive evidence that smoking prejudices sensory acuity. For example, smokers are usually insensitive to bitterness. To avoid other difficulties, assessors with moral or religious objections to consumption of certain types of food or beverage should also be excluded from a panel. The attitude of prospective panellists to consumption of a wide range of contrasting types of food and beverage should be established by questionnaire.

This basic information allows pre-selection of assessors with few potential problems and with an open mind. Initial testing Potential assessors, who satisfy all the pre-selection criteria, should be invited to the laboratory for an intensive series of tests. On arrival, the candidates should be welcomed, and every attempt should be made to relieve their inevitable stress. It should be emphasised to them that there is a wide distribution of ability to taste and to smell food products, and that there is no stigma attached if their senses should be found lacking. It should also be explained that the tests will take place in an isolated booth within the sensory laboratory, and that they will be invited to perform a series of simple tasks.

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Sense of taste The first series of tests are designed to establish that the assessor has sensitive taste receptors, and can detect the basic tastes: sweet, salt, sour and bitter. Assessors are presented with a set of four solutions (of sucrose, table salt, citric acid and caffeine), and are asked to taste them in the order of increasing intensity. After tasting each sample and before tasting the next, they should record the taste they detect, if any. Assessors who cannot detect a particular stimulus at five times the threshold concentration are unsuitable and should not be considered further. If a choice of assessors of equivalent sensitivity is available, the test should be repeated and assessors with the best overall performance chosen for further testing. Sense of smell The next test is designed to establish that assessors have a sensitive sense of smell. Samples of Danish Blue, Parmesan and Edam are finely grated and opaque containers with airtight lids are half filled with grated cheese, completely covered with a layer of cotton wool and the container sealed. The sealed containers are equilibrated for at least an hour at room temperature. A series of tests should be carried out in which the assessor is presented with five randomly coded containers. Three containers should be of one variety and two of another. Three sets of five containers should be prepared: (a) Set 1 of Danish Blue versus Parmesan, (b) Set 2 of Danish Blue versus Edam, and (c) Set 3 of Edam versus Parmesan. Assessors are presented with each set in turn and asked to classify the samples within each set into two groups. Assessors should be expected to correctly classify all samples. However, a single misclassification may be accepted. Successful assessors pass on to the next test. Ability to rank samples The third test establishes the ability of the assessor to rank samples in order of flavour intensity. A set of four processed cheese samples representing different levels of flavour intensity are presented to the assessor, who is asked to rank the samples in ascending order of acidity. Once again, assessors should be able to perform this task without error. A single mistake may be allowed. Descriptive ability Finally, assessors are presented with a set of four samples of processed cheese (extra lowfat, low-fat, and two contrasting samples of normal fat product) and invited to describe the main characteristic of each sample. This test is less objective than the initial three evaluations, but establishes whether an assessor is capable of intelligent description of an unknown product.

10.8.3 Acclimatisation and confirmation Assessors who perform adequately in the above series of tests are recruited to the panel for a 3- or 6-month probationary period. During this time, the probationer is familiarised

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with the established protocols used in the laboratory, and their performance is continually assessed (Hunter & Muir, 1997).

10.8.4 Sensory vocabulary General principles The construction of a sensory vocabulary for a class of food (i.e. yoghurt, processed cheese, butter, raspberries or coffee) is not straightforward. The end use of the results of the profiling determines the complexity of the vocabulary. For example, where profiling is used to monitor the quality of a distinct product, such as a single well-defined cheese variety, the list of attributes may be long to reflect the fine detail required. On the other hand, where a broad-brush but discriminant picture is required, a shortened vocabulary may be appropriate (Hunter & Muir, 1993; Muir et al., 1994, 1995; Hunter et al., 1998). Methods are available to refine complex vocabularies into their essential elements, and some success has been achieved in constructing vocabularies that have utility in an international context (Muir et al., 1997a; Nielsen et al., 1997). An efficient vocabulary should describe all the properties of the product, such as appearance, smell, flavour and mouth-feel. It should give equal balance to ‘good’ and ‘bad’ attributes. Vocabularies based only on product deficiencies when compared to a standard may have limited use in quality assurance but discount product of a superior profile to the standard. The vocabulary should be precise. There should be no ambiguity in the interpretation of terms, at least among the panel of assessors and the end users of the sensory information. Finally, vocabularies should be capable of evolution. For example, if a new stimulus is profiled and the assessors detect an attribute which is currently absent from the list of terms, a mechanism should be in place to incorporate this new attribute within the vocabulary. Moreover, where ratings for a particular attribute are consistently low and do not discriminate between samples, the attribute should be deleted from the vocabulary. A working vocabulary for processed cheese A vocabulary that has been useful for characterising different varieties of processed cheese is shown in Table 10.5. Evolution of the vocabulary Inclusion of the term ‘other’ is a valuable aid in ensuring that the vocabulary is comprehensive. Assessors are invited to describe any attribute of the test sample not included in the vocabulary, and to rate the intensity of the additional attribute. The results are inspected and if a number of assessors independently define a new attribute and if the ratings are significantly greater than zero, the additional term may be added to the vocabulary. The ability of this new attribute to provide useful information about the sensory profile of further sample sets is assessed and, if found useful, the new term is promoted to the main vocabulary.

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Table 10.5 Sensory vocabulary for processed cheese. Flavour

Mouth-feel

Overall intensity

Grainy

Creamy

Sticky

Salty

Mouth-coating

Acid/sour

Melt-in-the-mouth

Buttery

Fatty/greasy

Bitter

General

Other

Overall intensity

Aftertaste

Perceived spreadability

Overall intensity Persistence Source: adapted from Muir et al. (1997b).

10.8.5 Tasting protocol Environment Attention must be paid to the protocol for evaluation of samples. The key objective is to present the stimulus to the assessor in stress-free circumstances with no distractions. The environment must be clean and comfortable. The temperature, lighting and air supply should be controlled. Fresh, odour-free conditions are essential (Stone & Sidel, 1993). Isolation Assessors must be isolated from each other. Even where no vocal contact is made, the sight of a fellow judge grimacing as a sample is consumed can bias results. Rating of samples Rating of the attributes should be simple. When paper forms are used, a scale of length 125–150 mm is appropriate. Experience has shown that given appropriate anchor points (absent, extremely strong) assessors can be trained to use such scales with consistency. An example of a scale is shown below: ‘Please mark the scale according to how bitter the sample tastes Absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Extremely bitter Now rinse your palate with a plain biscuit and some cold water before assessing the next sample’

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Table 10.6

Serving order to allow for order of tasting. Serving order within and between sessions

Judge

1st replicate

2nd replicate

3rd replicate

4th replicate

1

1

2

3

4

3

2

4

1

2

3

1

4

4

2

1

3

2

2

4

1

3

2

1

3

4

3

4

2

1

1

4

3

2

3

3

1

4

2

4

3

1

2

1

2

4

3

3

4

1

2

4

4

3

2

1

1

4

2

3

4

1

3

2

4

2

3

1

5

2

3

4

1

3

2

1

4

1

2

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4

1

3

2

4

6

3

1

2

4

2

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1

2

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1

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2

1

4

3

7

4

2

1

3

1

3

4

2

3

1

4

2

4

1

2

3

8

1

4

3

2

4

1

2

3

4

3

2

1

1

3

4

2

9

3

4

1

2

2

1

4

3

2

3

4

1

2

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3

1

10

4

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Presentation order The presentation of test samples is critical. The assessor should not be able to identify the test subject by virtue of its coding and, if possible, care should be taken in the coding itself. For, example, the use of ‘A’, ‘B’ and ‘C’ as codes may subliminally order the samples in the assessor’s mind. In addition, the order of presentation of samples for assessment should be arranged to allow estimation of (and allowance to be made for) order of tasting effects. These effects are well documented, and strategies for evaluation have been advanced for both sensory testing with a trained panel (Muir & Hunter, 1991/2; Lavanchy et al., 1994) and preference evaluation using large consumer panels (MacFie et al., 1989). In contrast to presenting samples in random order, presentation is arranged such that every sample is assessed an equal number of times in each of the possible orders. By basing the design on that of a William’s Latin Square, information on first-order carryover effects can also be deduced (Williams, 1949). A corollary to this approach is that samples are evaluated one at a time in a predetermined order. An example of design balanced for order is shown in Table 10.6. Care must be taken to avoid operator fatigue. Sessions in which four samples are evaluated present no difficulty to an experienced assessor. However, if the test material is very strongly flavoured, it is more appropriate to reduce the number of samples tested in a single session. Consumption of a plain water biscuit or segment of apple followed by rinsing the mouth with cold clean water effectively moderates the effect of carryover. Water quality is important: soft or deionised still water should be used.

10.8.6 Analysis and interpretation of data Preliminary treatment The first stage of data analysis is to extract panel mean values for attribute by sample ratings unbiased for assessor, session and order of tasting. This is readily achieved by carrying out

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Table 10.7 Sample table of mean attribute ratings. Sample

Base type

‘Lipid’

Creamy flavour

Melt-in-the mouth

1

Retentate

2

Retentate

Anhydrous milk fat

50.6

63.6

Paselli®

41.9

52.6

3

Retentate

Dairy-Lo™

46.5

61.3

4

Retentate

Simplesse®

46.1

57.0

5

Powder

Anhydrous milk fat

49.6

60.6

6

Powder

Paselli®

36.0

49.2

7

Powder

Dairy-Lo™

37.4

50.6

Powder

Simplesse®

38.5

53.7

8

Standard error of difference of means

2.56

1.61

Source: Adapted from Tamime et al. (1999).

an analysis of variance. Because there is inevitably some degree of imbalance, it is most appropriate to apply a routine designed for such eventuality, such as the General Linear Model in Minitab (Minitab Inc., Quality Plaza, 1829 Pine Hall Rd, State College, PA 16 801-3008, USA). Further analysis may then be carried out to establish the significance of treatment effects. An example is shown in Table 10.7. Systems have been developed that integrate design, data capture and analysis of data (Williams et al., 1996; see also Muir & Hunter, 1992a,b; Muir et al., 1997a). Sensory space maps More powerful ways of representing differences between samples rely on the construction of sensory space maps. These maps may encompass all the attributes profiled or may focus on a single modality, e.g. flavour or mouth-feel. The starting point for these maps is a series of locations (one for each sample) in a notional multidimensional space where the number of dimensions equals the number of attributes. Most observers are incapable of visualising locations within spaces of more than three dimensions, and many people are comfortable only with two. This problem is resolved by simplifying the results and projecting higher dimensions onto a two-dimensional space. Principal components analysis (PCA) is a readily accessible routine for achieving this end, and a suitable routine is available within the Minitab suite of statistical software. PCA relies on assessors rating samples according to a common vocabulary and sensory maps produced by this route are usually straightforward to interpret. Principal components analysis PCA is a statistical technique that extracts a small number of latent factors to explain the major variation in a dataset. For example, a large attribute set (e.g. 24 attribute ratings) might be reduced into a small number of latent factors, typically less than five, called principal components (PC) that explain the main variance within the attribute ratings.

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Each PC is orthogonal, i.e. uncorrelated, to the other PCs, and each PC is described by a linear combination of all attributes of the form: PC score = v1 (rating1 ) + v2 (rating2 ) + · · · + vn (ratingn )

[10.1]

where v represents vector loading, and ratings are sample ratings for up to n attributes. The PCs are extracted in a hierarchical manner. The first PC is computed to maximise the variance explained. This information is then subtracted from the initial data matrix, and a second PC is derived from the residuals. Further PCs are derived in the same way. Clearly the residuals comprise both structured information and noise. The initial dimensions therefore have a higher information content than the later PCs. Selection of the appropriate number of PCs to explain the maximum amount of variance can be carried out in several ways. The simplest technique involves inspection of a scree diagram, i.e. a plot of variance explained as a function of the number of PCs. A more objective assessment can be made by using a validation method (test set, leverage correction or cross-validation). Each test sample has a unique set of values for the attribute ratings. Substitution of these ratings into equation [10.1] yields a score for each sample on that PC. The sample scores are used to construct sensory space maps. Clearly, samples will be located close together in sensory space only if their scores on the relevant PCs are similar. An example of a sensory space map is shown in Fig. 10.34. Samples of processed cheese were manufactured using either milk retentate or reconstituted SMP as the base together with one of four sources of ‘lipid’ (Muir et al., 1999; Tamime et al., 1999). The control sample contained AMFas the lipid source whilst the other three samples incorporated well-known fat replacers or mimetics. The sensory analysis yielded a table of mean values comprising 8 sample and 13 attribute values. PCA reduced this matrix to two PCs explaining 70.8 and 19.5% of the variance. The first PC was a complex combination of the attributes: bitter, buttery, creamy, flavour intensity and persistence of aftertaste, whilst the second PC was dominated by fatty/greasy mouth-feel.

Powder Anhydrous milk fat Dairy-Lo Paselli Simplesse

4 3

PC1score

2 1

Retentate Anhydrous milk fat Dairy-Lo Paselli Simplesse

0 −1 −2 −3 −4 −3

−2

−1

0 PC2 score

1

2

Fig. 10.34 Sensory space map showing relative orientation of samples of processed cheese in sensory space based on scores on first and second principal components.

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As shown in Fig. 10.34, there was clearly a significant difference between the samples in which retentate was the base when compared to powder. However, the differences between processed cheeses made using different lipid sources were less clear-cut.

10.9 Conclusions If the essential requirements for manufacturing a high-quality processed cheese and analogues were to be considered and as reviewed in this chapter, then it is likely that the most important aspects may be summarised as follows: • • • •

the quality of natural cheeses and other dairy ingredients are of good standard (i.e. adequate chemical composition and microbiological quality); correct heat treatment and processing conditions of the cheese blend; a clean and well-maintained processing plant and packaging equipment; correct storage of retail product at ambient or refrigerated storage, i.e. 5◦ C.

What is important about these aspects is that all these areas should form part of the commitment to GMP and application of an HACCP system to monitor the quality of the end-product. The actual degree of surveillance will vary in the light of experience in a particular plant, but the principle remains the same, namely that someone in authority must have an accurate picture of the entire operation, for without this the smooth running of the plant and the quality of the end-product will be at risk. In addition, the techniques for bacteriological enumeration of microorganisms have been universally standardised and accepted by the majority of government authorities worldwide. The primary factor that should be considered when determining the ideal testing method is the purpose of the analysis (i.e. quality control testing, at-line testing, rheological characterisation). Other factors that should be considered are time constraints, analysis expertise and available equipment. In an ideal situation a simple, rapid, low-cost method is utilised. However, although significant progress has been made on measurement of the functional properties of processed cheese, the available testing techniques still have some limitations. In general, there are rheological-based methods that provide critical and accurate data, but they require expensive equipment and are time-consuming to perform. In contrast, the available empirical-based methods provide crude results, but are simple to perform and do not require expensive equipment (Kapoor et al., 2007). A variety of light, confocal and electron microscopy techniques are now available for assessing processed cheese quality. The distribution of fat, polysaccharides and protein can be effectively characterised using light and confocal microscopy. TEM and highresolution cryo-SEM reveal details of the protein matrix and fat–protein interface that can help explain differences in fat emulsification and rheological properties. Perennial manufacturing problems, such as poor mixing, fat destabilisation, protein aggregation and buffer salt recrystallisation, can be rapidly characterised by relatively simple light and confocal microscopy techniques. Combining these techniques with electron microscopy provides a powerful set of tools for characterising processed cheese microstructure and how it influences product functionality and quality. A thorough understanding of the effect of composition, process parameters and storage on processed cheese quality therefore

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requires a multidisciplinary approach that incorporates microscopy with more established physical and chemical analyses. The four main elements of sensory characterisation apply to processed cheese. First, a trained panel of assessors is recruited, second a suitable environment is secured for product assessment, third a vocabulary of attributes describing the character of the cheese is assembled and, finally, a method of presentation of the results is devised. Methods of achieving these ends have been described and, if carefully applied, provide an effective means of assessing sensory character.

10.10 Acknowledgements Two of us (M.W. and J.D.) would like to thank SERTOP Ltd. (processed cheese manufacturing company in Tychy) for their kind assistance and allowing us to take some of the photographs that illustrate this chapter.

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ICMSF (2006) Microorganisms in Foods 7 , International Commission on Microbiological Specifications in Foods, University of Toronto Press, Toronto. IDF (1964a) Determination of the Fat Content in Butteroil , Standard 24, International Dairy Federation, Brussels. IDF (1964b) Determination of the Ash Content of Processed Cheese, Standard 27, International Dairy Federation, Brussels. IDF (1966) Standard Method to Count Lipolytic Organisms, Standard 41, International Dairy Federation, Brussels. IDF (1979) Caseins and Caseinates: Determination of Protein Content, Standard 92, International Dairy Federation, Brussels. IDF (1981a) Dried Milk: Determination of Titratable Acidity (Reference Method), Standard 86, International Dairy Federation, Brussels. IDF (1981b) Dried Milk: Determination of Titratable Acidity (Routine Method), Standard 81, International Dairy Federation, Brussels. IDF (1987a) Dried Milk, Dried Whey, Dried Buttermilk and Dried Butter Serum: Determination of Fat (R¨ose-Gottlieb Reference Method), Standard 9, International Dairy Federation, Brussels. IDF (1987b) Cream: Determination of Fat Content (R¨ose-Gottlieb Reference Method), Standard 16C, International Dairy Federation, Brussels. IDF (1987c) Cheese and Processed Cheese Products: Determination of Total Phosphorus Content , Standard 33C, International Dairy Federation, Brussels. IDF (1992) Milk and Milk Products – Sampling – Inspection of Variables, Standard 136A, International Dairy Federation, Brussels. IDF (1995) Milk and Milk Products: Guidance on Methods of Sampling, Standard 50C, International Dairy Federation, Brussels. IDF (1997a) Guidelines for Hygienic Design and Maintenance of Dairy Buildings and Services, Document No. 324, International Dairy Federation, Brussels. IDF (1997b) Sensory Evaluation of Dairy Products by Scoring (Reference Method), Standard 99C, International Dairy Federation, Brussels. IDF (1997c) Milk and Milk Products: Determination of the Fat Content , Standard 152A, International Dairy Federation, Brussels. IDF (2001a) Butter: Determination of Moisture, Non-Fat Solids and Fat Contents, Standard 80-1, Part 1: Determination of moisture content (reference method), International Dairy Federation, Brussels. IDF (2001b) Butter - Determination of Moisture, Non-Fat Solids and Fat Contents, Standard 80-2, Part 2: Determination of non-fat solids content (reference method), International Dairy Federation, Brussels. IDF (2001c) Milk and Milk Products: Detection of Salmonella, Standard 93, International Dairy Federation, Brussels. IDF (2002a) Milk Fat Products: Determination of Water Content (Karl Fischer Method), Standard 23, International Dairy Federation, Brussels. IDF (2002b) Dried Milk, Dried Ice-Mixes and Processed Cheese: Determination of Lactose Content , Standard 79-1, Part 1: Enzymatic method utilizing the glucose moiety of lactose, International Dairy Federation, Brussels. IDF (2002c) Dried Milk, Dried Ice-Mixes and Processed Cheese: Determination of Lactose Content , Standard 79-2, Part 2: Enzymatic method utilizing the galactose moiety of lactose, International Dairy Federation, Brussels. IDF (2002d) Milk and Milk Products: Determination of Nitrogen Content , Standard 185, International Dairy Federation, Brussels. IDF (2002e) Butter, Fermented Milks and Fresh Cheese: Enumeration of contaminating microorganisms, Standard 153, Colony Count Technique at 30◦ C, International Dairy Federation, Brussels. IDF (2003a) Butter: Determination of Moisture, Non-Fat Solids and Fat Contents, Standard 80-3, Part 3: Calculation of fat content, International Dairy Federation, Brussels.

326

Processed Cheese and Analogues

IDF (2003b) Butter, Edible Oil Emulsions and Spreadable Fats: Determination of Fat Content (Reference Method), Standard 194, International Dairy Federation, Brussels. IDF (2003c) Yoghurt: Enumeration of Characteristic Micro-organisms, Standard 117, Colony count technique at 37◦ C, International Dairy Federation, Brussels. IDF (2004a) Cheese and Processed Cheese: Determination of Total Solid Content (Reference Method), Standard 4, International Dairy Federation, Brussels. IDF (2004b) Cheese and Processed Cheese: Determination of Fat Content Gravimetric Method (Reference Method), Standard 5, International Dairy Federation, Brussels. IDF (2004c) Milkfat Products and Butter: Determination of Fat Acidity, Standard 6, International Dairy Federation, Brussels. IDF (2004d) Butter: Determination of Salt Content , Standard 12, International Dairy Federation, Brussels. IDF (2004e) Dried Milk: Determination of Moisture Content , Standard 26, International Dairy Federation, Brussels. IDF (2004f) Milk and Milk Products: Enumeration of Colony Forming Units of Yeast and/or Moulds, Standard 94, International Dairy Federation, Brussels. IDF (2004g) Caseins and Caseinates: Determination of Lactose Content (Photometric Method), Standard 106, International Dairy Federation, Brussels. IDF (2004h) Milk and Milk Products – Sampling – Inspection by Attributes, Standard 113, International Dairy Federation, Brussels. IDF (2004i) Dairy Plant – Hygiene Conditions – General Guidance on Inspection and Sampling Procedures, Standard 121, International Dairy Federation, Brussels. IDF (2004j) Caseins and Caseinates – Determination of Fat Content – Gravimetric Method (Reference Method), Standard 127, International Dairy Federation, Brussels. IDF (2004k) Butter: Determination of Salt Content (Potentiometric Method), Standard 179, International Dairy Federation, Brussels. IDF (2004l) Butter: Determination of Moisture, Non-Fat Solids and Fat Contents (Routine Methods), Standard 191-1, Part 1: Determination of moisture content, International Dairy Federation, Brussels. IDF (2004m) Butter: Determination of Moisture, Non-Fat Solids and Fat Contents (Routine Methods), Standard 191-2, Part 2: Determination of non-fat solids content, International Dairy Federation, Brussels. IDF (2004n) Butter: Determination of Moisture, Non-Fat Solids and Fat Contents (Routine Methods), Standard 191-3, Part 3: Determination of fat content, International Dairy Federation, Brussels. IDF (2004o) Milk: Enumeration of Microorganisms, Standard 131, Plate loop technique at 30◦ C, International Dairy Federation, Brussels. IDF (2004p) Milk: Estimation of Psychrotrophic Micro-organisms, Standard 132, Colony-count technique at 21◦ C, International Dairy Federation, Brussels. IDF (2005a) Dried Milk: Determination of Lactic Acid and Lactates, Standard 69, International Dairy Federation, Brussels. IDF (2005b) Milk and Milk Products: Quality Control in Microbiological Laboratories, Standard 169-1, Part 1: Analyst performance assessment for colony counts, International Dairy Federation, Brussels. IDF (2005c) Quality Control in Microbiological Laboratories, Standard 169-2, Part 2: Determination of the reliability of colony counts of parallel plates and subsequent dilution steps, International Dairy Federation, Brussels. IDF (2005d) Milk: Enumeration of Colony Forming Units of Psychrotrophic Micro-organisms, Standard 101, Colony count technique at 6.5◦ C, International Dairy Federation, Brussels. IDF (2005e) Milk and Milk Products: Enumeration of Presumptive Escherichia coli, Standard 170-1, Part 1: Most probable number technique using 4 methylumbelliferyl-β-d-glucuronide (MUG), International Dairy Federation, Brussels.

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IDF (2005f) Milk and Milk powder – Determination of Aflatoxin M1 Content – Clean-up by Immunoaffinity Chromatography and Determination by Thin-Layer Chromatography, Standard 190, International Dairy Federation, Brussels. IDF (2005f) Milk and Milk Products: Enumeration of Presumptive Escherichia coli, Standard 1702, Part 2: Colony-count technique at 44◦ C using membranes, International Dairy Federation, Brussels. IDF (2006a) Cheese and Processed Cheese Products: Determination of Citric Acid Content (Enzymatic Method), Standard 34, International Dairy Federation, Brussels. IDF (2006b) Processed Cheese and Processed Cheese Products, Standard 52, International Dairy Federation, Brussels. IDF (2006c) Casein and Caseinates: Determination of Moisture Content (Reference Method), Standard 78, International Dairy Federation, Brussels. IDF (2006d) Cheese and Processed Cheese Products: Determination of Chloride Content (Potentiometric Titration Method), Standard 88, International Dairy Federation, Brussels. IDF (2006e) Milk Products: Guidelines for the Application of Near Infrared Spectrometry, Standard 201, International Dairy Federation, Brussels. IDF (2006f) Milk and Milk products: Specification of Mojonnier-type Fat Extraction Flask , Standard 219, International Dairy Federation, Brussels. IDF (2006g) Milk, Milk Products and Mesophilic Starter Cultures: Enumeration of Citrate-fermenting Lactic Acid Bacteria, Standard 180, Colony count technique at 25◦ C, International Dairy Federation, Brussels. IDF (2006h) Milk products: Enumeration of Presumptive Lactobacillus acidophilus on a Selective Medium, Standard 192, Colony count technique at 37◦ C, International Dairy Federation, Brussels. IDF (2006i) Milk and Milk-based Products: Detection of Thermonuclease Produced by Coagulasepositive Staphylococci , Standard 83, International Dairy Federation, Brussels. IDF (2006j) Milk and milk products: Detection of Enterobacter sakazakii, Standard 210, International Dairy Federation, Brussels. IDF (2007a) Milk and Milk Products: Determination of Calcium, Sodium, Potassium and Magnesium Contents (Atomic Absorption Spectrometric Method), Standard 119, International Dairy Federation, Brussels. IDF (2007b) Cheese, Cheese Rind and Processed Cheese: Determination of Natamycin Content , Standard 140-1, Part 1: Molecular absorption spectrometric method for cheese rind, International Dairy Federation, Brussels. IDF (2007c) Cheese, Cheese Rind and Processed Cheese: Determination of Natamycin Content , Standard 140-2, Part 2: High-performance liquid chromatography for cheese, cheese rind and processed cheese, International Dairy Federation, Brussels. IDF (2007d) Milk and Milk Products Determination of Lactose Content by High-Performance Liquid Chromatography (Reference Method), Standard 198, International Dairy Federation, Brussels. IDF (2008a) Dried Milk and Dried Milk Products – Determination of Fat – Gravimetric Method (Reference Method), Standard 6, International Dairy Federation, Brussels. IDF (2008b) Cream: Determination of Fat Content – Gravimetric Method (Reference Method), Standard 16, International Dairy Federation, Brussels. IDF (2008c) Processed Cheese Products: Determination of Nitrogen Content and Crude Protein Calculation – Kjeldahl Method (Reference Method), Standard 25, International Dairy Federation, Brussels. IDF (2008d) Milk and Milk Products: Guidance on Sampling, Standard 50, International Dairy Federation, Brussels. IDF (2008e) Casein: Determination of ‘Fixed Ash’ (Reference Method), Standard 89, International Dairy Federation, Brussels. IDF (2008f) Rennet Caseins and Caseinates: Determination of Ash (Reference Method), Standard 90, International Dairy Federation, Brussels.

328

Processed Cheese and Analogues

IDF (2008g) Casein: Determination of Free Acidity (Reference Method), Standard 91, International Dairy Federation, Brussels. IDF (2008h) Milk and Milk Products: Determination of Nitrate Content – Method by Enzymatic Reduction and Molecular Absorption Spectrometry After Griess Reaction (Reference Method), Standard 197, International Dairy Federation, Brussels. IDF (2008i) Cheese: Determination of Fat Content – Butyrometric for Van Gulik Method , Standard 221, International Dairy Federation, Brussels. IDF (2008j) Cheese: Determination of Fat Content – Van Gulik Method , Standard 222, International Dairy Federation, Brussels. IDF (2008k) Milk and Milk Products: Guidance on Sampling, Standard 50, International Dairy Federation, Brussels. IDF (2009a) Milk Products: Determination of the Acidification Activity of Dairy Cultures by Continuous pH measurement (CpH), Standard 213, International Dairy Federation, Brussels. IDF (2009b) Milk and Milk Products: Method for the Enumeration of Pseudomonas spp., Standard 225, International Dairy Federation, Brussels. IDF (2009c) Dried Milk: Enumeration of the Specially Thermoresistant Spores of Thermophilic Bacteria, Standard 228, International Dairy Federation, Brussels. IDF (2010a) Milk Products: Enumeration of Presumptive Bifidobacteria, Standard 220, International Dairy Federation, Brussels. IDF (2010b) Fermented Milk Products-Bacterial Starter Cultures-Standard of Identity, Standard 149, International Dairy Federation, Brussels. Ingham, S., Larson, A., Smukowski, M., Houck, K., Johnson, E., Johnson, M. & Bishop, R. (1997) Potential uses of microbiological testing in cheese plant HACCP and quality assurance systems. Dairy, Food and Environmental Sanitation, 17, 774–780. Ingham, S.C., Hassler, J.R., Tsai, Y.-W. & Ingham, B.H. (1998) Differentiation of lactate-fermenting, gas-producing Clostridium ssp. isolated from milk. International Journal of Food Microbiology, 43, 173–183. ISI (2007) European Communities (Drinking Water) (NO. 2) Regulations S.I. No. 278, 2007 , Government Publications Sale Office, Sun Alliance House, Dublin 2. ISO (1996) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Detection and Enumeration of Listeria monocytogenes, Standard 11290, Part 1: Detection method, International Standards Organization, Geneva. ISO (1998a) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Enumeration of Mesophilic Lactic Acid Bacteria, Standard 15214, Colony-count technique at 30◦ C, International Standards Organization, Geneva. ISO (1998b) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Detection and Enumeration of Listeria monocytogenes, Standard 11290, Part 2: Enumeration method, International Standards Organization, Geneva. ISO (1999a) Microbiology of Food and Animal Feeding Stuffs: Preparation of Test Samples, Initial Suspension and Decimal Dilutions for Microbiological Examination, Standard 6887, Part 1: General rules for the preparation of the initial suspension and decimal dilutions, International Standards Organization, Geneva. ISO (1999b) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Enumeration of Coagulase-Positive Staphylococci (Staphylococcus aureus and other species), Standard 6888, Part 1: Technique using Baird-Parker agar medium, Standard 8870, International Standards Organization, Geneva. ISO (1999c) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Enumeration of Coagulase-Positive Staphylococci ( Staphylococcus aureus and other species), Standard 6888, Part 2: Technique using rabbit plasma fibrinogen agar medium, International Standards Organization, Geneva.

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ISO (2001a) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Enumeration of Psychrotrophic Microorganisms, Standard 17410, International Standards Organization, Geneva. ISO (2001b) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Enumeration of Beta-Glucuronidase-Positive Escherichia coli, Standard 16649, Part 1: Colony-count technique at 44◦ C using membranes and 5-bromo-4-chloro-3-indolyl beta-D-glucuronide, International Standards Organization, Geneva. ISO (2001c) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Enumeration of Beta-Glucuronidase-Positive Escherichia coli, Standard 16649, Part 2: Colony-count technique at 44◦ C using 5-bromo-4-chloro-3-indolyl beta-D-glucuronide, International Standards Organization, Geneva. ISO (2001d) Milk and Milk Products: Detection of Salmonella spp., Standard 6785, International Standards Organization, Geneva. ISO (2001e) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Detection of Escherichia coli O157, Standard 16654, International Standards Organization, Geneva. ISO (2002a) Butter, Fermented Milks and Fresh Cheese: Enumeration of Contaminating Microorganisms, Standard 13559, Colony-count technique at 30◦ C, International Standards Organization, Geneva. ISO (2002b) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Detection of Salmonella spp., Standard 6579, International Standards Organization, Geneva. ISO (2003a) Microbiology of Food and Animal Feeding Stuffs: Protocol for the Validation of Alternative Methods, Standard 16140, International Standards Organization, Geneva. ISO (2003b) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Enumeration of Microorganisms, Standard 4833, Colony-count technique at 30◦ C, International Standards Organization, Geneva. ISO (2003c) Yoghurt: Enumeration of Characteristic Microorganisms, Standard 7889, Colony-count technique at 37◦ C, International Standards Organization, Geneva. ISO (2003d) Yoghurt: Identification of Characteristic Microorganisms ( Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus), Standard 9232, International Standards Organization, Geneva. ISO (2003e) Inclusion of Precision Data, Standard 6888-1:1999/Amd 1:2003, International Standards Organization, Geneva. ISO (2003f) Inclusion of Precision Data, Standard 6888-2:1999/Amd 1:2003, International Standards Organization, Geneva. ISO (2003g) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Enumeration of Coagulase-Positive Staphylococci ( Staphylococcus aureus and other species), Standard 6888, Part 3: Detection and MPN technique for low numbers, International Standards Organization, Geneva. ISO (2003h) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Detection of Presumptive Pathogenic Yersinia enterocolitica, Standard 10273, International Standards Organization, Geneva. ISO (2003i) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Enumeration of Sulfite, Standard 15213, Reducing bacteria growing under anaerobic conditions, International Standards Organization, Geneva. ISO (2004a) Milk and Milk Products: Enumeration of Colony-Forming Units of Yeasts and/or Moulds, Standard 6611, Colony-count technique at 25◦ C, International Standards Organization, Geneva. ISO (2004b) Milk: Enumeration of Microorganisms, Standard 8553, Plate-loop technique at 30◦ C, International Standards Organization, Geneva. ISO (2004c) Milk: Estimation of Psychrotrophic Microorganisms, Standard 8552, Colony-count technique at 21◦ C (Rapid method), International Standards Organization, Geneva.

330

Processed Cheese and Analogues

ISO (2004d) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Enumeration of Presumptive Bacillus cereus, Standard 7932, Colony-count technique at 30◦ C, International Standards Organization, Geneva. ISO (2004e) Microbiology of Food and Animal Feeding Stuffs: Horizontal Methods for the Detection and Enumeration of Enterobacteriaceae, Standard 21528, Part 1: Detection and enumeration by MPN technique with pre-enrichment, International Standards Organization, Geneva. ISO (2004f) Microbiology of Food and Animal Feeding Stuffs: Horizontal Methods for the Detection and Enumeration of Enterobacteriaceae, Standard 21528, Part 2: Colony-count method, International Standards Organization, Geneva. ISO (2004g) Modification of the Isolation Media and the Haemolysis Test, and Inclusion of Precision Data, Standard ISO 11290-1:1996/Amd 1:2004, International Standards Organization, Geneva. ISO (2004h) Modification of the Enumeration Medium, Standard ISO 11290-2:1998/Amd 1:2004, International Standards Organization, Geneva. ISO (2004i) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Detection of Salmonella spp., Standard ISO 6579:2002/Cor 1:2004, International Standards Organization, Geneva. ISO (2004j) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Enumeration of Clostridium perfringens, Standard 7937, Colony-count technique, International Standards Organization, Geneva. ISO (2005a) Milk and Milk Products: Quality Control in Microbiological Laboratories, Standard 14461, Part 1: Analyst performance assessment for colony counts, International Standards Organization, Geneva. ISO (2005b) Milk and Milk Products: Quality Control in Microbiological Laboratories, Standard 14461, Part 2: Determination of the reliability of colony counts of parallel plates and subsequent dilution steps, International Standards Organization, Geneva. ISO (2005c) Milk: Enumeration of Colony-Forming Units of Psychrotrophic Microorganisms, Standard 6730, Colony-count technique at 6.5◦ C, International Standards Organization, Geneva. ISO (2005d) Milk and Milk Products: Enumeration of Presumptive Escherichia coli, Standard 11866, Part 1: Most probable number technique using 4-methylumbelliferyl-beta-D-glucuronide (MUG), International Standards Organization, Geneva. ISO (2005e) Milk and Milk Products: Enumeration of Presumptive Escherichia coli, Standard 11866, Part 2: Colony-count technique at 44◦ C using membranes, International Standards Organization, Geneva. ISO (2005f) Milk and Milk Powder: Determination of Aflatoxin M1 Content, Standard 14674, Clean-up by immunoaffinity chromatography and determination by thin-layer chromatography, International Standards Organization, Geneva. ISO (2006a) Microbiology of Food and Animal Feeding Stuffs: Guidelines for the Estimation of Measurement Uncertainty for Quantitative Determinations, Standard ISO/TS 19036, International Standards Organization, Geneva. ISO (2006b) Milk, Milk Products and Mesophilic Starter Cultures: Enumeration of Citrate-Fermenting Lactic Acid Bacteria, Standard 17792, Colony-count technique at 25◦ C, International Standards Organization, Geneva. ISO (2006c) Milk Products: Enumeration of Presumptive Lactobacillus acidophilus on a Selective Medium, Standard 20128, Colony-count technique at 37◦ C, International Standards Organization, Geneva. ISO (2006d) Milk and Milk-Based Products: Detection of Thermonuclease Produced by CoagulasePositive Staphylococci , Standard 8870, International Standards Organization, Geneva. ISO (2006e) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Determination of Low Numbers of Presumptive Bacillus cereus, Standard 21871, Most probable number technique and detection method, International Standards Organization, Geneva.

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ISO (2006f) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Detection and Enumeration of Coliforms, Standard 4831, Most probable number technique, International Standards Organization, Geneva. ISO (2006g) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Enumeration of Coliforms, Standard 4832, Colony-count technique, International Standards Organization, Geneva. ISO (2006h) Milk and Milk Products: Detection of Enterobacter sakazakii, Standard 22964, International Standards Organization, Geneva. ISO (2006i) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for Detection and Enumeration of Campylobacter spp., Standard 10272, Part 1: Detection method, International Standards Organization, Geneva. ISO (2006j) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for Detection and Enumeration of Campylobacter spp., Standard 10272, Part 2: Colony-count technique, International Standards Organization, Geneva. ISO (2007a) Microbiology of Food and Animal Feeding Stuffs: General Requirements and Guidance for Microbiological Examinations, Standard 7218, International Standards Organization, Geneva. ISO (2007b) Cheese, Cheese Rind and Processed Cheese: Determination of Natamycin Content , Standard 9233, Part 1: Molecular absorption spectrometric method for cheese rind, International Standards Organization, Geneva. ISO (2007c) Cheese, Cheese Rind and Processed Cheese: Determination of Natamycin Content , Standard 9233, Part 2: High-performance liquid chromatographic method for cheese, cheese rind and processed cheese, International Standards Organization, Geneva. ISO (2008a) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Enumeration of Yeasts and Moulds, Standard 21527, Part 1: Colony count technique in products with water activity greater than 0.95, International Standards Organization, Geneva. ISO (2008b) Microbiology of Food and Animal Feeding Stuffs: Horizontal Method for the Enumeration of Yeasts and Moulds, Standard 21527, Part 2: Colony count technique in products with water activity less than or equal to 0.95, International Standards Organization, Geneva. ISO (2008c) Milk and Milk Products: Guidance on Sampling, Standard 707, International Standards Organization, Geneva. ISO (2009a) Microbiology of Food and Animal Feeding Stuffs: Measurement Uncertainty for Low Counts, Standard ISO/TS 19036:2006/Amd 1:2009, International Standards Organization, Geneva. ISO (2009b) Milk Products: Determination of the Acidification Activity of Dairy Cultures by Continuous pH (CpH) Measurement , Standard 26323, International Standards Organization, Geneva. ISO (2009c) Milk and Milk Products: Method for the Enumeration of Pseudomonas spp., Standard 11059 International Standards Organization, Geneva. ISO (2009d) Dried Milk: Enumeration of the Specially Thermoresistant Spores of Thermophilic Bacteria, Standard 27265, International Standards Organization, Geneva. ISO (2010a) Microbiology of Food and Animal Feeding Stuffs: Preparation of Test Samples, Initial Suspension and Decimal Dilutions for Microbiological Examination, Standard 6887-5, Part 5: Specific rules for the preparation of milk and milk products, International Standards Organization, Geneva. ISO (2010b) Milk Products: Enumeration of Presumptive Bifidobacteria (Colony Count Technique at 37◦ C), Standard 29981, International Standards Organization, Geneva. ISO (2010c) Acidifying Starter Cultures: Standard of Identity, Standard 27205, International Standards Organization, Geneva. ISO (2010d) Fermented milk products: Bacterial starter cultures - Standard of identity, Standard 27205, International Standards Organization, Geneva. Jarvis, B. & Neaves P. (1977) Safety Aspects of UHT Foods: Thermal Resistance of Clostridium botulinum Spores in Relation to that of Spoilage Organisms and Enzymes, Technical Circular No. 644, Leatherhead Food Research Association, Leatherhead.

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Jervis, D. (2002) Application of process control. Dairy Microbiology Handbook (ed. R.K. Robinson), 3rd edn, pp. 593–654, John Wiley & Sons, New York. Jones M. (2003) Processing plants. Encyclopaedia of Dairy Science (eds H. Rogi´nski, J.W. Fuquay & P.F. Fox), pp. 1288–1294, Academic Press, London. Jonsson, A. (1990) Enumeration and confirmation of Clostridium tyrobutyricum in silageusing neutral red, D-cycloserine and lactate dehydrogenase activity. Journal of Dairy Science, 73, 719–725. Kalab, M. (1981) Electron microscopy of milk products: a review of techniques. Scanning Electron Microscopy, III, 453–472. Kalab, M. (1983) Electron microscopy of foods. Physical Properties of Foods (eds M. Peleg & E.B. Bagley, pp. 43–104, AVI Publishing Company, Westport. Kalab, M. (1984) Artefacts in conventional scanning electron microscopy of some milk products. Food Microstructure, 3, 95–111. Kalab, M. (1992) Food structure and milk products. Encyclopedia of Food Science and Technology (ed. Y.H. Hui), vol. 2, pp. 1170–1196, John Wiley & Sons, New York. Kalab, M. (1993) Practical aspects of electron microscopy in dairy research. Food Structure, 12, 95–114. Kalab, M. (1995) Practical aspects of electron microscopy in cheese research. Chemistry of Structure–Function Relationships in Cheese (eds E.L. Malin & M.H. Tunick), pp. 247–276, Plenum Press, New York. Kalab, M. (2005) Cheese: development of structure. A source for food structure studies. Available at www.magma.ca. Kalab, M., Yun, J. & Hing Yiu, S. (1987) Textural properties and microstructure of processed cheese food rework. Food Microstructure, 6, 181–192. Kalab, M., Modler, H.W., Cari´c, M. & Milanovic, S. (1991) Structure, meltability and firmness of processed cheese containing white cheese. Kalab, M., Allan-Wojtas, P. & Miller, S. (1995) Microscopy and other imaging techniques in food structure analysis. Trends in Food Science and Technology, 6, 177–186. Kapoor, R. & Metzger, L.E. (2004) Evaluation of salt whey as an ingredient in processed cheese. Journal of Dairy Science, 87, 1143–1150. Kapoor, R. & Metzger, L.E. (2008) Process cheese: scientific and technological aspect. A review. Comprehensive Reviews in Food Science and Food Safety, 7, 194–214. Kapoor, R., Metzger, L.E., Biswas, A.C. & Muthukummarappan, K. (2007) Effect of natural cheese characteristics on process cheese properties. Journal of Dairy Science, 90, 1625–1634. Karahadian, C., Lindsay, R.C., Dillman, L.L. & Deibel, R.H. (1985) Evaluation of the potential for botulinal toxigenesis in reduced-sodium processed American cheese foods and spreads. Journal of Food Protection, 48, 63–69. Kautter, D.A., Lilly, T., Lynt, R.K. & Solomon, H.M. (1979) Toxin production by Clostridium botulinum in shelf-stable pasteurized process cheese spreads. Journal of Food Protection, 42, 784–786. Khandke, S.S. & Mayes T. (1998) HACCP implementation: a practical guide to the implementation of the HACCP plan. Food Control , 9, 103–109. Kimura, T., Taneya, S. & Furuichi, E. (1979) Electron microscopic observations of casein particles in processed cheese. 20th International Dairy Congress, pp. 239–240. Klijn, N., Nieuwenhof, N.F.J., Hoolwert, J.D., van der Waals, C.B. & Weerkamp, A.H. (1995) Identification of Clostridium tyrobutyricum as the causative agent of late blowing in cheese by species-specific PCR amplification. Applied and Environmental Microbiology, 61, 2919– 2924. Klostermeyer, H. & Buchheim, W. (1990) Microstructure of processed cheese (in German). Dairy Science Abstracts, 52, 339. Koło˙zyn-Krajewska, D. (ed.) (2003) [Hygiene of Food Production] (in Polish), Wydawnictwo SGGW, Warszawa.

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Appendix: Example of a product quality information as a result of using a HACCP system

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Appendix (continued)

Index

accelerated ripening 137 acclimatisation, sensory 313–14 acid casein 224 acid-curd type cheese 87, 88, 89 acidification, direct 138 acidulants 225 ACP see analogue cheese products additives see also individual additives flavours 8–9, 133–41 legislation European Union 32–6 FAO 68 FSANZ system 59, 60 Lebanon 65 US/Canada 55 miscellaneous 7–12, 269 quality control 261, 269 aflatoxin 278 age of natural cheese 97, 99–101, 134, 136–8 American White cheese 303, 304 analogue cheese products (ACP) 219–39 applications/advantages 220 CSLM studies, quality control 303–11 definition 219–20 developments 236–9 functionality factors 228–36 legislation 219–20 manufacturing 220–8 quality control 287–8 replacement ingredients 236–8 annatto 11

antimicrobial activity 124 preservatives 163–7 legislation 32–6 nisin 9, 164–6, 277–8 antioxidants 32–6 assessors, sensory 311–19 ASSIFONTE 29 auger dump hoppers 185, 186, 187 Australia 59 Bacillus spp. 271, 273, 276 bacon, as additive 8 bacteriocins 9, 32–6, 124, 163–7, 277–8 bacteriological examination see microbiological hazards balanced mix formulation 5–7 batch cookers 2, 187–90 benzoic acid 164 biogenic amines 278 birds 254 blended formulations 85–6, 184–5 block packaging equipment 208–10 blood protein, decolourised 8 blowing of cheese 172, 267–8 blue cheese taste 9 Brazil 151–2, 163 brined cheeses 10 browning discoloration 142 Buffalo’s milk cheese 9 buffering 118–20 buildings hygiene 250–1 butter 10, 268

Processed Cheese and Analogues, First Edition. Edited by A.Y. Tamime. © 2011 Blackwell Publishing Ltd. Published 2011 by Blackwell Publishing Ltd.

342

Index

calcium binding, emulsifying salts 116–18 chelation 160, 161 natural cheese 88, 89, 92–3, 94, 99, 155 salts, as additive 8 calcium phosphate crystals 292, 295, 296, 297, 298 para-caseinate (CPPC) 306, 307 Canada 55, 57–9 Candida lipolytica subsp. planta 137 ι-carrageenan 11, 12 casein analogue cheese products 221, 222, 224, 233, 234 cheaper alternatives 236 caseinates 224 dispersion, emulsifying salts 120–1 hydrolysate, as additive 9 intact, natural cheese effects 97, 99–101 para-casein 160 para-caseinate 289 Cassis de Dijon principle 31, 42, 44, 47 CCP (critical control points) 255–8 CFR (Code of Federal Regulations) 52–4, 150 chakka 10, 137 Cheddar cheese calcium content 93, 94, 99 flavour atributes 134, 135 microscopy/microstructure 283–5 pH effects on PCPs 96–7, 98 recommended blends 6 cheese mixes 5–7, 184–7, 261–2, 263 Cheese Regulations (UK) 38–40 Cheese-tastic!T M 292, 293, 294, 295, 297 Cheez Whiz® 292, 293, 294, 296 chelating properties 161 chemical composition analysis 270–1 chemical flavourants 139–40 chemical hazards 249 Chile 62–3 chill roll technology 196–7 chocolate 8 citrates 111, 159, 235 CLA (conjugated linoleic acid) 11 cleaning requirements 254–5

Clostridium spp. 124, 271, 273, 275–9 clump hoppers 185, 186 Code of Federal Regulations (CFR) 52–4, 150 Codex Alimentarius Commission/ Standards 3, 26, 67, 68–73, 83, 150, 245 CODEX-STAN 285 - 1978 70–1 CODEX-STAN 286 - 1978 70, 71 CODEX-STAN 287 - 1978 70, 71–2 hazard definition 248 imitation processed cheese 73 review of existing standards 72 structure 69 collapsible tubes 213 colours 133, 141–2, 143 discoloration 142, 172 European Union legislation 32–6 process colours 142 sensory atributes 142–3 commercial spread composition 293 compositional requirements see also ingredients Codex Alimentarius Commission/ Standards 67, 68–73 commercial spreads 293 Germany 43–4 Hungary 51 UK named cheeses 39 UK processed cheese 39 US/Canadian legislation 58–9 concentrated milk 12 condensed phosphates 114, 115, 116–17 confocal scanning laser microscopy (CSLM) 303–11 conjugated linoleic acid (CLA) 11 continuous cookers 190–4, 195 conveyor belts 180, 181, 183, 184 cooking equipment 187–94, 195, 226–8 quality control 261–2, 263 requirements 167–9 cooling emulsifying salts 122–4 molten processed cheese 86 quality control 265, 286, 287–8

Index

rate requirements 170–1 vacuum flash cooling units 191–2 CPPC (calcium phosphate para-caseinate) 306, 307 creaming 122–4, 193–4 critical control points (CCP) 255–8 see also hazard analysis (appraisal) critical control points cryo-scannning electron microscopy (cryo-SEM) 283, 284, 285, 291–5, 297 crystal formation emulsifying salts 124–7 identification 310–11 quality control 292, 295, 296, 297, 298–302 shelf-life changes 172 CSLM (confocal scanning laser microscopy) 303–11 cup packaging 211–13 curd breakers 181–2 customary names 40 β-cyclodextrin 11 Czech Republic 48–9 dairy ingredient types 10–12 dairy powders 268 data analysis, sensory 316–19 decolorised blood protein 8 definitions 26–73, 81–3, 248–9 denatured whey protein 10 Denmark 46 descriptive abilities 313 direct acidification 138 direct pH alteration 95 direct steam injection 187–94 Directives (EU) 27–36, 247 discoloration 142 disinfection 254–5 dispatch 265 diversity of products 2–3 dried fruit 8 dump hoppers 195, 197 Edam cheese 134, 135 egg protein 8

343

Egypt 65–6 Eh (redox potential) 278 EMC (enzyme-modified cheese) 138, 156 Emmental 134–5 empirical melt tests 281–2 emulsifying salts 7 analogue cheese products 225, 234–5 antimicrobial activity 124 casein dispersion 120–1 cheese protein interaction 90–1 chelating properties 161 citrate 111 condensed phosphates 114, 115 cooling/storage 122–4 creaming 122–4, 193–4 crystal formation 124–7 European Union, legislation 32–6 functionality 110–29 lactates 115 main types 111–16 manufacturing 158–63 microstructure quality control 289 pH effects 161–2 phosphate-based 112, 113–15 properties 112 ideal 111 protein hydration 120–2 quality control 269, 306–8 roles/properties 116–27 selection criteria 127–9 shearing effects 122 structure formation 122–4 tartrates 115 enzyme-modified cheese (EMC) 138, 156 enzyme-treated retentate 10 EPS (exopolysaccharide)-producing cultures 156 equipment 179–98 analogue cheese products 226–8 direct steam injection 187–94 grinding 182–4 initial size reduction 181–2 packaging 204–15 slices manufacturing 195–8 transfer hoppers 185–7 unit operations 180–95

344

Index

Escherichia coli 266, 271, 273, 276 European Union legislation 27–36, 246–7 access to 27 additives 32–6 fat-related nutrient claims 32 hygiene 28–9 labelling of foods 30–2 natural cheeses 27–8 exopolysaccharide (EPS)-producing cultures 156 expansion 238–9 external decoration 213–14 FAO/WHO standards 3, 26 see also Codex Alimentarius Commission/ Standards fat analogue cheese products 232–3, 238 content 46, 48–9, 184, 185 emulsification see emulsifying salts globule size 286, 287–8, 289 nutrient claims 32 of plant origin 232, 268 substitutes 10, 287–8, 303 faults in processed cheese 295–7 filling machines 13 filtering 194–5, 196, 258, 264 final product 265–6 flavours 8–9, 133–41 analogue cheese products 225–6 chemical 139–40 fruit/vegetable 139 meat 138–9 natural cheeses as raw materials 134–5 natural flavourants 135–6 seafood 138–9 sensory atributes 142–3 storage changes 140–1 foamed processed cheese 11 formulation see also ingredients analogue cheese products 226, 227, 231–6

balanced mix 5–7 blends 85, 167 France 45–6 fromage fondue 45 fruit flavours 8, 139 functionality analogue cheese products 228–36 change effects 231–6 cheese components, PCP rheology/texture effects 81–106 classes 34 definition 228 ingredients, emulsifying salts 110–29 packaging materials 200–1 gas blowing 172, 267–8 Germany 42–4 GHP (good hygienic practice) 245–6 glass jars 211, 212 glassy phosphates 112, 113, 114 glycerol 10 GMP (good manufacturing practice) 180, 245–6 goat’s milk cheese 8 Graham’s salts 112, 113, 114, 117 grinding 167, 182–4, 261 Gruy`ere cheese 134–5 gums (hydrocolloids) 158 HACCP see hazard analysis (appraisal) critical control points hard cheese, creaming 123 hardness 119 hazard analysis critical control points (HACCP) 29, 278 background 247–8 buildings hygiene requirements 250–1 cleaning/disinfection 254–5 factors determining implementation 249–50 hygienic zones 251–2 implementation 248–58 monitoring the processing plant 260–6 pest control 252–4 verification 259

Index

heat treatment 12, 90, 167–9, 263 high mechanical action batch cookers 188, 189–90 history background 1–2 legislation 25–6 Codex Alimentarius Standards 68, 70 Irish 41 origins of standards 26–7 United Kingdom 37–8 US 51–3 manufacturing practices 148–50 origins of processed cheese 25 sliced cheese 149 holding pipes 191 homogenisation 12–13, 86, 122, 262, 264 hoppers 185–7 Hungary 50–1 hydration, protein 230–1 hydrocolloids 158 hydrolysate of processed cheese 8 hydrolysis, condensed phosphates 114–15 hygiene buildings 250–1 cleaning/disinfection 254–5 European Union, legislation 28–9 GHP (good hygienic practice) 245–6 hygienic zones 251–2 packaging materials 201–2 pest control 252–4 ICMSF (International Commission on Microbiological Specifications for Food) 249 ideal emulsifying salts 111, 127–8 identity standards 26–73, 150–1 IDF (International Dairy Federation) 3–4, 251–2, 266, 267, 271, 272–4 imitation processed cheese 2, 73 indirect pH alteration methods 95–6 individually wrapped slices (IWS) 192, 197–8, 214 information access to legislation 27, 37 ingredients

345

see also additives; compositional requirements; emulsifying salts analogue cheese products 223–6, 227, 231–6 balanced mixes 5–7 blends 85, 167 emulsifying salts 110–29 flavours 8–9, 133–41 preparation 261 selection 154–8 weighing 180 INS (International Numbering System) 59 insects 253 instrumental-based quality tests 282 intact casein content 97, 99–101 interactions, product/packaging 202–4 International Dairy Federation (IDF) 3–4, 251–2, 266, 267, 271, 272–4 ion exchange 116–18, 188 Iran 66–8 Ireland see Republic of Ireland iron 8 ISO (International Standards Organisation) 265, 271, 272–4 Italy 48 IWS (individually wrapped slices) 192, 197–8, 214 Japan 59, 60 jars 211–13 labelling of foods 30–2 labneh 10 lactates 115 lactic acid bacteria 138 Lactococcus lactis 164, 165 Lebanon 64–5 lecithin 12 legislation 25–73 see also Codex Alimentarius Commission/Standards analogue cheese products 219–20 Australia 59 Canada 55, 57–9

346

Index

legislation (continued ) Chile 62–3 Czech Republic 48–9 Denmark 46 European Union 27–36 France 45–6 Germany 42–4 Hungary 50–1 Italy 48 Japan 59, 60 Mercosur/Mercosul 60–2 Middle Eastern countries 63–8 Egypt 65–6 Iran 66–8 Lebanon 64–5 Syria 66 Turkey 63–4 New Zealand 59 quality control 246–7 Republic of Ireland 41–2 Spain 47 Sweden 46–7 The Netherlands 44–5 United Kingdom 36–41 United States 51–7, 150, 220 linear long chain phosphates 112, 113, 114 lipid sources 224–5 see also fat Listeria monocytogenes 271, 276 load cell conveyor belts 180, 181 long-chain polyphosphates 112, 113, 114, 117 low mechanical action batch cookers 187, 195 low-sodium processed cheese spread 11 lysozyme 166–7, 277 manufacturing 148–73 see also equipment; packaging; quality control analogue cheese products 220–8 cheese base 157 dairy ingredients 157–8 definitions 81–3 emulsifying salts 158–63

enzyme-modified cheese 138, 156 formulation of cheese blend 167, 223–6 HACCP flow chart 256, 278 history of practices 148–50 identity standards 26–73, 150–1 milk destabilisation/dehydration 87–8 natural cheese effects on PCPs 91–101 calcium content 92–3, 94 pH 93–7 protein characteristics 88–9 rheology/texture 81–106 patterns of production 3–5 preservatives 163–7 principles 87–91 processing condition effects 101–5 re-work cheese 157 Requeij˜ao 151–3 stages 5–14, 182–96 balanced mix formulation 5–7 cooling/storage 170–1 dairy ingredients 10–12 emulsifying salts 7, 158–63 filling machines 13 grinding/shredding 167, 182–4, 261 heat treatment 12 heating/cooking 167–9, 226–8, 261–2, 263 homogenisation 12–13 ingredients selection 5–7, 85, 154–8, 167 key steps 1, 6, 83–6, 153–71 miscellaneous additives 7–12 temperature effects 103–4 time effects 101–3 MAP (modified atmosphere packaging) 203, 204 margerine 8 mashed potato 8 matrix development 221, 222 maturity of natural cheese 97, 99–101, 134, 136–8 meat flavour 8, 138–9 melting characteristics 280, 281–3 Mercosur/Mercosul 60–2 metal containers 203, 206, 211, 213

Index

microbiological hazards bacteriocins 9, 32–6, 124, 163–7, 277–8 continuous cookers 192 factors affecting, scheme 274 ICMSF definition 249 natural cheese, quality control 267–8 packaging materials 201–2 quality/safety 271–9 microstructure assessment 283–311 cryo-SEM description 291–5, 297 CSLM as quality control tool 303–11 faults 295–7 matrix development 221, 222 overview 86–7 product development 297, 303 microwave appliances 184, 185, 238–9 Middle Eastern countries 63–8 milk 38, 87–8, 272–4, 277–8 milling 261 miscellaneous additives 7–12, 269 mixing 85–6, 184–7, 261–2, 263 see also compositional requirements modified atmosphere packaging (MAP) 203, 204 moisture content analysers 184, 185 molten cheese, filtering 194–5, 196 monitoring for HACCP 260–6 1-monoglycerides 12 monomeric phosphates 113–14, 116–17 Mozzarella substitute 220, 230 Mucor miehei 137 mustard oil 8 N -acetyl-hexosaminidase 166–7 named cheese composition 39 NaPC (sodium para-caseinate) 306, 307 natural cheese calcium content 88, 89 effects on PCPs 91–101 rheology/texture 81–106 European Union, legislation 27–8 flavours 10 pH 93–7, 98, 155–6

347

protein characteristics 88–9 proteolysis 99–100 qualities as raw material 134–5 quality control examination 266–8 microscopy 283–4, 285 milk preliminary treatment 277–8 milling/grinding/shredding 261, 262 selection 5, 6, 154–6 natural colours 141–2 natural flavourants 135–6, 268 The Netherlands 44–5 New Zealand 59 Nisaplin 166 nisin 9, 164–6, 277–8 nitrogen, water-soluble 99 NMR (nuclear magnetic resonance) 184, 185, 231 nomenclature, product types 2–3 nuts 8 oiling off 110, 162 okara 9 optional ingredients 81–3 see also additives orthophosphates 113–14, 116–17 packaging 199–215 equipment 204–15 materials 13–14, 200–4 functions 200–1 hygiene 201–2 shelf-life 202–4 specifications 36, 200 types 201 quality control 264–5 requirements 170 palm oil 10 paprika 8 Passelli® fat substitute 287, 288, 303 pasteurisation 190–4 Pasteurized Process Cheese (PPC) 53–4, 150–1 patents 148, 149 patterns of production 3–5

348

Index

PCA (principal component analysis) 135–6, 317–19 Penicillium roqueforti 137 pentrometry 280 peptisation 160 pest control 252–4 pH analogue cheese products 221, 235–6 batch cookers 188 emulsifying salts 118–20, 161–2 natural cheese 93–7, 98, 155–6 phosphates analogue cheese products 235 anions 7 condensed 114, 115, 116–17 crystals 292, 295, 296, 297, 298–302 emulsifying salts 112, 113–15 linear long chain 112, 113, 114 manufacturing 159 polymeric 114, 115, 116–17 ring-forming 113 phosphatidic acid 8 physical characteristics 279–83 physical hazards 249 pickled cheeses 10 pigments (colours) 32–6, 133, 141–3 plant-derived ingredients 8, 9, 224, 232, 236–7, 268 plastic containers 211–13 plastic tubes 213 polymeric phosphates 114, 115, 116–17 portion packaging 205–8 potassium sorbate 164 PPC (Pasteurized Process Cheese) 53–4 prawns 8 pre-cooked cheese 157, 194 preliminary treatment 277–8 presentation of sensory samples 316 preservatives 32–6, 163–7 nisin 9, 164–6, 277–8 principal component analysis (PCA) 135–6, 317–19 process colours 142 processing aids, definition 33 processing blended formulations 85–6

product classification 3 product development 287–8, 297, 303 production methods see manufacturing protein analogue cheese products 230–1, 233–4, 236 emulsifying salt interaction 90–1 heating/shearing effects 90 hydration 120–2, 230–1 natural cheese characteristics 88–9 proteolysis 99–100 sources 223–4 quality control 245–320 chemical composition analysis 270–1 crystal formation 292, 295, 296, 297, 298–302 hazard analysis 246–55 legislation 246–7, 248–55 microbiological quality/safety 271–9 microstructure assessment 283–311 physical characteristics assessment 279–83 sensory profiling 311–19 QUID (quantity ingredient labelling) 31, 41 ranking of samples 313 rapid visco analysis 283 ras cheese 10 raw materials 260, 266–70 re-work cheese 157, 194 redox potential (Eh ) 278 Regulations 27–36, 220, 246–7 see also legislation rennet casein 221, 224, 230–1, 233, 234 rennet-curd type cheese 87, 88, 89 see also Cheddar replacement ingredients 236–8 Republic of Ireland 41–2 Requeij˜ao 151–3 resistant starch 238 retentate, enzyme-treated 10 rheology analogue cheese products 230 definitions 81–3

Index

manufacturing overview 83–6 principles 87–91 microstructure 86–7 natural cheese effects 91–101 processing conditions, effects 101–5 tests 281, 282 rice starch 237 ring-forming phosphates 113 ripening of natural cheese 97, 99–101, 134, 136–8 rodents 252, 260 safety hazard analysis 246–55 microbial contamination 201–2, 271–9 salami 8 Salmonalla spp. 266, 271, 273, 276 SALP (sodium aluminium phosphates) 115 samples, sensory assessment 313 sampling, quality control 265–6, 269–70 SAPP (sodium acid pyrophosphate) 114 sausage shape packaging equipment 210–11 scanning electron microscopy (SEM) 283–5, 291–5, 297, 298–302 Schreiber melt test 281–2 seafood flavours 138–9 SEM (scanning electron microscopy) 283–5, 291–5, 297, 298–302 sensory aspects 142–3, 311–19 separability 192 shearing effects 90, 104–5 shelf-life 171–3, 202–4 short chain phosphates 114, 115, 116–17 shredding 167, 261 single-blade Stephan cooker 228, 229 size reduction 85, 181–2 slices 149, 214–15 smell, sense of 313 smoke condensate 8 sodium cations 7 sodium citrate crystals 292, 295, 296, 297, 298 sodium para-caseinate 306, 307

349

sorbic acid 164 soy protein 234 Spain 47 spoilage 192, 201–2, 271–8 stabilisers 32–6 standardised cheese mixes 184–7 standards see also Codex Alimentarius Commission/Standards; legislation Chilean 63 FAO/WHO 3, 26 identity/definitions 26–73, 150–1 microbiological analysis 272–4 national 81–3 Staphylococcus aureus 271, 276 starch 10, 237, 238, 308, 310 steam 187–94, 269 Stephan single-blade cooker 228, 229 sterilisation 12, 103–4, 168–9, 190–4, 202 storage cooling rates 170–1 creaming/structure formation 122–4 flavour changes 140–1 microstructure quality control 289–90 molten processed cheese 86 packaging material interactions 202–4 quality control 265 raw materials 260 shelf-life changes 171–3 STPP (sodium tri-polyphosphate) 114 Stresa Convention 48 structure formation 122–4 see also microstructure Sudanese white cheese 12 Sweden 46–7 sweeteners 32–3 Syria 66 taiz cheese 10 tartrates 115 taste, sense of 313 tasting protocols 315–16 TEM (transmission electron microscopy) 287–90, 303

350

Index

temperature analogue cheese products 221 continuous cookers 191, 192, 193 critical control point 255, 257, 258 heating/cooking 168–9 packaging 264 of processing, effects on PCPs 103–4 processing time, microstructure 307–8, 309 shelf-life changes 172 warehouses 260 terminology, product types 2–3 texture 81–106 texture profile analysis (TPA) 281 Tg-ase (transglutaminase) 9 thickeners 32–6 time of processing 101–3 titration behaviour 118–20 TPA (texture profile analysis) 281 transfer hoppers 185–7 transglutaminase (Tg-ase) 9 transmission electron microscopy (TEM) 287–90, 303 trisodium citrate 162–3 TSPP (tetrasodium pyrophosphate) 114, 122–3, 298, 301, 302 tub packaging 211–13 tubes, collapsible 213 Turkey 63–4 twin filtration system 196 twin ribbon blenders 185, 186 twin-screw augers 226, 227, 228 types of processed cheese 133 unit manufacturing operations blending to standardised mix 184–5 direct steam injection 187–94

filtering 194–5, 196 grinding 182–4 transfer to cooking system 185–7 weighing ingredients 180 United Kingdom 36–41 United States 51–7, 220 unmelted characteristics 279–81 UW melt profiler 282–3 vacuum flash cooling units 191–2 vegetable fats 232 vegetable flavours 139 vegetable protein 8, 224 verification of HACCP 259 viscosity 283 vocabulary, sensory 314–15 water analogue cheese products 231, 232 content, expressible, emulsifying salts 122 quality control 269 solubility, phosphates 112, 113 websites, European legislation 27 wedges packaging 205–8 weighing, ingredients 180 wheat fibre 9 whey proteins 10, 11, 12, 224, 237 White cheese 303, 304 WPC (whey protein concentrate) 141, 237 WPI (whey protein isolate) 234 zone division 251–2