More Baking Problems Solved (Woodhead Publishing in Food Science, Technology and Nutrition)

More baking problems solved Stanley P. Cauvain and Linda S. Young

Published by Woodhead Publishing Limited, Abington Hall, Granta Park, Great Abington, Cambridge CB21 6AH, UK www.woodheadpublishing.com Woodhead Publishing India Private Limited, G-2, Vardaan House, 7/28 Ansari Road, Daryaganj, New Delhi ± 110002, India woodheadpublishingindia.com Published in North America by CRC Press LLC, 6000 Broken Sound Parkway, NW, Suite 300, Boca Raton, FL 33487, USA First published 2009, Woodhead Publishing Limited and CRC Press LLC ß 2009, Woodhead Publishing Limited The authors have asserted their moral rights. This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. Reasonable efforts have been made to publish reliable data and information, but the authors and the publishers cannot assume responsibility for the validity of all materials. Neither the authors nor the publishers, nor anyone else associated with this publication, shall be liable for any loss, damage or liability directly or indirectly caused or alleged to be caused by this book. Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming and recording, or by any information storage or retrieval system, without permission in writing from Woodhead Publishing Limited. The consent of Woodhead Publishing Limited does not extend to copying for general distribution, for promotion, for creating new works, or for resale. Specific permission must be obtained in writing from Woodhead Publishing Limited for such copying. Trademark notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation, without intent to infringe. British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library. Library of Congress Cataloging in Publication Data A catalog record for this book is available from the Library of Congress. Woodhead Publishing Limited ISBN 978-1-84569-382-4 (book) Woodhead Publishing Limited ISBN 978-1-84569-720-4 (e-book) CRC Press ISBN 978-1-4398-0108-6 CRC Press order number: N10009 The publishers' policy is to use permanent paper from mills that operate a sustainable forestry policy, and which has been manufactured from pulp which is processed using acid-free and elemental chlorine-free practices. Furthermore, the publishers ensure that the text paper and cover board used have met acceptable environmental accreditation standards. Typeset by Godiva Publishing Services Limited, Coventry, West Midlands, UK Printed by TJ International Limited, Padstow, Cornwall, UK

Preface

In the manufacture of baked products we are dealing with ingredients and processes which have a `natural' background and are therefore subject to change. Such changes inevitably have an impact on the complex ingredientrecipe-process interactions which characterise the manufacture of baked products. This means that there is always a ready supply of new problems with baked products which need solutions. In addition to the natural variations that bakers have to cope with there are drivers for change from consumers, legislative sources and the desire for innovation. While these drivers may not directly create problems in baked goods qualities, they do challenge bakers' knowledge and ingenuity. We would argue that there is little difference between `problem solving' and innovation or new product development. Our premise is that both activities require bakers to have an intimate knowledge of many complex interactions and that there is little difference in finding solutions to a particular quality problem or identifying an appropriate route for new product development. By treating a quality improvement as though it were a quality defect it is possible to identify suitable courses of action for product development. For example, if a loaf of bread lacks volume then is diagnosing the causes of that defect so very different from asking the question `How do I make my loaf of bread larger?'. Since we wrote Baking problems solved we have become increasingly aware of the need for developing structures for arranging and storing knowledge to meet the different needs of bakers. Providing `instant' answers to problems is only one way to deliver information with value. In this volume we have continued to deliver some of those instant answers but also tried to provide fragments of information on different aspects of baking. To help new readers we have re-written Chapter 1 and included more information on knowledge

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structures and their development; processes which we believe are essential to the development of technical skills in baking. Apart from elements of Chapter 1 all of the information in this volume is new. In a number of cases the information provided in this volume is complementary to or extends that provided in Baking problems solved, so to help readers we have provided appropriate cross-references in, for example, the form `(BPS, pp. 1±2)'. Stanley P. Cauvain Linda S. Young

Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

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Problem solving: a guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 How to problem solve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 The record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 The analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 Modelling techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 Matching patterns and visualising changes . . . . . . . . . . . . . . . . . . . . 1.6 The information sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7 New product development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8 Some key ingredient and process factors affecting product quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.9 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.10 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Flours and grains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 We have seen references to the ash content with white flours but this is not a figure that appears on the specification from our UK miller. Can you explain what the ash content means and should we ask for it to be determined on our flours? . . . . . 2.2 What does the term grade colour figure mean in flour specifications? How is it measured? What are the implications for bread quality? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Can you explain the functions of the different components in the wheat grain and, after milling, their contributions to the manufacture of baked products? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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We understand that millers often use a mixture of different wheats to manufacture the flours that they supply to us. Can you explain why they do this? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We have heard several experienced bakers talking about the `new harvest effect' and the problems that it can cause. Can you explain what is behind this phenomenon and how we can mitigate its effects? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We have the water absorption capacity of our flour assessed regularly but find that this is different to the actual water level that we use in the bakery. What are the reasons for this difference and is it important for breadmaking? . . . . . . . . . . . . . . . Why is the protein content of wholemeal bread flour typically higher than that of white flours but the bread volume is commonly smaller with the former? . . . . . . . . . . . . . . . . . . . . . . . . . . . We get a significant variation in the quality of our wholemeal bread and rolls depending on which flour we purchase. What characteristics should we look for in a wholemeal flour specification to get more consistent results? . . . . . . . . . . . . . . . . . . . Since enzymes such as alpha-amylase are inactivated by heat during baking, is it possible to use heat-treatment of flour to inactivate the enzymes in low Hagberg Falling Number flours before baking? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We are considering making traditional German-type rye breads and have researched the recipes and production methods. Do you have any suggestions as to what characteristics we should have in the rye flour? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We have changed suppliers of our self-raising flour and find that we are not achieving the same product volume as before. If we adjust the recipe by adding more baking powder, we find that the products tend towards collapse. Can you explain why and how do we overcome the problems? . . . . . . . . . . . . . . . . . . . . . . We are a bakery working with a local farmer and miller to produce a range of local breads and want to use some different varieties and forms of malted grains that we are producing. Can you advise us on any special issues that we should be aware of? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Can we mix oats or oat products with our wheat flours to make bakery products? If so, are there any special issues that we should be aware of? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We wish to add non-wheat fibres to some of our baked products to increase their healthiness. What fibres can we use, in what products and what potential technical problems should we be aware of? What is resistant starch and can it be used in bakery products? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Other bakery ingredients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 We wish to reduce the level of salt (sodium chloride) that we use in our baked products. What do we need to be aware of when making reductions? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 What alternatives are there to using sodium chloride (common salt) in the manufacture of bread products? And how can we reduce sodium levels in our other baked products? . . . . . . . . . . . . 3.3 We have seen references to a `lag phase' for bakers' yeast; what does this mean and what are the implications for baking? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 Are there any particular precautions that we should take in handling, storing and using bakers' yeast in the compressed form? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 What different types of bakers' yeast are available? Would there be any particular advantages for us to use an alternative to Saccromyces cerivisii in the manufacture of our fermented products? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6 What effect does vinegar have on bread and why is it added? 3.7 What ingredients are commonly used as preservatives? Are there any particular benefits associated with different ones? . . 3.8 We have heard that alcohol can be used as a preservative. How is this achieved? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9 What are the possible alternatives to chemically based preservatives? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.10 What type of sugar (sucrose) should we use for the different products that we make in our bakery? . . . . . . . . . . . . . . . . . . . . . . . . . 3.11 Can you explain some of the main features of alternative sugars to sucrose and how they might be used in baking? . . . . . 3.12 What are the differences between diastatic and non-diastatic malt powders and how can they be used in baking? . . . . . . . . . . . 3.13 We read a lot about the different enzymes that are now available and how they might be used in baking. Can you tell us what they are and what functions they have? . . . . . . . . . . . . . . . 3.14 How do anti-staling enzymes work? Can they be used in cake as well as in bread and fermented products? . . . . . . . . . . . . . . . . . . 3.15 Can you explain the different terms used to describe bakery fats? What are the functionalities of the different forms in baking? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.16 We want to make a range of bakery products using butter as the main or only fat in the recipe. Can you advise us of any special technical issues that we need to take into account when using butter? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.17 We are using butter in several of our bakery products which comes in chilled at about 4 ëC (as cartons on pallets) and are encountering problems with variability in its processing. We

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recognise that it is likely to be associated with the temperature of the butter when we are using it. What is the best way to treat the butter in order to get a more consistent performance? What are the differences between dough conditioners and bread improvers? What consideration should we take into account when choosing which one to use? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . What is lecithin and how is it used in baking? . . . . . . . . . . . . . . . . What is meant by the term `double-acting' baking powder and what is the value of using such products? . . . . . . . . . . . . . . . . . . . . . We have been having some problems with the quality of our bread, pastries and biscuits, and one solution that has been recommended to us is that we should add a reducing agent to our recipes. Can you tell us more about reducing agents and how they function in baked products? . . . . . . . . . . . . . . . . . . . . . . . . .

Bread and fermented products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 What characteristics should we specify for white bread flour and why? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2 We make crusty breads in a retail store and recently we have been having complaints about our products going soft quickly. We have not changed our recipe or process. Can you help us understand what has happened? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 We are not a large bakery but are planning to part bake and freeze bread products for bake-off at some later time. What points should we be aware of? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4 When we re-heat par-baked products we find that they remain soft for only a short period of time, typically an hour or so, but they quickly go hard and become inedible. If we do not re-heat them we find that par-baked products can stay fresh for several days. What causes the change in the rate of firming? Is it the additional moisture lost on the second bake? . . . . . . . . . . . . . . . . . . 4.5 We have been freezing some of our bread products in order to have products available in times of peak demand. We notice that there is `snow' or `ice' in the bags when we remove them from the freezer. Can you tell us why this happens and how it can be avoided? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6 We are seeking to improve the quality of our bread products and are getting conflicting advice on what the optimum dough temperature ex-mixer should be. Can you advise us as to whether we should increase or decrease our dough temperature? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7 How can I calculate the amount of ice I need to replace some of the added water when my final dough temperature is too warm? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8 We are considering the purchase of a new mixer for the

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manufacture of our bread using a no-time dough process. There are two types of mixer that seem to be appropriate for our plant production needs, the spiral-type and the CBP-compatible type, but before making our decision we need to understand any issues with respect to dough processing and final bread quality. Can you please advise us? . . . . . . . . . . . . . . . . . . . . . . . . . . . . We are looking to buy a new final moulder for our bread bakery. Can you advise us on the key features we should look for and how they might impact on final bread quality? . . . . . . . . We are having problems keeping a uniform shape with our bloomers. They tend to assume a bent or `banana' shape (Fig. 19). This happens even though we take great care to straighten them when they are placed on the trays. Can you explain why we get this problem? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Why is a bread dough piece coiled after sheeting? Does the number of coils achieved have any impact on bread quality? . We have been taught to always place the seam of our moulded bloomer dough pieces downwards on the tray before proof but we do not take the same precautions with our pan breads. Can you explain the relevance of placing the bloomer dough piece `seam' down? Should we also do this with our pan breads? . . . We have been having problems with holes appearing in different places in our pan breads. Can you explain where they come from and how to eliminate them? Is there any relationship between the holes that we see inside dough pieces coming from the divider and the problems that we are experiencing? . . . . . . . . We are making open-top pan breads and find that the top crust of some of our loaves is being lifted off during the slicing process. Sometimes there is a hole underneath the crust while on other occasions there is not. Do you have an explanation for this problem? We have tried making the dough stronger by adding more improver but without any reduction in the problem, in fact it may have been slightly worse. . . . . . . . . . . . . . Can we make bread without using additives? What will be the key features of the ingredients and process that we should use? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We have had bread returned to us by the retail store through which it is sold. They are not satisfied with the quality. We have some pictures of the products concerned. This seems to be a `one-off' and we are at a loss to understand what has led to the problem. Can you help us understand where the problem came from? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We have noticed that loaves sometimes break only on one side of the pan but that the break is not formed consistently on one side. Can you explain why this is? . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Contents 4.18 We are making a range of crusty breads using a small bread plant. We appreciate the value of having an open cell structure to encourage the formation and retention of the crust. However, from time to time we have difficulty in achieving the desired degree of openness in the structure. Can you help us identify why this happens? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.19 We make sandwich bread for a large customer and they are concerned about the crumb characteristics of the products. What are the important ones? How do I measure these? What steps can I take to control or improve on these? . . . . . . . . . . . . . . 4.20 During the manufacture of bread and other fermented products we sometimes have small quantities of `left-over' dough from a mixing, can we add these back to other mixings or re-use them in other ways? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.21 We make bread and rolls using a bulk fermentation process. Can we use ascorbic acid to improve our bread quality? . . . . . . 4.22 Our total time for bread production from flour to baked loaf is set for about 6 hours. Currently we use a bulk fermentation time of 4 hours and a final proof time of 90 minutes. We find that with increased bread sales we do not have enough proving capacity. If we were to shorten the final proof time, what other changes would we have to make to maintain our current bread quality? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.23 In breadmaking what is the difference between a sponge and a ferment and when would they be used? We have also seen references to barms, can you tell us anything about these as well? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.24 How would we prepare and use a sponge with the Chorleywood Bread Process? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.25 Our bread and buns prove to a satisfactory height in about 50 minutes but we get no additional lift from the products in the oven. We have tried increasing their strength and using more improver but, whatever we do, we see no oven spring. Do you have any ideas as to why we are getting no oven lift? . . . . . . . . 4.26 What is the purpose of `knocking-back' the dough when using a bulk fermentation process to make bread? . . . . . . . . . . . . . . . . . . . 4.27 We have two bread lines running side-by-side, with the same equipment bought at different times. We are using the Chorleywood Bread Process (CBP) and do not quite get the same volume and cell structure when making the same pan bread product. We compensate by adjusting yeast and improver level but do not get the same crumb cell structure. Can you help us understand what is happening? . . . . . . . . . . . . . . . . . . . . . . . . 4.28 We are experiencing a problem with loaves baked in rack ovens since we bought new pans. As the enclosed photograph

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Contents shows, they are joining together above the pans. The portions of the loaves that touch have no crust formation, which makes them weak when they are de-panned and handled. How can we prevent this from happening? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.29 We wish to create a bolder shape and more open cell structure with our crusty sticks and have recently increased our dough development by mixing longer. Now we experience problems with the products joining together in the oven. If we underprove the dough pieces, we have problems with ragged bread and poor shapes. Should we reduce our mixing time back to its original level? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.30 We are finding that the crumb of our bread is too soft for slicing. We also notice a tendency for the sides of the loaves to slightly collapse inwards. We do not think that conditions in our cooler have changed, can you please advise us on what to investigate? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.31 We have spiral and twin-arm type mixers and would like to produce a finer cell structure with our sandwich breads. Can you suggest ways in which we might achieve this aim? . . . . . . . 5

Cakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 What characteristics should we specify for cake flour? . . . . . . . . 5.2 We are experiencing some variation in cake quality, especially volume. How important is it to control the temperature of our cake batters? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3 How do we calculate the likely temperature of our cake batter at the end of mixing and what temperature should we aim for? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4 What do the terms high- and low-ratio mean when they are applied to cake-making recipes? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5 We are looking to re-balance our cake recipes and have a set of rules that we work with. However, it would help us if you could explain the principles behind such rules of recipe balance as applied to cake making? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.6 We have been making cake muffins and find that when we cut them open they have large vertical holes in the crumb. Why is this and how do we eliminate them? . . . . . . . . . . . . . . . . . . . . . . . . . . 5.7 Why do some of our cake muffins lean to one side during baking? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.8 We have been making a range of different cake sizes using the same plain batter and get varying quality results in terms of their shape and appearance despite having adjusted the baking conditions. Do you have any advice? . . . . . . . . . . . . . . . . . . . . . . . . . . 5.9 We would like to change the physical dimensions of some our cake products to make different sizes and shapes. Do you have

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any advice that you can give us as to how to adjust the batter deposit weights for the different pan sizes? . . . . . . . . . . . . . . . . . . . Currently we add alcohol, in the form of spirits or liqueurs, to our celebration cakes after they have been baked and cooled. We leave them for a few days after treating them but this is taking up a lot of space. What advantages/disadvantages would there be if we added the alcohol to the batter before baking? . We are baking Genoa-type fruit cakes using sultanas and find that while the centre of the crumb is a nice golden yellow, around three sides of the cut face of the cake (the bottom and the two sides) the colour is much browner and darker. Can you help us identify the cause of this problem? . . . . . . . . . . . . . . . . . . . . We regularly measure the water activity of the individual components in our composite cake products and try to adjust them to reduce the differential between them to reduce moisture migration. Even though we do this we are still having problems keeping the cake moist during shelf-life. Can you give us some advice as to what we may be doing wrong? . . . . Why do some traditional cake-making methods specify a delay in the addition of the sodium bicarbonate and specify the use of hot water? Would this approach have any practical applications today? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We have recently changed the acid that we use for our baking powder mix and have adjusted the neutralising value accordingly. Subsequently we have been having some problems achieving the volume and shape that we want with our small cakes. Can you explain why we are having these problems? . . What are the factors that control the shape and appearance of the top of a cake? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We are seeking to reduce the level of fat that we use in some of our cake recipes but find that simply taking fat out adversely changes our product quality. What are the possibilities of using `fat replacers' to help us with our strategy? . . . . . . . . . . . . . . . . . . . We are using natural colours in our slab cake baking and find that we get variable results, not just from batch to batch but sometimes within a batch. Can you suggest any reasons for this problem? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Biscuits and cookies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 We have been trying to make soft-eating cookies and are having a degree of success with the recipe that we are using. The products are not expected to have a long shelf-life but we find that they are going hard too quickly. Can you suggest any ways of extending the period of time that the cookies will stay soft-eating? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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6.2 6.3 6.4 6.5

6.6 6.7

6.8

6.9 6.10 6.11

6.12

6.13 6.14 6.15

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What are Shrewsbury biscuits and how are they made? . . . . . . . What characteristics should we specify for our biscuit and cookie flours? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . What are the main issues that we should be aware of in the manufacture of savoury puff biscuits? . . . . . . . . . . . . . . . . . . . . . . . . . We assembled a selection pack of biscuits and cookies, one of which is a rectangular product coated on the top with icing. When the pack is opened after some time this coated biscuit has a `bowed' shape, the base is soft eating but the icing remains hard. Can you suggest reasons for these changes? . . . . How important are the dough and batter temperatures in biscuit and cookie making? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We are experiencing dark brown specks on the surface of our plain sheeted biscuits. We have been using the same recipe for a number of years without a problem. Can you identify the cause of the specks and suggest a remedy? . . . . . . . . . . . . . . . . . . . . We are having some problems with packing our rotary moulded biscuit lines. When we measure the thickness of the biscuits we have noticed that some are thicker than others. Can you suggest any reasons why we should be getting such variations? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We are having intermittent problems with shrinkage of our semi-sweet biscuits after they have been cut out from the dough sheet. How can we stop this from happening? . . . . . . . . . Is it important to use a fermentation period in the manufacture of crackers? What effects are we likely to see from variations in the fermentation time? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We are experiencing blistering on the surface of our semisweet biscuits and sometimes see cavities under the top crust and little hollows on the bottom. Can you identify the possible cause of the problem and suggest a solution? . . . . . . . . . . . . . . . . . We are manufacturing short-dough biscuits using a rotary moulder and have been offered an alternative supply of sugar. We notice that the new sugar is more granular than the material we have been using previously; would this have any effect on biscuit quality? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Is it possible to reduce the level of sugar in our biscuit and cookie recipes without affecting their quality? What would be the alternatives to sucrose we could use? . . . . . . . . . . . . . . . . . . . . . . We would like to reduce the level of fat in our biscuit recipes. How can we do this? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We have installed a new cutting and creaming machine for the preparation of our sandwich wafers and re-furbished the production area. We have found that we are now getting intermittent problems with the wafer sheets breaking up on

152 153 154

155 156

159

160 161 162

163

164 165 167

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Contents cutting. Can you offer an explanation as to why this might be happening? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7

Pastries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1 We have been experiencing considerable variability in processing our short and puff paste products; sometimes we have problems with paste shrinkage and on other occasions we get stickiness. We have checked our weighing systems and can find no problems with ingredient additions. We have no climatic temperature control in the factory or ingredient storage facilities, are these likely to be significant contributors to the problems? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2 We are looking to start production of croissant. In my travels I have seen many variations on products that are called croissant. Why are there so many different forms and how are they made? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3 What is the best way to use pastry trimmings? At present we are feeding them back into the sheeting stages . . . . . . . . . . . . . . . . 7.4 We are manufacturing savoury short pastry products that are blocked out to shape and lids by sheeting a paste with the same formulation. We wish to increase our production rate and are considering reducing or eliminating the rest periods in the production sequence. Can you advise us on their function and any consequences that we may face if we change them? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5 What method should we use to calculate the water temperature to deliver a consistent final paste temperature at the end of mixing? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6 We are making puff pastry, Danish pastries and croissant using all butter and often have problems with the processing of the pastes and feel that we do not get the best of quality from the final products. What are the best processing temperatures and conditions when using butter with such products? . . . . . . . . . . . . . 7.7 We would like to reduce the level of fat that we use to make our puff pastry but would like to retain pastry lift. Can you provide us with some guidance as to how we might achieve our objectives? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.8 Some of the short pastry cases that we make for restaurants to fill and serve have been returned to us as being `mouldy' on the base. We were surprised, as we thought that the water activity of the shells was too low to support mould growth, and when we examine the bottom of the pastries we can see that there is a discoloration but we do not think that it is mould. Can you identify what has caused the discoloration and how to eliminate it? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

168 169

169

171 174

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Contents 7.9

7.10

7.11

7.12 7.13

8

We are having problems with the custard tarts that we make. The pastry shell is very pale coloured but if we increase the baking time, we find that the custard filling is not very stable and shrinks away from the case during storage. If we raise the baking temperature, the custard filling boils and breaks down during storage. Can you give us any advice on how to get a better pastry colour without causing problems with the filling? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We are experiencing distortion of our pastry shapes. We have measured the shrinkage but find that it is not even. We have also noticed that the laminated products are experiencing some variation in product lift. What might be the causes of these problems? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We have been receiving complaints from customers that our short pastry which we use for meat pie products has an unpleasant eating character that they describe as `waxy'. The comments are most often related to the base pastry in the pies. Why is this? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We have been trying to freeze fully proved croissant for later bake-off. Can you identify the important criteria for their successful production? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . What characteristics should we specify for the flour that we use for making savoury and sweet short pastes? We make both fresh and chilled unbaked paste products. . . . . . . . . . . . . . . . . . . . . .

Other bakery products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1 We are freezing a range of unbaked, chemically aerated products including scones and cake batters and now want to include some variations using fresh fruits. We have carried out a number of trials and have a range of issues that are mostly related to the fragility of the fruit. Can you provide some advice? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2 We have been asked to improve the sensory qualities of our scones and have been able to do this by a number of recipe changes. While these changes have been largely satisfactory for our plain scones, the fruited varieties we make still tend to be too dry eating. Do you have any suggestions as to how we can make them more moist eating? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3 We make and bake scones on a daily basis. Recently we placed them unbaked in a refrigerator but the baked quality was poor. We used a retarder instead but we still found that the products were small in volume. Is it possible to retard unbaked scones and still produce an acceptable product? . . . . . . . . . . . . . . . . . . . . . . 8.4 What are Staffordshire oatcakes and how are they made? . . . . . 8.5 What are Farls and how are they made? . . . . . . . . . . . . . . . . . . . . . .

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186

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Contents 8.6

8.7

8.8 8.9

8.10 8.11

8.12

8.13 8.14

8.15 8.16

We are producing a variety of finger rolls using white flour. The rolls must be soft eating and retain their softness for several days; to achieve this we are using a roll concentrate. To help us cope with fluctuations in demand we freeze a proportion of our production but find that the defrosted product is very fragile and may even fall apart. Can you help us overcome this problem? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We want to add freshly baked deep-pan pizza to the product range that we sell through our bakery shop. We do not want to make small quantities of dough throughout the day for their manufacture but when we try to work with a larger bulk of dough we find that the variation in quality is too great, even when we refrigerate the dough in our retarder. What would be a suitable way for us to make the bases? . . . . . . . . . . . . . . . . . . . . . . What are the key characteristics of cake doughnuts and how do they differ from other types of doughnut? . . . . . . . . . . . . . . . . . . . . . We have been producing a range of cake doughnuts that are iced with various flavoured coatings. In order to cope with peak demands we have taken to freezing a quantity of the products. We have observed that progressively during storage a crystalline growth appears on the products. When they are defrosted, the growth disappears. Can you identify why this happens? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We have been approached by some of our customers asking if we can make gluten-free breads. How could we do this and can we match the quality of our regular bread products? . . . . . . . . . . We are not getting the quality of finish that we would like from the fondant we are using. Often the finished products lack gloss. Can you give us some tips on how to improve our use of the fondant? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Can you tell us something about Chinese steamed breads and their production? We make our standard breads using the Chorleywood Bread Process, would we be able to make these products using this process? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . What is cinnamon twist bread and how could we make it? . . . . We have been experimenting with retarding fruited rolls and buns. We find that the smaller products are quite satisfactory but loaves made using the same formulation and baked in pans have `stains' around the fruit pieces and a darker crust colour than we would like. Can you please advise us on how to cure these problems? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We are retarding rolls in our retarder-prover and find that they lean to one side and lose weight during storage. Can you advise us as to how to cure these problems? . . . . . . . . . . . . . . . . . . We want to extend the mould-free shelf-life of our flour

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Tortilla but when we try to make the dough more acid we have processing problems. What options could we consider for achieving our aim? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 8.17 In reading about the manufacture of hamburger buns we see references to the pH and TTA of the brew. What do these terms mean? When are they used and what is the purpose of controlling them? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 9

What is/are/why/how? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1 What is meant by the term `modified atmosphere packaging' and how can we use this approach in the production of baked products? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2 We have seen references to the Milton Keynes Process but can find very little technical information on the process. Can you tell me what it is (was) and how it is (was) used? . . . . . . . . . . . . 9.3 Can you explain the principles of vacuum-cooling of baked products and its potential applications? . . . . . . . . . . . . . . . . . . . . . . . . 9.4 I have heard the terms `glycaemic index' and `glycaemic load' used when describing bakery products. What are they and what is the difference? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.5 What are pro- and pre-biotics and how can they be used in our bread products? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.6 Can you please explain the difference between hydration and hydrolysis? What is their relevance to the manufacture of baked goods? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.7 What is meant by the term `glass transition temperature' and what is its relevance to baking? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.8 What is the Bohn's spot test and what is it used for? . . . . . . . . . 9.9 What does the term MVTR mean when applied to packaging and what is the relevance to baked products? . . . . . . . . . . . . . . . . . 9.10 We have heard people referring to synergy in the use of ingredients in baking processes, what is this process and can you identify any examples? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.11 What are polyols and how are they used in baking? . . . . . . . . . . 9.12 What value is there in measuring the colour of bakery products and how can we carry out the measurements? . . . . . . . . . . . . . . . . . 9.13 What is acrylamide? Where does it come from and how do we limit it? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.14 How can we measure the texture of our bread and cakes? Currently we use a hand squeeze test for bread and apply a `score' to the results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

205

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Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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205 207 208 209 211 212 213 214 215 217 218 220 222

1 Problem solving: a guide

`You can't solve a problem with the same type of thinking that caused it' Einstein The quote from Einstein may seem like a statement of the obvious but after many years of experience in the baking industry we have seen that the obvious is constantly overlooked when it comes to trying to solve problems or develop new products and processes. Indeed there is relatively little difference between solving a problem and creating a new product, in both cases you are required to use different thinking from that you would normally use for established products and processes. In essence both scenarios are vindications of Einstein's view. Problems that show as unexpected variations in bakery product quality do occur from time to time. Often considerable time, effort and money are required to identify the causes and solutions concerned. Unexpected quality variations are not the exclusive province of any particular size of manufacturing unit: they can occur in both large and small bakeries. Nor are they exclusive to the production bakery: even the best-controlled test bakery or laboratory can experience unexpected fluctuations in product quality. There is no magic to problem solving. It is normally achieved through critical observation, structured thought processes and access to suitable sources of information. In this chapter we offer a guide to some of the methods that might be employed when trying to solve bakery-related problems. In doing so we must recognise that baking is a complex mixture of ingredient and process interactions so that the solutions to our problems may not always be instant in nature and because ingredients and processes change, new solutions are always being discovered. The complex interactions which underpin baking dictate that there are seldom unique solutions to individual problems. In the majority of cases

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individual quality defects are overcome by changing a number of ingredient and process factors, some of which will be apparently unrelated, though careful study will often reveal that relationships do exist even where they are masked by more prominent effects.

1.1

How to problem solve

Successful problem solving usually requires a methodical approach. It is perfectly possible to stumble quickly on the required solution by chance but more often than not a haphazard approach to problem solving is wasteful of time, resources and money. In addition, stumbling on the solution by chance often means that the root cause of the problem remains unidentified and the opportunity is lost for the systematic assembly of information which may be valuable for solving similar problems in the future. Not all problems are solved using exactly the same approach but the critical elements of the problem-solving process are largely common. In problem solving we normally move from the problem to the cause and finally to the corrective action. However, we must recognise that on many occasions the manifestation of a particular problem does not necessarily have a unique and identifiable cause and so there may be other intermediate steps to take into account in determining the real cause of the problem. This situation can be described schematically as follows: Problem ! primary cause ! contributing factors ! corrective action Or in more simple terms as: What is seen ! why ! because of ... ! corrective action The basic process becomes apparent if we consider two examples of problems in bread making; the first, low bread volume, and the second, collapse of the sides of an open top pan loaf, often referred to as `keyholing' (BPS, pp. 57±8). Low bread volume Externally we observe that the bread is smaller than we expect and this may also have led to a paler crust colour because of the poorer heat transfer to the dough surface during baking. Internally the cell structure may be more open than usual. Since bread volume is a consequence of expansion of the dough by carbon dioxide gas from yeast fermentation and the retention of that gas within the dough matrix (Cauvain, 2007a), there are two potential primary causes of this problem ± lack of gas production and lack of gas retention. To separate the two we will need more observations, and an important one will be whether the rate of expansion of the dough in the prover and oven was normal or slower than usual. If the latter was the case then the primary cause of the problem is likely to

Problem solving: a guide

3

be lack of gas production, and potential contributing factors may include the following: · · · · · · ·

yeast activity or level too low; lack of yeast substrate (food); dough temperature too low; proving temperature too low; proving time too short; salt level too high; proving temperature/time/yeast combination incorrect.

On the other hand, if the proving had been at a normal rate and there was a lack of oven spring, then this would lead us to recognise that the problem would be lack of gas retention. In this case the list of potential reasons for the problem includes: · improver level too low; · incorrect improver formulation; · combination of improver and flour too weak for the breadmaking process being used; · enzymic activity too low; · energy input during mixing too low; · mixing time too short; · dough temperature too low. Note that the `dough temperature' too low appears in both lists because of its effect on yeast activity and the effectiveness of the functional ingredients in the improver, especially if ascorbic acid is used. Keyholing (BPS, pp. 57±8) Externally we observe there is a loss of bread shape but only at the sides of the product. Internally we may see the formation of dark-coloured, dense seams, often referred to as cores. The centre crumb may be more open than we normally expect for the product concerned. Why has this happened? Clearly we have no problems with gas production, since there is no evidence for slow proving and the bread had good volume. We have clearly retained the carbon dioxide gas produced, otherwise the bread would have low volume as described above. In this case the over-expansion of the crumb in the centre of the loaf leads us to the view that in fact the gas retention is excessive. Thus, the primary cause of the problem is excessive gas retention arising from a number of potential individual causes or combinations. The contributing factors may include: · improver level too high; · incorrect improver formulation; · combination of improver and flour too strong for process;

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· enzymic activity too high; · energy input during mixing too high; · mixing time too long. From the foregoing examples we can see that observation and reasoning are key elements in problem solving. The former can be readily systematised, while the latter will rely heavily on the availability of suitable information to use as the basis for comparisons. The potential sources of such information are discussed below. It is interesting to consider the process by which one might set about identifying the particular cause of a problem, such as the keyholing (excessive gas retention) of bread discussed above. The most likely mental process is one associated with probability achieved by matching the pattern of observations with ones previously experienced and remembered. When we recognise a general similarity between observation and stored image, we are likely to explore in more detail the factors most likely to contribute to the pattern we see. One potential analogy for how we problem solve is that of a tree. The main line of observation is via the central trunk with the potential to explore branches at many points. In the case of our bread problem, if we fail to identify the cause of the problem from our first consideration, then we will close down that line of reasoning, go back to the main theme (the trunk) and then set off on another branch of investigation. Our route through the branches of our reasoning or knowledge tree is complex and occasionally we may jump from branch to branch rather than going back to the trunk before continuing our investigation. The length of time that we take to identify the cause and the corrective actions needed varies considerably from occasion to occasion and from individual to individual, and is more likely to be related to our accumulated knowledge and experiences rather than logical reasoning. Our abilities to recognise and match subtle patterns are probably so intuitive that we are seldom aware of them.

1.2

The record

It is common for the manufacture of bakery products to be based on some starting formulation and formal method of processing the ingredients into the finished product. This will require some form of recorded details of the ingredients to use, their quantities, equipment, process settings and timings involved. Consult any standard recipe or book for bakery food preparation and you will find such details recorded for use by others. In almost all modern bakeries a formal production record will be set up for each of the product types and used by the manufacturing operatives to prepare the various items. Invaluable in problem solving is the formal record of what was actually carried out on a particular occasion. While many operatives will keep to the prescribed formulation and processing recipe, small variations about a given value can occur and lack of information of what the actual values were for a

Problem solving: a guide

5

given mix makes problem solving more difficult. It is normal for standard production specifications to allow a degree of tolerance for weights and operating conditions. For example, a temperature specification for a cake batter may be stated as 20  2 ëC. However, such a specification allows for replicate batters to be 18 or 22 ëC and a 4 ëC variation coupled with other small changes may have a larger effect of final product quality than normally considered. A formal record of production can encompass many aspects including the following: · Any variations in the source of the raw materials. For example, changes in flour or whole egg batches, or a new supplier of a particular ingredient. · Changes in analytical data, even where these are still within acceptable limits, because the cumulative effect of small changes in a number of individual parameters can have a large effect on final product quality. · The actual quantities of ingredients used compared with the standard values. For example, in breadmaking it is common to adjust the water level added in order to maintain a standard dough rheology for subsequent processing. In other cases deliberate changes from the standard formulation may have been introduced in order to compensate for some process change. For example, in bread dough the yeast level may be adjusted to compensate for a change in prover temperature so that final proving times do not vary. · The processing conditions, such as mixing times, energies, ingredients and batter or dough temperatures. Once again the values may fall within acceptable ranges but can still have a cumulative effect with other small changes in recipe and process parameters. · Process equipment settings which may vary according to `operator preference' or because of variations in other factors. For example, an unavoidably higher laminated paste temperature may result in greater damage to the laminated structure which may require a compensatory adjustment to roll gap settings during sheeting. · Process timings, such as baking or cooling times. · Changes in packaging materials. The record may be simplified by using the standard recipe as a pro forma against which to record variations. Such techniques have been commonly used to record the weights of individual dough pieces coming from the divider (see Fig. 1) and can be readily adapted for any aspect of bakery production. The record may be on paper, by input to suitable computer-based programs or may be gathered and stored automatically. In addition to the recipe and process records it is very important to have a formal record of finished product quality. Once again it will be common to have some form of product specification with appropriate tolerances against which to make an assessment. Such techniques are commonly the province of the Quality Control Department. The degree of detail recorded will vary. For use in problem solving the formal product specification or quality control record may require some adaptation and enlargement since small, but commonly

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Fig. 1 Example of a divider record sheet.

accepted, variations may hold the vital clue to the cause of a particular problem. In both the quality control and problem-solving contexts relevant data on the finished product may include the following: · Product size based on height or volume. Devices for measuring product dimensions may be used off- or on-line. They may be as simple as using a rule to measure loaf height or measuring product volume by seed displacement in a suitable apparatus (Cauvain, 2007a) or with laser sensors (e.g., TexVol instruments, BVM-L series, www.texvol.com; VolScan Profiler, Stable Micro Systems, www.stablemicrosystems.com). · Shape may be assessed subjectively and compared with an accepted standard. The introduction of image analysis offers new opportunities for recording product shape, even on-line (Dipix Technologies Inc, www.dipix.com). · The external appearance of the product and the recording of any special features that may be present or indeed the absence of expected features, e.g. lack of oven spring in bread. · Surface blemishes, their size and location on the product. · The coloration of all external surfaces. Descriptive techniques, comparison with standard colour charts, e.g. Munsell (no date), or tristimulus instruments (Anderson, 1995) may be used. Deviations from the norm should be clearly noted. · The appearance of the internal structure, if there is one. Most baked products have some form of internal structure that is an intrinsic component of product quality. Assessment of that internal structure may be subjective and describe the size, numbers and distributions of the cells (open spaces) which go to make the internal structure. Cell structures may be unevenly distributed in the product cross-section or form a `pattern' that is characteristic in different products. Deviations from the norm may be noted. Image analysis is now being used for objectively assessing internal cell structures (Whitworth et al., 2005). · The internal colour may be assessed using techniques described above for surface colour. It is worth noting that the presence of a cellular structure has an impact on the perception of colour and so it is often common practice to include some form of visual assessment, e.g. brightness, which is different

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from the true colour of a product. Some objective image analysis systems offer a measurement of crumb brightness, e.g. C-Cell (www.c-cell.info). · The physical characteristics that contribute to eating quality may be assessed subjectively with ad hoc or trained panels. Alternatively some form of objective test designed to mimic aspects of sensory analysis may be employed, e.g. texture profile analysis (Cauvain, 1991), squeeze and puncture tests (Cauvain and Young, 2006). · Product odour and flavour may be assessed subjectively on an ad hoc basis or with trained panels. The development of the so-called `electronic nose' may offer a more objective measure but has yet to approach human sensitivity. Whatever details are considered to be appropriate for the record, it is important to have a standardised format for recording the details. This usually takes the form of a standardised record sheet, paper or electronic, with blank spaces in which to enter the appropriate data or comments. Where a product attribute cannot be measured, an attribute `scoring' system might be used to provide a more objective basis for analysis of the problem. Any number of scoring systems may be employed. One example is given in Fig. 2 and others are given in the literature (e.g., Kulp, 1991; Bent, 1997a; Cauvain and Young, 2006).

Fig. 2 Example of product scoring sheet.

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The analysis

If a standard record sheet is available then the initial analysis can be as simple as considering whether the recorded data deviate from the process specification and in what direction. The effects of any changes can then be compared with existing knowledge bases (in whatever form) in order to provide the basis of a diagnosis. Sadly few bakery problems are solved with such a simplistic approach. Almost all bakery processes include an element of elapsed time, e.g. proving, baking and lamination, which must be taken into account when analysing the causes of problems. Many larger bakery operations involve continuous production, even though they are batch fed and this adds a further complication to take into account in the analysis. An example from our own experience is that of a plant manufacturing baked puff pastry shells, where deviations in the product dimensions were identified at the end of the baking process. In this instance the plant had to run continuously in order to be efficient and not compromise product quality (i.e., no gaps in the pastry sheet or the oven). The operation was batch fed from the mixer so that the relationship between a given mix batch and the product leaving the oven had to be established first. When this was done it then became possible to identify the contribution that any variation in the mix batch contributed to the problem. After establishing this relationship it became clear that batch to batch variation was not the prime cause of the problem observed, since simple plots of dough properties ex mixer (e.g., temperature or rheology) did not correlate with variations in product quality even when the elapsed time element had been taken into account. The solution to this particular problem lay in a plot of changes in product character with time (see Fig. 3), which upon analysis showed that the variation was more regular than first thought. At first glance it appeared to be the well-known `shift change effect' and to some extent that was true: not, in this case, because of the operator effect on process settings but because each new shift started with a new batch of re-work to add to the virgin paste. As the re-

Fig. 3 Effect of re-work on lift in laminated products.

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work aged, the effects on baked product character diminished. In this example a simple trend analysis provided the basis for the solution of the problem. One analysis technique that has started to be applied to cereal science and technology is `root cause analysis' (Stauffer, 2000). Not all bakery problems are likely to be potential subjects for this type of analysis, since a key element in this technique is the brainstorming session. Brainstorming usually implies that more than one person is involved and all too often many of us confront bakery problems alone or against a timescale that is insufficient to gather together the necessary team of experts. In manufacturing processes based on batch production, stopping the line until the problem is solved is an option; however, for many bakery processes anything other than a short-term stoppage is seldom an option. However, if the problem is a persistent one or of a catastrophic nature then root cause analysis can be a suitable technique to apply. The role of a team in employing root cause analysis is invaluable in solving intractable problems or making changes to product quality. In the latter case the technique would be to treat the required change as though it were a problem; e.g., if I want greater volume in a cake, then by diagnosing the cause of excess volume, I may well obtain clues as to how to increase cake volume.

1.4

Modelling techniques

The application of statistical methods of analysis is common in many areas of food manufacture. They can be used in problem solving and quality optimisation, though in the manufacturing environment modelling methods often tend to be confined to the plotting of trends using simple graphs as discussed in the example above for a laminated product. More sophisticated statistical and modelling techniques can play their part in helping to build up the information base on what the critical ingredient and process factors are which determine changes in product quality. Once identified, these critical factors can be logged and matched with problems when they occur. To develop such predictive models it will be necessary to carry out experiments in the test bakery or trials on the plant. While trials on the plant are preferred, they can be wasteful of raw materials, energy and time so that the most common practice is to carry out evaluations in the test bakery and `translate' the results to the plant. It is very important to establish any clear changes that are relevant when translating test bakery results to a plant environment. A simple example encountered by the authors was the development of a sponge cake recipe in a test bakery using a planetary-style mixer, while the plant used a continuous mixer to prepare the same recipe batter. In this case it is necessary to remember that less carbon dioxide gas will be lost during continuous mixing than with a planetary mixer so that baking powder levels should be adjusted downwards to compensate for this difference. A typical adjustment would be to reduce the baking powder level for a continuous mixer to be about 75% of that used on a planetary mixer in order to

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achieve the same sponge cake volume in both the test bakery and on the plant (Cauvain and Cyster, 1996). There are a number of examples of modelling techniques that might be applied to bakery products. Street (1991) provides a review of suitable techniques that may be applied to baked products and there are many examples in the scientific and technical literature. The concept behind the development of such mathematical models is that a relatively limited number of experiments may be used to build models that can be used to predict changes in bakery product quality as a consequence of changes in combinations of ingredients and processes. Once a predictive model has been established then the information can be used for problem solving. For example, suppose that we show by experimentation how loaf volume varies as a result of an interaction between the level of ascorbic acid in the dough and mixing time. At some later stage we may encounter a problem with low bread volume and then we would be able to use the output from our model to help decide whether the problem was associated with the level of added ascorbic acid or mixing time, or both. Furthermore we might use our model to show which changes were most likely to restore our bread volume to its original level. Baking is a complex food process with many ingredient and process interactions. These interactions lead to complicated models that are often difficult to apply. For example, for a given set of mixing conditions we would observe that bread volume increases with increasing levels of ascorbic acid reaching a maximum and thereafter there will be little change in volume for increasing additions of ascorbic acid. This occurs because the oxidation effect of ascorbic acid is limited by the availability of oxygen from the air incorporated during dough mixing (Cauvain, 2007b). The availability of oxygen is affected by yeast activity, so that yeast level becomes an influencing factor. Both yeast and ascorbic acid activity are temperature sensitive and proceed at a greater rate when the temperature increases. Dough temperature is a function in part of ingredient temperatures and in part the energy imparted to the dough during mixing. Energy transfer in turn is related to the mixing time. So, too, is gas occlusion to a lesser degree, because during mixing an equilibrium point is reached when the entrainment process is balanced by the disentrainment process. This equilibrium may occur before the end of the mixing time. So, for the example given above, while we set out to study the effects of the level of ascorbic acid and mixing time, we must also ensure that we measure: · · · ·

ingredient temperatures; final dough temperature; gas occlusion in the dough; energy transferred to the dough.

These records are necessary because we cannot independently control some of the properties concerned, e.g., mixing time, energy and dough temperature. Whenever we do work during mixing we must expect there to be a temperature rise. This relationship also holds true if a water or other coolant jacket has been

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fitted to the mixer and in this case we must remember that the coolant temperature in the jacket will also rise by the time that it leaves the jacket. There tends to be greater variability in product quality for products manufactured on a plant than one sees in many test bakery environments. This process `noise' in the data can mask some of the critical issues that control product quality and therefore weaken the value of any models that have been developed. There are a number of statistical techniques that can be used to help separate such noise from underlying effects, trends and relationships. In many manufacturing processes the specified product characteristics can be achieved by many different combinations of formulation and process conditions. Taguchi methods use experiments to search systematically and efficiently for combinations of `control' factors that minimise product variability in the face of variations in `noise factors' such as ambient temperature. Taguchi methodology has been applied to the manufacture of bakery products, in particular in a study of the factors that affect the quality of puff pastry (DTI, 1993). In some cases effective problem solving can be initiated by studying the effects of small perturbations on the plant. A major issue with carrying out trials on the plant is the potential loss of production arising from the manufacture of out-of-specification products. However, there is a distinct advantage to plant trials in that large numbers of samples are being made, which increases the potential for statistical and practical analysis. Most product specifications have a degree of tolerance associated with the final product so that small variations can be accommodated without loss of production.

1.5

Matching patterns and visualising changes

Sometimes when dealing with complex problems it is an advantage to sketch out the salient features with a diagram or create some collage of salient information on a board (like a story board for the creation of a film). A simple example is illustrated in Fig. 4 in which the potential routes for the migration of moisture in composite bakery products are identified, annotated with relevant data on moisture contents and product masses. The drawing of diagrams such as that shown in Fig. 4 helps to ensure that all of the relevant processes are considered before carrying out detailed calculations and investigations. Human beings have a significant capability for being able to match patterns in data and in many ways when we are problem solving we spend a lot of time comparing what we see with the patterns that we all hold in our minds. Subconsciously we look for a pattern of information in a current problem and compare that with previous patterns of events and information to see if they provide clues for solving the current quality problem. There are many different ways of creating patterns. The creation of knowledge trees and knowledge fragments is one example and is discussed in more detail in the following section. The knowledge tree is like a flow diagram similar to that created by engineers to show the movement of raw materials through various stages en

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Fig. 4 Schematic identifying the characteristics of the different components of a composite cake product and the potential routes of moisture migration.

route to becoming a finished product. The same basic principle is used by systems analysts when they are constructing diagrams to show the flow of information, with different symbols representing different types of activity or decisions which need to be made. Cauvain and Young (2006) illustrated possible examples of pattern matching for the baking industry using a series of `spider diagrams' to relate certain characteristics of wheat with those of the subsequent flour, dough and bread. As well as providing a relatively simple means of developing patterns relating raw materials and finished products, the process of deciding which characteristics to include in the various diagrams is an important first step in understanding the cause of quality problems. When it comes to identifying the key roles of different ingredients and processes in determining a particular aspect of final product quality, it is useful to be able to identify the relative importance of the individual changes. It may be possible through mathematical modelling to identify the relative importance of the effect of different ingredients, recipes and processes or process changes but it can sometimes be sufficient in problem solving to use a simple diagram to understand the different contributions (Cauvain and Young, 2006). An example of this type of approach is given in Fig. 5, which examines the impact of some process and ingredient factors on the hardness and crumbliness of cookies. The development of a gluten network in cookie dough is not usually considered to be desirable but if this should happen, e.g. through over-mixing, the resultant product will be harder eating. As the sugar level in a cookie formulation increases, the resultant product gradually loses its initial crumbliness and becomes harder (e.g. as seen with ginger nuts), while increasing additions of fat give increasingly crumbliness as the fat interferes with the development of the gluten structure. The angle at which the individual vectors proceed from the

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Fig. 5 The impact of some process and ingredient factors on the hardness and crumbliness of cookies.

origin gives an indication of the relative impact of any changes, so that this relatively simple diagram can provide a first indication of the potential interactions taking place in a particular baking environment. For example from Fig. 5, if we wish to reduce the fat level in a cookie formulation but do not wish to end up with a harder biscuit then we would consider a reduction in gluten development by adjusting mixing conditions or methods or changing ingredients, such as flour type, which contribute to gluten formation.

1.6

The information sources

Not many of the problems that we may encounter in the manufacture of bakery products are likely to be so unusual that they have not been encountered and recorded before. Even where an apparently new problem arises, access to suitable information sources often reveals a problem and solution so similar that it can be readily adapted to our particular needs. For example, most of the problems that we are likely to encounter in the production of cakes with heattreated cakeflours (BPS, pp. 30±1) will have similar solutions to those that would apply if we were using chlorinated cakeflours (BPS, pp. 32±3). Even though it may be the first time that we have used a heat-treated flour, we therefore have a suitable base for identifying the solution to our problem. The availability of suitable information is a fundamental tool for our ability to problem solve successfully. Traditionally such information sources could be classified as personal and written. More recently computer-based sources have become increasingly available sometimes as databases but in other cases in forms that would not be classified as an electronic equivalent of the written word.

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Personal Even in today's fast-moving electronic age there is no substitute for personal experience which builds one's own portable information source. However, few of us will spend long enough in positions that allow the systematic build-up of the appropriate knowledge through `trial and error' studies. Aspects of problem solving may be taught in our years of academic study but these are seldom detailed enough to provide us with the comprehensive information base required. Personal contacts with experts and consultants can be used to supplement the individual information base. Contact with other professional bakers and professional baking organisations are invaluable because it allows access to a wider range of experiences. Thus membership of professional bodies such as the British Society of Baking, the American Society of Baking and the Australian Society of Baking, which are linked with one another, has benefits in developing one's own knowledge base. Attendance at suitable conferences, technical meetings, workshops and short courses can provide relevant information. Written The scientific and technical literature provides the most obvious source for written material which aids in problem solving. Starting a collection of `useful' articles and some form of index is very helpful in establishing your own information base. Included in the written form are pictorial libraries of faults and associated text related to their identified causes. Such libraries may be built for oneself or may be purchased from a suitable source. Over the years many of the `rules' related to problem solving in baking have been summarised and published (e.g. Street, 1991; Bent, 1997b). These generally take the form of lists of faults and associated causes. In many ways such rules are of limited value because they seldom consider or assign a likelihood value and so a personal degree of judgement as to which of the causes to investigate first is required. Such lists tend to deal only with the more common problems and seldom consider interactions between ingredients or ingredients and processing. Also the causes of faults are given equal weighting; thus there is no expression as to whether a particular cause is more likely than another. The values of a personal record can be significantly increased by systemising the knowledge record. A series of checklists can be constructed to identify contributions of ingredients and processes to final products and their appropriate intermediates (e.g., dough, batter, paste). An example of such an approach is illustrated for pastry in Tables 1±3. Checklists may be populated with the type of information identified in Section 1.7. A `first level' checklist (Table 1) identifies the ingredients that may be used in the manufacture of pastry and considers the potential impact on the various final product characteristics. Filling in this first checklist is merely a question of identifying whether a particular ingredient has an effect or not; those that do have an effect could be marked with an `X'. In Table 1 the different quality of

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Table 1 Example of level 1 checklist for recording the potential effects of ingredients and their qualities on paste and pastry characteristics

the flour, fat, and sugar are known to have an effect and so are marked for consideration. Re-work has been included as an `ingredient' because of the profound effect that it has on both the paste and the final product; the re-work quality would be controlled by its age, temperature and length of storage time. Consideration is then given to whether varying the ingredient level will impact on paste characteristics and final product quality. The example illustrated in Table 2 does not include flour, since it is common practice to assess the impact of ingredients with respect to flour at a standard level in the bakery (Cauvain and Young, 2006). At this stage there is no need to consider the direction of impact. The final level 1 checklist considers the impact of the processing steps applied in the manufacture of the bakery product concerned. In Table 3 some examples related to the mixing, processing and baking of pastes are included. Again it is only necessary to identify whether there is an impact or not from a particular process step. The level 1 checklists help focus the subsequent line of reasoning that might be applied in problem solving or product development. The `second level' checklist considers the impact of the level of the different recipe ingredients and process settings. In this case it will be necessary to consider the direction of change for given product characteristics (e.g., larger, smaller) and link these with changes in ingredient level (e.g., higher, lower) or process conditions (e.g., mixing time longer or shorter). Examples of level 2 checklists are illustrated in Tables 4±6 and they show the type and range of information that might be

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Table 2 Example of level 1 checklist for recording the potential effects of ingredient levels of paste and pastry characteristics

Table 3 Example of a level 1 checklist for recording the potential effects of processing conditions on paste and pastry characteristics

Table 4 Example of a level 2 checklist for recording the potential effects of ingredient qualities on paste and pastry characteristics

Table 5

Example of level 2 checklist for recording the potential effects of ingredient levels on paste and pastry characteristics

Table 6

Example of a level 2 checklist for recording the potential effects of processing conditions on paste and pastry characteristics

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included. If an ingredient or process parameter was identified at level 1 then it is carried through to level 2. Entries at level 2 can be directional (as illustrated) or if hard data exist (e.g., from mathematical modelling), these can be entered instead to give the level 2 checklists a more `predictive' capability. Missing from the checklist approach is the ability to directly record complex interactions but they can be a useful first step in assembling the complex knowledge required for solving bakery problems. They can also be useful for gathering and systemising the information required for the development of computer-based knowledge systems (see below). Constructing knowledge trees and knowledge fragments Another approach to recording technical information can take the form of constructing knowledge trees. Usually the construction of the tree starts at the top and works downwards to the `roots'. In practice the information that it holds can be used from the `bottom up' for product development and from the `top down' for product and process quality optimisation. The construction of the knowledge tree starts with the identification of a final product or intermediate property of interest and proceeds by identifying all those factors that contribute to the identified property or characteristic, both individually and collectively. An example of this approach is given in Fig. 6 for lift in laminated puff pastry. Moving from the top of the tree downward we can see that the approach is to progressively break down complex interactions until single contributing factors are identified; these may be considered as the roots of the tree, even if not all of them are `planted in the ground'. Cauvain and Young (2006) provide another example of a knowledge tree for the eating quality of bread and cake products. As complex as these diagrams appear, they only par-

Fig. 6 Part of a knowledge tree identifying the factors that contribute to pastry lift.

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tially address the issues of the complex ingredient±recipe±process interactions which underpin baking. Sometimes it is not possible to develop a full knowledge tree and it is easier to break the structure down into a series of knowledge fragments. This is a technique that we have pioneered and used in many situations. An example of a knowledge fragment is illustrated in Fig. 7 and is one relevant to ascorbic acid oxidation in breads made using the Chorleywood Bread Process. The fragment identifies a number of the key interactions that take place in mixing and how they relate to the qualities of the final product. Fragments are visual aids that help you to quickly see relationships between pieces of knowledge. They can express or define information and knowledge about an ingredient, a term used in baking or a processing step or about any information you may wish to structure so that it is easy to use again, either as an aide-meÂmoire or to help in your understanding of a topic. They are constructed in a similar way to a `flow diagram'. The items of knowledge can be linked together using lines and arrows. They need to be structured and classified in a simple way and saved so that they can be retrieved easily when needed. They might be considered as a `diagrammatic knowledge-/data-base'. The key terms used in them can be indexed so that retrieval is easy. If faults or quality defects are shown in the fragments, they can be used to identify the questions that need to be asked to determine a solution to a baking problem or quality defect. They can help you to link all the technical information that you acquire about baking. In the example provided, Oxidation in CBP, all of the relevant knowledge about oxidation is illustrated. The mechanism by which ascorbic acid takes part in oxidation, the links to mixing and energy requirements, and possible processing issues are shown. Its contribution to gas retention is flagged. The result of underor over-oxidation for the product being considered, in this case generic plant bread, can be inserted. By referencing some of the key terms used in the fragments, e.g. gas retention, gas production, fault ± low volume, fault ± coarse structure, etc., the relevant fragments can be identified and examined when a product exhibits a particular fault, e.g. coarse structure. Any fragments showing this fault can be used in the trail to find the cause of the fault and its correction. Such knowledge fragments can have considerable value in their own right as they provide detailed information focused on one or two aspects of a larger and more complex structure. Knowledge (computer)-based systems Computing technology offers a special opportunity to help with problem solving, quality optimisation and product development. In particular, reasonbased programs, commonly known as `expert systems', can be used in fault diagnosis and linked with corrective action. The Flour Milling and Baking Research Association at Chorleywood was the pioneer in applying such technology to the baking industry. Later the work was continued in the Campden and Chorleywood Food Research Association.

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Fig. 7 Example of a knowledge fragment related to ascorbic acid oxidation in the Chorleywood Bread Process (ß Baketran 2008).

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Expert, or knowledge-based systems as they are now commonly referred to, can combine facts and rules to solve problems. The `rules' can take several forms including mathematical models, `rules of thumb' and `intuitive' rules. The latter may well take the form of `if I increase the level of ingredient X then property Y in the product will change in a positive direction' (cf. the checklist approach discussed above). Such rules may not quantify the degree of change, only the direction. Knowledge-based systems can contain many rules that should be capable of validation. They should not contain opinion but rather concentrate on facts. Such systems can perform a fault diagnosis within a few minutes and are capable of considering large information bases very quickly. They can consider many interactions and are often written to provide degrees of likelihood in the answers so that the process of identifying corrective actions and assigning priorities is more readily possible. Images and text can be integrated and displayed to provide pictorial display of product characteristics. In some cases it may be possible to diagnose faults with a knowledge-based system based solely on images run using touch-screen computing technology (Young, 1998a). Unlike humans, knowledge-based systems never forget and always consider all the necessary information. However, they are not perfect because they rely on human programming and so are only as good as the information they contain. Nevertheless, they can play an important role in aiding problem solving, quality optimisation and product development (through `what if?' questioning) and offer a significant advantage over the classical written fault diagnosis text lists. Knowledge-based systems have been applied for problem solving in the production of bread (Young, 1998a), cake (Petryszak et al., 1995; Young et al., 1998) and biscuits. In addition to their application for problem solving, they may be used in product development (Young, 1997), process optimisation, e.g. retarding (Young and Cauvain, 1994; Young, 1998b), and for training (Young, 1998a). The `Web' The development of the World Wide Web has increased the range of options available for information and contacts to help with problem solving. There are many sites that can be accessed for providing information but it is important to try to ensure that the information received has some validity and credibility. It is therefore best to deal with reputable and well-known sources. Developments in web-based technologies will considerably increase the availability of computer-based tools such as knowledge-based systems. Work has been undertaken to provide access to such programs on an on-line basis, linked with the transfer of appropriate baking technology (Young, 1999) but such approaches have yet to achieve their full potential in baking and allied industries. A number of professional bodies associated with baking offer their problemsolving services via web-based systems. There are also commercial organisations who offer assistance with problem solving, commonly on a fee-

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paying basis. Details of their services can be obtained from their relevant web sites.

1.7

New product development

Much of the information and advice that has been given so far in this chapter is related to problem solving. However, there are significant similarities between the processes involved in problem solving and in developing new bakery products. For example, it is common practice, before undertaking a new development, to consider the properties that are sought in the new product and compare them with existing product qualities. If the quality differences between the new product and the existing product are treated as though they are quality deficiencies, then the information and techniques which are commonly used in problem solving are now equally applicable to new product development. In this process the question is not `How do I solve this problem?', rather it is `How do I move the product quality in a given direction?'. Knowledge fragments and knowledge trees can have significant roles to play in new product development because they will contain the information which allows the product developer to make informed decisions as to which ingredient, recipe or process changes to make in order to manipulate product quality and should also contain some identification of the key product interactions. When new products are developed, the techniques described above should assist in moving the quality of the concept product under development smoothly to the finished product ready for launch in the marketplace. However, occasionally it can be forgotten that there needs to be a structure to the product development process itself. In the worst cases the point can be reached where a great deal of money is expended without achieving a robust sustainable product. The list below can be used as a guide to successful product development. It is not exhaustive and can be augmented for local circumstances. At each major stage it is advisable to consider a `Go/No go' decision for the product so that it is developed on a sound commercial and technological basis. Concept Discussion about product feasibility with · Marketing · R and D · Engineering · Quality control · Production · Procurement. Consumer research required? · Market studies · Trend analysis

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· Product positioning · Focus group testing. Defining the product · Characteristics · Specifications · Eating quality · Appearance/dimensions, etc. · Shelf-life requirements ± both organoleptic and mould-free · Formulation · Engineering requirements/equipment · Any legislation issues · Nutritional issues · In-house capability · Preliminary product costings/commercial viability of product · Consumer acceptance · Budget investigation · Project manager and team ± propose · Criteria for success ± define o Can the product be made easily and efficiently? o Can it be sold for the right price and make a profit? Go/No go decision point Product development investigation ± prototype product · Budget · Define timeline for the prototype product development · Define areas of responsibility · Formulation development for constituents of product, e.g. biscuit, cream, filling, coating · Flavour profile development · Ingredient assessments · Lab pilot-scale development of the product (including tasting) · Records of development of prototype, including photographs · Investigation of needs for processing equipment, e.g. have we got suitable equipment, can we buy it off the shelf, is it a one-off? · In-house expertise for product development and production · Consultants/specialist input required? · Training required? · Consumer acceptance trials? · Assessment of lab pilot-scale products · Quality analysis o shelf-life o stability

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o rheological properties o organoleptic properties o flavour profiling o other analytical tests required? · Potential market ± route · Costings for the product · Criteria for success ± revisit. Go/No go decision point Scale-up to commercialisation assessment · Budget · Timeline · Process development for large-scale production · Engineering work required ± equipment development/modification · Increasing production or baking capacity? · Manufacturing and baking specifications · Risk assessments · Packaging development/integrity testing/shelf-life issues. Prototype trials on the plant · Budget · Timeline · Ingredient procurement and assessment · Equipment ± purchase/recommendations, set-up, liaison with production schedule, skills required, personnel training, expertise to be brought in · Keeping/shelf-life trials · Consumer trials · Marketing input. Go/No go decision point Pre-launch trials · Specification and procurement of ingredients · Purchase of equipment if required · Marketing input · Packaging design · Tasting trials with consumers · Labelling · Quality control requirements · Plant/housekeeping/production team · Assessment of production product · Shelf-life trials continued. Go/No go decision point

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Launch · Marketing · Advertising · Packaging · Pricing · Procurement · Hand over to production team as a portfolio product · Set up quality assessment. On-going product maintenance/handover · Confirmation of product specification definition, e.g. archive of recipe and ingredient specifications, processing details, etc. · Quality control specifications and reports · Scheduling considerations · Consumer acceptance · Crisis management plan for potential disaster/mishaps, e.g. change of ingredient, change in legislation, plant breakdowns · Marketing plans · Keeping trials.

1.8 Some key ingredient and process factors affecting product quality The following lists identify examples of the primary factors to consider when looking at quality problems with some of the different groups of bakery products and provide summaries of some of the key ingredient and process (secondary) factors which affect product qualities. The lists are not comprehensive but may provide a useful guide to establishing the reader's own database, a series of personalised checklists or knowledge fragment and knowledge trees. Bread Primary factors · Cell creation · Gas production · Gas retention · Dough development · Dough rheology. Volume · flour protein quantity; · flour grade colour or ash; · improver level ± oxidants, emulsifiers, fats, enzyme-active materials; · improver composition ± oxidants, emulsifiers, fats, enzyme-active materials;

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More baking problems solved yeast level; dough development ± energy/time; dough temperature; prover conditions ± time/temperature/humidity; oven conditions ± temperature.

Crust colour · sugar levels; · improver level; · improver type; · dough enzymic activity; · fermentation conditions ± time/temperature/yeast level. Crumb cell structure · flour properties ± protein quantity; · improver level ± oxidants, emulsifiers, fats, enzyme-active materials; · improver composition ± oxidants, emulsifiers, fats, enzyme-active materials; · yeast level; · dough development ± energy/time; · dough temperature; · dough moulding. Crumb colour · flour grade colour/ash/bran level; · crumb cell structure; · dough moulding. Crumb softness · volume; · cell structure; · ingredients ± emulsifiers, enzyme-active materials; · moisture content; · baking conditions ± time; · storage conditions ± temperature/time. Cakes and sponges Primary factors · Cell creation · Gas production · Batter viscosity. Volume · recipe balance; · baking powder level;

Problem solving: a guide · emulsifier level; · mechanical aeration; · baking temperature. Crust colour · recipe balance ± sugars, milk products; · baking ± conditions temperature. Crumb cell structure · mixing time; · mechanical aeration; · recipe balance; · baking powder level. Crumb colour · Ingredients, e.g. egg level. Crumb softness · volume; · moisture content; · cell structure; · baking time; · storage conditions ± time/temperature. Pastries Primary factors · Paste rheology. Shape · recipe balance; · mixing conditions ± time/energy; · process conditions ± resting periods. Fragility · recipe balance; · mixing conditions. Eating qualities · recipe balance; · moisture content; · moisture migration; · storage conditions ± time/temperature.

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Laminated products Primary factors · Gas production · Gas retention · Dough development · Paste rheology. Shape · recipe balance ± fat level; · mixing conditions ± time/energy; · process conditions ± resting periods; · lamination conditions ± numbers of layers, temperature. Lift · recipe balance ± fat level and type; · mixing conditions ± time/energy; · production method ± English/French/Scotch; · process conditions ± temperature, resting periods. Eating qualities · recipe balance ± fat level; · fat type; · moisture content; · moisture migration.

1.9 Conclusions Many of us will be faced with the need to solve problems associated with baked products, whether we work in a bakery or the industries which supply it. Some will be minor and some extensive in nature, but they will all be important. To a large extent identification of the causes of the problem will be based on sound observation and the application of appropriate knowledge in a systematic manner. As bakers we have to deal with a mixture of complex ingredients and their many interactions with one another and the production processes we use. For practical bakers many of the causes of problems are `hidden'; for example, a change in flour properties is seldom obvious until a defective product leaves the oven. There is always a need to find the `quick' solution and traditionally this was based on training and experience. Today's bakers seem to get little of the former and are seldom given the time to obtain the latter. Modern information technologies can go some considerable way in providing suitable problem-solving tools for the modern baker. However, there is no single unique source that can provide all of the necessary solutions to baking problems but keen observation, a methodical approach and good information sources will almost always help identify cause and solution.

Problem solving: a guide

1.10

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References

(1995) Crust colour assessment of bakery products. AIB Technical Bulletin XVIII, Issue 3, March. BENT, A.J. (1997a) Confectionery test baking, in The Technology of Cakemaking, 6th edn. (ed. A. J. Bent), Blackie Academic & Professional, London, UK, pp. 358±385. BENT, A.J. (1997b) Cakemaking processes, in The Technology of Cakemaking, 6th edn. (ed. A. J. Bent), Blackie Academic Professional, London, UK, pp. 251±274. CAUVAIN, S.P. (1991) Evaluating the texture of baked products. South African Journal of Food Science & Nutrition, 3, November, 81±86. CAUVAIN, S.P. (2007a) Bread ± the product, in Technology of Breadmaking, 2nd edn. (eds S.P. Cauvain and L.S. Young), Springer Science+Business Media, New York, USA, pp. 1±20. CAUVAIN, S.P. (2007b) Breadmaking processes, in Technology of Breadmaking, 2nd edn. (eds S.P. Cauvain and L.S. Young), Springer Science+Business Media, New York, USA, pp. 21±50. CAUVAIN, S. P. and CYSTER, J.A. (1996) Sponge cake technology. CCFRA Review No. 2, CCFRA, Chipping Campden, UK. CAUVAIN, S.P. and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2006) Baked Products: Science, Technology and Practice, Blackwell Publishing, Oxford, UK. DTI (1993) Quality Optimisation in the Food Industry ± Applying Taguchi Methods in the Baking Industry, DTI Project CSA 1923, DTI, London, UK. KULP, K. (1991) Breads and yeast-leavened bakery food, in Handbook of Cereal Science and Technology (eds K.J. Lorenz and K. Kulp), Marcel Dekker, New York, USA, pp. 639±682. MUNSELL, A.H. (no date) Munsell System of Colour Notation, Macbeth, Baltimore, USA. PETRYSZAK, R., YOUNG, L.S. and CAUVAIN, S.P. (1995) Improving cake product quality, in Proceedings of Expert Systems 95, the 15th Annual Conference of the British Computer Society Specialist Group on Expert Systems, December, pp. 161±168. STAUFFER, J.E. (2000) Root cause analysis. Cereal Foods World, 45, July, 320± 321. STREET, C.A. (1991) Flour Confectionery Manufacture, Blackie Academic & Professional, London, UK. WHITWORTH, M., CAUVAIN, S.P. and CLIFFE, D. (2005) Measurement of bread cell structure by image analysis. In Using Cereal Science and Technology for the Benefit of Consumers (eds S.P. Cauvain, S.E. Salmon and L.S. Young), Woodhead Publishing Ltd, Cambridge, UK. YOUNG, L.S. (1997) Water activity in flour confectionery product development, in The Technology of Cakemaking, 6th edn. (ed. A.J. Bent), Blackie Academic & Professional, London, UK, pp. 386±397. YOUNG, L.S. (1998a) Baking by computer ± passing on the knowledge, in Proceedings of the 45th Technology Conference of the Biscuit, Cake, Chocolate and Confectionery Alliance, London, pp. 63±67. YOUNG, L.S. (1998b) Application of knowledge-based systems, in Technology of Breadmaking (eds S.P. Cauvain and L.S. Young), Blackie Academic & Professional, London, UK, pp. 180±196. YOUNG, L.S. (1999) Education and training for the future, in Proceedings of the 86th Conference of the British Society of Baking, British Society of Baking, pp. 13±16. ANDERSON, J.

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YOUNG, L.S. and CAUVAIN, S.P. (1994)

Advising the baker, in Proceedings of Expert Systems 94, the 14th Annual Conference of the British Computer Society Specialist Group on Expert Systems, December, pp. 21±33. YOUNG, L.S., DAVIES, P.R. and CAUVAIN, S.P. (1998) Cakes ± getting the right balance, in Applications and Innovations in Expert Systems VI, Proceedings of the 18th Annual Conference of the British Computer Society Specialist Group on Expert Systems (ed. A. Mackintosh) Cambridge, December, SGES Publications, Cambridge, UK, pp. 42±55.

2 Flours and grains

2.1 We have seen references to the ash content with white flours but this is not a figure that appears on the specification from our UK miller. Can you explain what the ash content means and should we ask for it to be determined on our flours? The ash test is based on the incineration of a known weight of a flour sample at 900ëC in a suitable furnace; the material that remains after incineration comprises the inorganic minerals and is referred to as the ash (ICC, 2005). There are alternative testing methods that use a lower temperature for heating the sample, e.g. the AACC method for ash determination uses a temperature of only 600ëC (AACC, 2008). Whatever the testing method that is applied the aim remains the same. The minerals in cereal grains are concentrated in the outer bran layers which surround the inner endosperm. Thus, as a general principle the higher the ash content of a `white' flour, the greater the proportion of bran which can be present in the sample. The complex geometry of the wheat grain and the physical properties of the materials concerned means that the bran skins cannot be `pealed' from the endosperm like layers on an onion and, even in the most efficient of flour mills, it is inevitable that some fragments of the outer bran layers will find their way into the white flour which essentially comes from the endosperm. The ash test may therefore be seen as an indicator of the `purity' of white flour in that the more of the bran which is incorporated with the wheat endosperm, the higher the ash level will be. It follows that since wholemeal flours are 100% of the grain, then the ash content will be considerably higher than that of white flours. In the UK (and elsewhere) there is a statutory requirement for white flours to be fortified with calcium carbonate at levels between 235 and 390 mg/100 g (The

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Bread and Flour Regulations, 1999) before the flour leaves the mill. This requirement is related to the nutritional status of flour. Calcium carbonate is an inorganic substance which remains as part of the ash residue on testing. However, unlike bran it has no technological impact in baking. Since calcium carbonate would measure as ash, using the test for UK flours will yield a higher value and distort the application of the information for bakery purposes. In light of the above scenario UK millers do not routinely use the ash test to monitor final flour quality, instead they use a test commonly referred to as the `grade colour figure' (see 2.2). This test, carried out with a `Colour-grader' with a specified light source (Cauvain, 2009), is based on the assumption that higher levels of bran will yield a darker flour colour. There is a broad agreement between ash and grade colour figure (see Fig. 8) but one value cannot be used to predict the other with any degree of certainty. This is because the distribution of minerals is not uniform throughout the wheat bran layers and the particle size of the bran also distorts the relationship. While neither test can be used to predict the results of the other, both have relevance to the breadmaking potential of a given white flour. In its simplest form the higher the ash value or grade colour figure, the poorer the gas retention capacity of the flour in breadmaking. This, in turn, means that loaf volume will fall if the ash or grade colour figure increases. Cauvain (2009) provides relevant ash data for a range of mill fractions included in an example of a straight run white flour. In broad terms the ash level has been equated with the `extraction rate' of flours (i.e., the proportion of the original grain turned into flour). Kent and Evers (1994) published data relating milling extraction rate to ash values and showed that an increase in extraction rate from 70 to 85% increased the measured ash level in the flour from 0.44 to 0.92%. However, ash levels should not be taken as an absolute indicator of extraction rate because, as noted above, as the minerals in the wheat grain are not uniformly distributed in the grain components and so the milling techniques that may be used can skew the data. References

(2008) Approved Methods 10th edn., AACC International, St. Paul, MN. (2009) Applications in the flour mill. In (eds. S.P. Cauvain and L.S. Young) The ICC Handbook of Cereals, Flour, Dough & Product Testing: Methods and Applications, DEStech Publishing, Lancaster, PA, pp. 91±124. ICC ± INTERNTATIONAL ASSOCIATION FOR CEREAL SCIENCE & TECHNOLOGY (2005) Determination of ash in cereals and cereal products, ICC Standard Method 104/ 1, Vienna, Austria. KENT, N.L. and EVERS, A.D. (1994) Technology of Cereals, 4th edn., Elsevier Science Ltd, Oxford, UK. THE BREAD AND FLOUR REGULATIONS (1999) SI 1999, No. 1136 ± SI 1998, No. 141, HMSO, London, UK. AACC

CAUVAIN, S.P.

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2.2 What does the term grade colour figure mean in flour specifications? How is it measured? What are the implications for bread quality? Grade colour figure (GCF) (sometimes written as Colour Grade Figure or Flour Colour Grade) is a measure of flour colour. The technique uses light reflectance at a specific wavelength from a flour-water paste held in a glass cell. It was developed by Kent-Jones and Martin (1950) and refined by Kent-Jones, Amos and Martin (1950). The `Colour Grader' has undergone a number changes to improve its reliability and sensitivity. In many countries GCF is an accepted method for the evaluation of mill performance and flour quality. While generally accepted as a measure of the level of bran present in white flours, it is appreciated that GCF is affected by a number of other factors, including the intrinsic colour of the wheat endosperm (Barnes, 1986) and the impact of any bleaching processes which may be carried out (bleaching white flours is seldom practised in modern mills). In the UK the mandatory addition of chalk to white flour means that the measurement of ash as a predictor of the breadmaking potential of the flour was misleading because the measured ash value was raised by the addition of the chalk (see 2.1). Thus GCF came to be used more readily as an indicator of the level of bran `contamination' in white flour. The form of wheat grains, especially the crease, means that it is difficult to completely separate the bran layers from the starchy endosperm and it is inevitable that small particles of bran `powder' find their way into white flour. The bran particles have the same size as the endosperm fragments and so cannot readily be separated by sieving. The level of bran particles may be reduced through aspiration (in purifiers) since they are less dense than the endosperm fragments but complete separation is seldom achieved. In general, the higher the GCF value, the higher the level of bran present in a given white flour, the poorer the gas retention properties in bread dough and the darker the bread crumb colour. This statement does not convey the complete picture for white flours, which are a composite of many different `white' machine flours obtained during wheat milling. The level of bran varies in each of these flours according to the layout and operation of the mill. Cauvain et al. (1983) provided examples of the variation in GCF amongst machine flours with relevant bread volume data. There is a general relationship between the two measured flours properties (see Fig. 8) but GCF cannot be accurately used to predict flour ash and vice versa. It should be noted that when the GCF test was developed it was intended to be used with white flours and so measurements on brown or wholemeal have limited relevance. Machine flours that are high in bran content (i.e. high ash or high GCF) may often be referred to as `low grade' flours to indicate their relatively poor breadmaking potential. The quantity of such flours produced and present in straight run flour is usually relatively small so the overall impact on flour GCF

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Fig. 8 Relationship between flour ash and grade colour figure.

and loaf volume arising from their addition is limited. Flours that are especially low in bran (i.e., low GCF and low ash) may often be referred to as `patent' or `top patent' flour. Such flours have good breadmaking potential even though their protein content may be lower than a straight-run flour. Cauvain et al. (1985) using a range of white commercial flours showed that as a general `rule of thumb' an increase in flour GCF of one unit was equivalent for its negative impact on loaf volume to a decrease in 1% of flour protein for bread made by the Chorleywood Bread Process. The GCF measurement method is not normally used to assess the quality of wholemeal flours; not least because the reliability of the measurements can be affected by the size on the bran particles which are present in the flour. In white flours the bran particles will be no bigger than the largest of the wheat endosperm fragments which are present. References

(1986) The influence of wheat endosperm on flour colour grade. Journal of Cereal Science, 4, 143±155. CAUVAIN, S.P., CHAMBERLAIN, N., COLLINS, T.H. and DAVIES, J.A. (1983) The distribution of dietary fibre and baking quality among mill fractions of CBP bread flour. FMBRA Report No. 105, Campden-BRI, Chipping Campden, UK. CAUVAIN, S.P., DAVIES, J.A. and FEARN, T. (1985) Flour characteristics and fungal alphaamylase in the Chorleywood Bread Process, FMBRA Report No. 121, CampdenBRI, Chipping Campden, UK. KENT-JONES, D.W. and MARTIN, W. (1950) A photo-electric method of determining the colour of flour as affected by grade, by measurements of reflective power. Analyst, 75, 127±133. KENT-JONES, D.W., AMOS, A.J. and MARTIN, W. (1950) Experiments in the photo-electric recording of flour grade by measurements of reflective power. Analyst, 75, 133±142. BARNES, P.J.

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2.3 Can you explain the functions of the different components in the wheat grain and, after milling, their contributions to the manufacture of baked products? Shapes vary among the various cereal grains though their main components are surprisingly similar. In the preparation of wheat flour we are dealing with the seed of the plant formed during its growing cycle. The individual seed grains are the next generation of plants and contain all of the nutrients and specialist components to start the growing cycle under appropriate conditions. The individual seed grains are composed of a series of different tissues, each with its own special function in the life cycle of the plant. In broad terms we describe wheat as being composed of a series of outer layers variously referred to as the seed coat or bran skins, an inner endosperm and the embryo. Unfortunately there is confusion in the use of the latter term and in common usage it is often referred to as the germ of the grain. The term germ is most commonly used within a milling context and refers to an embryo-rich fraction of the grain obtained during milling processes. For the seed the functions of the different components are relatively clear; the bran layers enclose and protect the food reserves (the endosperm) for the growth of the future plant while it is from the embryo that the proto roots and shoots will spring when conditions are appropriate. The physical structures and chemical composition of the seeds are far too complex to describe in a book on baking and so the reader is referred elsewhere for such detail (Lorenz and Kulp, 1991). The overall proportions of the three main wheat seed components vary slightly according to the wheat variety and the conditions under which it is grown but the variations are relatively small. To add to the confusion that commonly surrounds the different components of wheat grains, the definitions of bran, endosperm and embryo are fuzzy but in broad terms the grains (on a dry matter basis) are composed of 15% bran, 83% endosperm and 2% embryo. The moisture content of grains will vary depending on environmental factors; figures of 12±20% in the field are not uncommon while in the mill 12±15% are more likely. In whole grain an approximate analysis (% dry matter) would be: Sugars Starch Pentosans (soluble proteins) Protein Lipids (fats) Cellulose Minerals

2.5 71.5 3.5 15.0 2.5 3.0 2.0

The distribution of the different components throughout the grain is not uniform with the cellulose and minerals more likely to be found associated with the bran and germ and most of the starch in the endosperm. Thus in the different milling processes employed to manufacture white flours there is a concentration of some of the grain components into the different milling fractions.

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In the manufacture of bread and fermented products it is the proteins which are of greatest concern since they have the ability to form a gluten network capable of trapping the carbon dioxide gas generated by bakers' yeast fermentation; both the quantity (BPS, pp. 18±19) and the quality (BPS, p. 20) impact on the dough gas retention and processing properties. The most functional proteins for breadmaking are those largely found in the endosperm of the grain. The pentosans, or soluble proteins, make a significant contribution to the water absorption capacity of the flour (BPS, p. 27) because of their ability to absorb about seven times their own weight of water (Stauffer, 2007) which is 3± 4 times more than any other flour component. However, because they are present at low levels in flour their overall contribution to water absorption capacity is small. Starch plays a number of roles in baked products. During the manufacture of many baked products starch in the presence of water and upon heating undergoes a transformation known as gelatinisation and in this form is a significant contributor to structure formation, especially in cakes. In bread the gelatinisation of starch and its subsequent retrogradation in the loaf during storage is a key element of the staling (firming) process. During the wheat milling process some of the starch is physically damaged, which contributes to its functionality in baking (BPS, 25±6). Cellulose is most often linked with the bran content of the flour, which tends to have a negative effect on flour properties, especially dough gas retention (see 2.2) but makes a positive contribution to dietary fibre. The naturally occurring sugars in wheat grains are not usually considered to be important but it is worth noting that in the manufacture of bread and fermented products they do contribute to supporting yeast fermentation. The minerals and vitamins present in wheat grains contribute to the nutritional value of flours. The lipids present in wheat flour are mostly associated with the germ (Cornell, 2003) and to a lesser extent the bran. Their role in baking has not yet been clearly defined, in part because in order to study them it is first necessary to extract them from wheat flour and this may lead to a modification of their functionality which is not representative of how they would work in the original flour. References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. CORNELL, H. (2003) The chemistry and biochemistry of wheat. In (ed S.P. Cauvain) Bread making: Improving quality, Woodhead Publishing Ltd, Cambridge, UK, pp. 31±70. LORENZ, K.J. and KULP, K. (1991) Handbook of Cereal Science and Technology, Marcel Dekker Inc., New York, NY. STAUFFER, C.E. (2007) Principles of dough formation. In (eds. S.P. Cauvain and L.S. Young) Technology of Breadmaking, Springer Science + Business Media LLC, New York, NY, pp. 299±332. CAUVAIN, S.P.

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2.4 We understand that millers often use a mixture of different wheats to manufacture the flours that they supply to us. Can you explain why they do this? In every country where wheat is grown there are many varieties; in some cases the numbers may run close to or exceed 100. Modern wheat varieties are the result of selective breeding over many years as humankind matched wheat variety with climate and soils in the different parts of the world. The type of wheat grown is largely determined by environmental conditions such as the nature and length of the growing season. In the UK and elsewhere it possible to sow and grow wheat to over-winter and harvest in the autumn but in some parts of the world the severity of the winters may restrict wheat growing to spring planting alone. Often the focus of selective wheat breeding in the past was related to agronomic and economic factors such as increasing yield and building disease resistance. It is perhaps only in the last 40±50 years that greater attention has been paid to developing wheat varieties for their baking and end-use performance. Many bakery products and processes are closely linked with and traditionally based on the qualities of the locally grown and available wheat. In practice this means that taking wheat grown in one part of the world and using it to make a different product in another part of the world is not always successful without recipe or process adjustment. Try making a baguette with 100% strong Canadian wheat and the product is quite different from using French-grown wheats, and the reverse would be largely true in that French-grown wheats would not make good quality North American pan bread without adjusting the recipe and process used. The milling characteristics of individual wheats also vary. There are few examples of wheats which yield the `perfect' flour for a given bakery product and process. Even if there were, it is important to recognise that the quality characteristics of wheat drift with time. This is a well-known botanical problem seen with all plants. In practice new wheat varieties need to be developed on a regular basis to ensure an adequate supply of wheat of the appropriate quality for bakers. Even bakery processes change with time and this presents new challenges for millers to match their flours to those changes. The choice of wheats used by millers in their grist is influenced by factors such as the availability of different wheat types, both local and imported, and the manner in which their milling process is structured. Not all millers blend wheats before milling, some may mill wheat varieties separately and then blend the individual flours before sending the final product to the baker. There are advantages and disadvantages to the two ways of milling but discussion of these is outside the scope of this book. In summary, millers will have an intimate knowledge of the wheats available for their use and the likely performance characteristics of the flours that they will produce. By accessing and blending different wheat varieties they are seeking to deliver flours with the required performance characteristics and consistency for bakers.

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2.5 We have heard several experienced bakers talking about the `new harvest effect' and the problems that it can cause. Can you explain what is behind this phenomenon and how we can mitigate its effects? The `new harvest effect' is one of the great mysteries of the cereals world. It has been much discussed in the cereals industry but a lot of the evidence for its existence is apocryphal. There have been a number of scientific investigations related to the topic, generally with inconclusive results. It is said to be responsible for a number of different, usually unexpected, and occasionally catastrophic bread quality losses which occur around the period when wheat is newly harvested; these have included loss of bread volume and cell structure, but most commonly dough processing problems are the main issues that are identified by bakers. The basis for any effect is not clear but has variously been attributed to the ripeness of the wheat at harvesting, the short-term age of the wheat before it is incorporated into the milling grist and even the short-term age of the flour before it reaches the bakery. It is relatively uncommon for millers to make a complete transition from 100% `old' crop to 100% `new' crop; usually they will gradually increase the proportion of the new harvest wheat in the grist. In many parts of the world the global trading of wheat further complicates the transition as millers may be incorporating different new crop wheats at different moments in time. It is true that wheat quality does vary with different crop years but millers usually take this into account through suitable quality testing and adjust the mixed grist of wheats that they use accordingly (see 2.4). Milling and baking processes have changed considerably in the last 40 years and it may be that some of the past experiences that are re-told by bakers are no longer relevant. Those breadmaking processes which rely exclusively on the quality of the gluten network in the dough are likely to be the most sensitive to any changes in flour properties with harvesting year. In breadmaking processes where improvers and dough conditioners are added then the effects of small variations in flour quality are less likely to be noticeable. It is interesting to note that improver suppliers are known to make small changes to the formulation of the bread improvers around the new harvest period. The `new' harvest effect is not usually associated with minor changes, rather with more significant and unexpected quality losses. A common feature of these catastrophic failures is that they often disappear without apparent reason after a short period of time using the new flour has elapsed. One possible explanation is that in larger bakeries the process conditions have been settled and optimised for many months and are sensitive to the small changes in wheat quality, which inevitably occur from crop year to crop year. After a period of trial and error the problem usually dissipates as the plant is re-optimised to the new primary raw material quality. We are sorry that we cannot give you a more explicit explanation.

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2.6 We have the water absorption capacity of our flour assessed regularly but find that this is different to the actual water level that we use in the bakery. What are the reasons for this difference and is it important for breadmaking? The level of water that you add to flour for bread making depends on many factors, some determined by the properties of your flour, some by the requirements of the product you are making and some by the mixing and processing methods you use. The water absorption capacity of the flour tends to have less relevance in the manufacture of cakes, biscuits and pastries. There are a number of different methods by which the water absorption capacity of wheat flour is measured (for specific examples see Cauvain and Young, 2009). They are all commonly based on the principle of making a flourwater dough and measuring the rheological properties of that dough during mixing. As the dough mixes it exerts torque on one of the mixing arms and that torque is transmitted to a recording device, commonly a chart or digital display. The chart has a number of horizontal and parallel lines on it and is moving at a constant speed. As the flour begins to hydrate, the rheological properties of the flour-water mixture change and these are recorded on the chart. For flour water absorption estimation one of the horizontal lines is chosen as representing the desired consistency, and the amount of water added to allow the mixture to reach the chosen line is taken as the water absorption capacity of the flour. To some extent the chosen line is arbitrary and linked with a sensory (albeit expert) evaluation of the `ideal' dough consistency. The choice of dough consistency for the standard method cannot take into account all of the potential recipe and process variations that are used in breadmaking and so the flour-water absorption capacity value you are given should only be seen as a guide as to what may be used in the bakery and more importantly perhaps, as a prediction of any changes that you may need to make in order to accommodate variations in flour properties. Contributions to the measured water absorption capacity of flour come from a number of individual flour properties. These include: · The moisture content of the flour; the higher the moisture, the lower the water absorption capacity. · The protein content of the flour; the higher the protein content, the higher the water absorption capacity. · The level of damaged starch in the flour; the higher the damaged starch level, the higher the water absorption capacity. Other contributions come from the enzymic activity and the level of pentosans (soluble proteins) but these are usually relatively small by comparison with the effects of the main flour components. Wholemeal, bran-supplemented and fibreenriched flours will always have a higher water absorption capacity than white flours because of the level of bran and fibre that will be present. The optimum consistency for a bread dough is hard to define because much depends on how the dough will be processed. Hand processing allows for sensitive handling of the dough with ready adjustment of the pressures, which will be applied

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during moulding and shaping. When dough is mechanically processed, the processing equipment cannot adjust its pressures and so there is a much greater need for the consistency of the dough to be optimised and to remain as unvarying. In general, doughs which will be baked in a pan tend to have higher added water levels than those which will be baked on trays or the oven sole (i.e., freestanding). In the former case, a soft dough will more readily flow into the corners of the pans, while in the latter case, a stiffer dough will more readily retain its shape. For example, it is common to use lower water levels in the manufacture of UK-style bloomers, which traditionally have a round or oval cross-section. Too much water and the dough will flow during proof and yield an uncharacteristic and unacceptable flat shape. Some bread types depend on the production of a soft dough in order to achieve the required characteristics. In the manufacture of traditional French baguettes the added water levels may be several percentage points above the measured flour-water absorption capacity and above that used for pan bread production. The soft dough contributes to the ease of dough moulding and avoidance of the squeezing out of the large gas bubbles, which significantly contribute to the creation of the characteristic open cell structure of baguette. The individual dough pieces are proved in cradles of some form which stops them from flowing and the soft dough also contributes to the rapid expansion of the dough piece in the oven, which yields a high specific volume product. Cauvain and Young (2008) discuss the role of dough consistency and its impact on bread cell structure. They show how the gas bubble structure in stiff dough can be broken down and contribute to the formation of areas of damaged structure in the bread comprising coarse cell structure and dull coloured crumb (BPS, pp 87±8). While dough consistency may vary with product and process, there is one dough property that is commonly avoided in all cases, namely dough stickiness. In the bakery, problems with dough stickiness are usually associated with the water level added during dough mixing, and a common reaction to excessively sticky dough in the bakery is to reduce added water levels. A reduction in added water level may well improve the processability of the dough but high water levels per se are often not the main cause of dough stickiness. In many cases dough stickiness arises because of lack of dough development in the mixer; the greater the dough development, the higher the added water level may be. The other major contributor to apparent dough stickiness comes from subjecting the dough to shear forces during processing, such as during moulding, if these can be minimised then water levels can be optimised without compromising dough rheology and bread quality. References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2008) Bakery Food Manufacture and Quality: Water Control & Effects 2nd edn, Wiley-Blackwell, Oxford, UK. CAUVAIN, S.P. and YOUNG, L.S. (2009) The ICC Handbook of Cereal, Flour and Testing: Methods and Applications, DEstech Publishing, Lancaster, PA. CAUVAIN, S.P.

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2.7 Why is the protein content of wholemeal bread flour typically higher than that of white flours but the bread volume is commonly smaller with the former? Protein is distributed throughout the different components of the wheat berry but that distribution is not uniform. There tends to be less protein in the central endosperm portions of the grain (Kent and Evers, 1994). This non-uniform distribution of wheat protein is mirrored by an increase in the starch content. The protein/starch `gradient' in the grain cross-section reflects the manner in which the endosperm develops in the growing plant as the different components are synthesised. The starch granules are packed into cells with the protein fragments. The cell walls of wheat endosperm are mainly composed of arabinoxylans. Surrounding the starchy endosperm is the aleurone layer with dense, thick cell walls. Further out in the grain cross-section are the different layers which characterise the bran. Since the distribution of protein is not uniform throughout the grain, the protein content of the flour is often a reflection of the milling processes used to manufacture the flour. By definition wholemeal flour represents all of the grain crushed into flour and so the protein content of the final flour should be the same of the original starting grain. White flours are based on the separation of the starchy endosperm from the surrounding bran layers and they tend to have around 1% less protein than the original grain (viz. wholemeal flour). The precise difference in the protein content of the grain and the white flour produced from it varies slightly according to the milling technique employed. The presence of bran reduces the gas retention properties of the dough, which commonly yields lower volume in the finished product unless modifications are made to the breadmaking recipe and process. While there are proteins in the bran particles they do not readily form a gluten network as is the case with the proteins in the endosperm cells; in practice this protein may be considered as `non-functional'. The mechanism by which bran particles reduce dough gas retention is not fully understood. Some views suggest that the particles of bran `puncture' the gas cell walls in the dough. However, it is more likely that the bran particles represent areas of discontinuity and weakness in the gluten network, which more readily allow the coalescence of smaller gas bubbles as they expand during proof and the early stages of baking and so permit the escape of some of the carbon dioxide gas being produced by the yeast. For the reasons given above it is common practice to produce wholemeal flours with much higher protein contents than that of white flours. This is done either by choosing a high protein wheat within the milling grist or through the supplementation of the milled flour with dried, vital wheat gluten (BPS, p. 23). References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. KENT, N.L. and EVERS, A.D. (1994) Kent's Technology of Cereals, 4th edn, Elsevier Science Ltd., Oxford, UK CAUVAIN, S.P.

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2.8 We get a significant variation in the quality of our wholemeal bread and rolls depending on which flour we purchase. What characteristics should we look for in a wholemeal flour specification to get more consistent results? Wholemeal flours fall into two main categories: stoneground and roller-milled (BPS, p. 34). A key difference between the two is the particle size distribution; in general stoneground flours have a greater proportion of fine bran particles than the roller-milled type. It is well known that the presence of high levels of bran in wholemeal flours is responsible for the lower bread volume that is achieved by comparison with white flour from the same wheat, despite the fact that the white flour has a lower protein content. It is also known that finer bran particles tend to have a proportionally greater volume-depressing effect than coarse particles. In addition to the bran particle size difference there may be differences in the endosperm particle size of the two types of wholemeal flour. It is likely that the endosperm particle size of the stoneground form is coarser than that of the roller-milled type because the endosperm particles are subjected to considerably fewer grinding passages. One possible consequence of this difference is that the endosperm particles take longer to hydrate and if your mixing times are short, you may not see the same extent of gluten formation. You can check this with a few simple trials with extended mixing times. The protein content of your wholemeal flour should certainly be specified. This will reflect the protein content of the wheats chosen by the miller. It is possible to add vital wheat gluten to boost the protein content of your mix but gluten fortification is less effective with slower speed mixers (BPS, p. 23). The specification of the Hagberg Falling Number is as important with wholemeal flours as it is with white flours and you should also consider whether you should specify the water absorption capacity of the flours. You will need to remember that the water absorption capacity is only a guide as to what water level you will need to actually use for dough mixing. In the case of wholemeal flour this is an especially important point to bear in mind, since the bran and larger endosperm particles will be slow to hydrate. This often means that wholemeal flour doughs become stiffer during post-mixer processing and this can have a negative impact on dough handling properties and contribute to moulder damage and other product quality losses. You should try to maximise the water additions made to wholemeal flours, the initial tackiness that you observe when the dough has finished mixing should begin to disappear within a few minutes during processing. Optimising the added water level will also help you optimise dough development and the gas retention properties of the dough. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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2.9 Since enzymes such as alpha-amylase are inactivated by heat during baking, is it possible to use heat-treatment of flour to inactivate the enzymes in low Hagberg Falling Number flours before baking? The temperature at which alpha-amylase is inactivated depends on its source. There are three common sources: fungal, cereal and bacterial, which are inactivated at increasingly higher temperatures (BPS, pp. 59±60). Since you are asking about flour, then the source of the alpha-amylase is referred to as cereal (commonly from wheat, rye or barley). The exposure of flour to heat brings about a number of different changes. In addition to inactivation of the alpha-amylase there will be: · A loss of moisture. · The potential for denaturation of the protein. · Changes in the swelling and gelatinising characteristics of the starch. When heat is applied to flour it quickly loses moisture but as the moisture content falls to around 8% the rate of moisture loss with continued heating slows down. It appears to be that from this point on some of the more profound changes take place in flour properties. At low levels of heat input a reduction in the extensibility of the flour is usually observed (Kent-Jones, 1926). Prolonged heating leads to complete denaturation of wheat proteins and they lose their ability to form a cohesive gluten network in dough. Dry heat treatment of flour brings about changes in starch properties which are analogous to chlorination and this type of treatment is used to replace chlorination for flours intended for the manufacture of high ratio cakes and some other baked products (BPS, pp. 30±1). Heat treatment of flours should not be used where the product is intended for use in breadmaking. Thus, inactivation of alpha-amylase by heat should not be seen as a means of reducing the adverse effects of cereal amylase in breadmaking (BPS, pp. 57±8; Cauvain and Young, 2006). In some speciality flours, i.e. those destined for use in the manufacture of soups and sauces, inactivation of alpha-amylase is beneficial. In these cases the changes to the proteins and starch are acceptable, since they contribute to a discernible increase in batter viscosity. The changes which heat brings about increase the susceptibility of starch to amylase attack which would reduce the batter viscosity. With the amylase inactivated, batter viscosity can be maintained at an acceptable level. References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2006) The Chorleywood Bread Process, Woodhead Publishing Ltd, Cambridge, UK. KENT-JONES, D.W. (1926) A study of the effects of heat upon wheat and flour, especially in relation to strength. Thesis presented to London University, UK. CAUVAIN, S.P.

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2.10 We are considering making traditional German-type rye breads and have researched the recipes and production methods. Do you have any suggestions as to what characteristics we should have in the rye flour? Rye grain is more susceptible to pre-harvest sprouting than wheat. The starch in rye flour gelatinises at a lower temperature than wheat starch and therefore rye flour is much more susceptible to enzymic degradation by alpha-amylase. Another fundamental difference is that the proteins present in rye do not form a gluten network to any significant degree and the pentosans in rye are essential for water binding in order to form a dough. Thus, while some of the grain and flour testing methods are common to wheat and rye flours, different emphases are placed on the results when incorporated into flour specifications. The key quality requirements for rye flours are: · Minimum Hagberg Falling Number of 90 sec. · Pentosan content of 7±10%. · Water absorption capacity 68±75%. The water absorption capacity of rye flour is typically higher than that of wheat flour because of the much higher level of pentosans in rye flour. It is common practice to measure the gelatinisation characteristics of rye flour. The technique comprises heating a rye flour-water mixture at a constant rate from 30 to 90ëC and following the changes in viscosity that occur over this temperature range while the mixture is stirred. A typical instrument used for this purpose would be the BrabenderÕ AmylographÕ which records changes in viscosity in Amylograph Units (AU). The AU value will be related to the enzymic activity in the flour, the lower the AU value the higher the enzymic activity and consequently the poorer the shape of the loaves and the lower their volume. At very low AU values splits and other defects may be seen in the bread crumb (see Fig. 9).

Fig. 9 Rye bread made with flours with different AmylographÕ viscosities (reproduced with permission of BrabenderÕ GmbH & Co. KG).

A range of rye flours are often available varying from 100% whole grain through to a refined flour with low bran content, which allow the production of a wide range of rye bread types. It is worth noting that the acidification of rye dough and on occasions the pre-treatment of the flour with heat (scalding) are two common ways of restricting the enzymic activity in the final dough.

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2.11 We have changed suppliers of our self-raising flour and find that we are not achieving the same product volume as before. If we adjust the recipe by adding more baking powder we find that the products tend towards collapse. Can you explain why and how do we overcome the problems? Self-raising flours contain the mixture of a food grade acid and sodium bicarbonate required for the generation of carbon dioxide gas (BPS, p. 36). It is possible for the loss of gassing power to occur with storage time but this is not usually a significant problem as long as the flour is kept dry. In many parts of the world there are standards governing the volume of carbon dioxide gas that should be released from self-raising flour but these are usually set as minimum rather than absolute levels (BPS, p. 36). It may be that your previous flour supply was providing more than the required minimum and this is why you are now suffering from a lack of volume. However, the fact that your products collapse when you add extra baking suggests that this is not the most likely cause of your problem. The different food grade acids which are permitted for use in self-raising flour have different rates of reaction with sodium bicarbonate (BPS, pp. 189±90). This is important in controlling the release of carbon dioxide during processing; too early and the products tend to lack volume, too late and the products may tend to collapse. The data in Fig. 10 compare the rates of reaction for two commonly used food grade acids. From the description of the problem that you have given it would appear that your new source of self-raising flour is giving an early release of carbon dioxide and the level of extra baking powder that you have added to compensate is simply too high; try gradually reducing the level that you add and you should find a point at which you retain the product volume while avoiding collapse.

Fig. 10 Rates of reaction of food grade acids.

Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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2.12 We are a bakery working with a local farmer and miller to produce a range of local breads and want to use some different varieties and forms of malted grains that we are producing. Can you advise us on any special issues that we should be aware of? Adding grains in different forms to breads is a good way of introducing a variety of flavours and textures into your products. There are a few matters that you need to take into account in order to get the best results in your product. Wheat, barley and rye can be used to make malted grains and turned into a variety of granular products for adding to bread dough. One thing that you do need to be careful of is that the grain products are not hard and dry when you make them, as they can potentially cause unpleasant eating qualities if they are large particles. Two forms of grains are commonly used: crushed or flaked, and kibbled. The former will be prepared with a higher moisture content to aid preparation and so will be susceptible to mould growth. Steaming is commonly used to prepare grains for flaking. Kibbling yields much smaller pieces of broken grain which is very useful as a surface decoration. A key factor for you to consider is that the malting process initiates a significant level of enzyme activity in the grains and these enzymes will remain active in the dough. The amylase activity may cause problems with dough softening and contribute to side-wall collapse in the baked product (BPS, p. 83) or even keyholing in severe cases (BPS, pp. 57±8). If you do have this problem, then you may want to reduce the additions of other enzyme-active materials, such as malt flour, or use a less enzyme-rich improver if you are using a no-time dough process. There will be other enzymic activity to watch out for, most notably proteolytic activity, which contributes to dough softening and a weakening of the gas retention properties of the dough. The malting process generates complex sugars and these will also be carried into the dough with the malted grains. These should not be a problem but if you notice that the product crust colour becomes darker you may want to reformulate to reduce it. You may need to increase the protein content of the flour that you are using as the dough system will need to carry the non-functional malted grains. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

Further reading

and THOMAS, D.A. (1991) Malted cereals: Production and use. In (eds K.J. Lorenz and K. Kulp) Handbook of Ceral Science and Technology, Marcel Dekker, Inc, New York, NY, pp. 815±832.

PYLER, R.E.

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2.13 Can we mix oats or oat products with our wheat flours to make bakery products? If so, are there any special issues that we should be aware of? Oats, in common with many other grains, are composed of outer bran layers, an embryo (germ) and starchy endosperm; the latter, in contrast with many other grains contains significant amounts of protein and is rich in oil. The first stage in oat milling is to remove the husk or outer hull to yield clean `groats'. Oat milling follows a similar pattern to wheat milling but is less complex. The groats may be cut, flaked or milled or ground to yield oat flour, sometimes with the bran being taken off separately. The high level of oil in oats (typically 5±9%) is distributed relatively uniformly through the oat components which are also rich in lipase. Unless the lipase is inactivated by heat, oat products are very quickly prone to rancidity. The process of inactivating the lipase enzyme is known as `stabilisation' and comprises heating the oats with steam for up to 2h at over 100ëC. The stabilisation process also contributes to the development of a `nutty' aroma and flavour in oat products. Cut oats are usually milled to oatmeal of different size grades and it is these products which are most commonly used in baking. Perhaps the best known bakery products which use oatmeal are biscuits and cookies, where they may be included on their own or along with fruits and nuts. Oatmeal biscuits have a strong regional bias associated with Scotland and they are a dense and friable biscuit with a distinctive flavour. There are other regional products which use oatmeal such as Staffordshire Oatcakes (see 8.4). The consumption of oat bran has been linked with the potential for lowering blood cholesterol in the human digestive system and this has led to its inclusion in a number of food and drink products. The `active' ingredient in this context is the soluble fibre gum, beta-glucan. Oat flakes may find use along with other flaked grains in the manufacture of bread and rolls, either as part of the dough or as a surface dressing to provide texture. Oat bran and oatmeal are included in some breads where the distinctive aroma and flavour are seen as beneficial. The oat products are usually added to a strong white flour base since oats do not have the potential to contribute to the formation of a gluten network in the dough. There is a tendency for the bread products to have a slightly dry mouthfeel but when combined with a suitable filling, e.g. prawn mayonnaise, they make a popular sandwich type in the UK. Oat bran is also a key component of some speciality cake muffins. Further reading

and MCCONNELL, J.M. (2001) Oats. In (eds D.A.V. Dendy and B.J. Dobraszczyk) Cereals and Cereal Products, Aspen Publisher, Inc., Gaithersburg, MA, pp. 367±391.

WELCH, R.W.

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2.14 We wish to add non-wheat fibres to some of our baked products to increase their healthiness. What fibres can we use, in what products and what potential technical problems should we be aware of? What is resistant starch and can it be used in bakery products? There are a large number of fibres from many different sources that might be and have been proposed as additions to baked products. The range is so wide that it is not possible in a short answer to do more than offer some general pointers and a few examples. If you are going to make health claims then it is important that you first make sure that the fibres that you are proposing to use are permitted as additions to bakery foods and to identify any restrictions that might apply. You should also carefully check the potential validity and permissibility of any health-related claims that might be used on the product packaging or in any advertising and marketing promotions that you might wish to undertake. Health-related claims are becoming increasingly restricted in order to avoid misleading consumers. One of the more difficult issues will involve the definition and measurement of dietary fibre. As yet there is no universally accepted definition, though a statement by the European Food Safety Authority (EFSA) to the European Commission in 2007 concluded that a definition of dietary fibre `should include all carbohydrate components in foods that are non-digestible in the human small intestine' and went on to list such components as including `non-starch polysaccharides, resistant starch, resistant oligosaccharides with three or more monomeric units, and other non-digestible, but quantatively minor components when naturally associated with dietary fibre polysaccharides, especially lignin'. In the same statement EFSA commented on analytical methods available for the measurement of dietary fibre and considered that for practical purposes a single assay would be advisable but did not recommend what that might be. The definition of dietary fibre is also being considered at the time of going to press by the Codex Alimentarius Commission of the Food and Agricultural Organization of the United Nations. A common technical issue when you add fibres to bakery product recipes is their ability to absorb water, which necessitates an increase in recipe moisture levels. This is not usually a problem with bread dough or cake batters but can be a problem in the manufacture of biscuits and pastries where the requirement is to ensure that the extra water is baked out so the final products retain their crisp and hard eating characteristics. It is almost certain that any fibres that you add will contribute little or nothing to the formation or stabilisation of bakery products structure. This poses a number of issues, mainly for bread and cake making. In the case of bread, you may need to add extra protein or adjust the dough conditioner/improver to ensure that there is no loss of volume. In cake recipe balance, the extra water that is added along with fibres to maintain a suitable batter viscosity may require adjustment of the sugar levels in the recipe. You will need to be careful that the

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sugar and liquid levels do not exceed acceptable levels for the flour that you are using (e.g., treated or untreated). In practice the level of fibre addition is relatively low and can usually be included as `flour' when balancing recipes. Fibres come in many different forms from fine powder through flakes to whole grains and seeds. Choosing the form you want to use will depend on the product effect that you want to create; for example, whether you want the fibre to be visible, whether you want it as a surface finish or whether you want it incorporated directly into the dough or batter. Some of the fibrous grains and seeds have other interesting attributes related to their nutritional properties. In many cases the attraction of using a particular fibre is that they have a colour which is lighter than that of wheat bran and similar to that of wheat flour. The addition of such materials allows you to increase the fibre content of the product without detracting from the appearance of its crumb. This is often seen as an advantage in delivering the nutritional benefits of fibre to children. Some types of starch are more resistant to digestion in the large intestine than others and are considered in medical terms to act like dietary fibre and are known by the generic descriptor `resistant starch'. The term actually covers four types of resistant starch (RS): · RS1 ± considered to be physically inaccessible as part of intact or partly milled grains. · RS2 ± resistant starch granules in their `natural' form as might be found in potato, green bananas, some legumes and high amylose starches. · RS3 ± retrograded starches from typical sources such as cooked and cooled potato, bread crusts and some flaked products. · RS4 ± includes a wide range of modified starches. Further reading

(2003) High-fibre baking. In (ed. S.P. Cauvain) Bread making: Improving Quality, Woodhead Publishing Ltd, Cambridge, UK, pp. 487±499. LORENZ, K.J. and KULP, K. (1991) Handbook of Cereal Science and Technology, Marcel Dekker, New York, NY. MCCLEARY, B.V. and PROSKY (2001) Advanced Dietary Fibre Technology, Blackwell Science, Oxford, UK. KATINA, K.

3 Other bakery ingredients

3.1 We wish to reduce the level of salt (sodium chloride) that we use in our baked products. What do we need to be aware of when making reductions? Salt (sodium chloride) has a number of different functions in the manufacture of bakery products, some of which are product specific. The most immediately recognised one is to contribute to the flavour profile of the product. Salt has its own characteristics and is considered as one of the five basic tastes (the others are sweet, acid, bitter and the recently added, umami). In addition to its own distinctive flavour salt plays a significant role in enhancing other, often more subtle, flavours. Reductions in added salt levels in baked products are usually detected very readily by consumers, so we recommend that you make small but progressive reductions over a period of time so that the palate of your customers becomes `educated' for lower salt levels. Sodium chloride is one of very few chemicals which confer a salty flavour and it is not easy to `replace' the flavour contribution with other ingredients. Potassium chloride may be used to replace the sodium salt but, as the level of potassium chloride increases, there is a development of an unacceptable level of bitterness in the product. Each of the salt `replacers' that are offered has a distinctive flavour profile but all are different from sodium chloride. Other flavours enhancers are offered for use in lower salt foods but their suitability for use depends on the food in which they are to be used. In breadmaking, a possible route to increasing the flavour of bread is by using fermentation of all or part of the dough in the manufacturing process. However, it should be noted that the overall flavour profile of the final product will be different and may be less acceptable to all consumers. Again it may be a matter of educating the consumer palate. The other universal function of salt in baked products is that of a preservative. Additions of salt have been used to extend the mould-free shelf-life of cakes and

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many other bakery products (Cauvain and Young, 2008). Weight for weight salt is 11 times more effective than sucrose at reducing the water activity of baked products and so it has been a common addition to many recipes. If you are going to use lower salt levels then you may have to compensate for the increase in water activity with other anti-microbial strategies. In high water activity products (e.g., bread, hot-plate goods) the impact of salt on product mould-free shelf-life is very small. However, the water activity levels in such products are marginal for rope spoilage (BPS, p. 86) and so reductions in added salt levels should be approached with some caution. Rope spoilage is more likely to be a problem in wholemeal and mixed grain breads as the spore-forming bacteria are associated with the other layers of grains and so spore counts are likely to be higher. Salt plays some technological roles in the manufacture of bread and other fermented products. One of these is to limit the activity of bakers' yeast in the dough. Reductions in added salt levels will lead to increased gas production by the added yeast such that the dough may become `over-proved' in a standard proof time in the bakery. In such cases it may be necessary to either reduce proof times or lower added yeast levels in the dough; the latter is most commonly preferred, as the length of time used for dough proving has other technological benefits related to the rheological properties of the gluten in the dough; most notably to contribute to the uniformity of oven spring when the product is baked. Salt also makes a contribution to dough development and bread volume. Danno and Hoseney (1982) showed that Mixograph times to peak were shorter when salt levels were reduced, while other studies (Miller and Hoseney, 2008) have shown that loaf volumes were optimised at around 2% flour weight and that volume decreased when salt levels were both increased and decreased. Any losses in bread volume can be compensated for by other ingredient and recipe adjustments. Lowering salt levels in bread dough does lead to some adverse changes in dough rheological properties after mixing. In particular there is an increase in dough stickiness which may be of concern in highly automated plants or where ambient dough-processing temperatures are high. References

and YOUNG, L.S. (2001) Baking Problems Solved. Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2008) Bakery Food Manufacture and Quality: Water Control and Effects, Wiley-Blackwell, Oxford, UK. DANNO, G. and HOSENEY, R.C. (1982) Effect of sodium chloride and sodium dodecyl sulphate on mixograph properties. Cereal Chemistry, 59, 202±204. MILLER, R.A. and HOSENEY, R.C. (2008) Role of salt in baking. Cereal Foods World, Jan± Feb, 4±6. CAUVAIN, S.P.

Further reading

and ANGUS, F. (2007) Reducing salt in foods: Practical Strategies, Woodhead Publishing Ltd, Cambridge, UK.

KILCAST, D.

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3.2 What alternatives are there to using sodium chloride (common salt) in the manufacture of bread products? And how can we reduce sodium levels in our other baked products? Sodium chloride plays a number of significant roles in the manufacture of baked products besides that of conferring flavour. In doughmaking, the water activity effect has a direct impact on the development of the gluten structure in the dough and the rheological properties of the dough during processing. Some of the most important roles are associated with the control of water activity in dough and the baked bread and cakes. The strong effect of salt arises because of its ionic nature and its ability to form strong bonds with water molecules, thereby making them less available for a number of key baking reactions. In considering alternatives to sodium chloride for baked goods, the first point to note is that sodium chloride has a unique flavour. Its flavour profile is not shared with the other chlorides. For example, the direct substitution of sodium with other chlorides leads to baked products with an unacceptable bitter taste which is hard to mask; partial replacement at low levels is possible. At present the best option in bread is to seek to gradually reduce the level at which sodium chloride is added to bakery product formulations (see 3.1). While a number of `salt-replacers' are offered, most of these are in the context of boosting flavour when sodium chloride levels in recipes are being reduced. Most (if not all) of these replacers do not have the same functionality of sodium chloride with respect to dough structure formation and the control of water activity in the baked product and the restriction of microbial activity. Sodium-based compounds are common ingredients of the baking powders used in chemically raised baked products. Potassium and calcium bicarbonates may offer alternatives to the sodium form and non-sodium baking acids are already available. A key requirement when making a switch to a reduced or nonsodium baking powder will be to ensure that the rates of reaction in the baking powder are matched to the product requirements in order to avoid product quality losses. Even if baking powder reaction rates are matched with non-sodium baking powders, the residual salts from the reaction will have a different flavour profile from the sodium-based types and you will need to ensure that this is acceptable to consumers. Further reading

and ANGUS, F. (2007) Reducing Salt in Foods; Practical Strategies, Woodhead Publishing Ltd, Cambridge, UK.

KILCAST, D.

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3.3 We have seen references to a `lag phase' for bakers' yeast; what does this mean and what are the implications for baking? Bakers' yeast (Saccromyces cerivisii) is one of many different types of yeast which may be used or found in foods (Boekhout and Robert, 2003). Like all microorganisms, when placed in a suitable environment they begin to feed, and multiply. This process starts very slowly but as time progresses the rate of activity increases if the temperature remains constant and there is a ready supply of food. The key function of bakers' yeast in baking is the production of carbon dioxide gas. Modern strains of bakers' yeast are far more reliable than those that have been used traditionally. In the flour there is an initial supply of naturally occurring sugars (typically 1±1.5% by weight, see 2.3) and these are fermentable by the yeast. Later, as the combination of alpha- and beta-amylases in the dough get to work on the damaged starch granules, more sugar in the form of maltose becomes available to support fermentation. Sugars may be added to the dough formulation though in no-time dough processes the addition of extra sugar to support fermentation is not usually necessary but it may be added for its contribution to flavour and colour. Once the yeast has been added to the dough it takes a short while before its activity is sufficient for the generation of carbon dioxide gas and during this `lag' phase there is little change in the dough density. If we were to measure the density change with time after mixing, we would see little change for some minutes. Later dough density begins to fall as the carbon dioxide gas begins to diffuse into the gas bubbles in the dough and they expand. Typically the lag phase lasts around 10 minutes. This has limited impact when bulk fermentation processes lasting some hours are used for breadmaking but in no-time dough production the impact can be significant. The main effect of the yeast activity post-lag phase with no-time dough production will be seen in the divider and in particular on divider weight control. If a large bulk of dough is being divided volumetrically it is not unusual to see a drift in weight with dough standing time in the hopper. One of the advantages gained from the yeast lag-phase is that it will limit dough density changes and thereby improve divider weight control. Thus, in larger automated bakeries it can be of particular advantage to keep dough batch size at a level which requires the production and processing of an individual batch of dough in less than 10 minutes or so (Cauvain and Young, 2008). References

and ROBERT, V. (2003) Yeasts in Foods, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2008) Bakery Food Manufacture and Quality: Water Control & Effects 2nd edn, Wiley-Blackwell, Oxford, UK. BOEKHOUT, T.

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3.4 Are there any particular precautions that we should take in handling, storing and using bakers' yeast in the compressed form? In order to optimise the performance of bakers' yeast (Saccromyces cerivisii) in the manufacture of bread and fermented products it is important to ensure that it is kept in its optimum condition. Individual yeast cells are characterised by having a membrane which encloses the cell contents (Williams and Pullen, 2007). It is the latter that provide the yeast with its ability to produce carbon dioxide, ethanol and reproductive powers. In addition to providing a container for the cell contents, the membrane plays a critical role in regulating the flow of nutrients into and by-products (e.g., carbon dioxide) out of the cells. The flow of nutrients is controlled by osmotic pressure (Cauvain and Young, 2008). Compressed yeast is prepared under carefully controlled conditions in the factory (Williams and Pullen, 2007). A key requirement is that the cells (approximately 15 thousand million per gram) are intact (undamaged) and viable (alive). To ensure this and to minimise activity in the block, compressed yeast is commonly delivered at refrigerated temperatures, typically 4±8ëC and should be held at these temperatures until required for use (BPS, pp. 66±7). The particular precautions that you should take include: · Transfer the yeast as quickly as possible into refrigerated storage as soon as possible after delivery. Prolonged exposure to warm temperatures can lead to loss of activity through autolysis. This process is characterised by a darkening of the corners of the blocks, which may also spread along the edges of the blocks (BPS, p. 68). · Avoid having large quantities of yeast standing in the warm bakery waiting to be used. Try to establish a working pattern that draws out sufficient yeast for 1±2 h of production throughout the day. · Break down large blocks into a coarse crumble before adding it to the mixer as this will aid its dispersion throughout the dough. You may want to disperse the crumbled yeast into some of the recipe water before you use it but this is not essential with modern yeast strains and breadmaking practices. · Do not keep using the yeast after its shelf-life date has expired. There is a slow but progressive loss of gas production power in the yeast during storage, even under ideal refrigeration conditions (see Fig. 11). This will result in an increase in proof time or require the addition of extra yeast to maintain product proof volume. It may also lead to loss of bread volume through the action of glutathione from any yeast cells which have died. · Do not leave compressed yeast blocks unwrapped for long periods of time as they can dry out and lose activity. · Ensure that the conditions under which the yeast is stored remain optimum. It is important that the cell membranes remain intact. Amongst the cell contents are powerful reducing agents known as glutathione. This material is able to reduce the gas retention properties of gluten and also causes excessive flow of dough in the prover.

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· Fluctuations in storage temperatures can lead to the formation of unwanted mould colonies on the surfaces of the blocks if they have been exposed unwrapped to the atmosphere and so should be avoided. · Avoid freezing the blocks as the formation of ice crystals inside the cells, their growth during storage and subsequent defrosting results in rupturing of the cell membranes and the release of the cell contents.

Fig. 11 Effect of yeast storage time on gas production.

References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2008) Bakery Food Manufacture & Quality: Water Control and Effects 2nd edn, Wiley-Blackwell, Oxford, UK. WILLIAMS, T. and PULLEN, G. (2007) Functional Ingredients. In, Technology of Breadmaking 2nd edn (eds S.P. Cauvain and L.S. Young), Springer, New York, USA, pp. 51±91. CAUVAIN, S.P.

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3.5 What different types of bakers' yeast are available? Would there be any particular advantages for us to use an alternative to Saccromyces cerivisii in the manufacture of our fermented products? Yeast suppliers have many forms of Saccromyces cerivisii for use in the manufacture of bakery products. The compressed or block form used in many countries is both economical and practical. The yeast blocks are paper wrapped to limit exposure to air and to maintain humidity and limit moisture migration, which ensures better keeping qualities and active shelf-life. It comes in varying sizes from small cubes of approx 40 g to blocks of 0.5 to 2.5 kg. It can also be purchased as crumbled yeast. It should be stored in a refrigerator running at between 2 and 10ëC, ideally around 4ëC (BPS, pp. 66±7). The shelf-life of compressed yeast kept under the conditions recommended by the suppliers is between 4 and 8 weeks. Williams and Pullen (2007) showed how storing high activity compressed yeast at 15ëC for 14 days has a reduced activity to such an extent that that proving time of the dough in which it was used roughly doubled. Poorly kept compressed yeast quickly displays visible signs of deterioration, such as dark brown patches (BPS, p. 68). Dried and granulated (Fischer and Volker, 2008) yeasts are popular where a longer shelf-life product is required or where refrigeration is not practical, e.g. in warm climates. It comes in standard or instant forms. The instant form of dried yeast is available in vacuum packs and can be incorporated directly into the dough while the standard dried yeast needs to be hydrated before it is used. In their various forms dried yeasts have shelf-lives of up to two years. Some forms of dried yeast may also be incorporated into premixes for bakery products. Liquid or cream yeast is increasingly popular in modern plant bakeries as it is easily accurately and automatically dispensed into the mixing bowl. It is held in storage tanks which are gently agitated to prevent separation. In baking terms 1.5 kg liquid yeast is equivalent to 1 kg of compressed yeast for gas production. The shelf-life of the product is much shorter than the other bakers' yeast forms at between 10 and 14 days. Care needs to be taken to keep its storage temperature between 2 and 4ëC and the storage tanks should be cleaned out on a regular basis to reduce the risks of contamination with unwanted yeasts, moulds or bacteria which may result in the development of sour aromas and flavours in the dough. Frozen forms of bakers' yeast are also available from some suppliers. These products should be stored at ÿ18ëC and have shelf-lives of up to two years. They are usually added to the dough in the frozen form. The dry matter varies in the different forms of yeast from approximately 20% for liquid yeast to 95% for the dried yeast. If you are going to change from one form to another then the water level added to the dough will need to be adjusted according to the dry matter content of the different forms. There are different strains of Saccromyces cerivisii available and the yeast supplier will cultivate these to offer specific yeast for different baking products

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and processing methods. For example, the strain used for dough making in the Chorleywood Bread Process is able to generate carbon dioxide at a faster rate then other strains and avoids a `dip' in gas production at the critical moment when the dough pieces reach the oven (Williams and Pullen, 2007). While such yeast strains have a high fermenting power, they tend to be less stable and have a shorter shelf-life than other strains. For the production of sweet dough that is high in sugar (usually sucrose or dextrose) there are osmo-tolerant yeasts. These are able to cope with the increased osmotic pressure in the dough rather than being inhibited by the presence of the sugars (Williams and Pullen, 2007). There are strains which are better adapted for use in acid, low pH dough and others which are able to better perform when calcium propionate is present in the recipe. In principle any microorganism which is able to ferment sugars to produce carbon dioxide gas could be used in breadmaking. There are a large number of yeasts which would fit into that category which may come from the distilling and wine-making industries. Indeed yeasts from the brewing and distilling industries were the traditional source of gas production for bakers. Improved growth, osmo-tolerance, freeze-tolerance or aroma applications, have suggested the use of strains from Candida or Torulaspora. A few non-typical bakers' yeast strains have been patented for cold dough and nutrition applications and especially for stress tolerance; these include Saccromyces rosei, Saccromyces rouxii and Torulaspora delbrueckii. The availability of strains of Saccromyces cerivisii specifically for use in the manufacture of fermented products in bakeries is now highly developed and discussions with your supplier should help identify the type of yeast that is the most appropriate for the manufacture of your own products. References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. FISCHER, G. and VOLKER, L. (2008) Granulated yeast. f2m baking+ biscuit international, 6, 40±43. WILLIAMS, A. and PULLEN, G. (2007) Functional ingredients. In (eds. S.P. Cauvain and L.S. Young) Technology of Breadmaking 2nd edn, Springer Science+Business Media, LLC, New York, NY, pp. 51±92. CAUVAIN, S.P.

Further reading

and ROBERT, Cambridge, UK.

BOEKHOUT, T.

V.

(2003) Yeast in Food, Woodhead Publishing Ltd,

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3.6 What effect does vinegar have on bread and why is it added? Vinegar has the advantage of being considered by many as a natural preservative. The chemical name for vinegar is acetic acid (E260) and it is sometimes known as ethanoic acid. It has been used for many years as an inhibitor for the growth of rope bacteria (Bacillus subtilis) in bread. As a preservative it has little intrinsic anti-microbial activity and so is added to increase the acidity (reduce the pH) and retard the initial growth of the bacteria. Rope spores are present naturally in the soil and can be found on the outer parts of the wheat grain. They are also present in the air and can be passed on in flour or by equipment which has been in contact with contaminated dough (BPS, p. 86). The white spirit form of vinegar is diluted to a give a 12.5% solution and added at the rate of about 1L per 100 kg flour; equivalent to a rate of acetic acid addition of 0.125% based on flour weight. Such levels reduce the bread crumb to a pH of about 5.4; the general level suitable for protection from rope. The level of addition required for wholemeal breads is slightly higher. To achieve a pH of 5.4 the amount of vinegar added will vary from one type of bread to another depending on the pH of the ingredients, the natural buffering effect of the flour and whether the flour has been fortified with calcium carbonate. All flours have a buffering effect on the efficacy of the acetic acid with the buffering being greater in flours with higher levels of bran. Figure 12 shows the effect of acetic acid addition on the pH of breads. Vinegar has a small effect on the gassing rate of yeast and so yeast levels may be slightly increased to counter this and reduce the impact on proof time.

Fig. 12

References

The effect of acetic acid addition on the pH of breads.

and YOUNG, LS. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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3.7 What ingredients are commonly used as preservatives? Are there any particular benefits associated with different ones? The choice of preservative depends on the product type and the potential microogranisms which are prevalent in causing spoilage. Microbial spores are airborne in the bakery environment and also present in the dry ingredients (flour), their packaging and through contact with contaminated equipment and surfaces. Preservatives only inhibit spoilage ± they do not destroy the microorganisms and so good hygiene is a necessary adjunct to using preservatives. A comprehensive list of preservatives for use in bread and fine bakers' wares is given by Williams and Pullen (2007). Breads and other fermented products are high in moisture and are susceptible to microbial attack. Table 7 shows some of the commonly used preservatives along with their recommended levels of use within the European Union; there are other local limits for their addition and these should be checked before use. Using the materials at their recommended levels should ensure an extension of mould-free shelf-life by 2±3 days at temperatures of 20ëC. Vinegar is used to combat `rope' bacterial spoilage and has a small inhibiting effect against moulds (see 3.6). Table 7 Common preservatives for bread and fermented products Preservative against moulds Calcium propionate Propionic acid Sodium propionate Sodium dipropionate

Recommended usage (% of flour wt) 0.2 0.1 0.2 0.2

For flour confectionery products, such as cakes and muffins with intermediate moisture levels, the commonly used preservatives are sorbic acid and its salts. They are not efficacious in bread and fermented products as the levels required render the dough sticky and difficult to process, inhibit the action of bakers' yeast and yield products with poor volume and coarse, open structure (unless added in their encapsulated form). Sorbic acid and its easier handled salt ± potassium sorbate ± can be added up to 2000 ppm (in the finished product). The levels used depend on the product water activity and pH. Adding preservatives to give more than a 50% extension to shelf-life is not usually recommended (Cauvain and Young, 2008) as the preservative flavour can often be detected by the consumer. The lower the pH of the product, the greater the preservative effect as shown in Fig. 13. Acetic acid and its salts may be used in many bakery products (see 3.6), although they are less effective than others mentioned here. In some cases the use of acetates rather than propionates and sorbates may reflect local legislation or commercial preferences. As with all preservatives high levels of addition

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Fig. 13 Additional days' shelf-life obtained in cakes of different pHs when treated with sorbic acid at 1000 ppm product weight.

produce distinctive odours and taste in the products and once consumers have become accustomed to these it may be difficult to interchange them. For products such as Danish pastries with relatively short shelf-life, preservatives are less commonly used. If the pastries are fermented then the preservatives used in breads would be suitable and for cake-like ones sorbic acid and its salts would be appropriate. For low moisture biscuits and cookies mould growth is not usually a problem and so the addition of preservatives is not common. In some cases it may be appropriate to use a combination of preservatives to achieve the desired effect on shelf-life. This is because there are many different types of moulds and each of them can tolerate a slightly different set of conditions and type of preservative. In most manufacturing environments it is unlikely that the full range of mould types contaminating a product will be known. There are some very common ones (e.g., penicillium sp., aspergillus sp.) and usually the addition of one preservative is all that is required. However, in some cases a `broad spectrum' approach with a mixture of preservatives (and other inhibitory processes) may be used to ensure maximum impact. With mixtures of preservatives the extension of the mould-free shelf-life of the product may be increased beyond that achieved with a single preservative, though the overall impact may be difficult to quantify. References

and YOUNG, L.S. (2008) Bakery Food Manufacture & Quality: Water Control and Effects 2nd edn, Wiley-Blackwell, Oxford, UK. WILLIAMS, T. and PULLEN, G. (2007) Functional Ingredients. In Technology of Breadmaking 2nd edn (eds S.P. Cauvain and L.S. Young), Springer, New York, USA, pp. 51±91. CAUVAIN, S.P.

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3.8 We have heard that alcohol can be used as a preservative. How is this achieved? The use of alcohol as a preserving agent has been known for many years. Christmas cakes are often treated with alcohol after baking to add flavour and benefit from the preservative and anti-staling properties. Ethyl alcohol can be an effective preservative for breads. Added at levels between 0.5 and 3.5% of loaf weight it gives good extension of shelf-life (Legan, 1993). Figure 14 shows the percentage increase in mould-free shelf-life obtained when ethyl alcohol is added (Seiler, 1984). The effect is obtained whether the alcohol is added to or sprayed onto all surfaces of the loaf before packing and sealing. If the alcohol is coated on the inside of the bag before inserting the loaf and sealing, the increase in shelf-life is similar. The alcohol acts as a vapour pressure inhibitor and discourages moulds from growing. In the case of bread, addition of alcohol at levels higher than 1% of product weight can usually be detected by the consumer. If adding alcohol to fermented products or cakes, checks should be made on possible local excise duties payable and on any labelling issues. Although it may be costly to use alcohol as a preservative, it has significant potential for its antimicrobial properties and for anti-staling in bread and cakes (Pateras, 2007).

Fig. 14

Relationship between alcohol concentration applied and percentage increase in mould-free shelf-life.

References

(1993) Mould spoilage of bread: The problem and some solutions. International Biodeterioration and Biodegradation, 32, 33±53. PATERAS, I.M.C. (2007) Bread spoilage and staling. In, Technology of Breadmaking 2nd edn (eds S.P. Cauvain and L.S. Young), Springer Science+Business Media, New York, pp. 275±298. SEILER, D.A.L. (1984) Controlled atmosphere packaging for preserving bakery products. FMBRA Bulletin No. 2, April, Campden-BRI, Chipping Campden, UK, pp. 48±60. LEGAN, J.D.

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3.9 What are the possible alternatives to chemically based preservatives? With the desire for `clean' labels bakers have sought the help of ingredients with natural preservative properties. Bakers have known for centuries the preservative effect of using dried fruit, e.g. raisins, in their cakes and other products. Sorbic acid salts develop on the skins of the fruit as they dry and, together with the higher concentration of sugar within the fruit, contribute to the longer shelf-life of the product. Such preservatives will inhibit microbial growth but will not prevent bacterial activity. It should be noted, however, that for a truly `natural' dried fruit, the fruit should not have been treated with sulphur dioxide during the drying process. Many red-berried fruits have sorbic acid present as part of their composition and if added as a fruit concentrate, might add a small preservative effect. In many cases the preservatives found in fruits act best at low pHs, e.g. circa 2.0, and so are effective when used in acidic products such as fruit juices but will have a limited effect in the higher pH bakery products (as a general rule bakery products lie in the pH range 5.0 to 6.5). Benzoates, which are found naturally in cranberries, also work best at low pH. Using acid dough components, such as fermented wheat flour, in bread can provide a preservative effect. This is based on the natural lowering of the pH of the dough from the actions of lactic and acetic acid bacteria. To speed up acidification a special culture of lactobacilli is added. For white breads, sufficient acid dough should be added to bring the pH to below 5.0. In order to prevent rope an addition of 10% of acid dough in the final dough mix should be sufficient and it is claimed has the benefit of improving the flavour of the bread. Salt (sodium chloride) is a natural preservative. It occurs in sea water and also is mined. It works by locking up the water in the bakery product so that the moulds cannot use the moisture for growth. However, its addition is limited by taste and more recently by concerns over the level of sodium chloride in the diet. Similarly sugar can be used to extend shelf-life and again its addition has to be carefully considered as it may have an effect on the processing and the final product quality (Cauvain and Young, 2008). Many of the chemically based preservatives are `nature identical' and have been given E numbers to denote their acceptance for use in food products. Often they have been derived from organisms that occur in nature. Their dosage and effectiveness are well known. The variability in the potential effectiveness of `natural' (non-chemically based) preservatives needs to be considered when relying solely on them in products. Reference

and YOUNG, L.S. (2008) Bakery Food Manufacture & Quality: Water Control and Effects 2nd edn, Wiley-Blackwell, Oxford, UK.

CAUVAIN, S.P.

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3.10 What type of sugar (sucrose) should we use for the different products that we make in our bakery? Sugar (sucrose) has a number of different functions in baked products; in addition to the obvious contribution to product sweetness, it also has an impact on the formation of product structures, which in turn influences texture, eating qualities and shelf-life, both sensory and microbially (Cauvain and Young, 2006). Sucrose is available in a number of crystalline and liquid forms (various types of syrups). In summary, the main forms of sucrose that are used in the manufacture of baked goods are: · Granulated ± usually the coarsest crystalline, refined white form. · Caster ± smaller crystals separated from the preparation of the granulated form. · Pulverised ± may be manufactured by re-grinding a crystalline form. · Icing sugar ± a fine, powdered sugar obtained by grinding crystals. · Demerara ± a light brown, crystalline sugar with pigments derived from the natural sugar cane. · Soft brown ± a mixture of small crystalline sugar and molasses. · Molasses ± a dark coloured syrup, the residue of the sugar cane refining process. Many of the functions of sugar in baked products require that it should be in solution in the mix. This does not necessarily mean that you have to prepare a sugar solution in the bakery. Sugar has a high solubility (typically sucrose dissolves in half its weight of water at 20ëC) but the quantity that can actually get into solution depends on the level of available water and the temperature of the mix. The size of the crystals is important in determining the rate at which they dissolve and in low water systems (e.g., biscuit dough) this can be a critical factor in deciding which form to use. Some of the key requirements for sugar properties are summarised for the different baked product groups below. Bread If used at all, relatively low levels of sugar are added in the manufacture of bread. The water levels are relatively high and dough processing times from mix to oven are relatively long by comparison with other baked products and usually sufficient time is available for any added sugar to readily dissolve. This means that most of the crystalline forms can be used without creating any specific problems. Fermented products (e.g., rolls and buns) Sugar is commonly added to rolls, buns and other similar fermented products to improve product sweetness and crust colour. The levels of addition still tend to be low enough to allow for the use of all the crystalline forms. You should note that high level of added sugar can have an inhibitory effect on yeast activity (Williams and Pullen, 2007).

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Sponges and cakes Caster sugar is the form most commonly used in the manufacture of sponges and cakes. While granulated sugar will readily dissolve in the water present in sponge and cake batters, there can be problems with re-cystallisation on the surface of the baked product (Cauvain and Young, 2008). A common phenomenon when sugar re-cystallisation occurs is the formation of small white spots on the crust (BPS, p. 167) and in less extreme cases the brown crust colour may be tinged with a grey haze arising from many small sugar crystals too small to be seen with the naked eye. A crystalline form of sugar is preferred for many cake mixing procedures as it helps with the dispersion of the recipe fat and the incorporation of air into the mix (BPS, p. 150). Fruited cakes In cakes where a high proportion of dried fruit is added to the mix (e.g., celebration cakes) it has become traditional to use a proportion of brown sugars and syrups in order to add to the colour and flavour profile of the baked product. Biscuits and cookies Commonly the finer grades of sugar, e.g. pulverised, are used in the manufacture of biscuits and cookies. This is because the added water levels are relatively low and so there is a significant potential for sugar re-crystallisation of the surface of the products. In some biscuits brown sugars or syrups may be added to confer colour and flavour. Pastries Caster or pulverised sugar is usually preferred for the manufacture of pastries in order to avoid sugar spotting on the surface of the baked pastries. Other bakery products Icings, toppings and fillings often use a proportion of the finest sugar grades, e.g. icing sugar. If you are not able to access or store a range of sugar types you may have to consider modifying your mixing procedures. For example, with the coarser grades you may have to dissolve the sugar in the recipe water before adding it to the other ingredients. If the sugar levels in your product are high with respect to the water levels you may still have problems with re-crystallisation. References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2006) Baked Products: Science, Technology and Practice, Blackwell Publishing, Oxford, UK. CAUVAIN, S.P. and YOUNG, L.S. (2008) Bakery Food Manufacture and Quality: Water Control and Effects 2nd edn, Wiley Blackwell, Oxford, UK. WILLIAMS, T. and PULLEN, G. (2007) Functional ingredients. In (eds S.P. Cauvain and L.S. Young) Technology of Breadmaking 2nd edn, Springer Science + Business Media, New York, NY, pp. 51±92. CAUVAIN, S.P.

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3.11 Can you explain some of the main features of alternative sugars to sucrose and how they might be used in baking? The sugars used in baking fall into two main groups classed as mono- and disaccharides. Mono-saccharides are sometimes called `simple' sugars because they consist of one glucose molecule, while the di-saccharides comprise two glucose molecules in different configurations. There are a number of key differences between sucrose and the other sugars that may be used in baking; important ones are related to the impact on the gelatinisation characteristics of wheat starch and therefore product structure, their impacts on product water activity and in turn product shelf-life, and their relative sweetnesses (see Table 8). All sugars contribute to the Maillard browning reaction which forms the crust colour of baked products. The main mono-saccharides are fructose and glucose, both of which occur naturally in fruits. Fructose is an isomer of glucose (that is a glucose molecule with a different arrangement of atoms in the molecule) which can be obtained in the crystalline and liquid forms. It is a sugar which is often used in diabetic products because its initial metabolism in the human digestive system does not require insulin. Fructose may be used in a syrup form (high fructose corn syrup, mainly a mixture of fructose and dextrose) which is readily fermentable by yeast. Glucose may be used as a powder (dextrose monohydrate) or as a syrup (containing about 20%) water with different amounts of dextrose. The percentage of reducing sugars in the syrup is given by its dextrose equivalent (DE). Glucose syrups are found mainly in jams and fondants, though they may find use in cake and biscuit making. Dextrose solids are often used to extend the mould-free shelf-life of cakes but their level of addition is limited by the browning reaction that occurs. The main di-saccharides (in addition to sucrose) are maltose and lactose. Maltose finds its way into baked goods usually as part of malted wheat or barley products and finds use in bread and other fermented goods. It is commonly available in the form of a syrup with a low degree of browning. In its purer, crystalline form maltose has been used to slow down starch retrogradation. Lactose is present in milk products. Its use is limited because of its low solubility. It is a reducing sugar, which explains why the addition of milk powders increases the richness of crust colour in baked products. Lactose may also come as a component of hydrolysed whey products. Table 8 Relative sweetness of sugars Sugar Sucrose Fructose Maltose Lactose Glucose syrup

Relative sweetness 1.0 1.7 0.35 0.27 0.30

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3.12 What are the differences between diastatic and nondiastatic malt powders and how can they be used in baking? Malt flours are most commonly made from wheat, barley and to a lesser extent oats. After the malting process the products of the different cereals have slightly different characteristics but essentially they fall into two categories: diastatic in which a range of enzymes remaining active, and non-diastatic in which the enzymes are inactivated. The malting process is based on the partial germination of the grains. Initially the cleaned grains are `steeped'; that is mixed with a pre-determined quantity of water and stored under conditions which encourage the grains to germinate. After the requisite time, germination is arrested by removing water with the application of gentle heat. The `malt' is mixed with water and a liquor extracted. It is the malt liquor extract which is dried under varying conditions to deliver a range of malt powders with different characteristics. As all enzymes are heat sensitive, the greater the heat input during drying, the lower the enzymic activity which remains in the product. Also the greater the heat input, the darker the malt powder will be. All malt powder products have a slightly sweet, roasted flavour; the degree of flavour intensity varying with the degree of heat treatment used in the preparation. This distinctive malt flavour is carried through to the baked product with the intensity varying according to the grade of malt flour used and its level of addition. Clearly the more malt flour that is added to the product, the more pronounced the flavour will be. If your main interest in using malt is to confer flavour to products, then you can use either the diastatic or non-diastatic forms. The term diastatic activity refers to a suite of different enzymes that are present in the malt flour. The germination process in the grain is based on the conversion of starch to sugars to provide food for the early stages of plant growth. This means that the amylase enzymes, especially alpha-amylase, are a significant component of diastatic malt flours. As is well known, increases in the alpha-amylase levels in dough increase its gas retention properties. However, high levels of cereal alpha-amylase can lead to quality problems such as `keyholing', caving in on the side crust (BPS, pp. 57±8) as well as potential stickiness in the bread crumb and slicing problems (Cauvain and Young, 2006). Other enzymes may be active in the malt powder and these include proteolytic enzymes which can have adverse effects on gluten structures. References

and YOUNG, L.S. (2001) Baking Problems Solved. Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2006) The Chorleywood Bread Process. Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P.

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3.13 We read a lot about the different enzymes that are now available and how they might be used in baking. Can you tell us what they are and what functions they have? There are many different types of enzymes in the natural world and they are an essential part of the natural reactions in life. They may be described as organic or biological catalysts which accelerate the rates of critical reactions in plant and animal systems. They have a similar structure to proteins. They are characterised by the type of reaction that they catalyse and are very specific in action; that is they can only catalyse one specific reaction. All enzymes originate within the cells of which plants and animals are composed. For example, in the bakers' yeast cell are all of the enzymes that it requires to break down sugars and other nutrients for reproduction and growth. Various microorganisms are the main source of industrial enzymes. Specific microorganisms (commonly moulds) are developed under appropriate fermentation systems in a similar manner to that of bakers' yeast (Williams and Pullen, 2007). At the end of reproduction and growth period the cells are disrupted and the cell contents refined to separate out the different specific enzymes that are present. Commercial enzymes are usually of a high purity but most of them will have some residual or `side-effects' associated with other enzymes which are present in the sample. The commercial product is usually too concentrated to be used without being diluted and it is in this diluted form that enzyme preparations are used in the flour mill and bakery. Many ingredients used in baking (e.g., wheat flour, yeast, soya flour, malt flour) are enzymically active. The main groups of enzymes used as `extra' additions in the manufacture of baked goods are discussed below. However, it is important to recognise that enzymes require suitable conditions for them to work effectively. A suitable moisture level is one of the key requirements and enzyme activity in dry ingredients is low. If the moisture level is low the enzymes remain inactive but when the moisture level increases they can quickly become active. As might be expected for a biochemical reaction, enzyme activity is temperature sensitive with activity gradually increasing as the temperature is increased. All enzymes are eventually inactivated by heat, though thermal inactivation temperatures vary according to the particular enzyme, its source and the environment in which it is being used. In baking most (but not all) enzymes are inactivated by the temperatures achieved in the product during oven heating. Other factors that will affect enzyme activity include the pH (acidity) of the environment in which it used, the availability and condition of the substrate on which it acts and the water activity of the dough or batter. Before discussing the types of enzymes and their application in baking, the question of specificity of action must be considered. As stated above, enzymes are highly specific in their action and this specificity can extend beyond the action of an enzyme on particular substrate to include very specific sites of action within the substrate molecular structure. It is this increasing knowledge of the specificity of enzymes that has partly accounted for the increase in the range of products which are now available for use in baking.

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The addition of enzyme active materials to baked products is highly regulated and in most cases the source of that enzyme is specified. In many parts of the world legislation does not currently require enzymes additions to baked goods to be labelled and they fall into the general category of `processing aids'. Even as processing aids they will have required formal approval for use in the production of food. Amylases These are the best known groups of enzymes used in baking. There are two main types of amylase, known as alpha and beta. Together they are responsible for progressively breaking down starch (a complex carbohydrate composed of glucose chains) into dextrins, high molecular weight sugars and finally to simpler sugars such as maltose (which can be used by bakers' yeast). Both alpha- and beta-amylase are present in wheat flour. The level of alpha-amylase activity varies depending on a number of factors, not least of which is level of moisture in the maturing wheat ears. Beta-amylase is usually abundant in wheat flours but alpha-amylase levels may be low and so it is a common practice to augment its level through the addition of a suitable enzyme active material in the flour mill (Cauvain and Young, 2009). The measure of cereal alpha-amylase activity in wheat flour is measured using the Hagberg Falling Number test (BPS, p. 24). This description of the action of amylases is simplistic. Starch granules in flour are made up of two components: amylose a straight chained molecule and amylopectin a branched molecule. The action of alpha-amylase is commonly described as random with respect to the amylose and amylopectin molecules while that of the beta form is more specific and it cleaves relatively small molecules from the starch components (Williams and Pullen, 2007). Thus, the combined action of the two forms of amylase is critical in the use of amylase enzymes as bread improver. A key function of alpha-amylase in bread production is to improve dough gas retention and in consequence bread volume and softness (Cauvain and Chamberlain, 1988). The source of the alpha-amylase has a significant impact on the overall effect (BPS, pp. 59±60; Kulp, 1993; Williams and Pullen, 2007). Some forms of amylase are known to have anti-staling effects in bread. This arises from the generation of high molecular weight sugars which penetrate the starch granules helix structure and inhibit the re-crystallisation process after baking (see 3.14). Hemicellulases The action of hemicellulases is on plant cell-wall materials ± hemicellulose. The endosperm of wheat is composed of small cells which hold the starch, protein and lipids. The cell walls are composed of the large polymers mainly based on the sugar xylose. Hemicellulases (sometimes referred to as xylanases) act on the cell walls to break the material down into mainly xylose and arabinose. The net result of the addition of hemicellulase is to increase dough gas retention and to affect dough water absorption capacity. The effect of this group of enzymes is

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complex and the impact on dough water absorption capacity may be negative in some dough-making situations, with the addition of the enzyme causing an increase in dough stickiness. Lipases The addition of lipases has been shown to improve dough gas retention and bread volume. Their action is on triglycerides (fats, lipids) and the breakdown products of that action are in order: di-glycerides, mono-glycerides and finally fatty acids. The mono-glycerides formed from the action of lipase in dough are known to contribute anti-staling properties in bread and so it is seen as a potential replacement for emulsifiers in bread recipes (Rittig, 2005). Proteolytic enzymes This group of enzymes include proteases and proteinases and their action is on the gluten network formed in the dough. They are usually added to `weaken' the dough system and are sometimes used in biscuit production. They reduce dough gas retention and modify dough rheology making it softer and more readily processable (Kulp, 1993). They should be used with great care, if at all in breadmaking. Oxidases Glucose oxidase enzymes are sometimes used in bread making. In the presence of oxygen, they catalyse the oxidation of the beta form of glucose and in so doing produce hydrogen peroxide. The ability of the hydrogen peroxide generated in the dough to aid the formation of the disulphide bonds is said to be the basis of the improvement in dough gas retention (Vemulapalli et al., 1998). References

and CHAMBERLAIN, N. (1988) The bread improving effect of fungal alphaamylase. Journal of Cereal Science, 8, Nov., 239±248. CAUVAIN, S.P. and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2009) The ICC Handbook of cereals, flour, dough and product testing: Methods and Applicationss, DEStech Publishing, Lancaster, NJ. KULP, K. (1993) Enzymes as dough improvers. In (eds B.S. Kamel and C.E. Stauffer) Advances in Baking Technology, Blackie Academic & Professional, Glasgow, UK, pp. 152±178. RITTIG, F.T. (2005) Lipopan F BG ± unlocking the natural strengthening potential in dough. In (eds S.P. Cauvain, S.E. Salmon and L.S. Young) Using Cereal Science and Technology for the Benefit of Consumers, Woodhead Publishing Ltd, Cambridge, UK, pp. 147±151. VEMULAPALLI, V., MILLER, R.A. and HOSENEY, R.D. (1998) Glucose oxidase in breadmaking systems. Cereal Chemistry, 75, 439±442. WILLIAMS, T. and PULLEN, G. (2007) Functional ingredients. In (eds S.P. Cauvain and L.S. Young) Technology of Breadmaking 2nd edn, Springer Science + Business Media LLC, New York, NY, pp. 51±92). CAUVAIN, S.P.

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3.14 How do anti-staling enzymes work? Can they be used in cake as well as in bread and fermented products? There has been significant interest in using enzymes as anti-staling agents to augment the effect of emulsifiers or to replace them. When we refer to staling it is in the context of slowing down the firming of bread and cake crumb which comes from the retrogradation of starch during storage. This is in contrast to the increased softness which can be obtained by higher moisture levels in the baked product or through the increase of product volume (the latter is commonly a result of adding enzymes to bread formulations). There are two main groups of enzymes with anti-staling effects in baked goods and these are specific types of alpha-amylase and lipase; as is well known the former acts on damaged wheat starch breaking it down progressively to maltose, while the latter acts on triglycerides to eventually yield fatty acids. The starch polymer consists of a series of sugar molecules linked together as linear chains of amylose and branched amylopectin structures. Alpha-amylase is able to cut through these linkages at different but very specific points, depending on the types of amylase, to yield different sugars of varying molecular weights. Sugars are known to function as anti-staling ingredients in starch-based foods, probably by raising the glass transition temperature (see 9.7) and suppressing the re-crystallisation of the amylopectin (the main starch component responsible for staling in bread). In the case of lipase the specific action is to generate mono-glycerides in situ in the dough and mono-glycerides are proven anti-staling agents in bread. Again the specific type of lipase will dictate which specific mono-glyceride is generated and at what rate and level in the bread dough. The anti-staling effect of some enzymes is now well established in bread. In cakes it is less well established. Since the action of the specific anti-staling alpha-amylases is based on the production of a variety of sugars, it is difficult to see why this should be of significant benefit in cakes, which by virtue of their formulation already contain high levels of sugars. There is some evidence that supports increased softness values for cake crumb containing specific lipases. This is perhaps more understandable because of the generation of the monoglyceride which is known to have crumb softening effects in cake making. It is likely that any observable anti-staling effects of enzymes will depend heavily on the type of cake being produced and is more likely to be observed in low-fat cakes, such as sponge, or low-ratio cakes where the levels of sugar are lower.

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3.15 Can you explain the different terms used to describe bakery fats? What are the functionalities of the different forms in baking? Chemically all fats and oils consist of atoms of carbon (C) hydrogen (H) and Oxygen (O). They have the same basic structure which consists of a molecule of glycerol combined with up to three fatty acids. The basic nomenclature is mono-, di- and tri-glyceride according to whether 1, 2 or 3 fatty acids are attached to the glycerol molecule. The term oil is used to describe a fat in its liquid form. All fats become oils if the temperature is raised high enough and all oils become solid fat if the temperature is sufficiently reduced. The term oil is most commonly used for fats which exist as liquids at temperatures around 15±25ëC. Fats used in bakery practice are commonly a mixture of liquid and solid fat components and this may be expressed as the melting profile or solid fat index of the fat concerned (BPS, pp. 38±40). Fatty acids are one of the key building blocks of animal and plant tissues. There are different fatty acids and their physical and chemical form varies according to their chain length and absence/presence of carbon double bonds (C=C) in the chain. The significant impact of the different fatty acids is on the melting point of the fat and this determines whether the fat is solid or liquid at a given temperature. The degree of saturation in fats describes the number of carbon double bonds which are present. As the number of carbon double bonds increases, the degree of saturation decreases and so does the melting point of the fat; the downwards progression is from saturated to mono-unsaturated to poly-unsaturated so that highly saturated fatty acids tend to be solid. Saturated fats tend to be very stable and have a long shelf-life. They also tend to have highly functional roles in the manufacture of baked products; such as improving the gas retention properties of bread dough (Williams and Pullen, 2007), aid air incorporation in cake making (BPS, p. 150) and provide lift in laminated products (BPS, pp. 124±5). However, they also tend to have a negative health image. The proportion of the different forms of saturation varies according to the source of the oil/fat. Today there has been a significant move away from animal fats in bakery products (with the possible exception of butter) to vegetable-based fats, because many of them are low in saturated fats. However, this means they are also mainly in the liquid form and so do not have the baking functionality of the solid fats. The main exception is palm oil which is about 50% saturated and 40% mono-unsaturated fat. It is possible to modify the physical and chemical characteristics of natural oils. One method is hydrogenation, in which the oil is reacted with hydrogen gas at high temperatures and pressure. The process converts poly-unsaturates to mono-unsaturates and then to saturates and increases the functionality of the fat for different baking processes. The process of hydrogenation produces saturated fats but no significant levels of trans fats.

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However, partial hydrogenation, which had become more popular because of concerns over the consumption of saturated fats, generates significant levels of trans fats. While these fats retain functionality for baking, their `healthiness' in the diet has been questioned. The process of partial hydrogenation produces different levels of trans fats from different types of fat. The trans form of fat exists because there are two physical ways for a fat to form with the same combination of CHO atoms; the trans is one form and the other is known as the cis form. Trans fats do occur in nature and are present in products such as butter, milk and eggs. There are alternative ways to hydrogenation for providing baking fats with the functionality necessary for baking. Oils from natural sources, for example palm oil as discussed above, are a mixture of solid and liquid fractions and so the physical separation of the different fractions can be used to prepare a range of different fats with specific functional properties. Using this technique it is possible to prepare stearine oil fractions with melting points of up to 60ëC. The process is referred to as fractionation and has also been applied to butter to provide specific fractions which are better suited to processing at higher temperatures. Interesterification involves enzyme (lipase)-assisted modification of the oil or fat composition. Any oil or fat combination can be interesterified. Solid fats may exist in a number of crystalline forms depending on how they have been prepared in commercial practice. It is largely the cooling of liquid fats which determines the crystalline form, though the form may change during subsequent storage. It is said that fats exhibit polymorphism and the three crystalline forms are denoted as , 0 and . The  crystals have the lowest melting point and are small, unstable crystals. The transition is from  to 0 and then to ; the latter form tend to be the largest crystals and have the highest melting points. The crystalline forms of the fats have been linked with their functionality in baking (e.g., Cauvain, 2001). References

(2001) The production of laminated products. CCFRA Review No. 25, Campden-BRI, Chipping Campden, UK. CAUVAIN, S.P. and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. WILLIAMS, T. and PULLEN, G. (2007) Functional Ingredients. In (eds. S.P. Cauvain and L.S. Young) Technology of Breadmaking 2nd edn, Springer Business+Science Media, LLC, New York, NY, pp. 51±92. CAUVAIN, S.P.

Further reading

(1993) Fats and fat replacers. In (eds. B.S. Kamel and C.E. Stauffer) Advances in Baking Technology, Blackie Academic and Professional, Glasgow, UK, pp. 336±370. STREET, C.A. (1991) Flour Confectionery Manufacture, Blackie and Son Ltd, Glasgow, UK. STAUFFER, F.E.

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3.16 We want to make a range of bakery products using butter as the main or only fat in the recipe. Can you advise us of any special technical issues that we need to take into account when using butter? The composition of butter is usually fixed by local regulations. It is an emulsion of water-in-oil and typically contains more than 80% fat, less than 2% milk solids and less than 16% water. Despite having a fixed composition its performance in baking can vary. The best known variation comes with the twice yearly change in the feeding patterns for cows in many parts of the world (Rajah, 1997). With the change of feed come small but important changes in the underlying fatty acid composition and solid fat content, which can affect its ability to incorporate air during creaming processes in the manufacture of baked products (e.g., cakes and biscuits). Butter contains significant amounts of butyric acid (a low molecular weight fatty acid), which is volatile and makes a significant contribution to the flavour of the fat. The release of traces of this acid through the process of hydrolysis makes butter particularly susceptible to rancidity. To avoid any potential problems the butter will be delivered chilled and should be stored at the same temperature, typically around 4±6ëC. You should always use the butter within its designated shelf-life and you will find it helpful to set up a strict stock rotation system. The solid fat content of butter (BPS, pp. 37±40) at different temperatures is given in Table 9. The data highlight some of the technical problems with using butter. Because the solid fat content is very high at low temperatures, it cannot be used straight from the refrigerator but must have its temperature raised before it can be used. This `tempering' process takes time and requires careful control to ensure uniformity of processing performance (see also 3.17). Achieving the optimum processing temperatures with butter is very important for its effective use. For examples of relevant processing temperatures for laminated pastry products see 7.6. The solids content of butter is lower than normally considered suitable for cake making and there is a tendency for `all-butter' cakes to lack volume. Adding a suitable emulsifier to the recipe (e.g., glycerol mono-stearate) commonly solves the problem (BPS, p. 47). Table 9 The solid fat content of butter at different temperatures Temperature (ëC) Solid fat (%)

References

5 53

10 48

15 35

20 24

25 17

30 10

35 7

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. RAJAH, K.K. (1997) Cream, butter and milk products. In (ed. A.J. Bent) The Technology of Cake Making, Blackie Academic & Professional, London, UK, pp. 48±80. CAUVAIN, S.P.

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3.17 We are using butter in several of our bakery products which comes in chilled at about 4ëC (as cartons on pallets) and are encountering problems with variability in its processing. We recognise that it is likely to be associated with the temperature of the butter when we are using it. What is the best way to treat the butter in order to get a more consistent performance? In order to get a consistent processing and baking performance from butter you need to use it at temperatures between 14 and 20ëC, depending on the product. In the manufacture of cake batters and creams the butter plays a major role in the necessary air incorporation and so must be sufficiently plastic at the time of mixing; temperatures at the higher end of the above range are most suitable in such cases. For pastry making, temperatures towards the lower end of the range may be used but a significant degree of plasticity is still required (see 7.6). As your butter is arriving in the chilled form, you will need to raise its temperature by quite a few degrees before it is in its optimum temperature range. The best way to raise the butter temperature is to store it in warm environment, for example at temperatures between 20 and 25ëC (no more than 30ëC) but to obtain consistent performance it is crucial that the temperature of the whole carton reaches these temperatures. To achieve this you will need to make sure that there is sufficient air circulation around each carton and that you allow sufficient time for equilibration of the carton temperature to occur. The whole process can take several days and we suggest that you allow at least 4±8 days' equilibration before trying to use the butter. Do not be tempted to use high air temperatures to `speed-up' the process, as this can lead to significant `oiling' on the surfaces of the butter in the cartons and loss of functionality. Butter that has oiled and then cooled ends up with a different (larger) crystal structure, which makes it unsuitable for the manufacture of most bakery products. Radio-frequency heating and microwave have been suggested and used for tempering butter. This can reduce, but not replace, the storage time. Once again oiling of the butter should be avoided. In the manufacturing process the butter may well be pumped or extruded before use. The mechanical action that these processes involve helps in achieving a more uniform temperature distribution throughout the fat but should not be used to try and replace sound tempering procedures.

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3.18 What are the differences between dough conditioners and bread improvers? What consideration should we take into account when choosing which one to use? There is no precise definition of these terms. It could be argued that the term dough conditioner could include the use of materials to modify any dough-based product, which would include bread, biscuit and pastry doughs, while the term `bread improver' suggest that any effects are confined exclusively to bread and fermented products. However, in practice both terms are commonly used interchangeably and this can create some confusion. Both terms are used to describe a functional ingredient or a mixture of functional ingredients that are added at low levels in order to beneficially modify one or more characteristics of the final qualities of bread and fermented products or their processing intermediaries, i.e. the dough. All of the ingredients that would fall into this category will modify final product qualities and the vast majority will also modify the rheological properties of the dough. In a number of cases it is modification of the dough rheology that delivers the improvement to the final product. The compositions of dough conditioners and bread improvers are complicated and varied according to the particular bread product being made and processes used to make them. They may also vary with time as the formulations are adapted to changing raw material inputs, such as any changes in wheat and flour quality from one harvest year to the next, and to legislative and consumer pressures. When you are considering which dough conditioner or bread improver to use, you should consider first what quality changes you wish to effect and then identify which functional ingredient will deliver those quality changes that you are seeking. Examples of improvement categories and the functional ingredients that contribute to those improvements include: · Improved dough processing ± enzymes and reducing agents (e.g., L-cysteine hydrochloride, see 3.21). · Improved product volume ± oxidants (e.g., ascorbic acid), emulsifiers, enzymes. · Improved cell structure ± oxidants. · Improved crumb softness ± emulsifiers, enzymes. · Extended product shelf-life ± emulsifiers, enzymes. · Increased mould-free shelf-life ± preservatives. The individual ingredients that you will be able to choose from will be governed by local legislation and you should check carefully as to what is permitted for your country.

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3.19

What is lecithin and how is it used in baking?

Lecithin is a naturally occurring emulsifier found in animal and vegetable products such as milk, eggs (in the yolks) and soya beans, now the major source of the material. It is a liquid at temperatures around 20ëC and is soluble in oil. Purified and modified forms are available as a plastic liquid and in powder form (often blended with another food grade powder for ease of handling). The main constituent of lecithin in terms of its functionality is a mixture of phospholipids, with the combination of the different types being specific to its animal or plant source. As a component of egg yolk, lecithin plays a role in helping to stabilise the air bubbles that are mixed in during the preparation of cake batters. This role is especially important in the preparation of sponge products, which tend to have low levels of added fat. The lecithin phospholipids are part of the egg lipoproteins that are found at the interface of the air with the aqueous phase in cake batters and aid bubble stability at the time in the oven when the cake batter system changes from a water-in-oil to oil-in-water emulsion. Lecithin is often used along with other emulsifiers, such as glycerol mono-stearate, in sponge cake making. The addition of lecithin at low levels in the manufacture of cake doughnuts is said to reduce fat absorption during frying and to confer tenderness to the final product eating qualities. Lecithin may be used in the manufacture of some bread types. It enhances gas retention in the dough to a degree but less so than other more commonly used emulsifiers. In crusty breads it tends to give a thicker, denser crust, which retains its crispness for longer periods of time (Williams and Pullen, 2007). In biscuits, lecithin may be used as a means of reducing fat levels by up to 10% without adversely affecting biscuit quality. Dissolving the lecithin in fat makes it easier to handle (Manley, 2000) and it may help with the dispersion of the fat throughout the dough, giving it a smoother feel. In higher sugar cookies the addition of lecithin helps with the restriction of flow during baking. In the bakery low levels of lecithin (around 5%) are often found as a component of oil-based pan-greasing agents. References

(2000) Technology of biscuits, crackers and cookies, 3rd edn, Woodhead Publishing Ltd, Cambridge, UK. WILLIAMS, T. and PULLEN, G. (2007) Functional ingredients. In (eds S.P. Cauvain and L.S. Young) Technology of Breadmaking 2nd edn, Springer Science + Business Media, LLC, New York, NY, pp. 51±92. MANLEY, D.

Further reading

(1993) Lecithin and phospholipids in baked goods. In (eds B.S. Kamel and C.E. Stauffer) Advances in Baking Technology, Blackie Academic & Professional, Glasgow, UK, pp. 223±253.

SILVA, R.

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3.20 What is meant by the term `double-acting' baking powder and what is the value of using such products? Double-acting baking powders usually comprise a mixture of at least two baking acids and sodium bicarbonate. The overall composition of the baking powder will be balanced taking into account the neutralising value of both acids with respect to the sodium bicarbonate. Each of the acids will have a different rate of reaction (ROR) (see 2.11) and the intention is to spread and control the release of carbon dioxide gas over an extended period of time. Double-acting baking powders are most commonly used in the manufacture of cakes and are especially useful in the delivery of carbon dioxide production in the oven, which helps give cakes extra volume ± almost the cake equivalent of oven spring in bread. The process is shown schematically in Fig. 15. The level of sugars used in the manufacture of cake batters delays the gelatinisation of the wheat starch ± the main structure forming agent. This means that cake batters are fluid until relatively late on in the baking process. While the batter is fluid it is capable of expansion. With many of the faster-acting baking acids the release of carbon dioxide is mostly completed during mixing and the first few moments of baking, which may lead to a restriction of cake volume and a tendency for the products to have a peaked shape. This is commonly overcome by increasing the level of addition. An advantage of using a double-acting baking powder is that the flavour of the residual salt in the baked cake can be modified by using different baking acids. It is also possible to aid sodium reduction in baked products without unduly compromising product quality by using two different types of acids in the baking powder.

Fig. 15 The release of carbon dioxide from double-acting baking powder in cake baking.

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3.21 We have been having some problems with the quality of our bread, pastries and biscuits, and one solution that has been recommended to us is that we should add a reducing agent to our recipes. Can you tell us more about reducing agents and how they function in baked products? We should first start by defining what we mean by reduction. In chemical terms it is used to describe reactions in which hydrogen is added to an element or compound, or in which oxygen is removed from a compound. It is the opposite of oxidation. While both terms are used empirically to cover a number of similar reactions, in baking the reduction and oxidation reactions that take place are very close to the formal definition. A key reaction during mixing is the formation of disulphide bonds between the protein chains in the dough (Stauffer, 2007). Their formation is promoted by oxidation and they contribute to the elasticity of dough. The origins of this property are associated with the ratio of glutenin to gliadin proteins in the wheat flour, though oxidation processes that occur during dough mixing also make a contribution. If the dough is too elastic after mixing, then it may be difficult to process and it is common to consider adding a reducing agent to reduce the number of disulphide bonds that have been formed. A commonly used reducing agent in the preparation of fermented dough is Lcysteine, a naturally occurring amino acid used in the hydrochloride form to improve its solubility. The addition of L-cysteine hydrochloride is often recommended to reduce the level of work input required for the manufacture of bread by the Chorleywood Bread Process when using very strong flours or encountering difficulties with dough moulding. This approach should only be used when there is no alternative, more suitable flour available as the results of using L-cysteine hydrochloride are often equivocal. The addition of L-cysteine hydrochloride has been shown to be beneficial in the manufacture of other fermented products and has become a common ingredient in dough conditioner and improvers added in the production of rolls, pizza bases (Williams and Pullen, 2007) and hamburger buns. With all of these bakery products the main effect of the L-cysteine hydrochloride is to reduce the elasticity of the dough and to assist in achieving the desired shape without causing undue damage to the dough pieces during moulding. L-cysteine hydrochloride also finds potential use in the manufacture of short and laminated pastes to improve the blocking and sheeting processes involved. The gluten structure is less well developed in short pastry making than with laminated pastes but both can benefit from the addition of a reducing agent. In pastry making an alternative to the addition of L-cysteine hydrochloride is sodium metabisulphite. Both of these reducing agents need to be used with care in the manufacture of pastry products because the re-cycling of trimmings can lead to their progressively increasing concentration in the recipes being used with subsequent excessive softening of the paste. Long delays in paste

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processing can also lead to excessive softening of the paste when reducing agents are present in the recipe. Sodium metabisulphite has found use as a reducing agent in the manufacture of biscuits, especially the low-fat, low-sugar types embraced by the generic term `semi-sweet'. The level of gluten development occurring during the mixing of semi-sweet biscuit dough is considerably less than that achieved in bread dough mixing but with stronger flours it is still sufficient to contribute to biscuit shrinkage. This shrinkage may be seen during the sheeting processes but is commonly seen when the biscuit units have been cut from the sheet. In severe cases the shrinkage is immediately after cutting while in less severe cases it may only be observed as shrinkage after the biscuit has been baked. In this case the biscuit dimensions will differ from those used in cutting and round biscuit shapes commonly develop eccentricity. The use of sodium metabisulphite is not universally accepted (Manley, 2000) and common `additive-free' approaches are to more closely specify the qualities of the flour to be used or to add more water during dough mixing to yield a less elastic gluten network. The concern over the addition of chemical reducing agents has led to consideration of more `natural' forms. Bakers' yeast cells are a rich source of the natural reducing agent glutathione (Bonjean and Guillaume, 2003). In scratch bread making the yeast cells are intact and the glutathione has no direct contact with the dough proteins. However, if the yeast cell membrane is damaged then there is potential for the glutathione to react with the protein network. Freezing yeast and yeasted doughs leads to irreparable damage to the cell membrane, and the effect of the glutathione is undoubtedly one of the contributing factors to the loss of gas retention in frozen bread dough. Commercial extracts of yeast cell contents are available for use as a reducing agent. Glutathione (and L-cysteine hydrochloride) may be used in the manufacture of pasta to denature the gluten in the dough (Kent and Evers, 1994). Glutathione occurs naturally in flour. It is among the low molecular weight thiol compounds, though the amounts present in flour are small. Low molecular weight thiols diffuse rapidly through the dough and so despite their low concentrations they are likely to be active in affecting the rheological properties of the dough. In some instances changes in glutathione level have been linked with the `freshness' of flour and its performance in baking (Chen and Schofield, 1996). Glutathione levels do vary with wheat type and the ash content of the flour (Sarwin et al., 1992). The content of low molecular weight thiols (including glutathione) is known to be affected by oxygen, probably during the milling of wheat to flour and almost certainly during dough mixing. Kieffer et al. (1990) found that dough resistance fell and flour extensibility increased as the level of glutathione increased. No discussion of the use of reducing agents in baking is complete without including some discussion of the role of ascorbic acid. Chemically ascorbic acid is a reducing agent but its conversion to dehydro-ascorbic acid is responsible for its oxidising effects in breadmaking (Williams and Pullen, 2007). The

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availability of oxygen for the conversion is crucial in this context but, as has been shown, oxygen depletion can occur quite quickly in bread dough (Cauvain and Young, 2006). This suggests that in the anaerobic environment in the dough, which is attained after mixing the ascorbic acid present, has the potential to act as a reducing agent, and practical experiments show that if ascorbic acid is present in fermenting dough, then there can be loss of bread volume (see 4.21). However, if the dough is re-mixed (e.g., as during knock-back, see 4.26) then the re-introduction of oxygen allows for some further oxidation effect from the ascorbic acid. References

and GUILLAUME, L-D. (2003) Yeast in bread and baking products. In (eds T. Boekhout and V. Robert) Yeasts in Food, Woodhead Publishing Ltd, Cambridge, UK, pp. 289-308. CAUVAIN, S.P. and YOUNG, L.S. (2006) The Chorleywood Bread Process, Woodhead Publishing Ltd, Cambridge, UK. CHEN, X. and SCHOFIELD, J.D. (1996) Changes in glutathione content and breadmaking performance of white flour during short-term storage. Cereal Chemistry, 73, 1±4. KENT, N.L. and EVERS, A.D. (1994) Technology of cereals 4th edn, Elsevier Science Ltd, Oxford, UK. KIEFFER, R., KIM, J-J, WALTHER, C., LASKAWY, G. and GROSCH, W. (1990) Influence of glutathione and cysteine on the improving effect of ascorbic acid stereoisomers. Journal Cereal Science, 11, 143±152. MANLEY, D. (2000) Technology of biscuits, crackers and cookies 3rd edn, Woodhead Publishing Ltd, Cambridge, UK. SARWIN, R., WALTHER, C., LASKAWY, G., BUTZ, B. and GROSCH, W. (1992) Determination of free reduced and total glutathione in wheat flour by an isotope dilution assay. Z Lebensm Unters Forsch, 195, 27±32. STAUFFER, C.E. (2007) Principles of dough formation. In (eds S.P. Cauvain and L.S. Young) Technology of Breadmaking 2nd edn, Springer Science + Business Media, LLC, New York, NY, pp. 299±332. WILLIAMS, T. and PULLEN, G. (2007) Functional ingredients. In (eds S.P. Cauvain and L.S. Young) Technology of Breadmaking 2nd edn, Springer Science + Business Media, LLC, New York, NY, pp. 51±92. BONJEAN, B.

Further reading

and BRUMMER, J. (1995) Frozen & Refrigerated Doughs and Batters, AACC, St. Paul, MN. WEISER, H. (2003) The use of redox agents. In (ed S.P. Cauvain) Bread Making: Improving Quality, Woodhead Publishing Ltd, Cambridge, UK, pp. 424±446. KULP, K., LORENZ, K.

4 Bread and fermented products

4.1 What characteristics should we specify for white bread flour and why? The breadmaking potential of flour is strongly influenced by the proteins present in the wheat. There proteins hydrate and, with the input of energy during mixing, form the gluten network which provides much of the gas-retaining properties of bread dough. However, there are other flour properties that should be taken into account when deciding on a particular flour specification and there are process factors to consider, such as which breadmaking process you are using and what type of product you are making. As a guide you should consider the following as a minimum for white flour: · Protein content ± around 13% on a dry matter basis. This figure should increase by about 1% if you are using a process which uses bulk fermentation to mature the dough before processing or if you are making `free-standing', hearth- or oven-bottom type breads. As a general rule the higher the protein level in the flour, the greater its gas retention potential and therefore the greater the resultant bread volume and crumb softness. · A measure of the `purity' of the white flour; that is the level of bran particles which are present. This is often measured as ash or grade colour figure (see 2.1 and 2.2). The presence of bran has a negative impact; the higher the level of bran present, the poorer the gas retention of the dough. · The water absorption capacity of the flour, since this is an indicator of how much water will need to be added at the dough making. A number of different factors affect the water absorption capacity (see BPS, pp. 25±6). The measured water absorption capacity is only a guide as to the level that will be used in the bakery. It is usual for the actual level of water added to dough to

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be reduced when making free-standing breads, as this helps the dough to retain the required product shape during processing (Cauvain and Young, 2008). · Hagberg Falling Number ± typically this should be above 250 seconds (see BPS, p. 24). · Protein quality ± this is usually assessed by measuring the rheological properties of a flour-water dough. In general the flour should possess reasonable resistance to mixing or stretching, sufficient extensibility and good stability. There are a number of different tests which can give you this information. For a summary of the methods see BPS, pp. 21±2, and for more detailed information see Cauvain and Young (2009). · Flour treatments and additives ± ideally the flour should be untreated but if this is not possible any additions should be kept to a minimum. Common additions are ascorbic acid as a bread `improver' and alpha-amylase. If you are using a bread-making process in which the flour would benefit from the addition of bread improvers, it would be better to add them in the bakery as part of the recipe. Any additions to the flour should be discussed with your miller supplier. References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2008) Bakery Food Manufacture and Quality: Water Control & Effects, Wiley-Blackwell, Oxford, UK. CAUVAIN, S.P. and YOUNG, L.S. (2009) The ICC Handbook of Cereals, Flour, Dough and Product Testing: Methods and Applications, DEStech Publications, Lancaster, PA. CAUVAIN, S.P.

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4.2 We make crusty breads in a retail store and recently we have been having complaints about our products going soft quickly. We have not changed our recipe or process. Can you help us understand what has happened? Your problem was not related to baking but to your cooling and wrapping practices. You had recognised that crusty products should not be stored in impermeable films or plastic bags. If the products are too warm when they are placed in plastic bags then the loss of moisture from the product crumb results in condensation and the condensing moisture is absorbed by the crust turning it soft. It will also increase the risk of accelerated mould growth as the normally low moisture and water activity of the crust both increase. Even when products are adequately cooled before they are placed in impermeable plastic bags, the process of moisture migration from the product crumb to the atmosphere in the bag will occur. This is because the cell network in the bread crumb is open ± referred to as a `sponge' by cereal scientists ± and water can readily escape to the atmosphere. The relative humidity of the atmosphere is lower than that inside the loaf and so the driving force is for moisture to be lost from the crumb. Moisture migration will continue until equilibrium is reached in the bag, that is, the air, the product crust and the crumb all have the same moisture content. If this did happen before the loaf was consumed, the crust would be softer and the crumb drier than normally expected. The rate at which this would occur depends on many factors, not least the temperature at which the product is kept. It has become common practice with many crusty-style products to wrap them in `perforated' film or bags. The material used for the bag has a number of small diameter holes through which moisture can escape. This means that the equilibrium referred to above cannot occur. The positive benefit of this approach is that the moisture differential between crust and crumb is maintained and some of the original product crustiness is maintained. A disadvantage of this approach is that the product crumb will become drier faster than would be the case with an impermeable plastic bag. In fact your problem arose because of a subtle change in the type of perforated film that you were using. Feedback from the check-out staff in the store had indicated that bits of crust were contaminating the scanner and so you changed to a film with smaller diameter perforations. Doing this reduced the scanner problem but also reduced the rate at which moisture was lost from the product, in effect the system behaved more like an impermeable bag and the crust softened more rapidly. The way to reduce the scanner problem is certainly to reduce the perforation diameter but you need to increase the number of perforations per unit area of film so that the moisture vapour transpiration rates (see 9.9) of the two films are equal. The smaller diameter perforations will reduce the size of the crust particles which fall through and the increase in the numbers will maintain the loss of moisture at a level similar to that which you were getting before.

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4.3 We are not a large bakery but are planning to part bake and freeze bread products for bake-off at some later time. What points should we be aware of? The bake-off of frozen bread products gives bakers flexibility of supply to their customers. However, in freezing and baking-off such products it is important that they lose as little moisture as possible in order to reduce the rate at which the final baked product will firm (stale). When cooling the products after their first baking, the core temperature should be checked. A temperature of 30ëC should be aimed for in order to reduce the thermal shock that the products will experience when transferred to the freezer. It takes some time for heat to be drawn out from the product centre while the surface will freeze very quickly. It is better to cool the bread to ambient temperature in the bakery rather than put hot bread in the freezer. Covering the products can help to reduce moisture losses but ensure that you do not get condensation on the product as this will affect the final crust quality. You will get best results if you are able to use a blast freezer rather than a chest-type freezer. The speed of the air movement in a blast freezer can remove as much as 2±3% moisture from the product. To limit moisture losses, keep the freezing times as short as possible. Product core temperatures after freezing should be in the order of ÿ10ëC but remember that products with different dimensions (particular diameter or thickness) will freeze at different rates. Consider collating racks before loading and unloading the freezer ± i.e., fewer door openings ± or fitting an `air' curtain. Opening the blast freezer door reduces its efficiency, which means that the product takes longer to freeze and loses more moisture. Once the products are frozen you should get them into moistureimpermeable bags and into a storage freezer as quickly as possible to avoid moisture losses. The salt in the bread depresses the freezing point to around ÿ4 to ÿ6ëC and so once the temperature rises above this (for example, during packing) the product begins to defrost. Partial defrosting and then re-freezing results in `freezer burn'; this shows as white patches in the crumb which are hard to the touch and have a harsh mouthfeel (BPS, pp. 108±9; Cauvain and Young, 2008). The physical and chemical changes that have occurred in the crumb are not usually reversible so you need to take care of your storage conditions if you are to avoid this problem. Another common problem with frozen bake-off products is that called `shelling' in which the crust of the product detaches from the crumb (Fig. 16). This phenomenon arises because the different moisture content of the crust and crumb cause the two components to freeze and defrost at different rates, which strains the physical links between the two. The problem can occur at a number of stages of the bake-off process depending on its severity: · During frozen storage, especially if the product is stored for long periods of time. · On defrosting before second baking. · After second baking.

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Fig. 16

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Shelling of bakery problems.

With prolonged storage times you may see a combination of shelling and freezer burn. In preparing the product for bake-off, check the core temperature on defrosting in ambient conditions. Aim for a temperature of ÿ5ëC (just defrosted). At bake-off consider using higher temperatures than for standard baking with shorter bake times. Moisture loss during second bake depends more on time than on temperature and so accurate timing of bake-off is essential if the product is not to lose too much moisture. Bake-off products will always stale faster than scratch products and excess loss of moisture (either in the freezing or the baking off) will exacerbate this staling (see 4.4). References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2008) Bakery Food Manufacture and Quality; Water Control and Effects 2nd edn, Wiley-Blackwell, Oxford, UK. CAUVAIN, S.P.

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4.4 When we re-heat par-baked products we find that they remain soft for only a short period of time, typically an hour or so, but they quickly go hard and become inedible. If we do not re-heat them we find that par-baked products can stay fresh for several days. What causes the change in the rate of firming? Is it the additional moisture lost on the second bake? Your assumption is partly correct. Moisture will be lost from the products at both baking stages and it is more than likely that the sum of the two moisture losses will exceed that of a single bake. The lower the moisture content of the product the firmer the crumb. However, in order to fully answer your question we need to consider the process that cereal scientists call staling. Bread crumb firmness increases during storage even when no moisture is lost from the product. Schoch and French (1947) proposed the most commonly accepted models for bread staling. Their model for bread staling was based on the changes in the two major fractions of the starch in wheat flour, the amylose and the amylopectin, post-baking and during storage. Raw starch granules in flour have an ordered or crystalline structure and during dough mixing those which have been physically damaged during flour milling become hydrated. In the dough entering oven the starch first swells and then later gelatinises as the temperature increases to around 60±65ëC. Gelatinisation disrupts the crystalline structure and the amylose diffuses into the aqueous phase to form an insoluble gel which contributes to a soft crumb structure. On leaving the oven the bread cools and the amylose fraction quickly reassociates; this process gives bread crumb its initial firmness. The other starch fraction, the amylopectin, takes much longer to re-associate, usually several days. It is the process which is responsible for crumb firming during prolonged storage and is the one most commonly associated with bread staling. If stale bread is re-heated it is possible to reverse the amylopectin recrystallisation process and soften the crumb. However, when the breads cools the second time there is a noticeable increase in the rate at which it goes firm; what used to take days now takes a few hours. This increased staling rate is associated with the temperature that the product achieves during re-heating. It is essential to melt all of the amylopectin fraction in the product, which means that the centre crumb temperature should reach 65ëC. If this does not happen then a few unmelted crystals of amylopectin act as seed for the recrystallisation process, which proceeds much faster as a result. Many users are cautious about re-heating bake-off products and are concerned to avoid excess surface colour, consequently the crumb does not reach the critical temperature and re-firming rates can be rapid. Reference

and FRENCH, D. (1947) Studies in bread staling. 1. Role of starch. Cereal Chemistry, 24, 231±249.

SCHOCH, T.J.

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4.5 We have been freezing some of our bread products in order to have products available in times of peak demand. We notice that there is `snow' or `ice' in the bags when we remove them from the freezer. Can you tell us why this happens and how it can be avoided? Freezing products ready to meet peaks in customer demand is a common practice. Bread and rolls, if wrapped to prevent any moisture losses, will keep well in the frozen state. Bread products have a high moisture content and a high water activity. Once frozen, the products should be stored below their Tg (glass transition temperature) (see 9.7). Effectively this is the temperature at which all the soluble materials in the product become immobile or frozen. It has been estimated that approximately 30% of the water in bread remains unfrozen even at the usual storage temperature of ÿ20ëC. If the temperature of the frozen product rises above its Tg some of the moisture present can evaporate and sublime through the product to the surrounding atmosphere, in this case the inside of the bag in which it is packed. Once there the water vapour freezes into ice crystals and becomes visible as `snow' on the product (see Fig. 17). With the reduction, for health reasons, in salt levels in bread products, this problem is likely to occur earlier in the products' frozen life. This is because salt is a material which has the ability to `hold on to' the moisture in the product thus preventing its `escape' as vapour.

Fig. 17

Ice crystals formed in bread pack.

If the problem occurs frequently it would be wise to check that your freezer is operating correctly (temperature at or below ÿ20ëC) and try to minimise any opening and closing of its door and check its defrosting cycle. It is also beneficial to remove product in strict rotation so that any one product does not spend too long in the freezer. In addition, care should be taken that any product which is removed from the freezer is not left in a warm atmosphere, as the localised melting of the ice particles provides a good environment for eventual mould growth.

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4.6 We are seeking to improve the quality of our bread products and are getting conflicting advice on what the optimum dough temperature ex-mixer should be. Can you advise us as to whether we should increase or decrease our dough temperature? The control of the temperature of the dough delivered at the end of mixing is a critical factor in ensuring consistent final product quality because of its contribution to gas retention in the dough, gas production by bakers' yeast and dough rheology for processing. Whatever your choice of final dough temperature it is very important to ensure that you are consistent from dough to dough. Choosing the appropriate dough temperature to aim for after mixing is independent of producing a dough with a consistent final temperature. In general, raising the final dough temperature will encourage the yeast to work faster and this will speed up fermentation. One of the disadvantages of this will be that the bulk dough density will change more rapidly with time; as the bulk dough density decreases, this can lead to greater problems with divider weight control while processing the batch. Since the yeast will be more active, you may find that you can slightly reduce the level that you are using provided you do not compromise final proof time and oven spring. If you are using an improver then by raising the dough temperature you will gain increased activity from the ascorbic acid present, which should improve dough gas retention. There will also be an increase in the contribution of the enzymic activity in the dough and you need to make sure this does not adversely affect dough processing. In general, raising the dough temperature will make the dough easier to mould into shape but in some circumstances you may find that the dough becomes stickier and you may need to reduce added water levels. Warmer doughs not only tend to ferment faster, they also tend to prove more uniformly and this can lead to a more uniform, and sometimes shorter bake. The key advantage in reducing the dough temperature is that you can better control gas production in the early stages of dough processing and limit the potential impact of dough stickiness. However, lower dough temperatures have an adverse impact on gas retention and so there can be a loss of product volume and crumb softness. If you have a fixed proof time then you will need to add more yeast with colder doughs in order to maintain proof volume for the same time. This can lead to problems of product uniformity in the oven arising from the increased temperature differential between the surface of the dough piece and its centre. A common problem arising from using cool doughs and high yeast levels can be the development of ragged crust breaks (BPS, pp. 84±5). The ex-mixer dough temperatures commonly used in baking range from 24± 32ëC with bulk fermentation processes using the lower end of the range and notime dough making processes the higher end. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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4.7 How can I calculate the amount of ice I need to replace some of the added water when my final dough temperature is too warm? Using an ice slush (a mixture of water and crushed ice) or crushed ice to keep control of the dough temperature at the end of mixing is a practical solution to unacceptably high dough temperatures in the summer months, in countries with hot climates, and with stronger flours, which may require long mixing times or high mixing energies. The cooling capacity of ice is at least four times that of cold water as heat energy is used up in converting the ice to water at 0ëC. The ice must be in a form which is easily dispersed and can quickly use up the heat in the dough. In order to calculate the quantity of ice needed to replace added water a `heat balance' scenario must be used. The heat to be removed from the added water (in order to cool it to the required temperature), must be balanced against the heat required to convert the ice to water and then heat that melted ice to the required water temperature. The following formulae can be used to determine the quantity of ice which must replace a portion of the recipe added water to obtain the required water temperature to control the final dough temperature. A `heat balance' is achieved as shown on Fig. 18. The formulae using metric standards are given. Wi ˆ weight of ice Ww ˆ required weight of recipe added water Tt ˆ temperature of tap water in ëC Tr ˆ required water temperature in ëC Heat, Q1, to be removed from added water ˆ …Ww ÿ Wi †  …Tt ÿ Tr †  4:186 Specific heat capacity of water ˆ 4.186J/kg/ëC Heat, Q2 needed to melt ice and heat resulting water to the required water temperature ˆ Wi  334:6 ‡ Wi  Tr  4:186 Latent heat of ice ˆ 334.6 For heat balance Q1 ˆ Q2

Eqn (1)

…Ww ÿ Wi †  …Tt ÿ Tr †  4:186 ˆ Wi  334:6 ‡ Wi  Tr  4:186 For example: 40 kg of water is required for a dough mix. Temperature of tap water is 20ëC. Required temperature of water for the dough is 10ëC. Calculate how much of the added water would need to be ice. To cool (40 kg ± wt of ice) of water from 20 to 10 requires Q1 heat to be removed.

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Fig. 18 Heat balance calculation.

Q1 ˆ …40 ÿ Wi †  …20 ÿ 10†  4:186 ˆ …40 ÿ Wi †  41:86 This is the heat `available' to melt Wi kg ice, and to heat that ice water to 10ëC Q2 ˆ Wi  334:6 ‡ Wi  …10 ÿ 0†  4:186 ˆ Wi …334:6 ‡ 41:86† Using heat balance (Eqn 1), …40 ÿ Wi †  41:86 ˆ Wi …334:6 ‡ 41:86† 41:86  40 ÿ 41:86Wi ˆ 376:46Wi 418:32Wi ˆ 1674:4 Wi ˆ 4 Of the 40 kg of water required for the recipe, 4 kg should be added as ice and 36 kg added as tap water at 20ëC. It is worth remembering that the water that is `locked-up' as ice at the start of the mixing is not available to dissolve ingredients or start the hydration processes of the damaged starch and proteins in the flour. The likely impact on dough development will be small but may be more significant if a very large

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mass of ice is used. In practical terms it is better to use crushed ice as this aids the rapid dispersion of the small ice particles through the dough. In theory cube ice may be used but this should be avoided as much as possible. If you are going to routinely add ice to your doughs, make sure that you have a large enough ice-making capacity. You will not only need to calculate the mass of ice that you are likely to need for your mixings but also need to take into account the ability of your ice-making machine to deliver ice at the required rate. You may need to have some form of buffer container to hold the ice ready for use in the bakery.

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4.8 We are considering the purchase of a new mixer for the manufacture of our bread using a no-time dough process. There are two types of mixer that seem to be appropriate for our plant production needs, the spiral-type and the CBPcompatible type, but before making our decision we need to understand any issues with respect to dough processing and final bread quality. Can you please advise us? The first point to make is that both mixer types are perfectly suitable for making bread using a no-time dough process. In many ways your choice will be dictated by the type of bread that you wish to make and the final characteristics that your products should have. We have listed below the main technical issues that you should consider in making your choice. Plant capacity and mixing times Clearly it is important to ensure that you can provide sufficient dough to run efficiently with minimal gaps between batches when the products reach the oven. It is usually a relatively simple calculation to determine the batch size capability of the mixer. You will also need to consider the mix cycle time; the length of time from the start of ingredient delivery to the mixer and delivery of the mixed dough to the divider. The mix cycle time will include the actual dough mixing time along with all of the loading and transfer times required. In general, for reasons discussed below, the actual mixing time (not the mix cycle time) for spiral-type mixers is longer than that for CBP-compatible mixers; typical mixing times would be 8±14 minutes for the spiral (see BPS, p. 96) and 3±5 minutes for the CBP. These times may vary but it is worth noting that optimum mixing times for CBP doughs are quoted as 2±5 minutes (Cauvain and Young, 2006). Energy input and dough development During the mixing cycle energy is transferred to the dough by the mechanical action of the impeller. This energy is an important part of the development of a gluten structure in the dough with the appropriate rheological and gas retention properties; in general the greater the energy input, the greater the dough development and the greater the gas retention properties of the dough (see BPS, pp. 92±3) though the precise effects of increasing the level of energy input to the dough will vary according to flour quality (Cauvain, 2007). The total level of energy transferred to the dough during mixing depends to a significant degree on the length of the mixing time; the longer the mixing time, the greater the total energy transferred. However, it has been known for some time (Cauvain, 2007) that the `rate' at which energy is transferred to the dough also has an impact; in general, the faster the mixing speed, the faster the rate of energy transfer and the greater the improvement in dough gas retention for a given set of ingredients and dough recipe. CBP-compatible mixers exploit this effect by running at a higher speed than many spiral-type mixers, which explains, in part, why optimum mixing times are shorter with CBP-type mixers.

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The rate of energy transfer to the dough during mixing also depends on the physical geometry of the mixing bowl and the impeller blades that are used. In the case of spiral-type mixers, the introduction of a static bar or a twin spiral arrangement may be used to increase the rate of energy transfer to the dough and shorten mixing times. In the case of the latter form of spiral mixer, you could argue that this is the equivalent of a CBP-type mixer but there are other considerations to be taken into account (see below). Dough temperature control There is a direct relationship between the input of energy to the dough during mixing and its final temperature; the higher the total energy input, the higher the final dough temperature for a given recipe and batch size. In dough mixing the most common way to control the final dough temperature is through the adjustment of the initial water temperature (Cauvain and Young, 2008). It is common practice to have a sufficient supply of chilled water available in the bakery for dough mixing to help with the control of the final dough temperature and in some cases ice or ice-slush may be added at the start of mixing (see 4.7). Typical final temperatures for CBP-type dough will be in the order of 28± 32ëC while those for spiral mixed dough would be 24±28ëC. Traditionally spiralmixed dough tends to have a lower final temperature because usually less energy is transferred during mixing. CBP-type dough tends to have a higher final dough temperature not only because of the higher energy input but because the increased dough development yields a dough with dough rheological characteristics that allow it to be readily processed on the dough make-up plant at the higher temperature. Dough gas bubble structure and product cell structure The creation of the gas bubble structure in dough depends on the entrainment and sub-division of air during dough mixing (Cauvain, 2007). Many factors influence the gas bubble population (i.e., the numbers and sizes of gas bubbles) in the mixed dough. The initial gas bubble structure in the mixed dough is a major contributing factor to the final product cell structure. It is significantly affected by the mixer type. This is an important issue, since with no-time doughs there is no significant opportunity during processing to modify the gas bubble population to reduce its average size. In practice, when the dough leaves the mixer, the main change for the gas bubble is to increase in size. Thus if a fine and uniform cell structure is required in the final product, essentially it must be created in the mixer (see also below). Because gas bubbles grow after leaving the mixer, it is easier to create a coarser cell structure in the final product. The measurement of gas bubble populations in mixed dough has shown that spiral-mixed dough has a higher average bubble size and a wider range of sizes than typically seen with CBP-type mixers (Cauvain et al., 1999). Since the initial gas bubble population is a major determinant of final product cell structure, this means that spiral-mixed dough tends to yield final products with a greater average cell size with a wider range of sizes; in practical terms the cell

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structure of bread from spiral-mixed dough will have a coarser and less even structure than those from CBP-type mixers (but see the following section). The modification of product cell structure The preceding comments on the creation of gas bubble populations and product cell structures are important in understanding one of the key principles of the CBP, namely the control of product cell structure through the modification of the mixer headspace pressure (Marsh and Cauvain, 2007). Spiral-type mixers do not commonly have a facility for controlling the mixer headspace pressure, as the mixer bowl is mostly open to the atmosphere. The bowl of the true CBP-compatible mixer can be isolated from the surrounding atmosphere by means of lowering a close-fitting lid. Historically, (Cauvain and Young, 2006) the atmospheric pressure in the mixing bowl was reduced below that of atmospheric pressure in order to create a finer and more uniform cell structure in the bread (with accompanying advantages for crumb softness). Later developments of the CBP-compatible mixer (Cauvain, 1994) include the facility to have pressures above or below atmospheric and, most importantly, to change from one pressure to another during the mixing cycle. This development enables the creation of different gas bubble populations in the dough and therefore different cell structures in the final product. In practice this means that the same mixer can be used to create the fine and uniform cell structure required for sandwich bread or the coarse open structure required for French bread types simply through the manipulation of mixer headspace pressure. References

(1994) New mixer for variety bread production. European Food and Drink Review, Autumn, 51±53. CAUVAIN, S.P. (2007) Breadmaking processes. In (eds S.P. Cauvain. and L.S. Young) Technology of Breadmaking, 2nd edn, Springer Science+Business Media, LLC, New York, USA, pp. 21±50. CAUVAIN, S.P. and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2006) The Chorleywood Bread Process, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2008) Bakery Food Manufacture & Quality: Water Control and Effects 2nd edn, Wiley-Blackwell, Oxford, UK. CAUVAIN, S.P., WHITWORTH, M.B. and ALAVA, J.M. (1999) The evolution of bubble structure in bread doughs and its effect on bread structure. In (eds G.M. Campbell, C. Webb, S.S. Pandiella and K. Niranjan) Bubbles in Food, American Association of Cereal Chemists, St. Paul, MN, pp. 85±88. MARSH, D. and CAUVAIN, S.P. (2007) Mixing and dough processing. In (eds S.P. Cauvain. and L.S. Young) Technology of Breadmaking, 2nd edn, Springer Science+Business Media, LLC, New York, USA, pp. 93±140. CAUVAIN, S.P.

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4.9 We are looking to buy a new final moulder for our bread bakery. Can you advise us on the key features we should look for and how they might impact on final bread quality? The main function of the final moulder is to change the shape of the individual dough pieces to fit the product concept and deliver them in the appropriate form for final proof. Since there are many different sizes and shapes of bread products, there is no single moulder able to meet the requirements of all them. A typical bread dough moulder will comprise a chute feeding the pieces into a series of rollers (2±4 in number). Typically the pieces entering the rollers will have a round shape and the sheeting process by the rolls will yield a flattened elliptical shape. Immediately on leaving the rollers the leading edge of the dough `pancake' is lifted by a chain and the dough piece is rolled up like a Swiss roll before being carried underneath a moulding or pressure board. The gap between the board and the moving belt of the moulder is adjusted to yield the desired shape. Side guide bars may be fitted under the moulding board to help deliver a cylindrical shaped dough piece (a most common shape for bread products). The behaviour of the dough piece depends in part on the dough-making process that has been used. Dough that has undergone a period of bulk fermentation has a low density with large pockets of gas trapped in the gluten structure. Dough pieces passing through the sheeting rolls will become degassed and this action can contribute to making the cell structure of the final product finer and more uniform. In some dough types, e.g. baguette and ciabatta, the large gas pockets are an integral feature of the final product and so de-gassing of the dough is not advisable. Instead the moulding action will be designed to aid the retention of the large gas bubbles, though mechanical moulding is never likely to deliver the same final product cell structure that can be achieved with hand moulding. Modern no-time doughs have relatively low levels of gas in them and so the de-gassing function of the sheeting rollers has limited value. Such doughs also have a different rheological character and respond quite differently to heavy pressures during final moulding. In many cases the pressures can lead to damage of the gas bubble structure in the dough, which in turn leads to quality problems in the final product (BPS, pp. 87±8). Such quality losses are less likely to occur with longer moulding boards. As a general rule fine cell structure in bread is obtained by sheeting thinly and using just enough pressure under the moulding board to achieve the required shape. This sheeting is best achieved gradually in moulders with a greater numbers of rolls. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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4.10 We are having problems keeping a uniform shape with our bloomers. They tend to assume a bent or `banana' shape (Fig. 19). This happens even though we take great care to straighten them when they are placed on the trays. Can you explain why we get this problem? This can be a common problem in the production of free-standing breads and can easily be explained, though in some cases the solution can be quite difficult to achieve. The banana shape is actually created towards the end of the final moulding stage. As the dough piece passes under the moulding board on the final moulder and is extended in shape by the rolling action, the ends of the piece reach the side guide bars. The effect of the guide bars is to slow down the progress of the two ends of the dough piece while the centre continues to move at a higher speed. If you look closely at the dough pieces as they travel under the pressure board, you will see this happening and observe that the dough piece already has the banana shape you refer to (see Fig. 20).

Fig. 19

Bloomer with bent shape.

During the passage of the dough under the moulding board the ends and the centre of the dough piece are subjected to different levels of `twisting' force. This means that even though you are straightening the dough pieces by hand and even though you are giving them 45 minutes proof there is sufficient elasticity left in the piece for it return to the shape that it had taken on during moulding. This problem is more severe in bloomers because the dough often has a stiffer consistency to help with retaining the traditional round cross-section after baking. The moulder should be set to reduce the variation in twisting forces between the different parts of the dough piece. You should try to reduce the pressure exerted by the moulding board by setting it up so that the dough piece only reaches its full length half way under the board; ideally about two-thirds of the way down the length of the board. If you cannot do this without compromising other aspects of shape (e.g., sealed ends), then the ideal solution would be to use a moulder with a longer moulding board. You may find similar problems with any free-standing cylindrical-shaped products. If you are taking a larger dough piece and cutting it into smaller

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Fig. 20 Schematic of bloomer dough piece passing under the moulding board.

individual pieces, you are likely to find that uneven moulding contributes significantly to variations in dough piece dimension after baking. You can gain some benefit by proving the dough at a lower temperature for a longer time. The longer time and the reduced temperature differential in the dough piece both help to yield a more `relaxed' dough piece entering the oven, which should expand in a more uniform manner. If you do reduce the proving temperature, remember to slightly reduce the humidity as well otherwise the dough pieces will begin to flow and lose their shape. If you cannot make adjustments to the moulder or proving conditions, you might try a slight increase in added water level but there is a delicate balance here because more water in the dough can cause the bloomer to assume a flatter appearance (Cauvain and Young, 2008). You may also find it helps to mix the dough longer since you are using a spiral mixer, making sure that you keep the final dough temperature the same as for normal production. Reference

and YOUNG, L.S. (2008) Bakery Food Manufacture and Quality: Water Control & Effects 2nd edn, Wiley-Blackwell, Oxford, UK.

CAUVAIN, S.P.

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4.11 Why is a bread dough piece coiled after sheeting? Does the number of coils achieved have any impact on bread quality? The rationale for coiling a dough piece is closely connected with the process of sheeting dough and the traditional use of a period of bulk fermentation after mixing to `develop' the dough ready for dividing and processing as unit shapes. The density of dough at the end of its bulk fermentation period is very low and as much as 70% of the dough volume may comprise gas bubbles, a mixture of mostly nitrogen and carbon dioxide of various sizes (Cauvain, 2003). Some of the gas bubbles may be very large in size (several cm) and if they are retained in the dough piece which enters the prover, these bubbles commonly lead to the formation of unwanted holes in the crumb of pan breads (although they may be acceptable in baguette and ciabatta). Such large gas bubbles can readily be expelled from the dough piece by flattening them by hand or by pinning. An alternative was to pass the dough backwards and forwards through the sheeting rolls of a pastry brake. A similar process to the latter was achieved by passing the dough through a series of pairs of rolls, one set mounted above another, and this is the basis of the most common form of bread dough moulders. The expression of the large gas bubbles from the dough piece is an important contributor to the formation of a fine and uniform cell structure in the baked product, which in turn, is an important contributor to bread crumb softness and brightness; both are seen as desirable characteristics in white and many other bread types. The formation of a round dough piece after dividing is a common practice, even if hand moulding is undertaken. When such dough pieces are passed through sheeting rolls, they form an elliptical shape, which is then coiled (rolled like a Swiss roll) to form a crude cylindrical shape for final processing (Marsh and Cauvain, 2007). The number of coils that are achieved when creating the cylinder depends mainly on the length of the ellipse and is determined to a large extent by the design of the sheeting head of the moulder and the speed at which the dough piece passes through it. The general view is that sheeting thinly, and the subsequent increase in the numbers of coils that are achieved, delivers a finer and more uniform crumb cell structure. However, it should be noted that the volume of gas in no-time dough pieces reaching the final moulder is considerably lower (typically <20%) than that from bulk fermentation systems (typically 70%) and this implies that the impact of sheeting on final bread quality may be less marked. References

(2003) Breadmaking: an overview. In (ed. S.P. Cauvain) Bread Making: Improving Quality, Woodhead Publishing Ltd, Cambridge, UK, pp. 8±28. MARSH, D. and CAUVAIN, S.P. (2007) Mixing and dough processing. In (eds S.P. Cauvain and L.S. Young) Technology of Breadmaking, 2nd edn, Springer Science + Business Media LLC, New York, NY, pp. 93±140. CAUVAIN, S.P.

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4.12 We have been taught to always place the seam of our moulded bloomer dough pieces downwards on the tray before proof but we do not take the same precautions with our pan breads. Can you explain the relevance of placing the bloomer dough piece `seam' down? Should we also do this with our pan breads? The `seam' to which you refer is the tail-end of the sheeted dough pancake formed after it has been curled. It is seen as a curving line on the final moulded dough piece. Even with hand moulding a seam will be formed by the last portion of the piece to be moulded. In bakeries where dough pieces are panned by hand the traditional practice is to place them on a tray or in a pan with the seam on the bottom, that is, in direct contact with the metal tray or sling. There are a number of reasons for this procedure. The first is related to the appearance of the baked product. The portion of the dough which comprises the seam may not always be `sealed' in the final stages of moulding and often has the propensity to uncurl in the prover and the early stages of baking. Placing the seam downwards uses the pressure of the dough mass during expansion to reduce the risk of the seam unravelling. If the seam is placed on the sides or top of the dough pieces then any unravelling will cause unsightly splits in the crust. In principle the seam should be placed on the bottom for all dough pieces. In automatic plants this is not generally possible when making pan breads since there is no human intervention at the panning stage. This tends not to cause significant problems for the quality of lidded pan breads because the impact of the lid reduces the potential for unravelling of the dough curl. Similarly there is a reduced risk of unravelling when four piecing of the dough is used (BPS, p. 91), even when open top bread is made. The greatest risk of quality losses from the random positioning of the seam is likely to occur with open-top single piece bread. One aspect of the seam location not often appreciated is the potential contribution to the formation of unwanted holes in the product crumb. There is the potential for damage to the dough during sheeting (BPS, pp. 89±90; Cauvain and Young, 2008) and for the trapping of small gas pockets during curling, both of which contribute to the formation of unwanted holes. If the seam is placed downwards on the tray or in the pan, the pressures in the dough mass tend to squeeze out some of the larger gas pockets but if the seam is located in some other part of the dough piece, the pressures may be insufficient to eliminate the gas pocket and this can give rise to unwanted holes. References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2008) Bakery Food Manufacture & Quality: Water Control and Effects, 2nd edn, Wiley-Blackwell, Oxford, UK. CAUVAIN, S.P.

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4.13 We have been having problems with holes appearing in different places in our pan breads. Can you explain where they come from and how to eliminate them? Is there any relationship between the holes that we see inside dough pieces coming from the divider and the problems that we are experiencing? First, we should point out that it is almost impossible to make bread without having problems with holes from time to time. There are a number of different origins for the holes and there are a wide range of factors that contribute to their formation. When we refer to holes in bread crumb we usually mean features that are substantially larger than the holes we call the cell structure. In pan bread the latter range from 1±2 mm for sandwich-type bread up to 5±6 mm for farmhouse-type products. Large holes in bread crumb are a particular problem but equally a large number of smaller holes in the crumb can be a cause for concern. To help us understand the origins of holes and consider how we might eliminate them it is useful to know something about their key features and their location within the loaf. A useful diagnostic feature of holes is the appearance of the crumb that comprises their internal walls. The first clue of their origins is given by whether they have smooth walls or whether strands of crumb extend (or did extend) across the hole (i.e., does it have the appearance of a limestone cavern with stalactites and stalagmites?) (Fig. 21). In the case of the smooth-surfaced hole (see Fig. 22), it is an indication that the sides had never touched, while a rough surface to a hole suggests that some force ripped apart the crumb in the region of the hole. The other key feature for diagnostic purposes is the position of the hole within the loaf, bearing in mind the type of bread that is being made.

Fig. 21 Stranded holes.

At then end of mixing, all bread dough has small pockets of air trapped within its bulk. Some of these air pockets will carry through the divider to reach the dough moulding and processing stages. The survival of trapped air pockets during these stages depends in part on the moulding actions that are employed. If a first moulding step is employed, there is some potential for air pockets to be `moulded out', though, as discussed below, the degree to which this happens is

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Smooth sided hole.

very dependent on the dough processing methods being employed. In broad terms many of the trapped gas pockets greater than the sheeting gap employed during final moulding cannot survive because they will be burst by the action of the rolls. However, the rheological properties of bread dough are usually such that some trapped gas pockets become elongated in the direction of sheeting and remain trapped in the final dough piece, albeit in a modified form. The de-gassing of dough and moulding out trapped air pockets has been and still remains a popular theme in treatises on bread dough processing. Such actions can certainly be accomplished with some bread-making processes but less so with others. For example, as much as 70% of the volume of a bulk dough after fermentation and before it reaches dividing (Marsh and Cauvain, 2007) can comprise large pockets of gas, and the expanded and relaxed nature of the gluten structure offers limited resistance to de-gassing actions. In contrast, the gas levels in dough prepared by a no-time dough mixing process will typically comprise less than 20% of the dough volume and have a rheology more resistant to deformation. In such doughs eliminating trapped gas pockets would require the application of significant forces during moulding and such forces have significant potential for damaging the dough structure, leading to the formation of areas of coarse cell structure in the crumb cross-section (BPS, pp. 87±8). A common approach when holes are observed in the bread crumb is to increase the pressure put on the dough as it passes under the moulding board of the final moulder but this often only increases the risk of moulder damage (BPS, pp. 88±90). The gas cells trapped in a dough piece have a wide range of sizes from a few microns to 1±2 mm or more depending on the dough type. The larger gas cells have lower internal pressures relative to the smaller cells. This difference is an important factor in the growth of the gas cells when carbon dioxide is produced by bakers' yeast. Since carbon dioxide cannot form a gas bubble in dough (Baker and Mize, 1941), it will migrate preferentially to the areas of lower pressure, that is, the larger gas cells. The process is known as disproportionation and its consequences are that larger gas cells will grow proportionally larger than small gas cells in the dough. This process has a significant impact in the context of the formation of holes in bread.

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Fig. 23 Air occlusion in the dough pancake at the curling stage.

The position of the holes in the baked loaf provides a number of important clues as to their origins. Many unwanted holes come from the inclusion of gas pockets during the curling action after dough sheeting (see 4.11) and as the dough passes under the moulding board on the final moulder. In a loaf moulded from a single dough piece the relationship is fairly straightforward but with fourpiece bread it is no so clear. The tightness of the initial curl of the dough pancake as it exits the sheeting rolls contributes to gas pocket occlusion (see Fig. 23). Usually the holes in the loaf are centrally placed, have smooth sides and run horizontally through the product. While the gas pocket may start in the centre of the dough piece, it does not necessarily end up in the centre of the final slice cross-section. In pan breads much of the expansion of the dough in the prover occurs in the lower half of the piece (for an illustration of this effect see Whitworth and Alava, 1999) and the original `centre' may well end up about two-thirds of the way up the loaf. In the four-piecing of dough the re-orientation will mean that this type of gas pocket is still in the centre of the dough but largely confined to each of the two central portions and running at right-angles to the pan length (see Fig. 24). A further clue that the holes come from trapped gas pockets in curling is that they may follow the curling lines and so have a curved or crescent shape (see Fig. 25). The curling action in final moulding forms a rough cylinder, the ends of which are `open' (Marsh and Cauvain, 2007), with the potential for trapping gas in the final stages of processing under the moulding board. A traditional role for the moulding board is the elimination of trapped gas but, as already discussed, this depends on the dough condition at the time of moulding. Under the moulding board the dough is often constrained by two `guide bars' running the length of the moulder. The dough is `screwed' against these guide bars by the rolling action to `seal' the ends of the piece. It is at this time that gas pockets may be trapped. If the gas pockets are not eliminated, they are commonly seen as holes towards the ends of the loaf in both single and four-piece products.

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Fig. 24 Potential site of trapped air pocket (shaded section) from the curling stage (see Fig. 23) in single (upper) and four-piece bread (lower).

There is no single unique solution to eliminating holes in bread dough. To minimise the appearance of holes in bread you will need to pay particular attention to the rheological properties of the dough and the different settings that you are using during dough processing. In general you are looking to create a dough which has limited resistance to the deformation processes at work in the moulding stages. This implies optimising the level of water addition during mixing but also includes ensuring that dough development has been optimised; both under- and over-developed doughs contribute to the potential for trapping gas pockets and the risk of moulder damage.

Fig. 25 Trapped air pockets following dough moulding lines.

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References

and MIZE, M.D. (1941) The origin of the gas cell in bread dough. Cereal Chemistry, 18, 19±34. CAUVAIN, S.P. and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. MARSH, D. and CAUVAIN, S.P. (2007) Mixing and dough processing. In (eds. S.P. Cauvain and L.S. Young) Technology of Breadmaking 2nd edn, Springer Science + Business Media, New York, NY, pp. 93±140. WHITWORTH, M.B. and ALAVA, J.M. (1999) The imaging and measurement of bubbles in bread dough. In (eds. G.M. Campbell, C. Webb, S.S. Pandiella and K. Niranjan) Bubbles in Food, AACC, St. Paul, MN, pp. 221±232. BAKER, J.C.

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4.14 We are making open-top pan breads and find that the top crust of some of our loaves is being lifted off during the slicing process. Sometimes there is a hole underneath the crust while, on other occasions there is not. Do you have an explanation for this problem? We have tried making the dough stronger by adding more improver but without any reduction in the problem, in fact it may have been slightly worse The weakness that you are experiencing just underneath the top crust probably has more to do with the dough-moulding process rather than the `strength' of the dough-making system. Your own observations that adding more improver did not solve the problem tends to support this conclusion. Looking closely at the pictures of bread slices that you sent through you can see quite a few small holes throughout the crumb of the loaf. On their own these are not something that you would worry about but quite a few clearly follow the moulding lines formed in the dough when it is being curled-up after sheeting. They are smooth-sided and therefore originate as small pockets of trapped gas (see 4.13).

Fig. 26

Hole formed by the `un-zipping' of air pockets.

The example of the holes that you are getting illustrated in Fig. 26 follows the curve of the loaf crust and appears to be associated with the tail of the dough sheet formed in the final moulder. With hand panning the practice would be to place this `seam' on the bottom of the pan (see 4.12) where the gas pressure created in the dough against the bottom of the pan is likely to prevent the small gas pockets becoming larger. With mechanical panning it is not possible to ensure where the seam ends up with respect to the pan. If it ends up against the side of the pan, the chances of the trapped gas pockets becoming a hole are also reduced. However, if as has happened in the illustrated example, the seam ends up towards the top of the loaf, then there is the opportunity for the gas pockets to

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expand. There is some restriction to crumb expansion once the crust has formed but this often means that the trapped gas pockets coalesce along the moulding lines to form larger holes. This appears to be the case with the illustrated example as the small gas pockets have `un-zipped' along the interface of the dough curl. If the un-zipping effect does not form a large hole then it leaves behind a weakness just under the crust, which creates your problems at slicing. The problem will be more evident at the top of the loaf because of the extra expansion that the dough must accommodate. You are less likely to see this problem with lidded breads, though it does occur, and you may also experience some weakness just under any of the crusts. The weakness to which we refer is not related to the gas retention properties of the dough and the factors that contribute to that dough property but to a physical weakness in the manner in which the bread crumb is attached to the crust. In addition to the contribution made by trapped gas pockets, the differential in moisture content in the first few mm of the bread slice plays a role. We note that the crust colour on your loaves is quite dark because your customers prefer a heavier bake. This does make a contribution to your problem because it reduces the flexibility of the critical area where crust and crumb meet. Because you are automatically panning your dough pieces, there is no way you can guarantee the final location of the dough piece seam in the pan, so you will need to try and reduce the risk of trapping gas pockets in the dough during curling. We suggest that you examine the potential for increasing the level of water that you are using in dough making so that it is easier to sheet the dough and help with the elimination of trapped gas pockets in the final moulder. The degree to which you can do this depends on the operational conditions in your plant. Certainly you should look to reduce the risk of dough pieces skinning during processing. You should also examine your bread cooling process and see if there is an opportunity to reduce overall moisture loss and certainly try to minimise the moisture differential between crust and crumb. In this respect you might want to check the relative humidity in your bread cooler.

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4.15 Can we make bread without using additives? What will be the key features of the ingredients and process that we should use? There are many different types of bread and fermented products that are made without using additives, i.e. with just flour, water, yeast and salt. In order to develop the properties of the gluten network in the dough and improve its ability to retain carbon dioxide gas and expand during baking, it is usual to give a significant period of fermentation to the dough. The first stages of dough fermentation are usually carried out with the dough still in its bulk form, i.e. before it is divided into unit pieces for processing, proving and baking. The length of the bulk fermentation period varies according to the strength of the flour. In general, low protein flours are given shorter periods of bulk fermentation than high protein flours. This is because it takes longer for the natural enzyme-induced changes to modify the dough gluten quality with high protein flours. The length of the bulk fermentation time will also affect the development of flavour in the final bread. It is commonly considered that a bulk fermentation period of at least 3±4h is required for there to be a significant change in bread crumb flavour. In many cases the fermentation periods may extend for up to 24h. In bulk fermented dough a significant contribution to flavour comes from the action of lactic acid bacteria (Wirtz, 2003), which deliver distinctively acid flavour notes in the final product. Since you are relying on fermentation to modify the gluten network in the dough, it will be very important for you to control both the time and the temperature of fermentation. To achieve control of the latter you will need to work to a constant dough temperature and carry out the bulk fermentation under temperature-controlled conditions; if you do not do this then you must expect variable bread quality. If you do not wish to ferment the dough in bulk, then you may choose from one of the alternative methods that ferment only part of the flour and other dough ingredients for many hours before mixing them with the rest of the ingredients to make the final dough. These processes are known by many different and traditional names; such as sponge (and dough), flying ferments, sourdough and polish (Calvel, 2003) and each contributes different attributes to final product quality. Choosing the `right' flour will be very important to you as you are relying heavily on the flour proteins for gas retention. References

(2003) The Taste of Bread, Aspen Publishers, Inc., Gaithersburg, MA. (2003) Improving the taste of bread. In (ed. S.P. Cauvain) Bread Making: Improving Quality, Woodhead Publishing Ltd, Cambridge, UK, pp. 467±486.

CALVEL, R.

WIRTZ, R.L.

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4.16 We have had bread returned to us by the retail store through which it is sold. They are not satisfied with the quality. We have some pictures of the products concerned. This seems to be a `one-off' and we are at a loss to understand what has led to the problem. Can you help us understand where the problem came from? Identifying the cause of `one-off' problems can be very difficult. The best place to start is to look at any production records that you may have for the period in question. In particular you should look at any process information which might indicate changes in ingredient batch, recipe or deviations from the normal process times. If there are no suitable records available then you will need to start the investigative process by recording what you see and then work towards the likely cause of the problem. Our first observation is that there is a clear problem with the shape of the product and in particular the top, which is not uniform in appearance (Fig. 27). There are some dips in the surface which are also paler in colour than the surrounding areas. The pale colour tells us that these parts of the dough were not in contact with the lid on the pan for the whole of the baking period, otherwise they would have the same colour. What is does not tell us is whether these pale areas are formed because the dough pulled away from the pan (collapse) or whether they expanded too late to reach the lid.

Fig. 27 Loaf external appearance.

The outer edges of the loaf show that the dough had clearly filled the pan at some stage. If expansion of the dough was late in the oven then we would expect that the edges of the loaf would be the pale areas. So we can reasonably assume that the pale areas are associated with a collapsing back of the dough. The interior of the loaf shows considerable variation in cell structure with considerable compression at the base and the sides of the loaf (Fig. 28). In contrast the area in the centre towards the top is more open. This could be

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Loaf internal appearance.

because the lid was not heavy enough to cause compression under the top crust. However, we have already concluded that in places the dough was not in contact with the lid long enough to become as coloured as the rest of the crust. This internal effect is also consistent with a collapse of the dough early on in the baking process and an almost complete recovery of the shape later because of the significant gas production potential in the centre of the dough piece. Taken together these observations suggest that the problem is caused by overproof of the dough combined with a bumpy transfer between the prover and the oven. It is also likely that the oven temperature was on the low side and this in effect gave the dough piece a second short proof in the oven, which is why the piece was able to expand to mostly fill the pan. A check on production and plant operation records would be able to verify whether this was the case.

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4.17 We have noticed that loaves sometimes break only on one side of the pan but that the break is not formed consistently on one side. Can you explain why this is? The process that you are asking about is often called `oven spring' or `oven break' and is related to the ability of the dough to retain the rapid evolution of carbon dioxide gas in the first few minutes in the oven. The break forms when the pressure created by the expansion of the centre of the dough piece is sufficient to cause a break in the crust which has formed soon after baking starts. At this time the crust is still relatively soft and does not have sufficient strength to hold back the expansion forces. Because of its relation with dough gas retention, controlled oven spring is often seen as a desirable characteristic in fermented bread products. The aim is to have controlled and uniform expansion. In the case of pan breads the ideal is to have a small but uniform break along both sides of the loaf. The nature and precise location of the oven break on a loaf depends on many factors. The presence or absence of moisture in the oven atmosphere has a profound effect on the oven break. A low relative humidity tends to lead to the formation of ragged and uneven breaks, though this is usually a greater problem with oven-bottom or hearth breads (BPS, pp. 84±5), because of the lack of shielding from a pan. Raising the level of humidity in the early stages of baking through the deliberate introduction of steam is a common practical way to control oven spring with open-top pan breads. Steam may be introduced when baking lidded pan breads, though its impact may be limited by the presence of the lid. A common factor that can influence the formation and location of the oven break is the delivery of heat to the dough piece. For example, if the loaves are placed close to the side-walls of the oven, they will be exposed to greater radiant heat than other loaves more centrally placed. This causes the crust to set quickly and lose its elasticity. In some cases this may mean that the oven break is on the side nearest the oven wall, while in other cases it will occur on the opposite side of the loaf. Much depends on the total amount of heat and the rate at which it reaches the product. This will vary with different ovens and be influenced by temperature settings and air flow in the oven. It will also be influenced by the dimensions of the dough pieces, the strapping configuration of the pans and their spatial layout in the oven chamber. In order to get a uniform oven break it is very important to ensure that the dough is able to gently expand in the oven. Optimising the final proof of the dough so that it has the appropriate rheological characteristics is an important factor in achieving uniformity of expansion; as a `rule of thumb' bakers aim for the dough piece to achieve about 90% of the final bread volume in proof. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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4.18 We are making a range of crusty breads using a small bread plant. We appreciate the value of having an open cell structure to encourage the formation and retention of the crust. However, from time to time we have difficulty in achieving the desired degree of openness in the structure. Can you help us identify why this happens? You are quite right in recognising the important link between the openness of bread cell structure and the formation of a crisp crust. The openness of the final structure depends on two key factors; the ability to create large gas cells in the dough, and their retention during dough processing, proving and baking. When dough leaves the mixer, large numbers of small gas bubbles are trapped in the gluten network. Carbon dioxide from yeast fermentation inflates these small bubbles and they grow larger. Later on, during the proving and baking stages, the gas bubbles grow very large, begin to touch and coalesce (that is join together) to form even larger gas bubbles. It is these gas bubbles that eventually become the cell structure in your product. To help you appreciate the scales involved, the initial gas bubbles may range from 10±200 m in size, while the cells in the baked crumb are typically 5±15 mm; that is around 100 times larger. A key process in the gas bubble expansion is the generation of sufficient carbon dioxide gas in the processing time available. This will be affected by the yeast level you are using, and the dough and processing temperatures and times. Assuming you are not varying the time, then a likely cause of variation may well come from variations in dough temperature. You may be compensating for these by adjusting final proof times but often it is the amount of gassing that you get during the dough-processing stages (particularly between moulding stages) that makes the difference to the product structure. Some of the creation of an open cell structure occurs in the mixer as some mixers incorporate larger gas bubbles than others. After leaving the mixer it is best to divide the dough into individual pieces and limit any first moulding. If you have created larger gas bubbles then it is important to retain them during processing and this can only be done with gentle handling of the dough. If you find that you cannot achieve the openness of cell structure that you require then you may want to lengthen the first or intermediate proof time. If you do lengthen this time then you should make sure the temperature of the dough pieces does not fall and that there is no opportunity for skinning to occur. You may also need to slightly reduce your final proof time to maintain a constant dough piece size entering the oven. In summary, the key to getting a consistent cell structure in your final product is to ensure that there are minimal variations in dough temperature and to ensure that your moulding regime is preserving the larger gas bubbles. Think of the larger gas bubbles as being eggs and that the objective of dough processing is to carry them unbroken in the dough to the prover.

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4.19 We make sandwich bread for a large customer and they are concerned about the crumb characteristics of the products. What are the important ones? How do I measure these? What steps can I take to control or improve on these? In the manufacture of bread for sandwich making there are a number of important characteristics that your customer will look for. They include: · Loaf height ± whether lidded or open top, the heights of the loaves need to be consistent. The precise height will depend on the product type that you are manufacturing and the height specification and tolerances that you have agreed with your customers. · Uniformity of shape ± commonly sandwich makers want to have all breads with straight sides and a minimum of crust concavity. If the bread is lidded then there should be no dipping of the top crust. Deviations from straight sidedness can be difficult to eliminate and so you will need to agree some tolerances with your customer. · Minimal crust formation ± sandwich breads are not usually expected to have a thick or crisp crust. It is important to remember that crust extends beyond the region of the surface colour. Just underneath the crust it is common to find an area which is dry and firm eating. This is formed by the compression of expanding dough against the crust layers which are formed early on in the oven baking stage. In some cases this `inner crust' is of more concern than the outer crust because of its potential adverse impact on bread quality. · Crumb moisture ± the moisture content of bread crumb is related to softness as perceived by consumers; in general the higher the moisture content, the softer (fresher) the bread crumb will appear. Cauvain and Young (2008) noted an important relationship between crumb moisture and crust thickness and showed that an increase in crust thickness (combined outer and inner crust) could reduce the average crumb moisture content by 1%. · Crumb softness ± as noted above, this is an important property because of its relationship with consumer perception of freshness. It is significantly affected by crumb moisture content and by some recipe and process conditions. · Crumb cell structure ± commonly there is a requirement that the bread slices are completely free from major abnormalities. A common concern will be the presence of larger holes, as these have adverse impacts on the sandwich assembly operations. It is usual to have an agreed specification for your loaves and the forms of assessment that will be used to verify the product quality. Some of the most common forms of assessment are: · Moisture content ± measurement by an oven drying method (Cauvain and Young, 2008). · Shape ± this can be achieved using a simple template of the agreed slice specification (e.g., height, breadth, deviations from straight-sidedness) on which the actual slice dimensions can be recorded or a template laid over the

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slice to check their conformity. Alternatively you could use an image analysis system to take direct measurements of the slices, for example using the CCell bread slice imaging system (www.c-cell.info). · Crumb softness ± the simplest way to measure this property is by compression with the fingers. However, the sensory evaluation of softness is probably too subjective to use in a product specification and so it would be advisable to use some form of objective measurement (Cauvain and Young, 2009). You may find it helpful to measure both crumb softness and crumb resilience, as both properties are important in sandwich making; softness in terms of freshness perception and eating quality, and resilience in terms of butterability (see 9.14). Control of the key characteristics of sandwich breads will largely be achieved though good process control from recipe through to baked product. Once a product specification has been agreed with your customer the most important requirement will be for the manufacturing process to deliver as consistent a product as possible. Some of the control points which would benefit from particular attention include: · Optimising dough development because of its contribution to all important aspects of quality, especially crumb resilience. · Ensuring uniformity of the cell structure through the control of mixer headspace pressure if CBP-compatible mixers are used (Marsh and Cauvain, 2007). · Optimising dough rheology and the dough interaction with the final moulder to avoid `dough damage' and the formation of unwanted holes in the slice cross-section. · Improved crumb softness can be achieved through the careful addition of suitable enzyme additions at the recipe stage. You will need to be careful in choosing the type and level of crumb softening enzymes that you use to ensure that the bread crumb is not too soft for slicing (see 4.30). Getting the balance right between crumb softness and crumb resilience is very important. References

and YOUNG, L.S. (2008) Bakery Food Manufacture and Quality; Water Control and Effects, 2nd edn, Wiley-Blackwell, Oxford, UK. CAUVAIN, S.P. and YOUNG, L.S. (2009) The ICC Handbook of Cereals, Flour, Dough and Product Testing: Methods and Applications, DEStech Publishing, Lancaster, PA. MARSH, D. and CAUVAIN, S.P. (2007) Mixing and dough processing. In (eds S.P. Cauvain and L.S. Young) Technology of Breadmaking, 2nd edn, Springer Science + Business Media LLC, New York, NY, pp. 93±140. CAUVAIN, S.P.

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4.20 During the manufacture of bread and other fermented products we sometimes have small quantities of `left-over' dough from a mixing, can we add these back to other mixings or re-use them in other ways? With fermented products it is advisable to be cautious in using re-work. In products such as biscuits, which are cut from a sheeted dough, it is common practice to use dough left over from previous batches provided there are no product safety or quality concerns. For fermented re-work dough its storage and re-use should be carefully controlled, in terms of time and temperature, quality and quantity, so that the introduction of quality defects is avoided. For fermented products there are many factors of which to be aware. Using one type of re-work, e.g. white dough, with another type, e.g. wholemeal dough, must be avoided as such use may be considered as contamination from safety and quality viewpoints. In addition, one type of dough should only contain rework of the same type of dough as in many countries the permitted ingredients in the manufacture of a particular type of bread are limited by legislation. Storing re-work and using it at another time may result in products with quality defects such as poor and irregular cell structure, loss of volume and differences in external colour. If re-work is stored for any significant length of time, e.g. a few hours, doughs with higher temperatures may result in the development of `off-odours' or flavours in the final product. Such re-work should not be seen as a substitute for creating a `sponge and dough' product unless it has been kept under strictly controlled conditions. Re-work may be considered as an `ingredient' with specified characteristics. It should be incorporated into the mixer to ensure uniform dispersion and optimum control and should be limited to no more than 10% of flour weight for the new mix. Adding greater quantities than this can result in the re-work dough acting like a reducing agent with quality defects such as irregular cell structure and poor slice appearance. The use of re-work should be limited as much as possible in the manufacture of fermented products. Yeast activity leads to the continued evolution of carbon dioxide and the eventual depletion of sugars in the dough and loss of the crust colour-forming components in the dough. There will also be changes in the rheological properties of the gluten network in the dough which commonly contribute to loss of its gas retention ability. If fermented re-work must be used then its level of addition should be severely limited and it is important to ensure thorough mixing with the `fresh' ingredients. If using the Chorleywood Bread Process, the weight of this added re-work should be excluded when calculating the energy requirements for the mix.

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4.21 We make bread and rolls using a bulk fermentation process. Can we use ascorbic acid to improve our bread quality? Ascorbic acid (AA) is normally considered to be a reducing agent or antioxidant in the food systems but in breadmaking is commonly regarded as an `oxidising' agent. This is because in bread dough the AA reacts with oxygen from the air which is incorporated during dough mixing. The reaction in dough converts the AA to a substance known as dehydro-ascorbic acid (DHA) which acts as an oxidant and promotes the formation of disulphide bonds in the developing gluten network (Wieser, 2003). The presence of oxygen in the dough is an integral part of the oxidation process when AA is used. There is another important reaction involving oxygen in the dough and this is linked to yeast activity. During mixing and in the early stages of dough processing the yeast scavenges the oxygen molecules which are present with the result that the environment in the dough changes from being aerobic (i.e., with oxygen present) to anaerobic (i.e., without oxygen). The yeast can continue working and generating carbon dioxide in the anaerobic environment that has been created but the AA can no longer be converted to DHA. When this situation arises, the AA reverts to its usual chemical function as a reducing agent and can reduce the strength of the dough. In these circumstances there will be a loss of dough gas retention properties and in turn, a loss of bread volume. In bulk fermentation processes the environment in the dough will be anaerobic and so there is the potential for the AA to act as a reducing agent. The potential for using AA as an `improver' (that is to increase dough gas retention) depends on the length of the bulk fermentation time that you are using. If you are using short periods of time (say up to 2 h) you are likely to get some improvement in dough gas retention properties but with longer periods you are likely to see the opposite. You should avoid using AA in the sponge part of a sponge and dough process unless you need the reducing effect for some reason. In practice the levels of addition of AA for use in bulk fermentation should be low and limited to no more than 15±20 pp flour weight (0.15±0.20 g to 10 kg flour). Some millers supply flour treated with low levels of AA. You may want to check if this is the case because adding more ascorbic acid in the bakery could well create problems for your bread quality as described above. Reference

(2003) The use of redox agents. In (ed. S.P. Cauvain) Bread Making; Improving Quality, Woodhead Publishing Ltd, Cambridge, UK, pp. 424±446.

WIESER, H.

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4.22 Our total time for bread production from flour to baked loaf is set for about 6 hours. Currently we use a bulk fermentation time of 4 hours and a final proof time of 90 minutes. We find that with increased bread sales we do not have enough proving capacity. If we were to shorten the final proof time, what other changes would we have to make to maintain our current bread quality? Final proof has two important functions: one is to encourage the production of carbon dioxide gas by the yeast and the other is allow some modification of the rheological properties of the dough so that it will lose some of its elasticity. This latter change is important as it allows for a more gradual expansion of the dough in the oven and the delivery of a smooth and uniform oven bread. Bread which is `under-proved' is often characterised by a ragged or wild crust break, sometimes referred to as a `flying top' (Fig. 29).

Fig. 29

Flying top.

In view of the above comments there will be a minimum final proof time that you can use without compromising bread quality. You will need to explore the options for yourself, as this minimum time is affected by the dough temperature and final proof conditions. As a guide you could reduce your final proof time to about 60 minutes and we would suggest that (provided your have the process space available) you compensate by increasing your bulk fermentation time to about 4Ý h. This change should maintain your existing bread quality without the need for recipe changes. If you are not able to extend your bulk fermentation period then you would have to slightly increase the level of yeast that you are using to ensure that you maintain dough volume at the end of proof. You may find that with extra yeast you need to cut back your bulk fermentation time slightly.

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4.23 In breadmaking what is the difference between a sponge and a ferment and when would they be used? We have also seen references to barms, can you tell us anything about these as well? Both sponges and ferments are based on the principle of initiating yeast fermentation before the main dough mixing stage of bread making. The most significant differences between the two is the length of time for which they stand before being used and that the ferment will be of a much softer consistency. The basic recipe of a sponge comprises flour, water, salt and yeast, and after mixing, the sponge is allowed to stand for several hours before it (or a portion of it) is transferred to the mixer where the rest of the dough ingredients are added and dough preparation is completed (see example in 4.24). The ratio of water to flour in the sponge is similar to or slightly less than that used in a standard dough. The yeast level in the sponge is usually low as it will be fermenting for many hours, commonly 10±20. During the fermentation period the sponge will develop a distinctive acid flavour profile, which will be carried through to the final product. The sponge also contributes to the development of the final dough. After final dough mixing the bulk dough is usually divided immediately for further processing. A ferment is used in the `short ferment and dough bread making method'; this is now a less common process than the sponge and dough. Typically the ferment will contain flour and water in at least equal parts, all of the yeast but no salt. These ingredients are normally whisked together and allowed to stand for a short period of time, typically 20 minutes or so, before being mixed with the other ingredients. After final dough mixing it is common to leave the dough in bulk for a short period before dividing it into unit pieces for further processing. Barms are not often seen in use these days, if at all. They were based on the use of distillers' yeast from the maltings and were often seen in use in some bakeries on the west of Scotland. The formulae and methods used were complicated and relied on the preservation of a portion of barm for use in subsequent batches. The process started with malt and water being mashed together for several hours. A liquor was pressed from the mixture, flour stirred in and boiling water added to gelatinise the flour. The `scald', as it was called, gradually cooled over 24 hours and a portion of old barm from a previously prepared batch added. This mixture was then fermented for 3±4 days before baking. Barms were normally prepared twice a week.

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4.24 How would we prepare and use a sponge with the Chorleywood Bread Process? The preparation and use of a sponge with the Chorleywood Bread Process (CBP) is not difficult. The common use of a sponge is with no-time dough processes (i.e., the dough moves from completion of mixing to the divider without delay). The only special facilities that you will need would be the provision of space for storing the sponges. In order to get consistent results you should store the sponges under temperature-controlled conditions and cover them to prevent dehydration and the formation of a skin on the surface. It will be important to use the sponges in strict rotation. Ideally you would make one sponge for each dough and that is the basis of the recipe given below. In practice this may be difficult because of space conditions and so you may have to make a larger sponge and use portions for several successive doughs. If that is the case we suggest that the sponge should not be used for more than 20±30 minutes of dough making to minimise the risks of quality variations. In principle these precautions are no different to using a sponge with any other sponge and doughtype process. There is no need to fully develop the sponge so you may use another mixer for its preparation. You can use your CBP-type mixer for the sponge preparation but you need only mix for a short period of time; this will be helpful in controlling the sponge temperature (see below). The level of sponge that you prepare depends on the how much you wish to change the crumb flavour; the larger the quantity of sponge used, the stronger the flavour profile. We suggest that you try a quarter sponge; that is, using one quarter of the total flour weight to prepare the sponge as follows. Sponge recipe and method Ingredient Flour Water Yeast Salt

Weight (kg) 12.50 7.00 0.10 1.25

Mix to clear dough with a final temperature of 20ëC and ferment for 16 h. Dough making Add the sponge to the rest of the ingredients in the mixer, i.e. of the flour with appropriate water, salt, improver and yeast (the latter may be reduced by about 5±6% of its original level). Do not include the quantity of sponge in your energy calculation. Further reading

and YOUNG, L.S. (2006) The Chorleywood Bread Process, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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4.25 Our bread and buns prove to a satisfactory height in about 50 minutes but we get no additional lift from the products in the oven. We have tried increasing their strength and using more improver but whatever we do we see no oven spring. Do you have any ideas as to why we are getting no oven lift? There are two processes that contribute to oven spring: gas production and gas retention. By increasing the strength of the flour that you are using you should have improved the gas retention properties of your dough and the fact that there was no improvement in oven spring strongly suggests that the problem is with the gas production capabilities of the dough. Initially gas production in the dough relies on the ability of the yeast to ferment the sugars that are present in the wheat flour to produce carbon dioxide and alcohol (BPS, p. 65). If there are added sugars the yeast may use these; first the mono-saccharides (simple sugars) and later the di-saccharides. There is also some maltose sugar being produced as the amylase enzymes in the dough begin to break down the damaged wheat starch. The metabolic processes of yeast in bread dough are complex and are regulated by the osmotic pressure across the walls of the yeast cell. In part this osmotic pressure is affected by the nature and concentration of soluble ingredients in the recipe. In addition to the sugars already mentioned, soluble ingredients in the dough, which have an effect on yeast activity, include salt and preservatives such as calcium propionate. One of the complexities of the metabolic processes of yeast is that the cells adjust their metabolism according to the food sources that are available in the dough. However, the transition from one food source to another is not a straightforward relationship and at different times the metabolic processes in the yeast slow down and gas production falls. After the yeast has made the adjustment, gas production will again increase. From the description of your problem it appears that the yeast strain that you are using is making one of these transitions as the dough begins to reach the oven and so is not able to provide the last burst of carbon dioxide gas which normally contributes to oven spring. Different strains of bakers' yeast have different tolerances to sugar (osmotolerance) and calcium propionate. They produce carbon dioxide gas at different rates from other yeast strains in the dough and so may be more suitable for your bread and bun production. You will need to consult with your yeast supplier to find the most suitable strain of yeast for your particular recipe and processing conditions; once you have the most appropriate strain of yeast, we are sure that oven spring will be restored.

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4.26 What is the purpose of `knocking-back' the dough when using a bulk fermentation process to make bread? In bulk fermentation bread-making processes the dough is left to ferment in a suitable environment for a period of time, often many hours. During this fermentation period the volume of the dough will increase greatly as the yeast produces carbon dioxide gas which is largely retained in the dough; approximately 70% of the dough volume at the end of 2 or 3 hours of fermentation is gas. Knocking-back the dough is an operation commonly performed part-way through the prescribed fermentation, typically after half and usually before three-quarters of the prescribed period. However, some more traditional recommendations (Bennion and Stewart, 1930) are that knocking back should be carried out in the early stages of bulk fermentation. In small-scale production the operation may well be carried out by hand and this practice has given rise to an alternative description of the process ± `punching' the dough. With larger bulk doughs there is no reason why the process cannot be carried out with a mixing machine, though the mixing time will usually be very short, commonly only a matter of a couple of minutes on slow speed. A number of different reasons are given for carrying out a knock-back and it very likely that they all have some validity. They include the following: · To even-out temperature variations in the bulk of the dough ± there is no doubt that when a bulk dough stands for long periods of time, the surface of the dough will cool, in part as the result of surface evaporation. · To reduce the risk of the dough skinning from surface evaporation, though excessive skinning of the dough can lead to significant product quality problems. · To re-invigorate the yeast by eliminating `waste' products ± in this case the waste product is alcohol, high levels of which can have an inhibitory effect on yeast activity. One potential benefit of knocking back the dough not commonly discussed is the contribution that the energy of mixing makes to dough development. During fermentation the gluten network becomes stretched as the dough expands and remixing (since this is really what the knock-back is) transfers some energy to the dough (even by hand) and encourages the formation of a stronger gluten network, that is one capable of retaining more carbon dioxide gas during proving and baking. It is interesting to note that Bennion and Stewart (1930) recommend that `a bun dough should be knocked back every 20 minutes if a bun of good bulk [volume] and silk-like texture is required'. Reference

and STEWART, J. (1930) Cake Manufacture and Small Goods Production, Leonard Hill Limited, London, UK.

BENNION, E.B.

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4.27 We have two bread lines running side-by-side, with the same equipment bought at different times. We are using the Chorleywood Bread Process (CBP) and do not quite get the same volume and cell structure when making the same pan bread product. We compensate by adjusting yeast and improver level but do not get the same crumb cell structure. Can you help us understand what is happening? The operation of the CBP is almost unique in that the crumb structure can be manipulated by adjusting the mixer headspace pressure to create different structures (Cauvain and Young, 2006). In your case you are seeking a fine and uniform cell structure in your sandwich bread products and it is with these products in particular that you are noticing a difference. With both plants you are applying a partial vacuum, the application of which is delayed until part way through the mixing to encourage the initial oxidation of the dough by ascorbic acid. The same types of mixers were purchased at separate times. Initially you did not use one of them with partial vacuum even though the mixer had the capability. Close inspection of the equipment revealed that the two pressure gauges that were fitted to the mixer were of different types so that when they were regulated to the same dial setting they were in fact delivering different pressures in the mixing chamber. One dial reads down from 0 to 3000 of vacuum and the other reads up from 0 to 3000 of pressure. You have been setting both mixers at 2000 . These are old readings and it will be easier if we convert them to more modern units ± bars; in essence atmospheric pressure is 1 bar. In the case of the dial reading `vacuum', your setting is actually around 0.33 bar, while with the dial reading `pressure' it is around 0.67 bar. At 0.33 bar we would expect you to lose oxidation and have potential problems with coarseness of crumb cell structure (BPS, pp. 94±5). If you adjust the `vacuum' dial to 1000 (0.67 bar) you should more closely match bread quality. Authors' note: There can be confusion over pressure units when talking about partial vacuum because of the common use of atmospheric pressure as a standard. One bar is defined as 105 N mÿ2 (nearly equal to 1 atmosphere, i.e. 760 mm or 3000 mercury). Atmospheric pressures do vary with environmental conditions and height above sea level. The above problem was for a bakery at sea level. References

and YOUNG, L.S. (2001) Baking Problem Solved, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2006) The Chorleywood Bread Process, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P.

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4.28 We are experiencing a problem with loaves baked in rack ovens since we bought new pans. As the enclosed photograph shows, they are joining together above the pans. The portions of the loaves that touch have no crust formation, which makes them weak when they are de-panned and handled. How can we prevent this from happening? In the photograph it is clear that the dough has risen well during the early stages of baking and loaves in adjacent pans in the strap have touched (Fig. 30). Consequently these parts of the loaf did not form a solid crust and had a pale, underbaked patch on the side. On the ends of the strap where the dough has overflowed slightly a normal crust was formed.

Fig. 30 Touching loaf from new straps.

You indicated that you changed to new pans recently and now have four small pans across the rack width where you had three previously. If bread pans are strapped too closely together, then with a well-developed dough this `kissing' of adjacent loaves will occur. This is because the hot air in the oven cannot easily penetrate between the strap, and in effect you are prolonging the final proof of the dough, albeit in the oven. As general guidance, the gap between pans of a strap should be between 22 and 34 mm to allow adequate air circulation between straps in the oven. If the scaled weight of the dough piece deposited in the pans is too heavy then this may be a contributor to the problem. The scaling weights should be checked for consistency. With the current deregulation of bread weights in the UK it may be possible to reduce the scaling weight provided the finished baked weight is within specification for the product. Another option may be to reduce the gas retention properties of the dough a little (e.g., by using a slightly weaker flour or slightly less improver) provided the reductions do not compromise product quality (cell structure and softness). It may also be possible to use less yeast in the recipe provided the time to reach proof height is not too long and that oven spring is still evident in the baked loaf.

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4.29 We wish to create a bolder shape and more open cell structure with our crusty sticks and have recently increased our dough development by mixing longer. Now we experience problems with the products joining together in the oven. If we under-prove the dough pieces, we have problems with ragged bread and poor shapes. Should we reduce our mixing time back to its original level? This problem has similarities with that in 4.28. Our first response is that you should not seek to solve you problem by under-proving the dough pieces, indeed you own information suggests that this will only lead to unacceptable product quality. We do not recommend that you go back to your old mixer settings as this will only result in a loss of gas retention in the dough because it will be less well developed. This will not help you achieve the volume, boldness of shape and openness of cell structure that you are seeking in the final product. You have been scaling the dough pieces to give you a 400 g baked weight in the product but the indented trays that you are using were designed for a lower dough piece weight, which would deliver a baked stick weight of 300 g or slightly less. Now that you have improved the gas retention properties of the dough, the extra expansion that you get in the early stages of baking means that the cross-section of the stick is too large for the indent on the tray, the pieces are not supported at their sides and so flow over the edges to touch one another. You do not want to reduce your scaling weight to deliver a baked stick weight of 300g or less. This leaves you with two possibilities: one is to only bake 3 sticks per tray by placing dough pieces in alternate indents. This will reduce your overall baking capacity and you may need to reduce your batch size accordingly. The other solution would be to seek a new tray design with only 4 indents instead of 5 while retaining the tray width (Fig. 31). If you are going to use this solution then we also suggest that you seek a slightly deeper profile for the indents so that you can be sure of retaining a bold shape to your product.

Fig. 31

Alternative crusty stick trays.

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4.30 We are finding that the crumb of our bread is too soft for slicing. We also notice a tendency for the sides of the loaves to slightly collapse inwards. We do not think that conditions in our cooler have changed, can you please advise us on what to investigate? When bread leaves the oven the crust is firm but the crumb is still relatively soft. In the initial stages of cooling the crumb begins to firm as the amylose fraction of the wheat starch begins to retrograde (re-crystallise). The longer-term firming effect associated with bread staling is related to the retrogradation of the amylopectin fraction on the starch (Pateras, 2007). It is the initial increase in firmness because of the amylose retrogradation that allows bread to be sliced mechanically. The length of time that the bread spends in the cooler is usually linked with centre loaf temperature at which the bread can be sliced. Typical centre loaf temperatures for bread slicing are in the order 27±30ëC. Of course the ability to slice a loaf mechanically is also linked with the crumb moisture content and the lower the moisture content of the crumb, the easier it will be to slice. However, bread softness is reduced when the crumb moisture content is lower and so it is common practice to limit moisture losses as much as possible during cooling. The sides of loaves sometimes pull inwards if there has been excessive loss of water from the loaf during cooling. A number of ingredients that are used in the recipe also play a role in determining the initial crumb softness. For example, the addition of fat is said to improve crumb softness, though with the low fat levels used in many breads, this effect is most likely to be associated with the accompanying improvement in bread volume. The addition of anti-staling agents can have an impact on the initial crumb softness in addition to the longer-term anti-staling effects. In this context the addition of modified bacterial amylases has become popular in many bread types and high levels of addition have been associated with excessively soft crumb at slicing. The slight collapse inwards of the loaf sides also suggests that the level of enzyme addition is too high in your recipe. Check that the flour Falling Number is not too low and talk with your supplier about making a small reduction in the level enzyme addition in your improver. Reference

(2007) Bread spoilage and staling. In (eds S.P. Cauvain and L.S. Young) Technology of Breadmaking 2nd edn, Springer Science + Business Media, LLC, New York, NY, pp. 275±298.

PATERAS, I.M.C.

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4.31 We have spiral and twin-arm type mixers and would like to produce a finer cell structure with our sandwich breads. Can you suggest ways in which we might achieve this aim? Much of the final structure of bread is delivered by the mixer and its mixing action. During the mixing process small air bubbles are trapped in the developing gluten network. The numbers and sizes of those air bubbles are mostly determined by the mixing action with some input from ingredients like fat and emulsifiers (which tend to reduce the average size of the air bubbles). The mixing bowls of spiral and twin-arm type mixers are usually open to the atmosphere and so there is no opportunity to adjust the initial gas bubble population in the dough by changing pressures as is the case in the Chorleywood Bread Process (Cauvain and Young, 2006). During and immediately after dough mixing there is a gradual change in the composition of the gases in the bubbles trapped in the dough. Initially the bubbles contain a mixture of nitrogen and oxygen but the latter is scavenged by the added yeast. As the yeast begins to produce carbon dioxide, the gas diffuses into the nitrogen gas bubbles, and expansion of the dough begins. The expansion processes in the dough are complex and are related to the initial gas bubble size but, in summary, what happens is that the larger gas bubbles tend to expand to a proportionally greater extent than the small ones. As the gas bubbles continue to expand in proof and baking, they grow large enough to coalesce (join together) and it is these gas bubbles that form the basis of the cell structure in the loaf. The mixers that you are using tend to deliver an initially wide range of gas bubble sizes, which ultimately becomes a wide range of cell sizes in the loaf, so that the cell structure tends to be considered `coarse'. There is little that you can do in the mixer to change the situation, so any improvements will have to be introduced during dough processing. One way of producing a finer cell structure is to `de-gas' the dough. In essence what you seek to do is eliminate the larger gas bubbles while retaining the smaller ones. The de-gassing processes deliver a more uniform gas bubble population which will expand more uniformly during proof and deliver a more uniform (and usually finer) cell structure. The easiest way to de-gas the dough is to allow it to have a short period of fermentation in bulk (e.g., 1 hour) and to deg-gas portions of the dough by passing them backward and forth a few times through a pastry brake, this will eliminate the larger gas bubbles. After sheeting allow a short period for the dough to recover and then divide into units and process the dough as before. The short period of rest after sheeting and before dividing is to allow the dough to recover its extensibility and avoid structural damage in the subsequent moulding. Reference

and YOUNG, L.S. (2006) The Chorleywood Bread Process, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

5 Cakes

5.1

What characteristics should we specify for cake flour?

In cake making the main structural building block is the wheat starch rather than the protein, and this means that when it comes to specifying the flour, many of the protein-based measurements have limited relevance. Enzymic activity is limited in cake batters, in part by the low water activity because of the sugar content and this also has an impact on the list of properties which need specifying. In general, cake flours are derived from soft milling wheats and tend to have low protein content. Traditionally this would have been set up in an attempt to limit gluten formation in the batter. Although such thinking has little relevance today, it remains the case that cake flours are specified with low protein contents. The exception is flour intended for the manufacture of fruit cakes where the presence of extra protein contributes to the suspension of the fruit and other particulate materials in the batter and baked product. Cake flours that are intended for use in high ratio cake making are usually treated in some way. High ratio cake recipes are characterised by having sugar and liquid levels which are individually and collectively higher than the weight of flour. Two forms of treatment are used, both of which modify the gelatinisation properties of the starch in the flour, though by quite different means. One form of treatment is with chlorine gas (BPS, pp. 32±3) but the use of chlorination has become increasingly restricted around the world. Dry heat treatment (BPS, pp. 30±1) has replaced chlorination in many countries. The level of chlorination or heat treatment applied in the manufacture of cake flour may vary according to the potential use of the flour. For example, high protein flours intended for the production of fruited cakes may receive greater treatment than

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those intended for sponge or bar cake production. Another key property for high ratio cake flours is the reduction of the particle size of the flour (BPS, pp. 28±9) either by re-grinding or air classification, or a combination of both milling techniques. Unlike many bread flours it is not usual to add technologically functional ingredients to cake flours. Statutory or voluntary nutritional additions may be made. You will only need to specify a limited number of characteristics for cake flours. Typically they would be: Flour characteristic Moisture (%) Protein content (% as is) Particle size (m) Treatment

Low ratio cake flour

High ratio cake flour

14 8±10 (up 12 for fruit cake) Up to 150 None

14 7±10 (up to 12 for fruit cake) <90 Chlorination or dry heat

Traditionally some cake flour supplies contained raising agents to provide carbon dioxide during baking. They are referred to as `self-raising' flours and most often encountered for the home-baking market. The base flour tends to meet the specification for low ratio cake flour. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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5.2 We are experiencing some variation in cake quality, especially volume. How important is it to control the temperature of our cake batters? Almost all of the processes that are critical to successful cake quality are initiated in the mixing stages, so to maintain consistent batter and final cake qualities it is important to maintain a standard batter temperature. Variations in cake batter temperatures will have significant impact on the following processes: · The rate at which the soluble ingredients, mainly the sugars, will dissolve; the lower the batter temperature the longer it will take for the sugars to dissolve. This can have a profound impact when using coarser grained sugars such as the granulated form and can contribute to the formation of white spots or speckles on the baked cake (BPS, p. 167). · The rate at which the starch in the flour will hydrate; the lower the batter temperature, the slower the starch will hydrate. · The creaming and aeration properties of the fat; in general the lower the batter temperatures, the poorer the creaming properties of the fat in the sugarbatter method of cake making (BPS, p. 150) and the lower the likely aeration of the batter with all cake-making methods. In the latter case the baked cakes may lack volume and have poor eating qualities. However, the precise impact of temperature on fat performance depends on the solid fat index profile, which is determined by the mixture of oils which make up the fat (BPS, pp. 38±40). · The functions of emulsifiers used to aid batter aeration will be affected. · The rate at which the baking powder components will react. All chemical reactions proceed more slowly when the temperature falls or proceed more rapidly when the temperature rises. Of all of the potential impacts of variations in cake batter temperature the impact on baking powder reactions is perhaps the most important one. Variations in the rate of release of carbon dioxide from the baking powder reaction have direct impacts on cake shape, volume and structure. · The control of batter deposit weight will be more difficult to achieve because of variations in batter density linked with fat and emulsifier performance and baking powder reaction rates from batch to batch. In summary, you can expect that variations in the temperature of the batter that you produce will be associated with variations in cake shape, volume, appearance and structure. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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5.3 How do we calculate the likely temperature of our cake batter at the end of mixing and what temperature should we aim for? The prediction of the batter temperature at the end of mixing is relatively straightforward because the main inputs to the calculation come from the temperatures of the ingredients. Cake and other batters, have a relatively low viscosity and their low resistance to mixing means that relatively little heat is generated in the mixing process. There may some influence from the ambient temperature and equipment temperatures but this is usually confined to times when there are extremes of temperature, e.g. on cold start-up. To calculate the likely cake batter temperature you need only prepare a simple table of the ingredient contributions and calculate the weighted average. Because of the high level of water present in various forms in the formulation, it is less important to take into account the specific heat capacity of the various ingredients than would be the case with bread dough. The following example will help to illustrate the process. Ingredient Flour Fat Baking powder Sugar Liquid egg Water Total

Mass (kg)

Temperature (ëC)

Mass  temperature

100 50 2 110 30 75 367

25 20 25 25 4 15

2500 1000 50 2750 120 1125 7545

Batter temperature ˆ sum (mass  temperature)/total mass ˆ 7545/367 ˆ 20.6ëC. If you want to achieve a consistent batter temperature and want to compensate for variations in ingredient temperature, then we suggest that you adjust the water temperature. This simply means substituting the temperature of the water in the above table with an unknown, say T and then use the following calculation. The required final batter temperature is 20ëC. Thus, 367  20 ˆ 6420 + (75  T) where 6420 is the sum (mass  temperature) of ingredients without the water contribution Rearranged this gives T ˆ

…367  20† ÿ 6420 75

and so T, the required water temperature ˆ 12.3ëC.

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We would recommend that the final cake batter temperature be in the region of 18±24ëC. Low batter temperatures may lead to curdling (separation) of the batter (BPS, p. 165), impaired performance of the fat and unduly delayed release of carbon dioxide from the baking powder (see 5.2). All flours exhibit a phenomenon known as `heat of hydration' (Wheelock and Lancaster, 1970); that is when flour and water are mixed together, there is an increase in the temperature of the mix beyond the contribution of the individual ingredients. The drier the flour, the greater will be the heat of hydration. Many heat-treated flours have moisture contents significantly below 14% and this means that the heat of hydration can be significant. The heat of hydration can be calculated according to the formula provided by Wheelock and Lancaster and should be deducted from the target batter temperature before undertaking the appropriate calculations (see 5.2). In practice the effects are relatively small and seldom account for an increase in batter temperature of more than 1±2ëC. However, even such relatively small increases can have an effect on the rate of reaction of the baking powder and should be taken into account in order to minimise the impact on final product quality (Cauvain and Young, 2008). References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2008) Bakery Food Manufacture & Quality; Water Control and Effects, Wiley-Blackwell, Oxford, UK. WHEELOCK, T.D. and LANCASTER, E.B. (1970) Thermal properties of wheat flour, Starke, 22, 44±48. CAUVAIN, S.P.

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5.4 What do the terms high- and low-ratio mean when they are applied to cake-making recipes? In the construction of cake recipes it is traditional to use the flour as a base on which to determine the levels of the other ingredients being used. These are the so-called `rules' of cake recipe balance; originally developed empirically, they continue to have relevance in developing many types of cake recipe. This is because the rules have been linked with different aspects of product quality and collectively they provide a sound framework for optimising cake quality and remedying quality defects. The classical construction of cake recipes is based on the functionality of the individual ingredients and their contribution to the development of a cake structure. In this respect a key role is played by the level of sugar in the recipe, since this ingredient has a significant effect on the gelatinisation characteristics of the starch in the wheat flour. As starch is the main building block of the cake structure any changes to its gelatinisation characteristics will have a significant effect on cake quality. The addition of sugar in a cake recipe raises the gelatinisation temperature of the starch and so delays the `setting' point of the cake structure (the foam to sponge conversion). The other key ingredient in controlling the gelatinisation characteristics of starch is water. The level of water in the recipe is important for dissolving the sugar and providing moisture for the starch granules to hydrate, swell and ultimately gelatinise. Empirical work has shown that a sucrose concentration of around 0.5 delivers acceptable cake quality (Cauvain and Young, 2008) so this means that there is a direct relationship between the sugar and water levels used in a cake recipe. The terms low- and high-ratio are used to define the recipe types used in cake making. Low-ratio implies that the level of sugar and water (sometimes this is referred to as `liquid', which is the sum of ingredients such as egg or milk but only the water component of these ingredients, should be considered) in the recipe are individually lower than the level of flour; while high-ratio implies that they are individually greater than the flour weight. In order for the flour to be able to support a higher level of sugar and liquid, it is necessary for it to have been treated in some way; such treatment may be with chlorine gas (now less common; BPS, pp. 32±3) or with dry heat treatment (BPS, pp. 30±1). Also there is a tendency for high-ratio recipes to use fat in which an emulsifier has been added to aid batter aeration and stability. The external characteristics of high- and low-ratio cakes appear very similar and internally the high-ratio product tends to have a finer and more uniform texture (Fig. 32). However, when it comes to assessing the crumb characteristics of the two products, the high-ratio cake products exhibit softer and more tender eating properties. In part this comes from the higher moisture level, which usually remains in the baked high-ratio products, typically this will be in the order of 3±6% higher (Cauvain and Young, 2006).

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The key characteristics of low- and high-ratio recipes may be summarised as follows: Ingredient

Low-ratio

High-ratio

Flour treatment

None

Dry heat (or chlorine gas)

Sugar

Equal to or less than the flour weight

Greater than the flour weight

Water (from all sources) Equal to or less than the flour weight

Greater than the flour weight

Fat type

Fat with emulsifier

No special form

Fig. 32 Comparison of left, high- and right, low-ratio cakes.

References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2006) Baked Products; Science, Technology and Practice, Blackwell Publishing, Oxford, UK. CAUVAIN, S.P. and YOUNG, L.S. (2008) Bakery Food Manufacture and Quality: Water Control & Effects, 2nd edn, Wiley-Blackwell, Oxford, UK. CAUVAIN, S.P.

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5.5 We are looking to re-balance our cake recipes and have a set of rules that we work with. However, it would help us if you could explain the principles behind such rules of recipe balance as applied to cake making? The rules that you refer to have been developed empirically by bakers and verified by test baking. When first introduced they applied to non-treated cake flours and, although the values that are used to define the boundaries of acceptable ingredient levels have changed when using heat-treated or chlorinated flours, the principles remain sound today. As flour is the main structure contributor in cake making (mainly the wheat starch), recipes are usually constructed by defining ingredient additions with respect to flour; this explains why in many published recipes ingredient levels are quoted as percentage flour weight. The advantage of this approach is that rebalancing a given recipe is easier to understand in terms of an ingredient's functionality. It is possible to consider the rules of cake making on a percentage of total mix. The ratio of sugar to flour is the first rule that is considered and this is commonly defined on the basis of whether the recipe is `low' or `high' ratio (see 5.4). The egg and fats levels are usually balanced against one another. This rule is related to the impact of these two ingredients on the eating qualities of the final products; egg protein imparts a firming/toughening effect on the eating quality, while fat delivers tenderness. Once the level of egg has been decided, it is necessary to choose the final liquid level in the recipe. This should be balanced with the sugar level to deliver a suitable sucrose concentration in the batter (see 5.4). The liquids should include the egg, milk (if used as liquid milk) and water. You will need to be sure that you have identified all sources of water. While you can work with the liquids in their added form, you may find it more useful to separate out the water from egg and milk when doing your calculations. Some traditional rules set the baking powder level according to the egg:flour relationship on the basis that egg protein delivers part of the aeration required in cake batters. You should view any rule set with caution as they tend to apply to a restricted set of cake types. Many of the rule sets were developed for `Madeira' or loafstyle cakes and do not necessarily apply to the more highly aerated sponges. Also the nature of baking ingredients has changed and this has resulted in the adaptation of the traditional rule sets and changed the boundaries of the acceptable ingredient levels. The value of such `rules of thumb' is that they are founded on a significant knowledge base and at the very least, identify the role of the different cakemaking ingredients in forming the basic structure of modern cakes.

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5.6 We have been making cake muffins and find that when we cut them open they have large vertical holes in the crumb. Why is this and how do we eliminate them? The holes that you have seen are often referred to as `tunnel holes' and run vertically from the base of the muffin towards the peak top. As heat begins to penetrate into the muffin batter, the starch gel swells and begins to gelatinise. At this time there is a significant increase in batter viscosity in the outer areas of the deposit. Above these areas of high viscosity the batter is still relatively fluid and can expand upwards eventually bursting though the top crust and causing the muffin to form a peaked shape. The expansion comes from the evolution of steam and the generation of carbon dioxide from the reaction of the baking powder components and their thermal expansion. It appears that the tunnel holes first form in areas of the batter where the batter is close to gelatinising, and coalescence of the previous small gas bubbles is beginning to occur. These larger bubbles become buoyant and try to rise towards the surface of the muffin. The pressure in these large gas bubbles forces the batter apart as it starts to set and initiates the formation of the base of the tunnel hole. The portions of batter which have still to set offer less resistance to the expanding gases and they travel upwards forming the tunnel holes but as the heat continues to penetrate, they become trapped in the setting crumb (see Fig. 33).

Fig. 33 Tunnel holes in cake muffins.

Since batter viscosity and gelatinisation are important in determining the development of the tunnel holes, you could eliminate them by changing your recipe, particularly by re-balancing your sugar to water ratio with an increase in the level of water. However, these types of holes have become so characteristic of muffins that eliminating them may affect consumers' perceptions of your product quality, so proceed with caution. If you are going to re-balance your formula, you may prefer to call the product by another name.

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5.7 Why do some of our cake muffins lean to one side during baking? Because of the combination of recipe, deposit weights and pan dimensions, cake muffins tend to form a large bulbous head which slightly overflows the sides of the supporting pan. Usually the bulbous head is located more or less symmetrically and centrally on the product. The last portion of the batter to set during baking is about two-thirds of the way up the vertical height in the pan. The expansion of this portion of the batter provides sufficient force to encourage the formation of the bulbous head and break on the top crust. The control of heat input in ovens is a key element in the delivery of a uniform shape with cake products. All baked products receive heat at their surfaces, which is transmitted through to their centres. The rate of heat transfer depends on many factors related to dough or batter density, dimensions and oven conditions. Cake batters are less viscous than bread or cookie doughs and, as heat is slowly being conducted to the product centre, it is possible for convection currents to form in the batter before it sets. The magnitude of the convection currents depends on many factors; including flour treatment (Cauvain and Young, 2006) and the dimensions of the cake. Convection currents are more likely to occur in products which are relatively thick by comparison with their surface areas (e.g., loaf and slab cakes). When products are baking in the oven it is important that there is sufficient air movement around them to help with the uniform transfer of heat. If the gaps between products or pans are too narrow then the heat flow can be reduced and the crust of the product will take longer to form on that part of the product. In such cases the expanding batter will tend to move in the direction where the crust is weakest and yield a product which leans (Fig. 34). We suggest that you look closely at the spacing of your cake pans on your trays and the way in which they are placed in the oven.

Fig. 34

Reference

Leaning cake muffins.

and YOUNG, L.S. (2006) Baked Products: Science, Technology and Practice, Blackwell Publishing, Oxford, UK.

CAUVAIN, S.P.

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5.8 We have been making a range of different cake sizes using the same plain batter and get varying quality results in terms of their shape and appearance despite having adjusted the baking conditions. Do you have any advice? Traditionally bakers would change two aspects of their production if they used the same batter for different size products. One of these would be to change the baking conditions, which is what you have done. Heat can only reach the centre of the batter for each unit by being absorbed at the surface and then transferred to the centre (see also 5.7). In cake shapes that have a small surface area relative to their depth or thickness, the oven baking conditions are adjusted to allow the rate of heat penetration to be compatible with the various changes that occur in cake baking. As the batter is heated in the oven carbon dioxide gas from the baking powder present in the formulation is released. It is common practice to adjust the level of baking powder according to the cake type. The bakers `rule of thumb' is that the level of baking powder is higher for small cake units and lower for large cake units. Too much or too little baking powder for a given product recipe can have an adverse impact on cake shape (see 5.14). As a matter of interest, we took three recipes for three common cake products ± slab, loaf shape and cup cake ± and calculated the ratio of surface area (SA) to the thickness (T) of the batter deposit in the pan. Using this ratio we then plotted it against the traditional level of baking powder in the recipe with the results shown in Figure 35. The straight line should only be seen as a guide to one principle that should be employed in adjusting baking powder levels in cake recipes rather being indicative of an `absolute' relationship.

Fig. 35 Relationship between cake type and level of baking powder.

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5.9 We would like to change the physical dimensions of some our cake products to make different sizes and shapes. Do you have any advice that you can give us as to how to adjust the batter deposit weights for the different pan sizes? There is no simple formula that allows you to calculate batter deposit weights for different dimensions of pan. At first sight this may seem strange but in fact there is a perfectly reasonable explanation and it is related to the transfer of heat into the product during baking. In the oven, heat is absorbed by the surface of the batter before being conducted from the surface to the centre of the product. The rate at which the heat reaches the centre depends in part on the distance from the batter surface to the centre; in general terms the greater the distance from surface to centre, the longer it will take for the heat to travel the distance (for a given set of baking conditions). However, as cake batters have a low viscosity by comparison with most other unbaked products (e.g., dough and paste), there is potential for convection currents to be set up in the batter in the early stages of baking (Cauvain and Young, 2006). The potential for such convection currents is greatest in products in which the surface area is small relative to the depth (thickness) of the deposit. For cakes, the practical implication of the different rates of heat transfer are that the key changes in conversion from batter to cake, such as the generation of carbon dioxide from the baking powder and the transitions from foam to sponge, play a major role in determining the final structure of the baked product. Change the heat transfer rate and you can end up compromising key product characteristics. Bakers have learnt to compensate for these effects by adjusting baking conditions when changing product dimensions. The following table using the same batter formulation (except for level of baking powder ± see 5.8) illustrates the principles that we have described above and may help you in making your decision on scaling weights.

Pan shape Rectangular Rectangular Rectangular Square Round Round

Reference

Length/ diameter Breadth Depth (cm) (cm) (cm) 15 45 45 15 13 20

8.5 75 75 15

8 2.5 5 5 3 2.5

Pan Deposit Baking volume weight temperature (g) (ëC) (cm3) 1020.0 8437.5 16875.0 1125.0 398.2 785.5

300 3500 8500 370 250 320

185 205 190 190 190 200

and YOUNG, L.S. (2006) Baked Products: Science, Technology and Practice, Blackwell Publishing, Oxford, UK.

CAUVAIN, S.P.

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5.10 Currently we add alcohol, in the form of spirits or liqueurs, to our celebration cakes after they have been baked and cooled. We leave them for a few days after treating them but this is taking up a lot of space. What advantages/ disadvantages would there be if we added the alcohol to the batter before baking? The boiling point of alcohol is around 78ëC and so, as you might expect, a proportion of any alcohol added before baking will be evaporated during the baking process. There are few estimates as to how much of the alcohol added to a cake batter is lost during baking and they vary from 50±90%. There is a suggestion that the losses are lower with heavily fruited cakes of the type that you are making and greater with lightly fruited or plain cakes. It appears from the few data available that the traditional method of soaking the fruit in spirit before mixing and baking has no impact on reducing the losses. We might assume that the benefits of soaking in alcohol before baking are similar to those obtained by soaking the fruit in water; namely a reduction in the moisture migration from the cake crumb to the fruit so that the former stays more moist eating. The decision on whether to add them before or after baking depends on why you are adding the spirits or liqueur to your cakes. If you are using the spirits or liqueur as part of the description of the product, then you must be sure that you are following the appropriate guidelines and legal requirements. The position regarding alcohol as an `ingredient' is complicated and so you should seek local advice on what is permitted and what is not. On the one hand, you may be required to have sufficient spirit to `characterise' the product, while on the other hand, there may be restrictions as to whether the premises from which the products may be sold should have a licence to sell alcohol. Not all of the spirit or liqueur is alcohol, there are many other components which go to characterise this type of product. Many of these components have distinctive flavours and they are likely to be retained in the product, even if the spirit is added before baking. The anti-mould properties arising from the use of alcohol are well appreciated (see 3.8) and this is clearly a significant advantage if the spirits are added after baking, since losses from evaporation during storage will be relatively small. On balance it would appear that the greatest benefits to be gained from adding spirits or liqueurs to celebration cakes will come from adding them after baking rather than adding them to the mix. If nothing else the levels of addition will be lower, since you will not have to compensate for evaporative losses.

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5.11 We are baking Genoa-type fruit cakes using sultanas and find that while the centre of the crumb is a nice golden yellow, around three sides of the cut face of the cake (the bottom and the two sides) the colour is much browner and darker. Can you help us identify the cause of this problem? This type of discoloration is usually associated with the Maillard-type reactions which take place in baking (BPS, p. 98). These are the ones that give the brown colours of the crust. They are complicated reactions influenced by a number of different factors (Arnoldi, 2004) which involve sugars and proteins. You should look first at your baking conditions. Low baking temperatures and long baking times tend to increase the risk of caramelisation of sugars, especially in large cake units like slab cakes. You might also want to look at the distribution of heat in the oven, since the problem is exacerbated by having too much bottom heat. Some sources of sugars are more likely to cause browning of this type in cakes. Your problem will be exacerbated if you have sources of reducing sugars like golden syrup, glucose syrups, invert syrup or honey. These are commonly used ingredients intended to contribute flavour and in some cases to the retention of a moist eating character and longer mould-free shelf-life. As a `rule of thumb' you should limit the level of addition of such sugars collectively to no more than 10% of the total weight of sugars in the recipe. You can encounter similar problems if you are adding glycerol or sorbitol to extend product shelf-life. For recipe balance purposes you should consider these to be sugars and include them in the 10% limitation. One less than obvious source of reducing sugars is the fruit that you are adding, though if this is a problem then you will often see darker stains in the crumb around the pieces of fruit. You could wash and drain the fruit and see if this makes any difference to the problem. Be careful to check that the increased moisture content of the fruit does not cause you problems by raising the product water activity and shortening the mould-free shelf-life of the product. This will be particularly important if you are cutting the slab into smaller pieces and exposing the cut surface to view, as this increases the risks of mould contamination. Finally, check that you are not using too much sodium bicarbonate in the recipe as any residue will increase the cake pH and increase the extent of the Maillard reactions. References

(2004) Factors affecting the Maillard reaction. In (ed. R. Steele) Understanding and Measuring the Shelf-life of Food, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. ARNOLDI, A.

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5.12 We regularly measure the water activity of the individual components in our composite cake products and try to adjust them to reduce the differential between them to reduce moisture migration. Even though we do this we are still having problems keeping the cake moist during shelf-life. Can you give us some advice as to what we may be doing wrong? In addition to balancing the water activities of the cake components there are other factors which encourage the migration of water to take into account. First you should check your packaging. Moisture lost through the pack will create a moisture gradient which encourages moisture migration. Cardboard packaging has a low moisture content (and low water activity) so moisture in the pack atmosphere can be absorbed by the board and, since it is relatively permeable, can pass out to the atmosphere. As well as the permeability of the pack you should check the integrity of the pack seals to see that no moisture is escaping via this route. Even when the pack is not losing moisture to the surrounding atmosphere, moisture will migrate from the product into the pack atmosphere. The mass of water which can be held in the pack atmosphere is controlled by the saturated vapour pressure of the air. This is low at the typical temperatures used to store cake products but the greater the volume of air in the pack, the greater will be the mass of water required to achieve saturation. You may want to consider whether the pack size can be reduced. Sometimes it is better to over-wrap the cake product in a moisture impermeable film before placing it in a box. You should look closely at the formulation that you are using for your cream filling. Currently you are measuring the water activity of the filling but you should check that all of the sugars that you are using in the cream formulation are in solution (Cauvain and Young, 2008). If you are not getting all of the sugars into solution, then the crystalline material will increase the likelihood of moisture migration from the cake. The presence of crystalline material is not measured with a water activity meter. We suggest that you carry out a mass balance with composite products; that is, you calculate the moisture and water activities of the different components to see where the potential is for moisture migration, remembering to take into account the volume of air in the pack. We also find it useful to draw a diagram showing the likely movement of water in a composite cake system (see p. 12). Reference

and YOUNG, L.S. (2008) Bakery Food Manufacture and Quality: Water Control and Effects, Wiley-Blackwell, Oxford, UK.

CAUVAIN, S.P.

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5.13 Why do some traditional cake-making methods specify a delay in the addition of the sodium bicarbonate and the use of hot water? Would this approach have any practical applications today? The delayed-soda method of making cake batters is mainly used as a means of controlling the reaction of the baking powder components and the release of the carbon dioxide gas that is generated by that reaction. It was more commonly used in the manufacture of various forms of sponge cakes. The different baking acids that may be used in the manufacture of cake batters have different rates of reaction. If a so-called fast-acting acid is used, then the evolution of carbon dioxide would occur early in the batter mixing stage. While the batter is being agitated there is potential for that carbon dioxide to be lost to the atmosphere and not be able to contribute to the expansion of the cake in the oven. By delaying the addition of the sodium bicarbonate to later in the mixing process, the potential for losing carbon dioxide is reduced. Using the delayed-soda method will not reduce the potential for batter de-aeration, which can occur during the storage of the batter if it is stirred, or when it is being pumped through pipework or when it is being deposited before baking. A practical consequence of using the delayed-soda method for mixing cake batters is that the combined level of baking acid and bicarbonate might be reduced. This could have advantages in the current climate of seeking to reduce the level of sodium in bakery foods (see 3.2). Each baking acid, after reaction with the sodium bicarbonate, leaves behind a distinctively tasting salt; not everyone likes the `phosphate' after-taste which is characteristic of many baking powders. More traditional baking acids, such as tartaric acid, tend to be fast-acting in combination with sodium bicarbonate and by using the delayed-soda method you could change to such acids and modify the flavour profile of your products (and also reduce sodium levels in some cases). The specification of hot water is to encourage the rapid dissolution of the sodium bicarbonate. This was probably more relevant many years ago when the particle size of sodium bicarbonate was coarser than that of today. If you are using a finely divided form then you may find that you can readily dissolve the sodium bicarbonate in water at around 20ëC; this will have the advantage of not affecting the final temperature of the cake batter. Un-dissolved and un-reacted particles of sodium bicarbonate often show as dark spots on the crust or in the cake crumb.

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5.14 We have recently changed the acid that we use for our baking powder mix and have adjusted the neutralising value accordingly. Subsequently we have been having some problems achieving the volume and shape that we want with our small cakes. Can you explain why we are having these problems? The neutralising value refers to the proportion of a given acid that is required to completely neutralise (react) with a given amount of sodium bicarbonate; this proportion varies according to the chemistry of the acid (BPS, p. 76). In addition to having a different neutralising value, each acid has its own rate of reaction (ROR), which indicates the rate at which it will react with sodium bicarbonate to produce carbon dioxide gas. In addition, some of the baking acids and the sodium bicarbonate are available in different grades ± degrees of fineness ± and this, too, affects the ROR, because the acid and alkali go into solution at different rates. The ROR of a baking powder mixture and the timing of the release of carbon dioxide are important contributors to cake volume and shape. If the ROR is too rapid then much of the carbon dioxide will be released during mixing and the early stages of the baking process, which tends to lead to the cakes lacking volume and often having a shape which is peaked rather than rounded. A similar problem can occur if the ROR of the acid is too slow and the majority of the carbon dioxide is released when the structure of the cake has begun to set. A visual summary of the effect of the ROR of the baking powder on cake shape is given in Fig. 36. To find out where you are on the shape spectrum decide which cake outline best matches the product that you used to get and which matches the shape of your current cake products and this will tell you whether your ROR has increased or decreased. For example, if you used to get shape number 2 but now get shape number 3 then the ROR of your baking powder has increased.

Fig. 36 Effect of rate of baking powder reaction on cake shape.

To move the cake shape in a particular direction you may need to choose an alternative baking acid. The ROR can normally be obtained from your baking powder supplier. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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5.15 What are the factors that control the shape and appearance of the top of a cake? The main influences on the shape and appearance of the top surface of cakes fall into three categories: the balance of liquids to sugars in the recipe, the balance between mechanical and chemical aeration and the rate of heat transfer during baking. The concentration of the sucrose solution in cake recipes has a significant effect on cake shape (and other structural features). As the level of sugar in a cake recipe increases, the temperature at which the wheat starch gelatinises is raised and the batter stays fluid for longer in the oven. At low recipe sugar levels cakes tend to have a rounded and slightly peaked profile but as the level increases, the shape becomes progressively flatter (see Fig. 37). Continued increases in recipe sugar level lead to collapse of the structure so that a dip appears in the surface of the cake.

Fig. 37

The effect of increasing sugar level on cake shape.

The volume, structure and appearance of cakes depend on creating a gas bubble structure in the batter, which will be expanded by the release of carbon dioxide from the baking powder reaction. Achieving the right balance of mechanical and chemical aeration is important for controlling shape. The examples shown in Fig. 38 are based on cake recipes that have all been mixed to the same batter density but with different levels of baking powder in the starting recipe. This means that the batter with the lowest baking powder level has the highest proportion of air incorporated into the batter, while that with the highest level of baking powder has the lowest level of air incorporation. This follows because there is some reaction of the baking powder components in the initial

Fig. 38 Effect of baking powder level on cake shape.

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mixing stages and some of the carbon dioxide gas produced at this time remains trapped in the batter. The illustration shows that as the level of baking powder increases (for the same final batter density), the cake shape becomes less domed and eventually with high levels of baking powder a dip appears in the surface. The impact of high levels of baking powder is pronounced because a lot of the carbon dioxide gas is released in the oven at a time when the wheat starch is swelling and the cake structure is close to setting. The critical nature of the mechanical to chemical aeration balance can also be seen when the rate of reaction of the baking powder in the recipe is changed. A slow (late) release of the carbon dioxide commonly yields a product with a peaked shape and as the reaction rate increases, the cake shape gradually flattens (see Fig. 36). However, fast-reacting baking powders also give peaked-shape products. This is because most of the carbon dioxide escapes while the batter is very fluid and none is left for expansion at the starch swelling stage. Rapid heat transfer rates in the oven (high temperature) tend to cause the cake shape to become more peaked, as does a high top heat when baking in a deck oven.

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5.16 We are seeking to reduce the level of fat that we use in some of our cake recipes but find that simply taking fat out adversely changes our product quality. What are the possibilities of using `fat replacers' to help us with our strategy? There are two key roles for fats in cakemaking: one is to help with the soft and tender eating qualities that we associate with cakes and the other to help with foam promotion and bubble stability in the batter (BPS, p. 46). If you are going to reduce fat levels in your recipe, you will need to take both into account and this can lead to conflicting results. You may also experience some loss of flavour from your product. A typical effect of simply reducing fat levels in your recipe without making any recipe changes is illustrated in Fig. 39. The product has a lower volume, denser crumb and firmer eating qualities, which are often quickly detected by consumers.

Fig. 39

Effect of lowering fat level in cakes; left, standard recipe and right, reduced fat recipe.

You can overcome the loss of foam creation and bubble stability when you reduce fat level through the addition of a suitable emulsifier such as glycerol monostearate (GMS). However, you will find that the cake eating qualities may become a little firmer. You may find some advantage in reducing the egg level in your recipe (and adjusting water accordingly) as discussed in 5.5 but you need to be cautious as low levels of egg solids can result in increasing fragility of cake crumb and even the formation of unwanted cracks because of the lowering of protein levels. If this does happen then you could raise the protein content of the flour. There are claims for a wide range of fat replacers but it is worth bearing in mind that none of them delivers exactly the same qualities as fat and that their use in a reduced-fat cake recipe will always need other recipe changes in order to produce a satisfactory cake product. Broadly, fat replacers can be placed in one of three categories: carbohydrate-based, protein-based and fat/lipid analogs. A significant number of the fat replacers are aimed at reducing the calorific value of the final product and so weight for weight they deliver significantly fewer calories than fat.

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In many cases the carbohydrate-based fat replacers are composed of fibrous materials and so require the addition of extra water to the recipe in order to maintain a sufficiently fluid batter for processing. It is mainly the presence of the extra water that delivers the fat-mimicking properties of the material but the extra recipe water can lead to unbalancing of other recipe components, e.g. sugar, and will result in a higher moisture content in the final product. Unfortunately while the fat replacer may hold the water in the batter in most cases, it does not sufficiently bind water in the baked product, with the result that the product is more susceptible to mould growth. Similar issues apply to the protein-based fat replacers. The position with fat/lipid analogs is slightly different since such ingredients do tend to more closely mimic the `lubricant' effect of fat with respect to cake eating quality. However, these materials still lack the foam promotion and bubble stabilisation properties of fat and so commonly recipes incorporating them require the use of an emulsifier. If you are thinking of using any of the available fat replacers, it would be advisable to check on whether they are permitted in cakes and what, if any, special ingredient declarations need to be made. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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5.17 We are using natural colours in our slab cake baking and find that we get variable results, not just from batch to batch but sometimes within a batch. Can you suggest any reasons for this problem? Being derived from natural materials colours can be subject to variations in shade and intensity of the colour. This is usually well controlled by the supplier. All colours are affected by the pH of the medium in which they are used. Natural colours are especially sensitive to variations in batter pH and this can lead to problems when making additions of fresh fruits (BPS, p. 154). If this was the source of your problem, we would only expect you to see variations on a batch to batch basis as a reflection of the small variations in batter pH that can occur in any manufacturing environment. When used in baked products natural colours are likely to suffer from some instability during their storage. Commonly this will be seen as a loss of intensity of the colour but usually the overall storage time is too short for cakes for any significant variations to come from this source. The fact that you are getting variations between cakes manufactured within a batch is unusual. Some natural colours are known to lose colour intensity during baking, so one possibility is that the variations in colour that you see may reflect the degree of bake that a particular cake has received. As you will appreciate there are inevitably some variations in the degree of bake within an oven. Natural colours are particularly susceptible to the effects of exposure to light. In particular they tend to lose colour intensity with increasing exposure. Yellow colours appear likely to be more affected than reds. Your cakes are more likely to be affected by light if they are wrapped in clear film. This is often the case in cake manufacture based on slab cakes as it allows the consumer to see the product and its qualities. We suggest that you look closely at how your cake samples have been stored with respect to any light sources, whether natural or artificial. This should include all of the times for which the cut surfaces of the cakes are exposed to light sources, including standing times in the bakery while the composite product is being assembled before wrapping. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

6 Biscuits and cookies

6.1 We have been trying to make soft-eating cookies and are having a degree of success with the recipe that we are using. The products are not expected to have a long shelf-life but we find that they are going hard too quickly. Can you suggest any ways of extending the period of time that the cookies will stay soft-eating? Soft-eating cookies are usually baked to higher moisture contents than many types of biscuits and cookies; moisture contents may range from 6±12% compared with less than 5% with more traditional biscuit forms. This higher moisture content helps to confer some of the softer-eating character that you are seeking. To help get and keep the higher moisture content you may need to make slightly thicker cookies than you are used to. This approach will mean that more moisture is retained in the centre of the product and help with the softness and chewiness of the cookie. There will be a moisture gradient in the baked cookie with the upper and bottom crusts and the edges having lower moisture content than the centre. Gradually during storage you will find that the moisture from the centre of the cookie will migrate to the regions of lower moisture content with some loss of the soft-eating character. The rate at which this moisture equilibration occurs depends on a number of factors but is especially affected by the moisture-permeability of the pack that you are using. To reduce moisture losses and so retain the soft-eating character that you are seeking you should use a wrapper with a low moisture vapour transition rate (see 9.9) which limits moisture losses. You should also check the integrity of the pack seals, as moisture can readily pass out of the pack through any small gaps.

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In the oven it is generally recognised that when heated part of the sugar dissolves in the recipe water and melts to form an amorphous glass (a supercooled liquid). This sugar glass contributes to cookie flow and significantly affects the final cookie eating character. With the loss of moisture during baking the level of water available for keeping the sucrose in solution is lowered. As the cookies cool on leaving the oven, some of the sucrose that is present will recrystallise, which contributes to the hardness of their eating character. If more moisture is lost during storage, more sugar will re-crystallise and the eating character will further harden; it is for this reason that it is important to restrict the moisture losses during storage. In some biscuit products the moisture gradient between the centre and the crust regions can lead to problems of checking or the spontaneous breaking of biscuits (BPS, p. 201). Checking is more commonly a problem with biscuit products that are low in fat and sugar, e.g. semi-sweet and cracker types (Cauvain and Young, 2008). You should not experience any problems with checking; nevertheless you should watch out for any signs of the problem; for example, an increase in the crumbliness of your products. If you are including any nuts, chocolate chips or pieces of fruit in your cookies, they provide discontinuities or points of weakness in your products, which can be exploited by the strains that arise because of moisture migration within the cookie. Dried fruit pieces can also be a problem as they may absorb water from the moister areas of the cookie and so may increase the likelihood for sugar recrystallisation. One of the ways you can help keep the cookie soft is to replace part of the crystalline sucrose (sugar) with non-sucrose sugar syrup. This replacement will reduce the likelihood of the sucrose re-crystallisation during storage. Sugar syrups that may be used include glucose syrups and high-fructose corn syrup. You will need to carry out a few trials to find an appropriate level of replacement. Remember to adjust the water level in your recipe to allow for the water present in the sugar syrup (typically around 18±20%). High levels of glucose syrup may lead to excessive browning in plain cookies, with chocolate cookies this should be less of a problem. You may also notice a slight change in sweetness. References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2008) Bakery Food Manufacture & Quality: Water Control and Effects, 2nd edn, Wiley-Blackwell, Oxford, UK. CAUVAIN, S.P.

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6.2

What are Shrewsbury biscuits and how are they made?

Shrewsbury biscuits are one of several `old-style' English biscuits that were traditionally made by local bakers before the advent of large-scale biscuit and cookie bakeries. Collectively they would be referred to as `Confectioners' biscuits' and would be made on a relatively small scale. Many of the different terms for such biscuits have fallen out of use and a good number of Confectioners' biscuits have evolved into the main biscuit and cookie types familiar to us today. Many of the traditional recipes for Confectioners' biscuits tend to use butter as the fat and whole eggs as the moistening agents and many of the mixing processes are similar to those used in cake making. Shrewsbury is a medium-sized market town in the West Midlands of England and its name probably became attached to a biscuit type that was made in a local bakery in or near to the town. The following recipe will make Shrewsbury biscuits: Ingredient Soft flour Baking powder Butter Caster sugar Whole eggs Currants

Parts by weight 100 1.25 50 50 15 20

Mix the butter and sugar until slightly aerated. Mix in the eggs, add the flour and baking powder and mix to a clear dough (paste). If the fruited variety is required then add the currants towards the end of mixing. Sheet the paste to about 5mm thickness and cut out shapes with a 70 mm diameter plain or fluted cutter. Bake on sheets at 200±210ëC for 15±20 minutes and dredge the baked products with caster sugar while still hot. There are quite a few examples of biscuits that have associations with localities or towns. In England another example is Banbury biscuits, which have a similar recipe and make-up procedure, though in this case the caster sugar is applied before baking. Quite a few examples of such specialist biscuits are associated with market towns in the UK and this almost certainly reveals their traditional origins and original points of sale.

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6.3 What characteristics should we specify for our biscuit and cookie flours? The range of biscuit and cookie products is quite wide and so it is difficult to provide a flour specification that will cover all types. The flour properties required can be roughly split into two groups based on whether gluten development in the dough is desirable or not. The level of gluten development in biscuits is much less than that required for bread making (Cauvain and Young, 2007a) and we would reasonably expect that in general, biscuit and cookie flours will be lower in protein with modest gluten-forming potential. Even for laminated biscuit types like crackers, the required protein content will be modest, though slightly higher than that for semi-sweet sheeted biscuits, which in turn, may be slightly higher than that for rotary moulded short dough biscuits. The grist for biscuit flours will be based on the softer milling wheats with a limited, but often necessary, proportion of harder milling wheats. Typical biscuit flour protein contents will vary from 9±11% based on a 14% moisture basis. Protein quality may be measured using standard tests such as the Brabender Extensograph or the Chopin Alveograph (Cauvain and Young, 2009). Such tests are more applicable to biscuit types that undergo some form of sheeting during processing. The sheeting contributes to gluten formation, and high levels of gluten formation will exacerbate shrinkage of the products during processing and baking. In general, flour with low Extensograph resistance with significant extensibility is preferred (Cauvain and Young, 2007b). The flour ash or colour may be specified, though there is limited evidence to suggest that these properties are directly related to flour performance in the manufacture of biscuits. The specification of flour water absorption capacity is not necessary, even for cracker flours, because most biscuit and cookie doughs are made with as little water as possible in order to reduce the potential for gluten development and to limit the amount of water that must be removed during subsequent baking. Most flours destined for biscuit production are now untreated and any modification to the flour performance is usually carried out in the bakery through recipe additions, e.g. the addition of proteolytic enzymes or sodium metabisulphite to reduce its gluten-forming potential. References

and YOUNG, L.S. (2007a) Baked Products: Science, Technology and Practice, Blackwell Publishing, Oxford, UK. CAUVAIN, S.P. and YOUNG, L.S. (2007b) Flours for sweet goods, f2m Baking + Biscuit International: Reference Guide of Industrial Processes and Market Analysis, f2m Multimedia GmbH, Hamburg, Germany, pp. 54±57. CAUVAIN, S.P. and YOUNG, L.S. (2009) The ICC Handbook of Cereals, Flour, Dough & Product Testing: Methods and Applications, DEStech Publishing, Lancaster, PA. CAUVAIN, S.P.

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6.4 What are main issues that we should be aware of in the manufacture of savoury puff biscuits? The principles for manufacturing puff biscuits are similar to those for puff pastry. The biscuits themselves may be plain, slightly sweetened or savoury. The latter mainly use cheese to give the product flavour and in some cases a cheesebased cream is used to make a sandwich snack product. Many of the savoury forms of puff biscuits are small in size and served as snacks. The basic structure is formed by creating layers of a suitable fat between dough. The steam pressure created by the evaporation of water during baking forces the dough layers apart to give the characteristic flaky structure (BPS, pp. 124±5). The creation and control of the integrity of the fat and dough layers is therefore an important part of the lift mechanism for puff biscuits. In general the degree of lift that gives satisfactory puff biscuits is slightly less than you would seek in the manufacture of puff pastry. Typically around 96 fat layers are suitable for puff biscuits. Fewer layers yield thick biscuits, which are very flaky in character, while with greater numbers of fat layers, the products become thin and lose flakiness due to the breakdown of the integrity of the fat and dough layers. The level of laminating fat used in the recipe will tend to be lower than in the manufacture of puff pastry. Typically the level of laminating fat for puff biscuits will be around 40% of the flour weight in the base dough. Higher levels of laminating fat tend to yield products which show a greater degree of shrinkage and which are very fragile. A range of flours may be used in the manufacture of puff biscuits, though the tendency is to use stronger ones suitable for bread making. Weaker flours may be used but they are better suited to manufacturing processes with limited rest periods between the different sheeting and laminating stages. Weaker flours are also less tolerant to process interruptions. Cheese, whey and milk powders may be added for flavour and colour in the manufacture of puff biscuits. Cheese powders are high in fat and proteins and tend to reduce the lift and flakiness of the final product. Cheese powders tend to have a short shelf-life because of their high fat content and should be used with care in order to avoid unwanted rancid flavours being carried through to the final products. A common practice in the manufacture of savoury puff biscuits is to spray the surface of the product with oil immediately after baking (Manley, 2000). This treatment gives the products a shiny surface and enhances its colour. Spraying may also be used to add flavour. However, oil-based sprays and flavours are susceptible to rancidity and so care is required in their use. References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. MANLEY, D. (2000) Technology of Biscuits, Crackers and Cookies, 3rd edn, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P.

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6.5 We assemble a selection pack of biscuits and cookies, one of which is a rectangular product coated on the top with icing. When the pack is opened after some time, this coated biscuit has a `bowed' shape, the base is soft eating but the icing remains hard. Can you suggest reasons for these changes? As you know, biscuits are very low moisture baked products and this contributes to their hard eating character. Because they have a low moisture and low water activity, they are susceptible to absorbing moisture from the atmosphere and this makes them soft eating. This particular biscuit has obviously absorbed moisture and as well as becoming soft eating has begun to expand. It is not unusual for biscuits to expand when they absorb moisture; the degree of expansion is very small and often goes unnoticed. However, in this case the icing on top of the biscuit has remained hard and not significantly changed its dimensions and the overall effect is for product to assume the slightly bowed shape that you see. It may be the case that many of the different biscuit types in the pack have been affected to some degree or another. It is interesting that the icing has not been affected by the available moisture. Icings are usually quite likely to absorb moisture and go sticky, especially if there is a lot of crystalline material present. In this case it would appear that your icing formulation and preparation has minimised the potential for the icing to absorb water. The moisture which has caused this problem may come from a number of sources. There are at least three possibilities to consider: 1. That the biscuits have been stored in a damp atmosphere. If the products are in a box then the lid may not be properly fitted. If they are over-wrapped then the seal may not be secure. Of course once the biscuits have been sold then you have no control over the conditions under which they are stored. 2. The volume of air in the pack around the biscuits can be quite large and if they were packed in a damp environment then there could be the opportunity for moisture migration into the products during subsequent storage. 3. A strong possibility is that the moisture which has caused this problem comes from other products in the pack. This would be the case if any of the other biscuits have relatively high moisture content fillings, e.g. fig rolls (fig newtons). If you want to include such products in the pack then you may have to over-wrap these separately in a moisture-impermeable film before they are placed in the pack. If you do not want to do this then you will have to change the selection of biscuits that you put in the pack.

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6.6 How important are the dough and batter temperatures in biscuit and cookie making? The temperature of biscuit doughs and batters is important in controlling a number of the key chemical reactions and in influencing the processing of the dough. The temperature requirements of biscuit and cookie doughs are quite diverse and so we will discuss them under five different headings: wafer batters, semi-sweet sheeted, short-dough rotary moulded, wire-cut and deposited, and crackers and other laminated biscuits. Wafer batters In the preparation of wafer batters the temperature will play an important role in determining the viscosity of the batter, which in turn will impact on its flow properties while it is being pumped through the processing equipment and its behaviour at depositing. It is important that the batter flows readily onto the plates and will quickly spread to fill the whole of the plate in order to get a complete wafer sheet. Low temperatures yield batters with high viscosity and the deposit weight may have to be increased in order to ensure that a complete wafer is formed. High deposit weights tend to result in wafers with a harder texture after baking because they are denser. The aeration of wafer batters is a most important aspect in production. Some wafer batter formulations may contain yeast and be given a short period of fermentation before depositing. Thus, temperature control is required in order to achieve consistent results. The more common method of aerating wafer batters is through the addition of sodium or ammonium carbonates or a combination of both. Neither of these chemicals is particularly affected by variations in batter temperature since most of their reaction occurs when the batter is deposited onto the wafer plates for baking and the temperature is much higher. One reaction that is affected by batter temperature is that of the alphaamylase present in the flour. The amylase acts on the damaged starch granules and reduces the viscosity of the batter by breaking down the starch and releasing the water that is had been holding. It is common for wafer batters to stand for a period of time before depositing and so any variations in batter temperature can have a profound impact of batter viscosity. High batter temperatures should be avoided to reduce the potential for amylase activity. Semi-sweet sheeted A key requirement for the processing of semi-sweet biscuit doughs by sheeting is to deliver a particular dough rheology in a consistent manner. The dough rheological properties are strongly influenced by the flour properties and the development of the gluten structure in the dough during mixing. A particular problem with semi-sweet sheeted doughs can be the tendency of the cut pieces to shrink back after cutting or during baking giving misshapen products. This problem is most commonly related to high levels of gluten formation in the initial dough. In general the warmer the dough, the softer will be its consistency and the more readily it will sheet. Warmer doughs also tend to have less

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elasticity and so may better keep their shape after having been cut from the sheet. In some cases in the manufacture of semi-sweet biscuit dough a reducing agent (e.g., sodium metabisulphite, L-cysteine hydrochloride, see 3.21) or proteolytic enzymes may be added to help reduce the elasticity of the dough. It is worth noting that the action of both reducing agents and proteolytic enzymes will be temperature sensitive and that higher dough temperatures will encourage greater chemical and biological activity. This is an important consideration in the re-use of biscuit sheet trimmings since the higher level of activity resulting from the combination of higher temperatures and long recycle times can cause considerable changes in dough rheological properties. The low water levels used in making semi-sweet doughs means that there is significant resistance by the dough during mixing, which in turn, means that there will be significant heat generated. The strong relationship between energy transfer and temperature rise during dough mixing and its contribution to dough development is well-understood in the case of bread making (Cauvain and Young, 2006a) but less so in semi-sweet biscuit making, though it is recognised that significant temperature rises do occur during mixing. Indeed in some cases the achievement of a final set dough temperature is used to determine the final mixing point (Manley, 2000). Short-dough rotary moulded The higher levels of sugar and fat used in short-dough biscuits recipes restrict the formation of a gluten structure in the mixed dough (Cauvain and Young, 2006b). The level and the choice of the type of fat being used in the recipe plays a significant role in determining the consistency of the mixed dough, the way in which it will process and the eating qualities of the baked product. The melting profile and the final melting point of the fat play a major role in determining the organoleptic acceptably of the baked biscuit. High melting point fats (e.g., above 40ëC) tend to yield biscuits with a `waxy' mouthfeel, while low melting point fats tend to confer `oily' characteristics to the baked products. The type of fat used has an impact on the mixing method employed for the manufacture of short-dough biscuits. Commonly the mixing process for shortdoughs comprises two stages: the first one is often described as a `creaming' stage in which the fat is mixed with the sugar and other ingredients before the flour is added and this requires the fat to have the appropriate melting profile to give good dispersion and aid with the incorporation of air. Careful control of the dough temperature during mixing is required in order to maintain the key roles of the fat in the recipe, and in the manufacture of shortdough biscuits, final mix temperatures are much lower than with semi-sweet biscuit doughs. Wire-cut and deposited Wire-cut cookie doughs are of a similar consistency to short-dough biscuits but often the recipes will contain particulate inclusions such as chocolate chips and

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nuts. The considerations with respect to the importance of dough temperatures are similar to those for short-dough biscuits. Deposited biscuits are similar to cake batters and so the control of batter temperature is important for the control of gas production by the baking powder and the batter viscosity. The batter temperatures used will be lower than those used in the manufacture of wafers because there is no yeast present. Crackers and other laminated biscuits Many cracker formulations contain yeast and use periods of fermentation (see 6.10) followed by lamination of the dough to achieve their characteristic crisp and flaky structures. There are a number of variations on the fermentation system including sponge and dough, straight dough and continuous fermentation systems. In all cases control of the dough temperature is very important in order to optimise the contribution by the yeast to gas production. In cracker-making processes which employ long fermentation times there is the potential for significant flavour development. The added yeast will contribute to the final flavour profile but equally important will be the contribution from the naturally occurring lactobacilli and other microogansims. In some cases a specific culture of lactobacilli may be added at the start of mixing in order to achieve a specific flavour profile. The temperature used in the fermentation processes associated with cracker production may be varied to encourage a particular flavour profile. Temperature ranges Some typical temperature ranges for different groups of biscuit products are given below. Product Wafers Semi-sweet sheeted Short-dough rotary moulded Wire-cut and deposited Crackers and other laminated biscuits

References

Temperature range for dough or batter (ëC) 22±32 40±46 18±22 16±24 30±38

and YOUNG, L.S. (2006a) The Chorleywood Bread Process, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2006b) Baked Products: Science, Technology and Practice, Blackwell Publishing, Oxford, UK. MANLEY, D. (2000) Technology of Biscuits, Crackers and Cookies, 3rd edn, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P.

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6.7 We are experiencing dark brown specks on the surface of our plain sheeted biscuits. We have been using the same recipe for a number of years without a problem. Can you identify the cause of the specks and suggest a remedy? We have examined your recipe and can not see any particular problem with the ratios of the ingredients that you have been using. However, the cause of the problem is clearly associated with one ingredient in particular ± namely the sodium bicarbonate that you are adding. The specks are based on particles of undissolved and un-reacted sodium bicarbonate which on heating in the oven turn dark brown in colour. It is most likely that the grade of sodium bicarbonate that you are using has changed. There are at least 3 or 4 different grades that may be used in food production. The finesses of the grade will dictate how quickly the sodium bicarbonate dissolves and thus how quickly it reacts with any acid materials to produce carbon dioxide gas. There is clearly a balance to be achieved; very fine grades will react faster and may release the carbon dioxide gas too early in the manufacturing process, which will result in loss of lift in the biscuits. Using a coarser grade of sodium bicarbonate will delay the gassing reaction but may lead to the problems that you are experiencing. Commonly the sodium bicarbonate should have a particle size less than 0.06 mm. The problem is likely to be exacerbated by the low water levels that are used in biscuit doughs. If there is no alternative to using the coarser grade of sodium bicarbonate then you may have to change the mixing procedure and move to what is often called `delayed soda addition'. In this case you should mix your dough as usual but hold back a small quantity of water and the sodium bicarbonate. The bicarbonate should be dissolved in the water that you have held back and only added to the dough at the very end of mixing. It is important not to mix the dough for too long after the addition of bicarbonate and water because the bicarbonate is now in solution and so is able to react with the acids in the recipe. If you have long resting or processing times after dough mixing then the delayed soda approach will not be helpful because of the risk of losing too much carbon dioxide gas before baking and so you have no alternative but to change to a finer grade of sodium bicarbonate. Incomplete reaction of the sodium bicarbonate may also lead to a yellowish colour in the biscuit crumb because of the alkaline conditions and the potential for a soapy taste.

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6.8 We are having some problems with packing our rotary moulded biscuit lines. When we measure the thickness of the biscuits we have noticed that some are thicker than others. Can you suggest any reasons why we should be getting such variations? Close examination of the samples that you provided showed that the main problem is not that the biscuits vary in thickness but that many of the individual biscuits are in fact `wedge-shaped'; i.e. one edge of the biscuit is thicker than the opposing edge. As the biscuits are not necessarily uniformly orientated at the time of packing, this is what is giving rise to your problem. First of all you need to establish if the wedging is uniform across the oven band. You can do this simply by removing a complete row of biscuits from across the band retaining their individual orientation with respect to the direction of travel along the plant. From this action you can establish the `leading edge' for future trials. Next you stack the whole row of biscuits one on top of one another (with the same leading edge orientation) and see which way the stack tilts; this will tell you if the wedging lies in one particular direction. In some cases the occurrence of wedging may be more complicated and you may have to measure the two thicknesses (leading and trailing edges) for each biscuit. If you are seeing variations in the direction of wedging across the band, you should confirm this by collecting several rows of biscuits to check the orientation of individual lanes. The pattern of wedging that you see in the products leaving the oven is indicative of the pattern in the dough pieces leaving the rotary moulder. Once you have established this pattern, it can be used to check progress in eliminating the problem. There are a number of potential reasons for the occurrence of wedging; they include: · Running the extraction and moulding rolls at different speeds. · High levels of water leading to a softer dough, which is more likely to allow extrusion of the dough through the front or rear of the moulds (i.e., formation of tails). · High levels of syrup in your recipe. Remember, if you are using high levels of syrup, you should compensate for any water that might be present in the ingredient. · High levels of fat leading to softer dough. · Using a low melting point (low solid index) fat which increases the softness of the dough. · Higher final dough temperatures, which lead to a softening of the dough because less of the added fat will be solid. · Changes in sugar particle size, either finer or coarser (see 6.12). You should also look closely at your extraction roller to make sure it is not worn, especially if the problem is only associated with a few lanes of biscuits.

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6.9 We are having intermittent problems with shrinkage of our semi-sweet biscuits after they have been cut out from the dough sheet. How can we stop this from happening? Shrinkage can be a relatively common problem with semi-sweet biscuits because of the degree of gluten formation that occurs in such doughs during mixing. The problem is exacerbated by the uni-directional nature of the sheeting and cutting process. The sheeting stages transfer some energy to the biscuit dough and this adds to the development of the gluten network that is already present. To reduce or eliminate the problem you will need to look closely at your ingredients and recipe, mixing and processing conditions. Among the possible reasons for the intermittent nature of the problem are: · Variations in flour quality with respect to both protein content and protein quality. While the flour may be within specification, you should look closely at the data to see if the problems are associated with times when the properties are closer to the limits of the specification. · Variations in the weights of key ingredients to the mixer. You should check each of these carefully for consistency of delivery. · Variations in dough temperature ex-mixer. These may be within your specification but is the problem associated with one end of the acceptable range? You may have to adjust the range or the mid point or move the dough to a less sensitive position. · Variations in standing time before processing. Delays after mixing can lead to variations in dough consistency as the water is absorbed by the different ingredient and recipe components and as the dough temperature changes. · Any trimmings that are recycled should be carefully controlled in terms of weight of addition and condition. In the case of the latter variations in age and temperature can have a significant impact on dough rheology. · Check the plant speeds. A common cause of variations is running the plant at different speeds. · You should look closely at those points immediately after sheeting where the dough is taken away on conveyors. A common practice is to allow a degree of `relaxation' in the sheet by building-in a small, hanging-loop in the run of the dough sheet. This releases a little of the tension which has built-up in the dough as it passes through the sheeting rolls; the length of time that the dough sheet spends under reduced tension is short but it can have a significant impact, especially after the last of the sheeting rolls and before cutting.

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6.10 Is it important to use a fermentation period in the manufacture of crackers? What effects are we likely to see from variations in the fermentation time? A function of the fermentation time in the manufacture of crackers is the modification of the gluten network which has been formed in dough mixing; in particular to reduce its elasticity and increase its extensibility so that it is easier to machine the dough and to create the required laminated structure, which delivers a flaky texture in the finished product. During the fermentation period there is a small increase in dough acidity, which not only contributes to the rheological properties of the dough but also potentially to baked cracker flavour and colour. During fermentation there is considerable enzymic activity from both the flour and yeast sources. It is important to recognise that fermentation is not just a matter of time but it is also affected by temperature (fermentation increases as temperature increases) and yeast level (higher yeast levels yield greater fermentation). Thus, in practice fermentation time is seldom considered as a single variable. Long fermentation times lead to considerable gassing activity by the yeast and increased enzymic activity. The latter will be dominated by the amylase activity of the damaged starch in the flour and by proteolytic activity, both of which result in softening of the dough, which makes it more difficult to handle and process. This may result in the need for increased dusting flour with some potential loss of cracker lift. Low dough pHs coming from extended fermentation times may increase the likelihood of cracker shrinkage. The main impact of shortening dough fermentation times is that the dough will be tougher (more resistant to deformation) and harder to machine. Commonly this leads to an increase in sheeting rolls pressures with the risk of crushing layers and losing cracker lift and flakiness. If you do want to reduce fermentation times then you may find it helpful to add a little extra water to the dough formulation to yield a softer, more machinable dough or to add dough softening agents such as L-cysteine hydrochloride (see 3.21) or proteolytic enzymes (see 3.13). You will need to be cautious when using dough-softening agents as there can be a progressive buildup of their levels through the continued use of re-work and eventually the dough may become too soft for machining.

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6.11 We are experiencing blistering on the surface of our semi-sweet biscuits and sometimes see cavities under the top crust and little hollows on the bottom. Can you identify the possible cause of the problem and suggest a solution? You may be experiencing two slightly different problems with your products, though baking conditions are implicated in both cases. The blistering probably comes from a lack of humidity at the feed end of the oven. In order to obtain a smooth surface appearance, the humidity in the first two or three zones of the oven needs to be high. The humidity in the early stages of biscuit baking comes mainly from moisture evaporated from the biscuit dough pieces themselves. Commonly humidity is regulated by the extraction dampers fitted to the oven and in order to maintain a high initial humidity these need to be fully closed for the first one or two zones. If this does not have the desired effect, you may need to consider the introduction of extra humidity via the steam jets. You may find that by increasing the oven humidity, the biscuit stack height falls slightly; if this is the case and the change is unacceptable, you may want to consider compensating by slightly increasing the biscuit aeration levels. The cavities and hollow bottoms that you sometime observe are created by steam trapped during baking. Hollow bottoms can be a particular problem if you are baking on solid trays or oven bands. Changing to wire mesh should help eliminate this problem. Hollows underneath are also known to be related to using a sugar with a coarse grain (see 6.12). With respect to the cavities underneath the top crust we suggest that you investigate the docking pin arrangements with your products. The docking holes should go right through the dough piece to ensure the ready release of steam. You may find that this also helps with the problem of hollow bottoms. Cavities under the top crust may also be associated with the aerating agents that you are using. Larger particles of ammonium bicarbonate (vol) will release significant quantities of gas in the oven, essentially blowing the dough piece apart. Check that the particle size of your supply of vol has not increased or dissolve the vol in water before adding it to the dough during mixing. For more information on using vol in biscuits see BPS, p. 193. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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6.12 We are manufacturing short-dough biscuits using a rotary moulder and have been offered an alternative supply of sugar. We notice that the new sugar is more granular than the material we have been using previously; would this have any effect on biscuit quality? We suggest that you are cautious before switching to the alternative source of sugar. The particle size (coarseness) of the sugar that you use will have effects on a number of different dough and biscuit properties. You need to bear in mind that the water and sugar levels typically used in short-dough biscuits are such that not all of the sugar that you are adding will go into solution in the available water, so that un-dissolved grains of sugars are likely to be present. The rate at which the sugar particles will go into solution is affected by their particle size, with coarse-grained sugars taking longer to get into solution in the available water. Water is lost during the biscuit baking process so that there is even less water available to keep the sugar in solution when the product cools, which increases the potential for sugar re-crystallisation. Once again the initial particle size of the sugar has a potential effect as coarser-grained sugars are more likely to recrystallise as large sugar grains in the baked product. Some of the likely impacts of sugar particle size include: · The appearance of visible sugar crystals on the biscuit surface when using coarse-grained sugars (though in some cases this may be seen as a positive product character). · An increase in the grittiness of the biscuit eating character with the use of coarse-grained sugars. · Biscuit hardness tends to increase with sugar particle size. · An increased tendency to the occurrence of hollow bases as the particle size of the biscuits increases (see 6.11). · Variations in biscuit flow with varying sugar particle size. This is a most important change because of the impact on biscuit dimensions, including stack height (thickness), which will affect the subsequent performance of the biscuit wrapping equipment. Biscuit flow increases as the particle size of the sugar decreases. · Biscuit dough firmness increases when using coarser sugars, probably because there is more water available for absorption by the flour. · Dough piece and biscuit weights tend to increase when using coarser-grained sugars.

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6.13 Is it possible to reduce the level of sugar in our biscuit and cookie recipes without affecting their quality? What would be the alternatives to sucrose we could use? Reductions in the sugar (sucrose) level in your biscuits and cookies will have an immediate effect on dough handling and the final product quality. This is because sucrose plays a number of important roles in the manufacture of biscuits and cookies. In the dough its effect on water activity is part of the reason for the inhibition of gluten development during mixing. In broad terms the effect of reducing added sucrose levels would be like changing a short-dough biscuit recipe to become more like that of semi-sweet product. In practice you may find it difficult to continue to rotary mould reduced-sugar short doughs and you may experience increased shrinkage after release from the mould and almost certainly when the products are baked. In the baked product sucrose makes important contributions to product sweetness, crust colour, flow and shape in cookies and the texture of the product, particularly the hardness and crunchiness of the eat, so there are quite a few consideration to take into account. The main features of the alternative sugars to sucrose are discussed in 3.11. The crystalline nature of sucrose and its particle size (see 6.12) are important in the creaming process, which is typically part of short-dough mixing. The sugar crystals aid the dispersion of fat throughout the dough and contribute to some air incorporation. Liquid sugars will not be able to make the same contribution as sucrose, though some of the sugars that are powders can deliver some of the required functionality. To some extent product sweetness and colour can be adjusted using different combinations of sugars, perhaps with a compensatory re-balancing with other recipe ingredients, such as milk powders. More difficult to replace will be impact that sucrose has on the formation of the cookie structure and ultimately on its texture. Manley (2000) summarised in diagrammatic form the changes taking place in biscuit dough during baking. The baking time for biscuits is much shorter than that of common bread types but there is still time for a similar series of changes to occur; namely expansion of the structure, loss of water and structure setting. In the case of biscuits the relatively low added water levels and short baking time probably militate against a significant degree of starch gelatinisation in the structure formation process so that reducing or changing sugar levels is not likely to have the major impact that it does with cake batters though you can still expect some changes in biscuit properties. More important in the context of structure formation and texture for biscuits and cookies is the formation of a super-saturated sugar solution in the oven. The solubility of sucrose is high and increases dramatically as the dough piece temperature increases. The formation of this super-saturated sugar throughout the biscuit matrix contributes to the expansion of biscuits and cookies in the oven but as the structure begins to become porous, the escaping gas leads to collapse of the structure to yield (usually) a thin final product. Commonly this

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collapse occurs in the oven, depending on sugar level. In some biscuit and cookie types the collapse may not begin to occur until the product is cooling after it has left the oven. As well as contributing to the expansion of the product, the super-saturated sugar solution which is formed in the oven also permits considerable flow or spread and this spread needs to be controlled in order to maintain final product characteristics. As the product cools, the sugar solution solidifies and becomes rigid, often forming a characteristically cracked surface (see Fig. 40). The impact of the different sugar solubilities and their effect on product flow will be an important factor to take into account when re-formulating for lower sucrose levels.

Fig. 40 Surface cracking on high-sugar cookies.

The crunchiness and crumbly eating character of many cookie products is a direct result of the high levels of recipe sucrose, and reductions in sugar levels will result in the loss of those eating characters and a harder, more flinty texture. In many high sugar products the re-crystalisation of sugar on cooling contributes weak points in the cookie structure and contributes to the shortness of its texture. Some of this effect comes from starting with a proportion of coarse sucrose particles in the recipe, most alternative sugars and sugar replacers are not available with the same range of crystalline forms as sucrose and so are not able to make a similar contribution to texture. Reference

(2000) Technology of biscuits, crackers and cookies, Woodhead Publishing Ltd, Cambridge, UK.

MANLEY, D.

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6.14 We would like to reduce the level of fat in our biscuit recipes. How can we do this? A reduction of fat will lead to changes in processing requirements because of the potential for greater gluten formation and an increased risk of shrinkage during processing and baking. As the fat level in a biscuit recipe is reduced, there is an increase in product weight, see Fig. 41. The fat also contributes to the shortness of the eating quality. There will also be an increased risk of checking (BPS, p. 201). In the manufacture of crackers the fat contributes to product lift as part of the `cracker dust' which is laminated into the product.

Fig. 41

Impact of fat solids on cookie piece weight.

The most common way of enabling fat reduction in biscuit making is through the addition of suitable emulsifiers. The most commonly used emulsifiers for this purpose are diacetyl tartaric esters of mono- and diglycerides of fatty acids, usually referred to as DATA esters or Datem, sodium stearoyl-2-lactylate, SSL, and lecithin (see 3.19). The rates of emulsifier addition would be at about 1.5% of the fat weight in the original recipe and this would allow for a reduction of around 20% of the original fat level. For example, if the fat level was 16% or 16 g in 100 g mix; the rate of addition of the emulsifier would be 0.24 g in 100 g mix and the new fat level would then be 12.8 g. Obviously when the ingredient percentages are adjusted back to a 100 g mix the percentage of fat will not be 12.8% because the total ingredient weight is slightly less; the new percentage fat level in 100 g mix would become 13.2%. If you do encounter excessive shrinkage during processing, you can consider the addition of a reducing agent like sodium metabisulphite or L-cysteine hydrochloride (see 3.21), or the addition of proteolytic enzymes (see.3.13). Reference

and YOUNG, L.S. (2000) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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6.15 We have installed a new cutting and creaming machine for the preparation of our sandwich wafers and re-furbished the production area. We have found that we are now getting intermittent problems with the wafer sheets breaking up on cutting. Can you offer an explanation as to why this might be happening? The fragility of wafers is determined by a number of recipe and process factors but since you have not changed any of these during your refurbishment then we need to look more closely at how the wafer sheets are treated after they leave the oven. Immediately after baking, wafer sheets have very low moisture contents, commonly less than 2%. Because they have such low moisture contents they are prone to picking-up moisture from the atmosphere. The rate and degree to which they pick-up moisture will commonly be related to the relative humidity of the atmosphere and the length of time to which the sheets are exposed to that atmosphere. If you have any data on the relative humidity of the atmosphere in the cutting and preparation areas before and after the changes were made that would be helpful in understanding why you are now having problems; especially if the relative humidity of the refurbished facility is now lower, for example because there is less air movement from the baking areas than before or if you have installed better extraction facilities. We suggest that you look closely at the moisture content of the wafer sheets at cutting to see if this is lower than before. One of the problems with wafer sheets is that the moisture distribution throughout the sheet is not uniform and some equilibration will occur as the sheets are cooled and stored. Often wafer manufacturers allow a `conditioning' period after baking while the wafers are cold in order to allow for equilibration of the moisture content throughout the sheet. In some cases the wafer conditioning process may be carried out in an atmosphere with specific relative humidity control to adjust the moisture content of the sheets to optimise the cutting process or even with the addition of moisture by spraying the sheets with water. Such processes must be carefully controlled as high moisture content wafers (e.g., above 4%) have less than satisfactory eating qualities. We suggest that you look closely at the control of the wafer cooling and storage conditions to ensure that they are uniform in terms of wafer temperature at the time of cutting and that any storage times are consistent.

7 Pastries

7.1 We have been experiencing considerable variability in processing our short and puff paste products; sometimes we have problems with paste shrinkage and on other occasions we get stickiness. We have checked our weighing systems and can find no problems with ingredient additions. We have no climatic temperature control in the factory or ingredient storage facilities, are these likely to be significant contributors to the problems? Producing and using pastes at consistent temperatures is very important in ensuring consistent processing and optimum final product quality. Ideally you should be controlling ingredient and environment temperatures along with the delivery of a consistent paste temperature ex-mixer. To advise you on the best way to eliminate your problem we need to consider the various influences. Ingredient temperatures Flour and fat are the main ingredients to concern us. Since your flour is stored in non-insulated silos you must expect the temperature of this ingredient to vary with changes in climatic conditions. The common way of coping with such variations is to adjust the temperature of the water added to the mix (see 7.5). Remember that water levels are low in pastes by comparison with those used in bread dough, so the cooling potential of the recipe water is lower. You need to make sure that you have an adequate supply of chilled water and often you may need to resort to the addition of ice or an ice-water mix. In colder periods you may need to provide heated water. Relatively high levels of fat are added to the base dough of pastry products

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and so variations in fat temperature will contribute to variations in paste temperature. It is best to keep the fat at a constant temperature and only try to adjust paste temperatures ex-mixer using water at the appropriate temperature. The functional properties of fats are related to their `temperature histories' and it is best not to subject them to too many warm and cold cycles. Ideally you should hold your fat at a similar temperature to your processing environment or slightly lower than your ideal paste temperature ex-mixer. If you are using re-work added to the mixer then you should ensure that this is at a constant temperature. If it comes from a chilled environment then you should make sure that the temperature throughout the batch is uniform. Processing temperatures Ideally you should have a constant processing temperature. This is particularly important if you have long rest periods or are using fats that are particularly temperature sensitive. You will find that pastry lift is directly related to paste processing temperature for a wide range of laminating fats (see Fig. 42).

Fig. 42 Effect of processing at temperatures of 12 and 19ëC on puff pastry lift.

In the manufacture of laminated products variations in paste temperature can directly affect the integrity of the layers. Higher processing temperatures often result in breakdown of the layering as the laminating fat `oils'. In such cases the paste becomes sticky and is usually compensated for through the increased use of dusting flour on the plant or by lowering the added water level both of which introduce other problems. Low paste temperatures make the dough firmer and more difficult to sheet. Commonly this means that extra sheeting pressure is applied during processing, which can then lead to breakdown of the layering of the laminations. Most laminating fats will lose some of their plasticity at lower temperatures and this can lead to loss of layer integrity and subsequent pastry lift.

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7.2 We are looking to start production of croissant. In my travels I have seen many variations on products that are called croissant. Why are there so many different forms and how are they made? An essential feature of the products that we call croissant is that they are made from a laminated dough, that is one which comprises alternate layers of a fermented dough and a suitable fat. Most people consider the origins of the product to be in central Europe and a number of legends suggest that they are associated with conflicts between the Western world and the Turkish empire of the Middle Ages. One story suggests that they were a special bread to celebrate the role that bakers played in saving Vienna from attack ± the traditional crescent shape being a symbol associated with the invaders. The primary shape of the croissant, which is thick in the middle and thin at the ends, comes from rolling a triangular shaped piece of dough cut out from a thinly sheeted laminated paste. Whatever the true origins of croissant it does appear that the first shapes were in the form of a crescent with the two thin ends curved inwardly towards one another. The main regional variations to this shape include forms in which the two `horns' are stretched to join together to form a ring (common in Spain) and others where the croissant is not curved and remains straight (common in Germany). Another variation, which is often considered to be very important, is related to the definition of the `shoulders' formed on the piece after rolling the paste triangle; in some cases they should be prominent, while in others they should not. In addition to variations in shape we now commonly see variations in size. Many baked products have changed in form since their first introduction, as they have evolved to meets consumer needs and marketing strategies. For example, in its `classic' form the croissant should have a very flaky texture, which can often leave a mass of crumbs behind when it is eaten. This does not suit all tastes and new forms have evolved in which the flakiness of the product has been reduced and begun to assume a more `bun-like' texture. We leave it to you to decide which form of croissant you wish to make. However, whatever your choice, the characteristics of croissant are controlled by a few key recipe and process features. In summary these features are: · · · · · · · · · ·

The quality characteristics of the flour. The mixing of the base dough. The quality characteristics of the laminating fat. Yeast level in the base dough. The ratio of laminating fat to base dough. The numbers of fat layers created during lamination. Roll gap settings during sheeting. Resting periods between lamination and sheeting stages. Paste processing temperature. The triangle size of the unit croissant.

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· Recycling paste trimmings. · Prover conditions. There are also some significant interactions which need to be considered in the successful manufacture of croissant. The quality characteristics of the flour In general strong flours are needed for croissant production but it is important to form an extensible gluten to avoid problems during the sheeting and lamination stages. Using stronger flours will commonly mean that longer resting periods are required between individual sheeting and laminating stages. The mixing of the base dough The common practice is to `under-develop' the base dough by comparison with bread production. This is said to allow for the extra development that occurs when the dough and paste are sheeted, and it is true that the pressure of the sheeting rolls does transfer some energy to the dough. However, it is the rheological character of the base dough leaving the mixer that is most important if a uniform and cohesive sheet is to be formed. Under-development during mixing does not automatically deliver the appropriate dough rheology. The quality characteristics of the laminating fat The laminating fat will be extruded onto the base dough before the initial folding stages (in small bakeries it may be applied as sheets) and it is important that the fat is plastic enough to form as complete an initial layer as possible to help with lift in baking (BPS, pp. 124±5). Butter is a popular fat used in the manufacture of croissant but its melting point is low and this makes it difficult to use without refrigeration of the paste during production (see 7.6). Yeast level in the base dough The level of yeast in the base dough will depend on a number of other recipe, e.g. the level of sugar, and process factors, e.g. processing and final proof temperatures. The production of carbon dioxide gas by the yeast in the base dough will disrupt the layered structure of the product, especially during proof, and this can reduce lift. The ratio of laminating fat to base dough In the manufacture of croissant the ratio of laminating fat to base dough has less impact on pastry lift than would be the case with puff pastry. This is because of the disrupting effect of the yeast activity. The level of laminating fat will have a significant effect on the eating quality of the product and its flavour, especially if butter is used as the laminating fat. The numbers of fat layers created during lamination As a general rule, relatively few fat layers are created in croissant, typically 18± 32. This is in contrast to puff pastry production where the numbers will be two

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or three times greater. Once again it is the disrupting effect of the yeast activity that has to be taken into account and so the aim is to try and keep the fat and dough layers intact to gain lift and contribute to the flaky eating character of the final product. Roll gap settings during sheeting A key aim during sheeting is to avoid breaking up the fat layers in the paste, as this will allow the ready escape of steam from the base dough and restrict lift in the oven. The roll gap settings which are used are strongly influenced by the rheological character of the base dough and the need to achieve a particular width ready for the laminating (folding) stage which follows sheeting. Resting periods between lamination and sheeting stages Resting periods are helpful in adjusting the rheological character of the paste. Longer periods help the paste to relax and make it easier to sheet; easier sheeting leads to less damage of the dough and fat layers and makes it easier to achieve the required sheet widths for further processing. However, longer processing times permit greater yeast activity and so a balance must be struck between the two requirements. Paste processing temperature The control of paste processing temperature is important in retaining the integrity of the fat layers; too low and the fat will be brittle, too high and the fat will readily turn to oil. Lower processing temperatures helps limit yeast activity before final proof. The triangle size of the unit croissant The dimensions of the triangle are important in determining the final appearance of the croissant. We suggest that you try rolling a few different shaped triangles and see which one you prefer. Recycling paste trimmings There will always be some trimmings from the paste sheet during production. You can re-use these by adding them to the mixer but you must control their level and age in order not to introduce unwanted product variation (see 7.3). Prover conditions Your chosen proof temperature should be lower than used with bread to avoid oiling of the fat and loss of lift. Prover temperatures in the range 30±32ëC are usually suitable with a humidity of 70±80%. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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7.3 What is the best way to use pastry trimmings? At present we are feeding them back into the sheeting stages The production of trimmings in the manufacture of pastry products is inevitable; they mostly come from trimming the paste sheets during processing. It is common practice on automatic plants to gather them at various processing points and feed them back during the sheeting stages, though in some cases they may be added directly into the mixer to be incorporated with fresh ingredients. Puff pastry trimmings are often used as a means of incorporating fat into the base dough. To make the best use of trimmings there are a number of important factors to consider. They include the following. Age and condition All pastes contain microflora which are capable of changing the pH of the trimmings and contributing to spoilage and the generation of off-odours and flavours. Such reactions are time and temperature dependent and so it is best to have a standard length of time in which the trimmings are used and a fixed storage temperature under which they are held. If the trimmings are gathered automatically on your plant then the time will typically be too short for any significant effects. If you are keeping the trimmings for any length of time then the lower paste pH that you get contributes to pastry shrinkage. Temperature Storing trimmings at reduced temperatures before use is a useful way of maintaining lower paste temperatures for processing. If you choose to do this, you should ensure that the temperature in a given batch of trimmings is as uniform as possible; for example, by spreading them out on sheets rather than holding them in tubs for chilling. You may also need to ensure that they do not unduly dry out. Level of addition Bakers often see the re-incorporation of trimmings as a financial issue. However, in many cases they should be seen an `ingredient', as their condition can have direct impact on the quality of the paste during processing and the baked product. In some cases the `standard' paste product cannot be made without trimmings being present and it may be necessary to produce a paste at the start of a production run to act as though they were trimmings. This is especially true if the trimmings are kept for any length of time (the pH effect) or held at reduced temperatures. It is worth noting that the continued re-use of trimmings will lead to a progressive concentration of sub-components in production and this may have unwanted effects, e.g. increasing concentration of paste relaxants, which may make the paste sticky. This is usually dealt with by incorporating a `break' into the production cycle when any unused trimmings are sent to waste.

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7.4 We are manufacturing savoury short pastry products that are blocked out to shape and lids by sheeting a paste with the same formulation. We wish to increase our production rate and are considering reducing or eliminating the rest periods in the production sequence. Can you advise us on their function and any consequences that we may face if we change them? Rest periods are used in the manufacture of pastry products at different points in the production sequence. Their primary function is to allow for the modification of the rheological properties of the paste so that its subsequent behaviour is optimised and the required final product characteristics are achieved. The rheological properties of the paste are largely determined by the degree of gluten development that occurs in the mixing and machining of the paste. Following mixing and machining, the rheological properties of the paste change with resting time; the longer the resting time, the greater the rheological change (the rate of change will also be influenced by the temperature at which the paste is resting). Commonly the rheological changes are referred to as `relaxation' of the paste. Savoury short pastry products typically have less gluten development than puff paste and resting periods tend to be relatively short after mixing to make it easier to obtain the required shape and reduce the risk of shrinkage when forming (blocking) of the pastry shape. The resting period may apply to the bulk paste before dividing or the individual units (billets) after dividing. If you are going to reduce the resting period then you may need to modify the paste rheology in some other way; such as the addition of a paste `relaxant'. The most common paste relaxant is L-cysteine hydrochloride, which acts on the protein network and reduces the strength of gluten formation in the paste, which in turn, reduces the need for resting periods. Proteolytic enzymes may be used but these tend to be less effective. Caution should be exercised when using a paste relaxant in a production environment that yields high levels of paste trimmings. Since the paste trimmings will be re-used in subsequent mixings there is a gradual build-up of the level of the relaxant as production continues and a point may be reached at which problems with paste stickiness may be experienced. An alternative way of reducing paste resting times may be through the addition of extra water to the paste at the initial mixing stage. The extent to which this can be practised will depend on the capabilities of the plant to operate with a softer paste. If you take this approach then you may also have to consider a small reduction in mixing time, as higher initial water levels tend to lead to greater potential for gluten formation in the mixer. One function of resting periods not always appreciated relates to the temperature of the paste, especially in the production of pie pastry where the use of hot water is practised. In this case part of the rheological change in the paste comes from the cooling of the paste after mixing.

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7.5 What method should we use to calculate the water temperature to deliver a consistent final paste temperature at the end of mixing? Most paste preparation methods are designed to minimise energy transfer during mixing. Nevertheless, we recommend that you take into account any temperature gain that might be experienced. First, you should make a number of pastes in which you record the main ingredient temperatures ± flour, fat (not laminating fat) and water ± and the final paste temperatures that were achieved for your given mixing time. You may already have such data in your records and you could use these. Next, calculate the ingredient contributions by summing the individual contributions of weight and temperature multiplied by their specific heat capacity. For example: 100 kg flour @ 20ëC ˆ 2000  0.4 30 kg fat @ 20ëC ˆ 600  0.7 30 kg water @ 10ëC ˆ 300  1.0 Total heat input ˆ 2900 Total heat input/total mass ˆ 2900/160 which gives an expected base paste temperature of 18.1ëC Actual paste temperature was 20.5ëC Thus temperature rise was 2.4ëC The approximate water temperature for future mixes could then be calculated using the following formula: Total mass ingredients  (required paste temperature ÿ temperature rise) ÿ (Heat input from flour and fat) / Mass of water There will be small errors in the last calculation because the specific heat capacities of the ingredients used are not taken into account, but since the variations in ingredient masses will be very small for a given recipe, the method still has practical value. If you are making laminated pastries then the choice of the final mixed base paste temperature should be matched with that of the laminating fat for ease of processing. This approach will also optimise the integrity of the fat and dough layers after lamination. If the base paste and the laminating fat temperatures are not matched, there will be transfer of some heat from the warmer to the colder component but unless you are using long resting times, the practical effect will be small.

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7.6 We are making puff pastry, Danish pastries and croissant using all butter and often have problems with the processing of the pastes and feel that we do not get the best of quality from the final products. What are the best processing temperatures and conditions when using butter with such products? Butter has a positive marketing image because of its `natural' associations and is a popular fat to use in pastry making. The melting profile of butter makes it a particularly pleasing fat for incorporating into pastry products but unfortunately it is not the easiest of fats to use in processing. Butter has a relatively low melting point (BPS, pp. 38±40) and a tendency to `oil' during pastry processing, creating problems with sheeting. To overcome this particular problem you will need to ensure that the dough temperature after mixing and the paste processing temperatures are kept as low as possible. This may mean you will have to air-condition the pastry processing area. The data illustrated in Fig. 43 show how important the effect of paste processing temperature can be on the lift of all-butter pastries. It is equally important that the processing temperature is not too low because butter lacks plasticity at lower temperatures and the integrity of the layering in the pastry will be lost with subsequent loss of lift.

Fig. 43

Effect of processing at temperatures of 19 and 12ëC on puff pastry lift when using butter.

The low melting point of butter also creates problems for proving Danish pastries and croissant, so you will find it an advantage to restrict the temperature in the final prover to around 30ëC with a relative humidity of 60±75%. These conditions will help avoid flow and loss of boldness and shape. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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7.7 We would like to reduce the level of fat that we use to make our puff pastry but would like to retain pastry lift. Can you provide us with some guidance as to how we might achieve our objectives? As you know the laminating fat plays a major role in delivering lift in puff pastry and other laminated products. As soon as you reduce the ratio of laminating fat to base dough you will experience some loss of lift. However, there is some potential for making other changes to your recipe and process which may be of help. You have not provided any specific recipe or production details so we can only provide you with general guidance. The first point to make is that the potential for reducing fat levels depends on the ratio of fat to base dough and the number of laminations that you are giving the paste during processing. The general pattern is that for any ratio of laminating fat to base pastry, lift increases to reach a maximum before falling as the number of laminations increases. The loss of lift comes from the crushing and loss of integrity of the dough layers in the paste. Depending on the ratio of laminating fat to base dough and the number of laminations that you are giving then it may be possible to use less with fewer laminations to maintain pastry lift. You could investigate using a stronger flour to maintain the integrity of the dough layers but if you do then you may need to lengthen the resting times that you are using during processing. This may be difficult on a plant with a fixed throughput. With stronger flours you may find that increasing the mixing time has some positive benefit on pastry lift. This is akin to using more energy on the mixing of bread dough. Commonly pastry dough is less developed than bread dough but extending the mixing time well beyond that normally considered appropriate, e.g. from 2 to 5 and even 10 minutes, can produce a more extensible gluten network, which retains the integrity of the dough layers in the paste during sheeting. If you do lengthen the mixing time to such an extent then you may need to use crushed ice to help you control the final base dough temperature. As noted in 7.1 you may find that you can adjust the processing temperature to a lower value and still maintain lift. Any potential benefit from this type of change will be influenced by the type of laminating fat that you are using; for example see Fig. 43 which illustrates the effect of processing temperature when using butter. Lowering the processing temperature increases dough resistance to deformation and so again you may need to adjust paste resting times to avoid problems with product shaping. The addition of trimmings tends to reduce pastry lift, especially if they are being folded into the paste during sheeting. There are two options, you could reduce the overall level of trimmings that you add or you could change to mixing the trimmings into the base dough. Adding the trimmings at the mixer roughly reduces their negative impact on pastry lift by about 50%.

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7.8 Some of the short pastry cases that we make for restaurants to fill and serve have been returned to us as being `mouldy' on the base. We were surprised as we thought that the water activity of the shells was too low to support mould growth and when we examined the bottom of the pastries we can see that there is a discoloration but we do not think that it is mould. Can you identify what has caused the discoloration and how to eliminate it? We can confirm that the problem is not related to mould growth even though the discoloration has a similar appearance to mould colonies (see Fig. 44). Almost certainly the problem is related to a chemical reaction between the pastry base and the pans in which they are held before baking. The paste will be slightly acid and this accelerates a reaction between the paste and a source of iron to form iron compounds which turn dark when the pastry is baked-off.

Fig. 44

Dark marks on the base of refrigerated pastry shells.

You are storing the unbaked pastry pieces in a refrigerator overnight before they are baked and such discolorations are sometimes seen with retarded dough pieces (BPS, p. 113). It is a little surprising that you have had this problem, as the moisture content of the pastry base will be somewhat lower than that of dough, but it may be that there was some condensation on the pastry bases when they were transferred to refrigerated storage and this may have encouraged the reaction. The most obvious course of action would be to make and bake the pastry bases without refrigerating them. If this is not possible, you should look at the condition of your pans and discard any which are scratched or damaged. Alternatively, you could block the pastries into foil cases placed in the pans. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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7.9 We are having problems with the custard tarts that we make. The pastry shell is very pale coloured but if we increase the baking time, we find that the custard filling is not very stable and shrinks away from the case during storage. If we raise the baking temperature, the custard filling boils and breaks down during storage. Can you give us any advice on how to get a better pastry colour without causing problems with the filling? Too much heat input increases the loss of water from the custard causing it to shrink away from the pastry case and crack. During storage the low water activity of the egg gel allows more water to escape and it will continue to shrink and, as illustrated in Fig. 45, cracks may appear on the surface. Excessive heat input during baking causes the egg custard to boil and the gel to break down ± a process often referred to as syneresis (BPS, p. 145). The sample that you provided is just beginning to show this problem.

Fig. 45 Cracks on the surface of custard tarts.

It is always difficult to find the best combination of baking time and temperature in the manufacture of egg custards to yield the required pastry colour without compromising the filling qualities. Rather than trying to colour your pastry by changing baking conditions, you could substitute a portion of the sucrose in the paste recipe with dextrose; this is a reducing sugar and will colour more readily than sucrose. If you have no dextrose then you can use a glucose syrup, remembering to make allowance for the water in the glucose syrup. Dextrose and glucose syrup are less sweet than sucrose (weight for weight) but as you are only replacing a portion of the sucrose, you may not notice the difference in flavour. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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7.10 We are experiencing distortion of our pastry shapes. We have measured the shrinkage but find that it is not even. We have also noticed that the laminated products are experiencing some variation in product lift. What might be the causes of these problems? There are quite few causes of pastry shrinkage (BPS, p. 129) which include using a flour that has too high a protein content and over-mixing the paste, which yields excessive gluten formation in the paste or base dough for laminated pastries. Often paste shrinkage can be minimised by making resting periods longer (BPS, p. 128). If this is not possible on an automatic production line, you can consider adding a paste relaxant such as L-cysteine hydrochloride. You describe the problem as being uneven shrinkage, which suggests that it is not an ingredient or mixing problem but more likely to be related to paste processing. Check that resting times are being controlled and that you are not experiencing undue production stoppages. If such issues are not the cause of the unevenness in product shrinkage then you will need to look more closely at your paste sheeting and product cutting methods. You should examine the way that you are using paste trimmings. If you are feeding them in during sheeting, you should make sure that they are being uniformly distributed across the paste sheet. If you are adding them back at the mixing stage then they should be recycled at regular time intervals and in regular proportions to your virgin paste and ideally, they should be at a consistent temperature. When sheeting short pastes, the forces are all aligned in one direction along the length of travel down the plant, which aligns the gluten network in a particular direction, and when different shapes are cut from the sheet, the paste elasticity can cause distorted shrinkage especially with round or complex shapes. The most common way of reducing this problem is to employ a cross-pinning roller; this is a small wheel which moves rapidly backwards and forwards at right-angles to the direction of the paste sheet just before the cutter and its action helps even out the stresses in the sheet. If you have one, make sure that it is doing its correct job, if you do not have one then you may want to fit one. The process of laminating paste will even out some the stresses referred to above, though employing a cross-pinner before cutting the shapes is still a good idea. However, there is a more fundamental processing problem for you to consider, namely that after the paste has been folded and is then re-sheeted, a characteristic `w-shaped' pattern is formed in the paste (see Fig. 46). This occurs in many plants because of the characteristic `lapping' motion while the paste is still moving down the plant. The spread of the `w' depends on the number of laminations that you are giving the paste with respect to the speed of the plant. At edges of the laminated paste there can be tendency for the laminating fat to be expressed from within the layers when they are sheeted and if more laminations are carried out, it becomes re-distributed in the subsequent layering. Thus in some parts of the paste sheet there are small variations in the dough to

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fat ratios and this contributes to variations in lift and shrinkage. The extent of the variation can be assessed by sampling products across the sheet width and extending along the band to cover at least one full `w' formed of the sheet (e.g., as shown by the shaded sections in Fig. 46).

Fig. 46

Typical processing pattern on laminated pastes.

To reduce the variation you will need to reduce the length of each `w' so that they spread over a shorter distance and this usually requires the plant speed to be slowed down; such a change may not be possible, as it will reduce the plant throughput. Alternatively you may find that a change in the number of laminations that you give the paste will reduce the degree of variability that you are experiencing. Commonly lift and shrinkage go hand-in-hand so that a reduction in the number of layers may give you less shrinkage; you will need to carry out some trials to see if the loss of lift is acceptable to you. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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7.11 We have been receiving complaints from customers that our short pastry which we use for meat pie products has an unpleasant eating character that they describe as `waxy'. The comments are most often related to the base pastry in the pies. Why is this? The sensory characteristic that you describe is directly related to the type and properties of the fat that you are using. The crispness of the pie paste that you are making and its retention throughout life is of prime importance in delivering a product which consumers consider to be appropriate ± soft and soggy pastry is most often associated with `staling' in pastry terms. All bakery fats are a mixture of oil and solid fat fractions (BPS, pp. 38±9). In pastry making one of the ways in which pie pastry crispness is maintained is by using a fat with a high melting point fraction. However, if the melting point of the fat is above that of the temperature in the human mouth then it does not `melt in the mouth' and leaves behind a waxy sensation, which is most often referred to as `palate cling'. The problem is also linked with the proportion of the fat component with the high melting point, the greater the proportion of the high melting fat fraction, the greater the sensation of palate cling. This particular problem is often seen with animal fats, which are more popular in meat pie production because of their contribution to product flavour and with hydrogenated fats. When the unbaked product enters the oven the fat component begins to melt and becomes oil. Ultimately all of the solid fat fractions will become liquid. Under the influence of gravity some of the liquid fat drains into the base pastry and fills up the small voids that are present in the paste from mixing and processing. In addition to fat from within the paste there will be a significant contribution from the fat in the meat fillings that you are using. Since the fat comes from an animal source then it will have a high melting point. The combination of the two drainage processes increases the proportion of fat that is present in the base paste and so makes the problems of palate cling more noticeable in that area of the pie. Since you are unlikely to be able to make a suitable meat filling with a low melting point fat, we suggest that you change to a lower melting point fat in the preparation of your short paste, which should help reduce the problem. Reference

and YOUNG, L.S. (2000) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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7.12 We have been trying to freeze fully proved croissant for later bake-off. Can you identify the important criteria for their successful production? There is significant interest in freezing fermented and proved dough pieces with the intention that the pieces are removed from the freezer and transferred straight to the oven for baking. This would make the product very convenient to use in a range of bake-off environments. However, there are some significant technical challenges to overcome. As is well known, yeast cells die during freezing and subsequent storage. This means that when the dough pieces are removed from the oven there is no potential carbon dioxide gas production from the yeast. In addition, during storage the carbon dioxide gas that has already been evolved in the proof phase gradually leaks out of the dough. In the prover the carbon dioxide gas diffuses into the nitrogen gas bubbles trapped in the dough but during freezing and storage the diffusion process is reversed and in some cases this leads to collapse of the dough structure. The freezing of proved laminated pastries is more successful than that achieved with bread doughs. This is because the mechanism by which croissant and Danish doughs expand does not rely exclusively on the release of carbon dioxide gas but is more closely related to the pressure of steam generated during baking which is trapped between the dough layers of the paste. In broad terms this means that frozen proved laminated products still have the potential to expand and yield products of relatively `normal' appearance. The most important criteria for frozen proved laminated doughs are essentially the same as those that would apply to the product when freshly produced. The only exception may be that the pieces are not fully proved before being transferred to the freezer, as a small degree of proof may still occur in the dough pieces in their initial phase of freezing. As a general principle, if the recipe and process will make a good fresh product, it will make an acceptable one if frozen. There tends to be a small loss of product quality with freezing. It is important to ensure that the dough pieces are quickly frozen and once frozen are not allowed to defrost and be refrozen. This can be a very damaging process and is more damaging than would be the case with unproved frozen dough. Care should also be taken to limit moisture losses at any stage during freezing and storage. The products should be stored in moisture-impermeable film and if they are wrapped in bulk, e.g. in boxes, it may be necessary to overwrap the bulk container. Bulk wrapping of products is possible but be careful to avoid having large numbers of dough pieces in a box or too many boxes stacked on top of one another. The increased pressure on frozen dough pieces at the bottom of a stack can cause them to defrost and become deformed in shape.

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7.13 What characteristics should we specify for the flour that we use for making savoury and sweet short pastes? Usually the specification for pastry flours is not very comprehensive because there is no need for significant gluten formation in the paste, and recipe water levels are much lower than would be used in bread making. The general view is that soft wheat flours with a moisture content of around 14% and a protein content of 8±10% are suited to the manufacture of both savoury and sweet paste products. It is probably advisable to avoid flours with low Falling Numbers, since they are high in cereal alpha-amylase. This is because it is common practice to recycle paste trimmings in product and the trimmings may be stored for some time before being used. During the storage period the alpha-amylase will act on the starch in the flour causing the paste to soften and become sticky. This may later cause problems during paste processing. We note that you are making unbaked paste products, which you subsequently chill for a period before they are baked. Because you are making such products, you should specify that the flour has a low ash (see 2.1) or grade colour figure (see 2.12). The need for an ash specification is not related to the colour of the baked pastries but to the potential for enzyme-assisted oxidation of the polyphenols naturally occurring in wheat bran. During refrigerated storage the oxidation reaction can cause the bran particles to become dark brown or black in colour. The larger the size of the bran particles, the more evident the dark spots will appear. If the bran is finely divided then the paste may assume a grey, almost dirty appearance. The oxidation reaction will continue as long as the products are held in refrigerated storage. The same problem can occur with both savoury and sweet pastes and can also be a problem with puff pastry stored under refrigerated conditions (BPS, p. 132). Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

8 Other bakery products

8.1 We are freezing a range of unbaked, chemically aerated products including scones and cake batters and now want to include some variations using fresh fruits. We have carried out a number of trials and have a range of issues that are mostly related to the fragility of the fruit. Can you provide some advice? You have clearly recognised the main problem with using fresh fruits in that the skins of most of them tend to be susceptible to mechanical damage and this can lead to the `bleeding' of the contents into the dough or batter. On defrosting and baking, a commonly observed problem is the presence of discoloured streaks in the baked crumb. The colour of these streaks varies according to the fruit being added and the pH of the batter (see BPS, pp. 251±2 for an explanation of the pH scale). There are many naturally occurring colours in fruits which can contribute to the colour change and it can occur in many different situations (for examples see BPS, pp. 154, 168 and 234). Some of the problems with the fragility of the skin are manifest at the dough and batter mixing stage. You should try to delay the addition of fruits as late as possible in the mixing process and use as low a speed as is possible to disperse the fruits. It is possible to obtain some fruits already frozen and this makes the product more robust (provided you do not let them defrost). However, you should still try to add these products as late as possible during mixing and also get them into the freezer as quickly as possible. In your case the problem is exacerbated by the freezing and thawing process that you are employing. Fresh fruits are high in moisture, often around 60±70% or higher. As the unbaked products begin to freeze, ice crystals begin to form

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within the cells of the fruit matrix. As the temperature continues to fall, the crystals can grow very large and begin to puncture the skin. In the frozen state not much change takes place but when the products are defrosted, the ice crystals melt and leave holes in the walls of the fruits and the cell contents begin to leak out. You are not re-mixing the dough or batter and so you might expect that the problems would be limited. Indeed they are but what tends to happen is that the crumb immediately around the fruits pieces is affected and you often get discoloured rings or patches; this can be just as undesirable as discoloured streaks. To reduce the problems you should look at your freezing operation. In general, rapid freezing favours the formation of smaller ice crystals and this can contribute to a reduction in the damage to the skins of the fruit. However, you need to remember that it takes some time for the cold front in a deep freeze to travel to the centre of products and so it is not simply a case of lowering the temperature of the freezer. You will need to check the time that it takes for the core of the products to be frozen because the potential for ice crystal growth is greater in the product core. It may be that you will need to turn to using a blast freezer rather than a static one. In the blast freezer the movement of the air across the product speeds up the freezing process and will help in the reduction of the ice crystal size in the fruits. However, there are other issues to consider with blast freeizing and one of these is that the air movement can remove some of the product moisture (1±2%), so you will need to check that this does not adversely affect the final product when baked and eaten. In theory if you could stop the fruit pieces from freezing then you would prevent the formation of ice crystals and in turn, eliminate damage to the skins. Such processes are often referred to as `cryo-protection' and are often based on the infusion of materials like glycerol (glycerine). By way of an example as to how this might work, to lower the freezing point by about 20ëC (e.g., to keep the material unfrozen at ÿ20ëC, a typical frozen storage temperature) you would a need a concentration of about 50% glycerol/50% water and this would need to be infused into the fruit. A potential problem would be the change in product flavour. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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8.2 We have been asked to improve the sensory qualities of our scones and have been able to do this by a number of recipe changes. While these changes have been largely satisfactory for our plain scones, the fruited varieties we make still tend to be too dry eating. Do you have any suggestions as to how we can make them more moist eating? A common problem with fruited baked products is that the crumb of the products tends to become dry eating with extended shelf-life (BPS, p. 216). This problem is most commonly associated with the migration of moisture from the crumb to the dried fruit inclusions. Typically the moisture content of the dried fruits is less than 20% in order to restrict the potential for microbial growth during storage; this is a little lower than the moisture content of your plain scones but the sugar content of the dried fruits is very high, often around 60%. This combination of lower moisture and higher sugar in the fruit pieces means that the natural movement of water is from the crumb of the scone to the fruit pieces. Some of this moisture migration will occur during the baking process but a significant proportion will occur during storage. This moisture migration phenomenon explains why the problem is not readily observed with the fresh scones but becomes increasingly apparent during their storage. In the case of the scones that you make with pieces of candied fruits, the problem is even greater because the fruit pieces have even higher sugar contents. The most usual way to improve the eating quality of fruited products in these circumstances is by soaking the fruit pieces for a short period of time to raise their moisture contents (Cauvain and Young, 2008). When the excess moisture is drained away, some of the sugar which had been present will be lost and this double change will reduce the driving force for moisture migration. However, raising the moisture content of the dried fruit pieces is not without its potential problems: · The skins of the soaked fruit become more fragile and so there is a tendency for them to break during mixing leading to dark streaks in the crumb. · The overall moisture content of the scone and its equilibrium relative humidity can increase which increases the susceptibility of the wrapped product to mould growth. You will need to check this carefully. References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2008) Bakery Food Manufacture and Quality: Water Control and Effects, 2nd edn, Wiley-Blackwell, Oxford, UK. CAUVAIN, S.P.

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8.3 We make and bake scones on a daily basis. Recently we placed them unbaked in a refrigerator but the baked quality was poor. We used a retarder instead but we still found that the products were small in volume. Is it possible to retard unbaked scones and still produce an acceptable product? A retarder is always a better option than a refrigerator for storing unbaked items. This is because the surface area of the cooling fins in the retarder are much greater than in a refrigerator, which helps maintain a high relative humidity and moisture in the unbaked product. As a `rule of thumb' you should keep unbaked products in a retarder at as low a temperature as you can achieve without freezing the product. In practice temperatures around ÿ3ëC are quite suitable. However, your problem is to do with the loss of carbon dioxide from the dough. Even at refrigerated temperatures there is progressive reaction of the baking powder components and with virtually no gluten network in scone dough the carbon dioxide gas generated is free to escape to the atmosphere. This is why your products are losing volume when you bake them off. The rate at which the carbon dioxide gas is lost depends on the rate of reaction of the baking powder (see 2.11). Even if you are using the slower acting baking acids, long storage times will allow for significant reaction and loss of carbon dioxide gas. You may find that by increasing the level of baking powder you can restore some of the product volume on bake-off but the higher levels of residual salts will change the flavour profile of the baked product. An alterative would be to switch to using a micro-encapsulated baking acid or sodium bicarbonate. The coating delays the reaction of the baking powder components and so should help delay much of the gas production until the bakeoff period. An example of such an approach is illustrated in Fig. 47; note you cannot expect to use the encapsulated material for your fresh scone production. There are a number of commercially encapsulated products available.

Fig. 47 Comparison of carbon dioxide evolution in scones during refrigerated storage.

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8.4

What are Staffordshire oatcakes and how are they made?

Staffordshire is a region (county) in the midlands of England and the oatcake in question is a regional product. The Staffordshire oatcake should not be confused with the Scottish Oatcake, which is a biscuit (cookie). Both products use oatmeal as one of their essential ingredients but the final products are very different. The Staffordshire oatcake appears to date from the 19th century when they were baked on a hot plate over an open fire. There are a number of variations on the recipe but a typical one is as follows: Ingredient Water Strong flour Fine oatmeal Salt Skimmed milk powder Yeast Bicarbonate of soda

Parts by weight 100 30 13 1.0 1.0 0.3 0.3

As shown by the recipe above, the oatcakes are made from a very fluid batter. Blend the dry ingredients, except for the yeast and the bicarbonate of soda. Disperse the yeast in about two-thirds of the water mass, add the mixture to the dry ingredients and mix to a lump-free, smooth batter (about 5±6 minutes at a medium speed on a planetary-type mixer). Cover the batter and leave to ferment at about 20ëC in a draught-free area for 1.5 h. At the end of the fermentation period dissolve the bicarbonate of soda in the remaining water, add to the fermented batter and mix thoroughly. Deposit 9±10 g of batter per oatcake onto a greased hotplate at about 225ëC and bake for about 1.5 minutes on one side, turn the oatcake over and complete baking with about another 1.5 minutes. The final product should be covered to keep soft until ready for use. The final product may be eaten hot or cold. They may have savoury (typically cheese) or sweet (typically jam) fillings spread on them before being rolled up like a Swiss roll or folded like a wrap for serving. The products are best eaten within a short period of time after preparation. As with all hot-plate goods Staffordshire oatcakes have a high water activity, and stringent hygiene precautions should be observed in their preparation, storage and use.

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What are Farls and how are they made?

Farls are a traditional chemically aerated or soda-bread originating from Ireland. They are made in two main forms: white and wheaten, the latter being based on a brown flour (a blend of white flour and bran) which was traditionally referred to as `wheatmeal' to distinguish it from wholemeal. Traditional recipes would be as follows: Wheaten Farl (based on 100 parts brown flour) Brown flour 100.0 Salt 1.7 Malt flour 2.3 Baking powder 6.8 Fat 18.0 Sugar 13.6 Bran 4.5 White flour 36.0 Milk 90.0 Mix to a clear dough. You adjust the milk to give a smooth, easily handled dough. Scale units at 1 kg, mould round, flatten slightly with a rolling pin and cut into four quarters. Brush the top with water and sprinkle on some brown flour. Bake at around 230ëC for 15 minutes. White Farls (based on 100 parts of white flour) Flour 100.0 Baking powder 3.1 Salt 1.6 Malt flour 2.0 Fat 4.2 Milk 70.0 Proceed as for wheaten Farls. Some recipes suggest the addition of a small level of yeast, around 4 parts to boost volume. Buttermilk may be used to replace milk if a more distinctive flavoured product is required.

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8.6 We are producing a variety of finger rolls using white flour. The rolls must be soft eating and retain their softness for several days; to achieve this we are using a roll concentrate. To help us cope with fluctuations in demand we freeze a proportion of our production but find that the defrosted product is very fragile and may even fall apart. Can you help us overcome this problem? In addition to the fragility that you are experiencing, from the samples that you provided we see that they all have a very coarse cell structure and a dull, almost dark, crumb colour. The products were certainly very soft but there was no resilience to the crumb, which had a pasty eating quality. A key factor in delivering a soft and resilient crumb is the development of a fine and relatively uniform cell structure in the product; from our observations of your product this is not happening. A number of different factors will contribute to dough development; they include the choice of flour, roll concentrate (improver) and mixing conditions. Your product range is based on white flour but includes several variations with seeds and grains added. These will reduce the gas retention properties of the dough; in effect you are asking the flour you are using to `carry' some inert materials. As a basic choice you should use a flour with a protein content of 12± 12.5% (on a 14% moisture basis) with a low ash or grade colour figure (see 2.1 and 2.2). The protein is the basic building block of dough development and will contribute to the crumb resilience that your products lack. Having chosen a suitable flour, it is just as important to choose a suitable mixing time for optimising the development of the gluten network. It turns out that you are using a spiral mixer with a combination of 2 minutes mixing on slow speed and 4 minutes in fast speed. You should increase the second speed mixing stage to at least 8 or even 10 minutes. You can compensate for the slightly higher dough temperature by using a lower water temperature. From the information that you provided it would be perfectly reasonable to use a slightly higher dough temperature, as this will increase the oxidation potential of the ascorbic acid in your roll concentrate. Currently your dough temperature is only 22±24ëC, you can certainly increase this to 26±28ëC. If you experience problems with excess gassing during processing, slightly reduce the level of yeast in your recipe. If you optimise your choice of flour and dough mixing conditions, you may find that you can reduce the level of roll concentrate that you use. The components in the roll concentrate that make contributions to crumb softness are the fat, emulsifiers and some of the enzymes; currently you are relying on these to deliver a soft product but you should see these as a `top-up' to basic dough development not an alternative to it.

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8.7 We want to add freshly baked deep-pan pizza to the product range that we sell through our bakery shop. We do not want to make small quantities of dough throughout the day for their manufacture but when we try to work with a larger bulk of dough, we find that the variation in quality is too great, even when we refrigerate the dough in our retarder. What would be a suitable way for us to make the bases? One way of spreading your pizza production throughout the day is to make a larger dough which you split up after mixing and process into pizza base shapes ready for proof. You will need to have a reasonable number of pans available. Preferably these should be ones that you can stack one inside another but if you do not have this type available then you can use a series in thin metal or plastic sheets, which are placed on top of one set pans to allow you stack others on top. The method that we are going to suggest requires you to have access to both a prover and a retarder (though not at the same time) and you will need to be able to fit the production into your existing production plan, or to be able to modify it to accommodate the new production. After you have prepared the bases and loaded them into the pans you should put them into the prover; we suggest that you use temperatures in the region of 25±35ëC and certainly no higher. Depending on your yeast level you will need to give the dough pieces 1±2 h proof and it is important to maintain a reasonable humidity level, say around 70%. You can stack the pans for proof if you wish, though it is not critical at this stage, it all depends on how much space you have available. After the bases have been proved they should transferred to the retarder for cooling and storage. The retarder temperature should be in the range ÿ3 to ‡3ëC and you should stack the pans on top of one another to keep the humidity high enough to prevent skinning. When you need bases for baking you simply take a base from the retarder, spread on the tomato sauce, add the topping and transfer to the oven for baking. The proved pizza bases cool quickly in the retarder because they are thin and the cool temperature in the retarder limits any further gas production but the method gives you ready proved pizza bases that can be turned into the baked product in a few minutes. Since you are using metal pans you need to make sure that they remain in good condition in order to avoid any problems with the dough reacting with the metal (BPS, p. 113), though probably the retarded storage time is too short for this to be an issue. You may find it helpful to have some small holes in the base of your pans to allow trapped steam to escape and avoid blisters and hollows on the base (BPS, pp. 81±2). Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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8.8 What are the key characteristics of cake doughnuts and how do they differ from other types of doughnut? The two main classes of doughnuts are those based on making a low viscosity cake batter and a fermented dough. The cake doughnut is made by depositing the batter directly into the hot oil for frying. The most common form of cake doughnut is ring-shaped and they are often topped with a coloured and flavoured icing or glaze (see Fig. 48). The most common form of the fermented doughnut is a ball or finger shape with jam or jelly injected into the shape and the outer surface dusted with fine sugar crystals. In formulation terms cake doughnuts tend to have a higher sugar level than fermented forms and use baking powder as the sole aerating agent. Overall cake doughnuts tend to be denser and have a less well defined cellular structure than fermented doughnuts; the eating qualities are distinctly `cake-like' with a less chewy eating character. The choice of flour is important for the manufacture of cake doughnuts and it is common practice to use lower protein flour than with fermented doughnuts. Often the flour will have a reduced particle size (BPS, pp. 28±9) and may have had some post-milling treatment; i.e. heat-treatment (BPS, pp. 30±1) or chlorination (BPS, pp, 32±3) in those parts of the world in which its use as a flour-treatment agent is still permitted. It is important to control the release of carbon dioxide gas by the baking powder reaction in cake doughnuts. The generation of carbon dioxide is not only part of the expansion mechanism but is also part of the means of controlling the degree of fat absorption during frying. The pressure from the expanding gases prevents the absorption of fat as long as the gas cells in the dough are intact (BPS, p. 112). If the carbon dioxide is released too soon during frying, the final product lacks volume and has a dense and `fatty' eating character. If the carbon dioxide is released too late then the product will often have a distorted shape.

Fig. 48 Doughnut types: left, fermented; right, cake.

Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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8.9 We have been producing a range of cake doughnuts that are iced with various flavoured coatings. In order to cope with peak demands we have taken to freezing a quantity of the products. We have observed that progressively during storage a crystalline growth appears on the products. When they are defrosted, the growth disappears. Can you identify why this happens? The growths that you are describing are most likely due to the formation of sucrose hydrate on the surface of the icing (Cauvain and Young, 2008). During the freezing of the iced doughnuts freeze-concentration can occur in the icing. The presence of a high level of sugar in the icing considerably depresses the freezing point of the mixture of sugar and water. As the temperature begins to fall, some of the water in the icing begins to form ice crystals and is no longer available to keep the sugar in solution, the concentration of the remaining sugar solution is increased and the freezing point is further depressed. This cycle of action continues until the temperature of the freezer is reached. In the icing there are two processes taking place: one is crystal nucleation and the second is crystalline growth or propagation. Nucleation is the coming together of two or more sugar molecules in the appropriate arrangement for crystal growth. However, for crystal growth to occur, the sugar molecules must be sufficiently mobile to aggregate. The freeze concentration effect taking place in the icing probably means that there is a concentrated and unfrozen sugar solution even when the products are placed into storage and so the potential is there for crystal growth to occur. First we suggest that you look closely at your initial freezing and frozen storage regimes. Try to make sure that the temperature to which you first freeze your products is as close as possible to that at which they will later be stored. Keep transfer times between the initial and storage freezer as short as possible and minimise any opportunities for moisture losses before over-wrapping. This type of problem is exacerbated by any periods of defrosting and refreezing during storage because the rate at which the products will re-freeze in storage will be considerably lower than used initially. A slow reduction in temperature favours crystal growth and the retention of more water in the overall structure of the growth. While the growths may disappear on defrosting, it is not unusual to be left with localised white spots, pitting and streaking on the icing surface. You can try re-formulating the icing by adding more glucose (BPS, p. 236). References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P. and YOUNG, L.S. (2008) Bakery Food Manufacture and Quality: Water Control and Effects, 2nd edn, Wiley-Blackwell, Oxford, UK. CAUVAIN, S.P.

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8.10 We have been approached by some of our customers asking if we can make gluten-free breads. How could we do this and can we match the quality of our regular bread products? In the manufacture of gluten-free breads it is not possible to use the glutenforming proteins that are present in wheat, rye and barley to create a product structure and so greater emphasis is placed on the structure-forming properties of starches from different sources. Because gluten is not formed in the product, the final structure is `un-bread-like' being friable and lacking chewiness. There are many different forms of starch which are used in the manufacture of gluten-free products; including highly refined wheat starch, rice, potato, maize and tapioca. Creating and controlling the product bubble structure relies heavily on the presence of suitable stabilisers commonly based on emulsifiers and gums, while non-wheat protein sources contribute to the physical strength of the structure, with egg and milk proteins being the most commonly used components. Gluten-free breads are commonly aerated by yeast, sometimes in a mixture with baking powder. Cauvain (2008) gives an example of a gluten- (wheat) free bread as follows: Sorghum flour Maize starch Yeast (compressed) Salt Skimmed milk powder Sodium carboxy methyl cellulose Dried egg albumen Water

Parts 50.0 50.0 8.3 2.1 12.0 1.0 15.0 80.0

The batter may be deposited into small bread pans at 460 g, proved for 45±60 minutes and baked. There will be no oven spring so the batter can be proved to the top of the pan. Rice starch or flour may be used instead of sorghum flour. Sugar (4 parts) and oil/fat (1.5 parts) may also be used The production of gluten-free breads is a specialist activity and you may find it easier to use one of the many prepared mixes that are commercially available rather than make your own product from scratch. These mixes have the advantage of eliminating the need to source less common ingredients and the starch components can be guaranteed as gluten-free. If you are going to make gluten-free products in your bakery, it is very important that you are aware of the risks of cross-contamination and you should seek specialist advice on how to set your bakery up for the manufacture of such products. Reference

(2008) Other cereal in breadmaking. In (eds S.P. Cauvain and L.S. Young), Technology of Breadmaking, 2nd edn, Springer Science+Business Media, LLC, New York, NY, pp. 371±388.

CAUVAIN, S.P.

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8.11 We are not getting the quality of finish that we would like from the fondant we are using, often the finished products lack gloss. Can you give us some tips on how to improve our use of the fondant? The lack of a gloss finish with your fondant suggests that you are over-heating it when preparing it for use. The temperature to which fondant is heated before use is very important; to get a gloss you should only heat the fondant to about 38ëC. Over-heating the fondant results in the formation of larger crystals when it cools and these do not reflect the light so well ± hence the product looks dull. To get the best results you should heat the product carefully to the required temperature with continuous stirring. If the product is too thick to work with then you should adjust the consistency with a stock or `simple' syrup (see below for the formulation). Once the fondant has reached the required temperature, hold it at that temperature using a water bath and avoid fluctuations in temperature as much as possible. Keep the fondant pot covered when not in use and scrape down any crystals which may form above the fondant bulk. Avoid letting a skin form on the top of the fondant bulk. Try to heat only sufficient fondant for your particular needs in a day and avoid having large quantities of fondant scraps. While it is perfectly possible to re-use these, they do contribute to the dullness of the finish. If you do have a large quantity of scraps, try to find an alternative use for them, such as incorporation into fillings and creams where the appearance of the finish is less critical. Always use a stock syrup to adjust the consistency of the fondant, never use water alone. The syrup should be added a little at a time with stirring to ensure full dispersion. Try to avoid making the syrup too runny and having to add fresh fondant stocks. The formulation for typical stock syrup is as follows: Sugar Water Glucose Cream of Tartar

Parts 100 83 17 0.15 (optional)

The glucose is to limit the re-crystallisation in the syrup. Bring the mixture to the boil and remove any scum which forms, as this will contain impurities that may encourage re-crystallisation. Cool the syrup, strain to remove any sugar crystals that may form and store in covered containers ready for use.

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8.12 Can you tell us something about Chinese steamed breads and their production? We make our standard breads using the Chorleywood Bread Process, would we be able to make these products using this process? Chinese steamed breads, or `man-t'ou', are known to have been eaten in China for around 3000 years. It is a staple food of the wheat-growing areas of northern China but is consumed throughout the country, commonly warm at breakfast, though they are often available at all mealtimes. They are known in many other countries throughout south-east Asia and increasingly further afield. It derives its common name, steamed bread, from the characteristic method of steaming (rather than baking), which produces a round, roll-sized product with a smooth, white, thin crust. Externally the surface should be free from blemishes. Internally the products have a close cell structure, bright crumb colour and a distinctly chewy eating character. The product is mainly eaten plain, though sweet and savoury fillings are used. They are eaten warm. The tradition is for the product to be freshly made, often using overnight fermentation so that the product is ready for breakfast. A common recipe and method for their traditional production is based on a mixture of 100 parts of a low protein breadmaking flour, 0.5 parts yeast and 50± 55 parts water; there is no salt in the recipe. The dough is thoroughly mixed (commonly by hand) and fermented for 3±16 h. The yeast level may be adjusted to use less for the longer fermentation times. Should the dough soften excessively during the fermentation time then more flour may be added, the dough re-mixed and then allowed to stand for about another 15 minutes before processing. After fermentation the bulk dough is divided into 100±200 g pieces and either moulded round or to a rough cylindrical shape. A short proof period of about 15 minutes is given before transferring the pieces to the steamer where they are steamed for 15±20 minutes suspended on wire mesh trays. The specific volume of the final product is modest, typically around 2.0 ml/g which is much lower than that of UK pan breads (around 3.5 ml/g). Cauvain and Huang (1986) studied the application of the Chorleywood Bread Process (CBP) to the production of Chinese steam bread and found that it was possible. Cauvain and Young (2006) published the following details: Ingredient Untreated flour Compressed yeast Water Ascorbic acid

% flour weight 100 1 60 0.0075 (75 ppm flour weight)

· The dough was mixed at atmospheric pressure to a total of 11 Wh/kg dough in the mixer. · Final dough temperature 30  1ëC.

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· · · ·

Scale at 100 or 200 g. Mould round. No intermediate proof. Prove at 40ëC and 85% relative humidity; 15 minutes for 100 g and 30 minutes for 200 g pieces. · Steam for 15±20 minutes. Cauvain and Huang (1986) found that some of the `conventional' CBP recipe and processing parameters were not suitable for the manufacture of Chinese steamed bread. One of the reasons for these findings was probably related to the low product-specific volume that was expected. In summary their key findings were: · The optimum flour protein was around 10% (on a 14% moisture basis); higher protein flours tended to cause product collapse. · High level of ascorbic acid caused product collapse. · The addition of fat caused small depressions on the product surface. · Work inputs of less than 11 Wh/kg resulted in cavities under the top surface of the product, while higher levels caused product collapse. · High cereal alpha-amylase caused dough handling problems and product collapse. In summary their findings showed that Chinese steamed bread made by the CBP required little by way of addition of dough conditioners or bread improvers to deliver the required product quality. Most steamed bread products call for a white flour essentially free from bran particles which would otherwise spoil the appearance of the crust. However, not all steamed breads are based on white wheat flour; one variation is made using a proportion of buckwheat flour, which yields a product with a distinctive flavour and even more distinctive purple colour. References

and HUANG, S. (1986) Chinese steamed bread. FMBRA Bulletin No. 4, Campden-BRI, Chipping Campden, UK, pp. 151±158. CAUVAIN, S.P. and YOUNG, L.S. (2006) The Chorleywood Bread Process, Woodhead Publishing Ltd, Cambridge, UK. CAUVAIN, S.P.

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What is cinnamon twist bread and how could we make

The distinctive feature of cinnamon twist bread is that it prepared by spreading a cinnamon-based filling onto a sheet of bread dough and then rolling the dough up like a Swiss roll. The end result is a loaf which when cut open has a `swirl' of filling from the rolling process. We have traced a recipe and method for this unusual product that you could use as a basis for some trials Dough Ingredient Bread flour Yeast Water Liquid whole egg Honey Salt Skim milk powder Sugar Fat

% flour weight 100.0 5.0 55.0 10.0 4.0 1.9 6.0 6.0 10.0

Filling Based on a dry mix of caster sugar and cinnamon in the ratios of 7:1. Processing details · Mix the dough and ferment for 1 h at about 25ëC. · Scale the bulk dough into units of 2±2.5 kg, mould round and rest for about 10 minutes. · Sheet the dough pieces to 10mm thickness, brush with butter or margarine and sprinkle on the filling. · Roll up the dough forming a long cylinder which can be cut into the length required for your pan. We suggest that the finished weight should be around 250±280 g. · Prove for about 40 minutes. Avoid full or over-proof as the dough softens and is liable to flow over the sides of the pans and lose its `loaf' shape. · Bake at about 190ëC for 25±30 minutes. The high sugar content will give a dark crust colour. If this is too dark you could cut back on the added sugar, though this may affect the sweetness of the product.

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8.14 We have been experimenting with retarding fruited rolls and buns. We find that the smaller products are quite satisfactory but loaves made using the same formulation and baked in pans have `stains' around the fruit pieces and a darker crust colour than we would like. Can you please advise us on how to cure these problems? It is not unusual to see variations in quality when different forms of retarded products are made with the same dough formulation. The differences arise because it takes longer for the heat to be extracted from the centre of large dough pieces than it does from smaller ones. In your case the pan loaves will cool and warm more slowly in the retarding and proof phases respectively. A key stage is the retarding phase, which is intended to considerably slow down yeast activity in the dough so that it may be stored for extended periods before later warming and baking. In addition to yeast activity there will be significant enzyme activity in the dough. In particular the amylase enzymes will be reacting with the damaged starch in the flour and converting them to maltose. With the long storage periods that characterise retarding there is significant potential for such activity. The maltose that is produced effectively increases the level of sugars that are present in the dough and this gives increased Maillard browning (BPS, p. 98), which is the cause of the darker crust colour that you see. To minimise the crust colour increase you should have the retarding temperature as low as possible, we suggest temperatures around ÿ4ëC. The dough will not freeze because the presence of salt and sugar depresses the freezing point. You will have to start your proofing phase a little earlier to allow for the slightly colder dough. If the above suggestions do not work then you may have to make your bun loaves using a formula with a slightly lower sugar level. Another change which takes place in your products is the gradual seepage of sugars from the fruit into the surrounding dough. This occurs because the fruit and the dough have different moisture contents and water activities; first water moves from the dough to the fruit pieces, then the sugars dissolve and the sugar solution diffuses out of the fruit. The sugars coming out of the fruit are different from the sucrose that you have added and, when they are heated, they go brown at lower temperatures ± hence the stains on the side of the loaves where the heat inputs are greater. This problem will be difficult to eliminate but again lowering the retarding temperature will reduce the rates of moisture transfer and diffusion of the sugar solution. Alternatively you could wash the fruit to reduce its sugar content, drain off the excess moisture and allow the fruit to dry before using it. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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8.15 We are retarding rolls in our retarder-prover and find that they lean to one side and lose weight during storage. Can you advise us as to how to cure these problems? All dough products lose some moisture during storage during retarding and this accounts for the loss in weight that you are experiencing. The weight loss occurs because the relative humidity of the dough pieces (typically around 95%) is greater than that of the atmosphere in the retarder and there is evaporation of moisture from the dough surface. To maintain a high relative humidity in the retarder chamber the evaporator coil surface is much larger than in standard refrigerators. This reduces the likelihood of moisture in the retarder chamber condensing out and forming ice on the cooling coils. Moisture that condenses lowers the relative humidity of the chamber atmosphere and increases the differential between the chamber air and the product so that the latter will continue to lose moisture in an attempt to achieve equilibrium. Moisture losses from retarded products can be reduced by lowering the cold storage temperature. We would recommend that you reduce your retarding temperature to below 0ëC but keep it above ÿ5ëC, e.g. around ÿ3ëC, to minimise weight losses. You may find it necessary to give a slightly longer proof period to compensate for the slightly colder dough but the difference should only be a few minutes. Lower yeast levels also lead to lower weight losses from the dough pieces, whatever the storage temperature used. If you do decide to use lower yeast levels then you will certainly need to compensate by increasing proof times after retarding. Another factor that contributes to weight losses is the movement of air across the product. Commonly air velocities are low in retarders and usually they are just sufficient to maintain uniformity of the chamber air temperatures. High air velocities will lead to dehydration of the dough pieces though once again this can be reduced using lower retarding temperatures and lower yeast levels. The problem that you have with dough pieces leaning is linked with the weight losses that you are experiencing. If you look closely you will notice that the dough pieces lean towards the air inlet. As the air enters the chamber and impinges on the dough piece it drives off a little moisture from the first surface that it encounters but drives off relatively little moisture from the surfaces of the dough on the other side of the roll ± just as we notice less air movement when we stand in the lee of a hill on a windy day. The dehydrated surface loses its flexibility and cannot expand when carbon dioxide gas is produced and even with the low levels generated in the retarder the dough pieces expand in a lopsided fashion; i.e. leaning towards the air inlet. Once again lowering the retarding temperature should reduce this problem. Further reading

(2007) Dough retarding and freezing. In (eds. S.P. Cauvain and L.S. Young) Technology of Breadmaking, 2nd edn, Springer Science + Business Media LLC, New York, NY, pp. 175±206.

CAUVAIN, S.P.

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8.16 We want to extend the mould-free shelf-life of our flour Tortilla (Fig. 49) but when we try to make the dough more acid we have processing problems. What options could we consider for achieving our aim? Acidifying the dough is sufficient for inhibiting the development of rope (see BPS, p. 86 and 3.6) and is a common way to extend mould-free shelf-life, especially when there are preservatives present in the recipe. The magnitude of the combined effect depends on the particular pairing used. The combination of potassium sorbate and an acid is more effective as an anti-mould agent than using calcium propionate and acid. Usually you would use potassium sorbate as an anti-mould preservative in the manufacture of cakes but not in fermented products because of the inhibiting effect that it has on yeast activity. Since your products are powder-raised then it is perfectly possible to use potassium sorbate. Lowering the pH of the dough has an effect on its rheological properties and this is the reason for some of your processing problems. At low pHs the elasticity of the dough often increases and this can make shaping more difficult. One way around this problem would be to use an encapsulated acid which has no significant effect in dough mixing and processing. Fat is normally used as the encapsulating agent and in the oven the fat will melt, releasing the acid. In this form the acid is still effective at lowering the final product pH and so you still get the combined benefit of preservative and low pH. Another way of lengthening the product mould-free shelf-life is by lowering the water activity of the product. Once again the combination of lower water activity and potassium sorbate is more effective than either approach on its own. Another way to lower the water activity would be by adding glycerol or some other polyol (see 9.11)

Fig. 49 Flour tortilla.

Reference

and YOUNG, L.S. (2000) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

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8.17 In reading about the manufacture of hamburger buns we see references to the pH and TTA of the brew. What do these terms mean? When are they used and what is the purpose of controlling them? In the manufacture of hamburger buns it is common practice to pre-ferment part of the flour with water and yeast before adding the mixture to the remaining ingredients for mixing into the final dough and processing into buns. This prefermentation stage has a number of advantages including the modification of the rheological properties of the final dough which assist in improved processing and flow of the shapes in the pan. The other important change that occurs as a result of the pre-fermentation stage is the development of acidic flavour notes in the final product. During pre-fermentation the acidity of the dough falls and so the pH (BPS, pp. 251±2) of the brew falls. However, the measurement of pH alone does not provide the necessary information on the formation of acids in the brew and it is common practice to measure the total titratable acidity (TTA). The TTA test measures both the dissociated acids (which directly impact pH) and the undissociated acids under specified conditions and provides relevant information on the expected flavour profile in the final baked product. In broad terms the two properties are related in that the TTA of a brew increases as its pH falls. However, one of the problems associated with using pH as the sole predictor of the degree of fermentation in the brew is that some of the ingredients that may be used in baking have a buffering effect in the brew. The presence of buffering agents means that, even though the amounts of organic acids in the brew increase, the hydrogen ion concentration (pH) does not significantly decrease. In a number of parts of the world the mandatory or voluntary addition of calcium carbonate to wheat flour introduces a significant buffering agent. It is worth noting that changes in brew pH and TTA are not exclusively controlled by bakers' yeast fermentation. The presence of lactobacilli, and other less desirable microorganisms in the flour can make significant contributions to the generation of organic acids. Regular cleaning out of the brew tanks is essential. Unexpected changes in TTA in the brew can often be an indicator of the presence of high levels of unwanted microorganisms, which can be an important indicator of the need to clean out the brew system. Reference

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

9 What is/are/why/how?

9.1 What is meant by the term `modified atmosphere packaging' and how can we use this approach in the production of baked products? Modified atmosphere packaging is the term used to describe the way the atmosphere surrounding a product in its packaging material is changed from air to some other combination of gases in order to extend product mould-free shelflife (mfsl). It is also known as `gas flushing'. The gases employed are usually carbon dioxide or nitrogen, commonly as a mixture of the two. This form of preservation is suitable for many types of baked product and, whilst it has cost implications, it does not affect product flavour, aroma or appearance, and it does not need to be declared as an ingredient on the product label. Carbon dioxide has an inhibitory effect on the growth of aerobic microorganisms such as moulds. The greater the concentration of CO2, the greater is the preservation effect (Pateras, 2007). It can give up to 400% additional shelf-life days. It is often used for higher value products. It is known that some moulds are more affected than others, e.g. those present on shorter shelf-life products such as breads are less sensitive than those present on cakes with lower equilibrium relative humidity (erh). Figure 50 shows the typical increases in mould-free shelf-life for different bakery products at different concentrations of CO2. Because the packaging atmosphere is gaseous, it has the advantage of protecting all surfaces of the product. The inert gas, nitrogen, can also be used as the flushing gas, though it does not exhibit any anti-mould activity. It is the fact that the nitrogen replaces the oxygen and causes the atmosphere surrounding the product to become anaerobic that inhibits mould growth. In this case the percentage of nitrogen in the

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Fig. 50 Increase in mould-free shelf-life of various bakery products packaged in different concentrations of CO2.

headspace must be at least 99% by volume and great care must be taken with the seals and wrapping material to ensure that no oxygen (as air) can enter the pack. Nitrogen is more commonly used along with CO2 to prevent the package collapsing as CO2 is absorbed into the product. Whether using carbon dioxide or nitrogen, care must be taken over the integrity of the seals of the packaging and the permeability of the packaging material, which is often laminated. If longer increases in shelf-life are required then a gas-impermeable material should be used. Reference

(2007) Bread Spoilage and Staling. In (eds S.P. Cauvain and L.S. Young) Technology of Breadmaking, 2nd edn, Springer Science + Business Media, New York, NY, pp. 51±91.

PATERAS, I.M.C.

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9.2 We have seen references to the Milton Keynes Process but can find very little technical information on the process. Can you tell me what it is (was) and how it is (was) used? There is relatively little technical literature on the Milton Keynes Process (MKP). Launched in 1995 it was a patented process (Anon, 1995) based on the production of part-baked breads of many different sizes, including pan breads, but differed from other part-baked products of the time in that an extended ambient shelf-life of 5±12 days before second baking was claimed. The process took its name from the city in the UK in which the part-baked bread products were manufactured (Grindley, 1996). The process was evolved by a consortium of four companies; a retail baker, a plant baker, a machinery manufacturer and a bread improver company (Bent, 2007). Pan breads were mixed using CBP-compatible mixers, while oven bottom and French sticks were prepared with a spiral-type mixer. The dough recipe was essentially the same as would be used with CBP and no-time dough making with the addition of a suitable enzyme for retaining crumb softness in the bread. There were no special aspects of dough processing, steam was used in the initial bake and crust colouration was kept to a minimum in the first bake. Immediately after leaving the oven the warm products in their pans or on trays were transferred to be cooled under vacuum. Using this technique cooling times were reduced for all product sizes. After cooling and depanning, the products were sprayed with a preservative solution to help achieve the 5±12 days mould-free shelf-life. It was claimed that the preservative was volatilised during the second baking stage. It is well understood that bread staling is reversed by a second bake (Pateras, 2007). However, in order to fully refresh the products, the core temperature must exceed 60±65ëC and the rate of staling after the second bake is considerably faster than after the initial bake. In practice this meant that consumers who were used to purchasing baked products which took 3±4 days to become unacceptably firm were faced with the MKP product which could take as little as 3±4 hours to reach the same state. As a consequence the level of sales of bread products baked in the retail stores fell markedly and, after an initial fanfare of excitement, the process slipped quietly into history. References

(1995) Manufacture of Baked Farinaceous Foodstuffs, Patent WO 95/30333. (2007) Speciality fermented goods. In (eds S.P. Cauvain and L.S. Young) Technology of Breadmaking, 2nd edn, Springer Science + Business Media, New York, NY, pp. 245±274. GRINDLEY, E. (1996) Made in Milton Keynes. Bakers' Review, January, 16±17. PATERAS, I.M.C. (2007) Bread spoilage and staling. In (eds S.P. Cauvain and L.S. Young) Technology of Breadmaking, 2nd edn, Springer Science + Business Media, New York, pp. 275±298. ANON

BENT, A.J.

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9.3 Can you explain the principles of vacuum-cooling of baked products and its potential applications? The vacuum cooler comprises a sealable chamber in which the internal pressure can be reduced to a level considerably lower than atmospheric pressure. When the pressure inside a closed vessel is lowered and maintained below atmospheric pressure, the temperature at which water boils is lowered considerably. This is because a liquid boils when its saturated vapour pressure is equal to the atmospheric pressure. For example, in the natural world water boils at progressively lower temperatures as the height above sea-level increases. The impact of reduced pressure on the boiling point of water can be considerable; for example, if the pressure is reduced to half an atmosphere (i.e., 0.5 bar), the boiling point falls from 100 to around 80ëC. Since evaporation losses play a major role in cooling baked products, holding the products at lower pressures to extract the latent heat considerably reduces the cooling time required. For example, Wiggins and Cauvain (2007) compared the core temperature of loaves cooled conventionally with those subjected to vacuum cooling and showed that that the times taken to achieve a temperature of 25ëC were about 100 and 10 minutes respectively. It should be noted that the vacuum cooling conditions will vary according to the type of product being cooled. There are a number of different points to consider. The first is that even though the temperature at which the water boils has been considerably lowered, the rate at which moisture leaves the centre of the product will be affected by the product dimensions. Heat (and moisture) can only be lost from the surface of the product and it will always take longer for the evaporation front to reach the centre of the product. In practice this can mean a significant differential in moisture losses between the product surface and its centre. For crusty bread products this may be acceptable but this will not be the case for pan breads. This effect may well have been one of the contributing factors to the failure of the Milton Keynes Process (see 9.2). Some bakery products can benefit the application of vacuum cooling. This is especially true for products with `delicate' structures, which are difficult to handle at the end of the baking processes but are key to final product quality; two examples are Panettoni and malt breads. One of the claimed benefits for the application of vacuum cooling is that the normal baking time can be reduced because of the contribution it makes to the physical stability of the baked product structure. This advantage may be negated by the likelihood that overall moisture losses from vacuum cooled products may be higher than with conventional cooling. Reference

and CAUVAIN, S.P. (2007) Proving, baking and cooling. In (eds S.P. Cauvain and L.S. Young) Technology of Breadmaking, 2nd edn, Springer Science + Business Media, New York, NY, pp. 141±174.

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9.4 I have heard the terms `glycaemic index' and `glycaemic load' used when describing bakery products. What are they and what is the difference? Both terms are used to describe the way food is digested by the body. The glycaemic index (GI) of a food measures its immediate effect on blood glucose levels over a short period of time following ingestion of a food. It is the blood glucose profile of 50 g of available carbohydrate in a test food compared to 50g of glucose. On the Index, glucose is taken as 100 since it causes the greatest and most rapid rise in blood glucose ± all other foods are rated in comparison to glucose. In layman's terms GI is a measure of how quickly a particular food triggers a rise in blood sugar level and the rate at which blood sugar level drops off. It is a physiological measure of how fast, and to what extent, a carbohydrate food affects blood glucose levels. The type of carbohydrate in a food influences blood sugar levels. GI has its limitations in that it can only be accurately measured from a blood sample. It only measures the `available' carbohydrate, and ingredients that reduce digestibility, such as resistant starches, are not taken into account, as they are digested later in the lower intestine. Processing can change a food's GI value. Fat, protein and a lower pH in a food all reduce its GI. The table below shows the GI categories that foods can be placed in (the sugar glucose has a ranking of 100). GI

Rating

Low Medium High

<36 36±50 >50

The glycaemic load (GL) of a food is an expression of how much impact or power the food will have in affecting blood glucose levels. It is calculated by taking the percentage of the food's carbohydrate content per portion and multiplying it by its GI value: GL ˆ

% carbohydrate per portion  GI 100

GL is thus a measure that incorporates both the quantity and quality of the dietary carbohydrates consumed. For example, the GL of one slice of seeded loaf is only 8. In contrast, a slice of brown or white bread has a GL of 16. This means that ordinary brown or white bread will spike blood glucose levels (higher GL), and the seeded loaf will not (lower GL). In addition, the GL of a roll (equivalent to two slices of bread) is more than 20, and that of a bagel (equivalent to three slices of bread) is more than 30. In simple terms the GI

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indicates the extent to which a food will raise blood glucose levels, whereas the GL is the `power' or `push' behind the GI. Comparison of the GI and GL for some typical bakery foods. Product White bread Wholemeal bread Crackers Shortbread biscuit

Carbohydrate concentration

GI

45 47 60 68

40 50 80 55

GL (typical portion) <70 (1 slice) <5 (1 biscuit) <5 (1 biscuit)

Satiety is another term linked to GI; it is a measure of the time a food gives us a feeling of `fullness'. A food which is high in carbohydrates with low GI takes longer to digest and so gives the feeling of `fullness' for a longer period of time. The term has come to the fore recently with the concerns over obesity and the drive towards healthier eating. An index of satiety has been drawn up (Holt, 1998) and examples are given below (compared with white bread with an index of 100) but the credibility of this approach has yet to achieve universal acceptance. Product Wholemeal bread Cake Cookies Croissant Crackers

Reference

Satiety index (%) 157 65 120 47 127

(1998) Diabetes Interview, May, pp. 1, 12±14. www.mendosa.com/satiety.htm

HOLT, S.

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9.5 What are pro- and pre-biotics and how can they be used in our bread products? A probiotic is a living microorganism considered beneficial to the human body, particularly in the functioning of the gut. These beneficial bacteria are found naturally in various fermented foods, e.g. yoghurt, but do not survive heat and so would be destroyed by the high temperatures employed in baking and so have no significant role in the technological formulation of bakery products. Prebiotics are non-digestible dietary fibres that provide a food source for beneficial bacteria and enhance the benefits of probiotics. Bifidobacteria (good bacteria) contribute to health by enabling the digestive system to produce short chain fatty acids that lower the pH in the digestive system. This in turn helps to increase the absorption of the minerals calcium and magnesium in the body. The intestine contains 70±80% of the body's immune cells and about the same number of neurons as in the spinal chord. Prebiotic dietary fibres are found naturally in plants and can, in some cases, be produced by enzymatic conversion from sugar. They pass unaltered through the stomach, and are fermented by gut microflora and selectively stimulate the growth and activities of bacteria. The high molecular weight sugars referred to as oligosaccharides dominate this category and they include fructooligosaccharides (FOS), inulin, arabinogalactans and lactulose. FOS and inulin are particularly favoured by lactobacilli and bifidobacteria in the gut. Lactobacilli can convert sugars into lactic acid, inhibiting the proliferation of certain harmful bacteria, while also lowering the pH of the gut. Bifidobacteria convert dietary fibre to lactic acid Inulin and oligofructose are made from chicory root (good source) and are also found in artichokes, leeks, onions and garlic. In their pure form they have a clean taste and are hygroscopic (prevent water loss) and when used in cereal bars help keep them soft-eating. They increase beneficial bifidobactria in the colon by creating a barrier effect thus reducing the potential impact of `bad' bacteria such as salmonella and clostridia. The use of prebiotics, such as inulin, in bread products has been part of a growing market of health-promoting speciality products. They can be incorporated at low levels in bakery formulations. The structure and colour of the product into which they are incorporated should be monitored. If you are going to use prebiotic ingredients you should check that they are approved for use in your geographical location. You should also check the validity of any health claims that you make and whether they are permissible for use in marketing and promoting any products containing prebiotics. Further reading and information

(2006) The Functionality of Probiotics and Prebiotics: Bringing life to functional foods and beverages. http://www.naturalproductsinsider.com/articles/06oct16feat02.html MYERS, S.

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9.6 Can you please explain the difference between hydration and hydrolysis? What is their relevance to the manufacture of baked goods? Hydration and hydrolysis refer to reactions that involve water. Hydration is the addition of water to a substance while hydrolysis indicates those chemical changes in which water reacts with a substance to yield two or more products. Hydration is the more familiar term in baking because it is a necessary first step in the formation of doughs and batters. In bread making the hydration of the flour proteins during mixing aids the formation of the di-sulphide bonds that are an important element of dough development. Hydration of the flour proteins also occurs in the manufacture of biscuits, cakes and pastries but in the case of these products, the development of a gluten network is limited by recipe and process factors. The processes of hydration and hydrolysis are best understood by considering the reactions between water and starch in baked products. When starch is mixed with water the granules become hydrated; that is water penetrates the granules and this is part of the process related to the water absorption capacity of the flour (BPS, p. 27). In wheat flour, it is the damaged starch which is most rapidly hydrated and absorbs about four times the water that will be absorbed by the undamaged granules (Stauffer, 2007). The hydration of starch leads to hydrolysis. However, in order for the hydrolysis to occur with wheat starch both alpha- and beta-amylase enzymes need to be present. In most cases both enzymes are present and so are able to catalyse the hydrolysis reaction. The full hydrolysis reaction may be described as follows: Starch + water (in the presence of amylase enzyme) yields glucose + fructose The above reaction is a simplified version of a complex reaction that takes place in the manufacture of baked products. The heat that is introduced during baking inactivates the enzymes and overall process times are too short for the full conversion of all of the starch to sugars. This is just as well because starch is an important component in baked product structure, even in bread with its extensive gluten network. A substantial part of the starch is not hydrolysed and in baked products there are a series of substances that are intermediate between starch and sugars; most notable of which are the dextrins, which can give rise to problems with bread quality. References

and YOUNG, L.S. (2001) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK. STAUFFER, C.E. (2007) Principles of dough formation. In (eds S.P. Cauvain and L.S. Young) Technology of Breadmaking, 2nd edn, Springer Science + Business Media, New York, NY, pp. 299±332. CAUVAIN, S.P.

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9.7 What is meant by the term `glass transition temperature' and what is its relevance to baking? In simple terms the glass transition temperature refers to the temperature below which a food will be stable, i.e. not change, when stored for long periods of time. It is commonly referred to by the notation Tg. The glass transition temperature of a particular food is unique to that food and is directly related to its composition. The stability of a food refers to its physical, chemical and microbial condition (Roos, 2007). The concept of glass transition comes from polymer science. The composition of bakery foods is a mixture of complex polymers (e.g., the starch and proteins). Above their Tg, bakery foods are considered to exist in a `rubbery' state. The use of the word rubbery does not refer to the texture of a product but indicates that it is unstable and likely to undergo change during storage; the staling of bread is an obvious example as the product increases in firmness even though it may not be losing water in storage (Pateras, 2007). If the temperature at which the bread is stored is lowered, a point is eventually reached at which firming stops, this is the Tg for that bread and the product is now said to be in a `glassy' state. In the glassy state the product will have a very long shelf-life because the water in the product is effectively immobilised in the product. Materials may have a number of glassy states depending on how the glass has been formed (Reid, 2007). The rate at which a bakery product cools to reach its Tg has a significant effect on how the water molecules become immobilised in the product and how it will behave in storage. Many bakery products are stored and consumed at temperatures at which they exist in a rubbery state and this limits their microbial and sensory shelf-lives. This knowledge of a product's Tg and in particular how to manipulate it through re-formulation to achieve a more stable storage state has significant practical implications for the development of bakery products. One of the difficulties facing bakers is that the glass transition concept is not easily applied in the practice of product re-formulation. More readily applied is the measurement or calculation of water activity (or equilibrium relative humidity) and it is this property that finds most practical use in baking (Cauvain and Young, 2008). References

and YOUNG, L.S. (2008) Bakery Food Manufacture and quality: Water Control and Effects, 2nd edn, Wiley-Blackwell, Oxford, UK. PATERAS, I.M.C. (2007) Bread spoilage and staling. In (eds S.P. Cauvain and L.S. Young) Technology of Breadmaking, 2nd edn, Springer Science + Business Media LLC, New York, NY, pp. 275±298. REID, D.S. (2007) Water activity: Fundamentals and relationships. In (eds G.V. BarbosaCanovas, A.J. Fontana, Jr., S.J. Schmidt and T.P. Labuza) Water Activity in Foods: Fundamentals and Applications, Blackwell Publishing, Oxford, UK, pp. 15±28. ROOS Y.R. (2007) Water Activity and Glass Transition. In (eds G.V. Barbosa-Canovas, A.J. Fontana, Jr., S.J. Schmidt and T.P. Labuza) Water Activity in Foods: Fundamentals and Applications, Blackwell Publishing, Oxford, UK, pp. 29±48. CAUVAIN, S.P.

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9.8

What is the Bohn's spot test and what is it used for?

The Bohn's spot test was developed for use with soda crackers and is designed to test their alkalinity. The test is based on applying a chemical indicator to a broken surface of the product; the colour of the spot which indicates the pH of the product. The reagent is phenol red indicator prepared by dissolving 0.02 g phenol red in a small amount of ethyl alcohol and diluting the mixture to 100 ml with distilled water; ready-made solutions may also be available. A drop of distilled water is first placed on the surface of a freshly broken surface of a cracker followed by a drop of the prepared indicator and the colour change observed. The relationship between the colour and the pH of the product is as follows: Colour Lemon yellow Orange Pink to red Reddish purple Purple

pH range below 7.0 7.1±7.4 7.5±7.7 7.8±8.2 above 8.2

Other reagents that are colour sensitive can be prepared (or obtained) to cover other ranges in the pH scale. Such tests can only be applied to products that are not coloured. In addition to quickly revealing a product pH, spot tests of this type can be used for identifying whether the components of baking powders are fully reacted because un-reacted baking powder components will show as vividly coloured spots. An alternative method for determining the cracker pH would be by using a pH meter. Grind about 10 g of the products to a fine powder in a pestle and mortar and suspend the ground material in 100 ml of distilled water, leave for a few minutes before checking the pH with the meter.

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215

9.9 What does the term MVTR mean when applied to packaging and what is the relevance to baked products? MVTR stands for Moisture Vapour Transpiration Rate and when applied to packaging material it is a measure of the rate at which moisture passes through a wrapping material. In metric units it is a measure of the grams of moisture which would pass through 1 square metre of packaging material per 24 hours at a temperature of 38ëC in an atmosphere of 90% relative humidity. In the USA, a similar term Water Vapour Transpiration Rate (WVTR) is used and is expressed in grams per 100 square inches per 24 hours at 100ëF with 90% relative humidity. For example a 25 m gauge basic co-extruded polypropylene film might have a MVTR of 5 g/m2/24 h @ 38ëC. Moisture-impermeable films would have a zero MVTR. Examples of other films are metallised polypropylene, coated cellulose (XS) and foil. Packaging is used for baked products to preserve optimum product quality and prevent contamination by microorganisms or other means, to protect them from physical damage and to make them attractive and to deliver ingredient, nutritional and other information to consumers. When purchasing packaging materials for baked products the baker has to decide whether it is advantageous or not to the product for moisture to pass out through the wrapping film or whether the packaging needs to prevent moisture escaping or entering the pack. In the case of biscuits using a moistureimpermeable wrapper is about restricting the risk of moisture being absorbed from the atmosphere by the product resulting in a soft rather than crunchy-eating product. The consumer would perceive this softening as a staling of the product. The permeability of packaging materials can affect moisture migration in the product by affecting the relative humidity of the atmosphere surrounding the product (Cauvain and Young, 2008). Packaging materials with low moisture vapour transmission rates create high relative humidities in the pack atmosphere and this means that an equilibrium can be reached between product and atmosphere. The impact on product quality will depend on factors like the ERH of the product, since products with low ERHs lose water less readily. Packaging films can be used to keep the product's key attributes for a longer period as the type used influences the rate of moisture movement both within and from the product, and therefore the product freshness. An example is bread packaged in a moisture-impermeable film, the product reaches equilibrium fairly quickly, with the crust softening but with little loss of moisture from the product overall. This situation is suited to pan bread character but not to crusty breads. In crusty breads, some extension of freshness, i.e. retention of crust crispness, can be achieved by allowing some moisture to escape from the product to the surrounding atmosphere so that there is always a moisture gradient throughout the product. The negative side to this approach is that the crumb moisture content falls rapidly to a level that is organoleptically unacceptable. A perforated film is most commonly used to slow down moisture loss from crusty products while trying to retain crust crispness (see Fig. 51).

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Fig. 51

Perforated film with crusty bread product.

The permeability of the wrapper may be deliberately increased to maintain the eating quality of the product. For example, semi-permeable wrappers may be used to prevent pastry products from reaching equilibrium with their fillings thereby maintaining pastry crispness. The link between the type of packaging and the quality of stored foods is discussed in some detail by Stollman et al. (1996). The volume of air enclosed in the pack has a significant role to play as the amount of moisture that can evaporate depends on the mass of moisture that can be held by the air in the pack. Fluctuating temperatures, e.g. in transport or storage, can create significant problems, as the mass of water that the air is capable of holding varies with temperature. Wrapped products moving from high to low temperatures are at risk from condensation with subsequent quality losses and increased risks of microbial growth. References

and YOUNG, L.S. (2008) Bakery Food Manufacture and Quality: Water Control and Effects, 2nd edn, Wiley-Blackwell, Oxford, UK. STOLLMAN, U., JOHANSSON, F. and LEUFVEN, A. (1996) Packaging and food quality. In (eds C.M.D. Man and A.A. Jones) Shelf Life Evaluation of Foods, Blackie Academic & Professional, London, UK, pp. 40±51. CAUVAIN, S.P.

What is/are/why/how?

217

9.10 We have heard people referring to synergy in the use of ingredients in baking processes, what is this process and can you identify any examples? Synergy can be said to have occurred when the combined effect of a composite addition of two or more ingredients is greater than the sum of the individual contributions. In simple terms it is like saying that if two ingredients contribute 2 units of effect then the end benefit of adding them in combination is greater than 4, in other words it is a case of 2 ‡ 2 ˆ 5. In many cases when you encounter the term being used in baking parlance it is being used to describe `additive' effects when 2 ‡ 2 ˆ 4. The term is most commonly used in connection with the mixture of components that characterise bread improvers and dough conditioners and most usually linked with dough or bread quality improvements in terms of loaf volume and crumb softness. A well-documented instance of synergy is that related to the addition of ascorbic acid and potassium bromate in the manufacture of bread. Chamberlain and Collins (1981) studied the effect of mixtures of the oxidants (the use of potassium bromate being permitted in the UK at that time) in the Chorleywood Bread Process. They considered that the synergy between the two oxidants came not from an interaction between the two oxidants but from individual reactions with different thiol groups of the proteins that were unique to each of the two oxidants. They also showed that the application of partial vacuum during mixing had a direct impact on the synergy and concluded that different mixers influenced the degree of synergy. Another example of synergy is the increased effectiveness of anti-microbial ingredients when the pH of a bakery product is lowered. In this case the microorganisms are confronted with so-called `hurdle' effects. The opportunities for using pH to control microbial growth on bakery products are relatively limited because most baked products have pHs in the range 5.0±7.5 and in this range most microorganisms will remain active. However, the combination of preservative and pH can be very effective. For example, Cauvain and Young (2008) cite data showing that in cake (92% equilibrium relative humidity) treated with the addition 1000 ppm sorbic acid, lowering the pH from 7.0 to 5.0 increased the mould-free shelf-life of the product from around 5 to 21 days. The addition of the sorbic acid alone had only increased the shelf-life by 1 day (i.e. 4±5 days). References

and COLLINS, T.H. (1981) The Chorleywood Bread process: oxidising improver effects of potassium bromate and ascorbic acid. FMBRA Report no. 95, Campden-BRI, Chipping Campden, UK. CAUVAIN, S.P. and YOUNG, L.S. (2008) Bakery Food Manufacture and Quality: Water Control and Effects, 2nd edn, Wiley-Blackwell, Oxford, UK. CHAMBERLAIN, N.

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What are polyols and how are they used in baking?

Polyols, or polyhdric alcohols to use the full descriptor, is a term used to cover a wide range of sugar alcohols, that is ingredients derived from the reduction of sugars (both mono and polysaccharides). They have some common attributes including that they have fewer calories per gram than sugar and are not associated with tooth decay. Because of these two properties, polyols are often seen to be alternatives to sugars, especially in cakes and biscuits, especially in the context of calorie reduced products. This sometimes leads to the claim that polyols can be used as fat-replacers but in practice they supply none of the functionality of fat in baked products. Among their other properties polyols have a cooling effect on the tongue and do not readily take part in Maillard browning reactions. A particularly important property of some of the polyols is that their addition will lower the water activity of a product with the benefits of increasing the mould-free shelf-life of products. For example, sorbitol solids are twice as effective as sucrose (weight for weight) at lowering product water activity and so may be used in cake formulations to increase ambient shelf-life. Polyols affect the glass transition temperature of baked products and so may be used in product formulations for frozen products to minimise product changes as the result of storage or to encourage changes in product eating character, see Fig. 52 (Cauvain, 1988). Polyols have a significant impact on starch gelatinisation characteristics so that when used in cake making they will affect product shape.

Fig. 52

Effect of polyols and freezing on cake crumbliness.

What is/are/why/how?

219

One of the negative features of polyols and their use is that high levels of use can contribute a laxative effect. For this reason their levels of daily consumption may be subject to mandatory and voluntary restrictions, especially in products aimed at children or the elderly. You should check the position for your own part of the world before undertaking any product development, as this may limit the practical levels of addition that you might make. Remember that if you use more than one polyol, it is the total of their addition which must be used in making any estimates as to likely daily consumption. Examples of polyols include: · Sorbitol, 2.6 calories/g, approximately 50±70% sweetness of sucrose, used in cakes to lower water activity (see above), available as an aqueous-based liquid. · Xylitol, 2.4 calories/g, 100% sweetness of sucrose, used in special dietary foods. · Maltitol, 2.1 calories/g, approximately 75% sweetness of sucrose, used in cakes and chocolate. · Isomalt, 2.0 calories/g, approximately 45±65% sweetness of sucrose, used in wafers. · Lactitol, 2.0 calories/g, approximately 30±40% sweetness of sucrose, used in cakes, cookies and chocolate. · Mannitol, 1.6 calories/g, approximately 50±70% sweetness of sucrose, used in chocolate flavoured coatings. · Erythritol, 0.2 calories/g, approximately 60±80% sweetness of sucrose, used in low calorie foods. · Hydrogenated starch hydrolysates, 3.0 calories/g, approximately 25±50% sweetness of sucrose, used in low calories foods. · Fructo-oligosaccharide, derived from sugar beet, 2.0 calories/g, approximately 30% sweetness of sucrose, used in cakes, cookies, crackers and biscuits. · Tagatose, derived from lactose, 1.5 calories/g, approximately 92% sweetness of sucrose, used in frostings and fillings. · Trehalose, occurs in nature (e.g., honey), commercially derived from corn starch, 4 calories/g, approximately 50% sweetness of sucrose, used in frosting and fillings, claimed to have cryo-protectant effect on protein structures and cell structures which may be dehydrated or frozen. The latter claim is commonly linked with freezing bakers' yeast. Reference

(1998) Improving the control of staling in frozen bakery products. Trends in Food Science and Technology, 9, 56±61.

CAUVAIN, S.P.

Further reading NELSON, A.L.

(2000) Sweetners Alternative, Eagan Press, St. Paul, MN.

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9.12 What value is there in measuring the colour of bakery products and how can we carry out the measurements? The crust and crumb colours of bakery products are important properties. The former is one of the immediate features of a bakery product that is seen and recognised by consumers. In most cases consumers will see `deviations' from the normal product crust colour as an indication that the product concerned does not have the quality that they are seeking and so may reject the product as unsuitable. The formation of a particular crust colour is directly related to oven baking conditions and the product formulation. Both are important because of their respective influence on the Maillard reactions (BPS, p. 98), which are largely responsible for the brown colour of the crust of most bakery products. The Maillard reaction products also contribute to product flavour. The measurement of crust colour is not only a useful indicator of variations from the product norm but can also be used to aid diagnosis of those quality problems that can change the colour. The measurement of product crumb colour can also be used to aid the diagnosis of quality problems. Many of the ingredients used in the manufacture of bakery products make a direct contribution to crumb colour. For example, the intrinsic colour of the flour endosperm will affect bread colour as will the level of ash or bran present in a white flour (see 2.1 and 2.2 respectively). In the case of crumb colour there is a complication arising from the cellular structure itself, as different cell sizes reflect light to different degrees and this affects the perception of crumb colour, especially when the crumb is viewed in glancing light. This is an important consideration as this is comparable to the assessment of product colour made by experts and consumers alike. However, it is separate from the fundamental colour of the product. There are a number of different ways in which colour can be assessed in the bakery. It has become relatively common to measure the crust and crumb colour of bakery products using various forms of colorimeter. The numerical output of a colorimeter is related to standards developed by the Commission Internationale de l'Eclairage (CIE) and comprises a series of tristimulus (i.e., three) values defined as XYZ which are also related to other defined colour spaces, such as Yxy and L*a*b*. In simple terms a colour space is a method for expressing the colour of an object using numbers under carefully defined and controlled conditions. A number of different colour spaces have been developed over the years, hence the different notations that are encountered. However, the common element to each colour space is that the colour of an object is defined by three values. The different colour values are related mathematically and so it is common for a given colorimeter to have the ability to deliver readings in all of the standard notations. One of the earliest ways of expressing colour was developed by an American artist, A.H. Munsell, who devised a method of expressing colour using a series

What is/are/why/how?

221

of paper colour chips. He classified the colours according to their hue, lightness and saturation. The principle of this approach is illustrated by the so-called colour solid shown in Fig. 53, which has a spine of lightness values based on white to black. A given colour (hue) around the circumference of the solid will become more saturated (intense), the further the point is on a given radius from the central spine. The Munsell colour chip-based system remains available today and can often be used for visually matching colours in many applications. For example, a few baked product crust colours use a limited number of `brown-coloured' chips. Visually matching crumb colour with Munsell chips is more difficult because of the effects of cell structure.

Fig. 53 Schematic of a `colour solid'.

Reference

and YOUNG, L.S. (2000) Baking Problems Solved, Woodhead Publishing Ltd, Cambridge, UK.

CAUVAIN, S.P.

Further reading

and SALTZMAN, M. (1981) Principles of Color Technology, 2nd edn, Wiley-Interscience, New York, NY.

BILLMEYER, F.W.

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9.13 What is acrylamide? Where does it come from and how do we limit it? Acrylamide is a neurotoxin suspected to be a carcinogen in animals and humans. It is formed as a result of side reactions that take place in starchy/high carbohydrate foods alongside the Maillard reaction and in the presence of asparagines, a reducing sugar (such as glucose) and heat (baking, frying or toasting). Asparagine is a natural occurring amino acid present in some proteinrich raw materials of plant origin which include grains and flours. The levels of acrylamide that form in baked products are very low and only occur at temperatures above 120ëC. This means that any acrylamide that is present is most commonly associated with the crust of baked products. It can be limited by controlling the formation of the precursors to acrylamide (mainly asparagines) by altering the mechanisms by which it is formed; e.g. by reducing the temperatures and time in baking or reducing or replacing some of the acrylamide-promoting ingredients, such as the reducing sugars, in the formulation. It is claimed that when using some types of processing, such as prolonged fermentation, acrylamide formation can be minimised. Introducing steam in the final part of baking has been shown to reduce the formation of acrylamide (www.heatox.org). It has also been shown to be limited by the addition of ingredients such as free glycine (another naturally occurring amino acid) but it should be noted that adding high quantities of glycine to bread dough may lead to reduced yeast activity. Some ingredient manufacturers have developed enzyme preparations based on aspariginase from Aspergillus niger or Aspergillus oryzae as part of a acrylamide reduction strategy (de Boer et al., 2005). These enzymes convert asparagines into another naturally occurring amino acid called aspartate or aspartic acid. This means that the asparagine is no longer available for taking part in the acrylamide-forming reaction and it is claimed that such enzymes do not affect the nutritional properties, browning or taste aspects of products. In the EU, the Confederation of the Food and Drink Industries (CIAA) has released a series of `Toolbox' guides advising manufacturers on how they can reduce acrylamide in the manufacture of foods (http://www.ciaa.be/documents/ brochures/CIAA_Acrylamide_Toolbox_Oct2006.pdf). Reference

and MEIMA, R.B. (2005) Reduction of acrylamide formation in bakery products by application of Aspergillius Niger asparaginase. In (eds S.P. Cauvain, S.E. Salmon and L. S. Young) Using Cereal Science and Technology for the Benefit of Consumers, Woodhead Publishing Ltd, Cambridge, UK.

DE BOER, L., MEERMANS, C.E.M.

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223

9.14 How can we measure the texture of our bread and cakes? Currently we use a hand squeeze test for bread and apply a `score' to the results You can measure baked product texture using trained assessors or with instrumentation. The latter has the advantage that the results are objective and they can be saved on a PC for quick retrieval and comparison with other results. The values measured can be linked to a scoring system when consumer panels have rated the product characteristics being measured. The most appropriate parameters for the texture of bread and cake products are firmness (compression of the crumb) and resilience (spring back after pressing). These are the product attributes most commonly linked with consumer perception of `freshness' with bread and cake crumb. In the case of bread and the consumer squeeze test, there is an expectation that bread products are easily squeezed but the product must also spring back after compression. Spring back is less important with cake crumb but softness remains a key property. There are a number of different instruments capable of measuring crumb softness and resilience. Texture analysers, e.g. Stable Micro Systems TA.XTPlus Texture Analyser, are found in many research and quality testing laboratories using different probes and fixtures according to the type of measurement required (Cauvain and Young, 2009). There are a number of different methods that can be employed. One of the common techniques for assessing baked product texture is known as Texture Profile Analysis (TPA), which employs a double compression of the product crumb. The TPA profile of seven texture parameters was first established by Szczesniak (1963) using sensory panels and related to objective measurement (Bourne, 1978). The measurements made using TPA are strongly correlated to the biting and chewing actions of consumers. Figure 54 shows a typical curve from a TPA test on bread crumb. While firmness is the component most often measured in assessing texture, several other components also contribute to overall texture. Crumb resilience can be determined by using relevant software in the appropriate instruments and repeated compressions can be made on the same sample enabling sample adhesiveness and cohesiveness to be measured. When using instruments to assess product texture (or indeed if using sensory assessment) it is important to take the measurement in the same location of each sample in order to reduce the variations in readings (Cauvain, 1991). The areas close to the crust should be avoided, as they will have a disproportionately large effect on the test results, because they will tend to be lower in moisture content than the bulk of the product crumb. It is also the case that many baked products, especially fermented products baked in pans, tend to have an uneven density distribution throughout a slice cross-section; usually the crumb density is lower in the centre of the product than it is near to the crust because of cell compression resulting from centre crumb expansion. Both the product moisture content and the sample density impact on sensory and objective texture measurements and it is advisable to have the relevant data when assessing the results of trials.

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Fig. 54

Typical texture profile analysis curve for bread crumb.

One instrument that mimics the squeeze test carried out by consumers is the Bread V Squeeze Rig (Cauvain and Young, 2008). It enables testing of packaged and unpackaged loaves. The rig allows repeatable, scientific analysis of the freshness and appeal of bread. It consists of `V' shaped, rounded `fingers', which are lowered onto the loaf and the force required to compress the bread is measured. The lower the recorded force and the higher the value of springiness, the fresher the loaf. This non-destructive test offers simplicity in operation and speed of assessment as the loaf requires no sample preparation and can be analysed within the packaging. It enables the assessment of changes that occur in increased resistance to compression (firming) and a loss of recovery when compressed, i.e. decreased springiness, as the loaf ages. References

(1978) Texture profile analysis. Food Technology, 32, July, 62±66, 72. (1991) Evaluating the texture of baked products. South African Journal Food, Science and Nutrition, 3, Nov., 81±86. CAUVAIN, S.P. and YOUNG, L.S. (2008) Bakery Food Manufacture and Quality: Water Control and Effects, 2nd edn, Wiley-Blackwell, Oxford, U.K. CAUVAIN, S.P. and YOUNG, L.S. (2009) The ICC Handbook of Cereals, Flour, Dough & Product Testing: Methods and Applications, DEStech Publishing Inc, Lancaster, PA. SZCZESNIAK, A.S. (1963) Classification of textural characteristic. Journal of Food Science, 28, July±August, 385±389. BOURNE, M.

CAUVAIN, S.P.

INDEX

Index Terms

Links

A acetic acid

60

acrylamide

222

air classification

129

alcohol addition in cakes

63

61

64

122

140

aleurone layer

43

alpha-amylase

46

55

68

185

199

212

121

201

sources ammonium bicarbonate amylase activity

45 163 70 48

Amylograph Units

46

amylopectin

70

88

amylose

70

88

anti-staling agents anti-staling enzymes arabinogalactans

126

126 72 211

arabinose

70

arabinoxylans

43

This page has been reformatted by Knovel to provide easier navigation.

72

Index Terms ascorbic acid

ash

Links 10

21

81

117

123

192

199

217

33

asparagine

222

aspariginase

222

aspartate

222

aspartic acid

222

B bacterial amylase baguette

126 97

baked products

186

acrylamide

222

205

base-making for freshly baked deep-pan pizza

193

Bohn's spot test

214

bread texture measurement

223

Chinese steamed bread and CBP

198

cinnamon twist bread

200

colour measurement

220

doughnut

194

195

extended mould-free shelf-life of flour Tortilla farls

203 1

flour Tortilla

203

fragility of defrosted finger rolls

192

glass transition temperature

213

This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

baked products (Cont.) gluten-free breads

196

glycaemic index and load

209

comparison for some typical bakery foods

210

GI categories

209

hamburger buns

204

hydration and hydrolysis

212

increase in mould-free shelf-life of various bakery products packaged in fferent concentration of CO2

206

ingredients synergy in baking process

217

lack of gloss finish of fondant

197

manufacture

xix

Milton Keynes Process

207

modified atmosphere packaging

205

MTVR

215

perforated film with crusty bread product

216

polyols

218

pro- and pre-biotics

211

retarding rolls in retarder-prover

202

schematic of colour solid

221

scones

188

Staffordshire oatcakes

190

189

stains around fruit pieces and darker crust colour of loaves

201

texture profile analysis curve for bread crumb 224 This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

baked products (Cont.) vacuum-cooling principles

208

variations in using fresh fruits in scones and cake batters bakers' yeast

186 53

available types fermentation lag phase

58 204 55

precautions in handling, storing and usage yeast storage time on gas production

56 57

bakery fats

73

bakery ingredients

52

alcohol

63

alternatives to chemically based preservatives anti-staling enzymes

64 72

applied alcohol concentration and percentage increase in mould-free shelf-life

63

bakery fats

73

butter

75

diastatic vs nondiastatic malt powders

68

double-acting baking powder

79

dough conditioners vs bread improvers

77

76

effect of acetic acid addition on pH of breads

60

enzymes 69 This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

bakery ingredients (Cont.) lecithin

78

preservatives

61

reducing agent

80

salt

52

sodium chloride alternatives

54

sugar

65

vinegar

60

baking

10

new problems which need solutions

ix

baking conditions

138

Banbury biscuits

152

barley

48

barms

119

batter viscosity

136

benzoates

64

beta-amylase

55

bifidobacteria

211

billets

175

biscuits and cookies

150

coated biscuits

212

155

dark brown spots on plain sheeted biscuits surface

159

fat level reduction

167

flour characteristics

153

impact of fat solids on cookie piece weight

167

impacts of sugar particle size 164 This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

biscuits and cookies (Cont.) intermittent problems with wafer sheets breaking up on cutting

168

main issues in savoury puff biscuits manufacture role of dough and batter temperatures

154 156

temperature ranges

158

wire-cut and deposited

157

role of fermentation time in manufacture of crackers

162

rotary moulded biscuit lines

160

semi-sweet biscuits

161

short-dough biscuits

164

Shrewsbury biscuits

152

163

soft-eating cookies, ways to extend time that the cookies will stay soft-eating

150

sucrose alternatives

165

sugar level reduction

165

surface cracking on high-sugar cookies

166

bloomer bent shape

98

dough piece passing under moulding board

99

relevance of placing dough piece seam down

101

shape

98

Bohn's spot test

214

Brabender Amylograph 46 This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

Brabender Extensograph

153

bran

43

bread and fermented products

83

alternative crusty stick trays

185

125

amount of ice needed to replace water when final dough temperature is too warm

91

ascorbic acid use as improver in bulk fermentation process bloomer

117 98

bread dough piece coiled after sheeting

101

100

CBP two lines running side-by-side yield breads with different volume and cell structure

123

crispy sticks bolder shape and more open cell structure crusty bread effects of changing proof time final moulder flying top

125 85

113

118 97 118

heat balance calculation

92

ice crystals formed in bread pack

89

key ingredient and process factors affecting product quality

27

loaves, see loaves low volume making bread without using additives

2 109

no oven lift in bread and buns 121 This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

bread and fermented products (Cont.) ‘ne-off' problems with bread quality optimum dough temperature pan bread

110 90 102

par-baked products re-heating

88

part bake and freeze bread products

86

107

purpose of knocking-back the dough when using bulk fermentation process

122

re-using of left-over dough from mixing

116

sandwich bread

114

shelling of bakery problems

127

87

snow or ice in bags of frozen bread products

89

spiral-type vs CBP-compatible type mixer

94

double gas bubble structure and product cell structure

95

dough temperature control

95

energy input and dough development

94

plant capacity and mixing times

94

product cell structure modification

96

sponge ferment and barms

119

preparation and usage with CBP

120

white bread characteristics

83

This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

bread improver

40

50

90

117

123

217

vs dough conditioners

77

Bread V Squeeze Rig

224

buffering agents

204

bulk fermentation process

117

purpose of knocking-back the dough even-out temperature variations in the bulk of the dough

122

re-invigorate the yeast by eliminating waste products reduce the risk of dough skinning buns

122 122 121

butter best processing temperatures and conditions

177

best treatment for consistent performance

76

as main or only fat in recipe

75

solid fat content at different temperature

75

buttermilk

191

butyric acid

75

BVM-L series

6

C C-Cell C-Cell bread slice imaging system

7 115

This page has been reformatted by Knovel to provide easier navigation.

107

Index Terms

Links

cake muffin large vertical holes

136

lean to one side during baking

137

leaning cake muffins

137

tunnel holes

136

cakes

128

advantages and disadvantages of addition of alcohol to batter before baking

140

batter deposit weights and different pan sizes

139

variations in using fresh fruits

186

browning in Genoa-type fruit cakes

141

cake batter temperatures calculation

131

effect on cake quality and volume

130

cake flour characteristics

128

cake muffins

136

137

delayed-soda method and use of hot water effect of lowering fat level

143 147

effect of neutralising value on small cake volume and shape

144

factors affecting water migration from cake cream filling formulation

142

packaging

142

factors that control the shape and appearance of the top of a cake 145 This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

cakes (Cont.) heat transfer rate during baking

146

mechanical and chemical aeration balance sucrose solution concentration

145 145

fat level reduction

147

high- vs low-ratio cakes

134

key characteristics of low- and high-ratio recipes

134

key ingredient and process factors affecting product quality

28

limited number of characteristics for cake flour

129

meaning of high- and low-ratio terms in cake making recipes

133

potential routes of moisture migration

12

relationship between cake type and level of baking powder rules in recipe balance

138 135

shape effect of baking powder level

145

effect of increasing sugar level

145

effect of rate of baking powder reaction

144

variable results with natural colours in slab cake

149

varying quality results from same plain batter used in different cake sizes 138 This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

calcium carbonate

33

204

calcium propionate

121

203

Candida

59

caramelisation

141

carbon dioxide

56

205

CBP, see Chorleywood Bread Process cellulose

38

chalk

35

Chinese steamed bread

198

chlorination

45

128

chlorine gas

128

133

Chopin Alveograph

153

Chorleywood Bread Process

194

21

36

59

80

116

123

127

198

217 Christmas cakes

63

ciabatta

97

cinnamon twist bread cis fats

200 74

co-extruded polypropylene film

215

coated biscuits bowed shape

155

sources of moisture in packed

155

coated cellulose

215

Codex Alimentarius Commission of the Food and Agricultural Organisation of the United Nations

50

Colour Grade Figure 35 This page has been reformatted by Knovel to provide easier navigation.

Index Terms Colour Grader

Links 35

colour solid

221

Commission Internationale de I'Eclairage

220

Confectioners' biscuits

152

Confederation of Food and Drink Industries

222

cookies

150

impact of some process and ingredient factors on hardness and crumbliness of cookies

13

crackers role of dough and batter temperature

158

role of fermentation time in manufacture

162

crispy sticks

125

croissant different forms and manufacturing process

170

important criteria for successful production of freeze fully-proved croissant key recipe and process features

184 172

crusty bread achieving desired degree of openness in structure quick softening

113 85

cryo-protection

187

cup cake

138

custard tarts

180

This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

D Danish pastries

62

DATA esters

167

Datem

167

delayed-soda method

143

159

dextrin

70

212

dextrose

180

dextrose equivalent

67

dextrose monohydrate

67

di-glyceride

71

di-saccharides

121

diastatic malt powders

68

dietary fibre

50

Dipix Technologies Inc

6

dsaccharides

7

disulphide bonds

73

80

double-acting baking powder carbon dioxide release in cake baking

79

dough conditioner

40

50

dough stickiness

42

90

77

doughnut cake doughnut key characteristics

194

crystalline growth on cake doughnuts during storage types dry heat treatment

195 194 128

133

This page has been reformatted by Knovel to provide easier navigation.

217

Index Terms

Links

E egg protein electronic nose

135 7

emulsifier

75

enzymes

69

erythritol

219

ethanol

56

ethyl alcohol

63

European Food Safety Authority

50

extraction rate

34

127

214

F Falling Number

126

farls

191

fast-acting acid

143

fat

135 replacers

185

147

fatty acids

71

73

fermentation

52

119

fermented products and bread

83

final proof

118

finger rolls fragility of defrosted finger rolls firmness Flour Colour Grade flour Tortilla

192 223 35 203

This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

flours and grains

33

alpha-amylase

45

ash content

33

functions of different components in wheat grain

37

malted grains

48

new harvest effect

40

non-wheat fibres

50

oats

49

rates of reaction of food grade acids

47

rationale in mixing different wheats for flour manufacture

39

relationship between flour ash and grade colour figure resistant starch

36 50

rye bread made with flours with different Amylograph viscosities

46

rye breads

46

self-raising flour

47

term grade colour figure

35

water absorption capacity

41

wholemeal bread flour characteristics and specifications

44

vs white flour protein content and bread volume

43

flying ferments

109

flying top

118

foil

215 This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

fondant

197

fractionation

74

freeze bread products

86

snow or ice in bags

89

freezer burn

86

French baguettes

42

fructooligosaccharide fructose fruited buns

211

219

67 201

G gas bubble expansion

113

gas flushing

205

gelatinisation

38

Genoa-type fruit cakes

88

133

136

218

141

germ

37

German-type rye breads

46

glass transition temperature

72

89

213

glucose

67

195

222

141

180

glutathione

56

81

gluten

56

glucose syrup

gluten-free breads

196

glycaemic index

209

glycaemic load

209

glycerine

187

glycerol

141

187

203

This page has been reformatted by Knovel to provide easier navigation.

Index Terms glycerol monostearate golden syrup grade colour figure

Links 75

78

147

141 34

35

44

45

H Hagberg Falling Number hamburger buns, pH and TTA of brew

204

hand squeeze test

223

heat balance

91

heat of hydration

132

heat transfer rate

139

heat treatment

194

hemicellulases

70

hemicellulose

70

high fructose corn syrup

67

honey

141

hurdle effects

217

hydration

212

hydrogen ion concentration

204

hydrogen peroxide

71

hydrogenated fats

183

hydrogenated starch hydrolysates

219

hydrogenation hydrolysis

46

73 212

This page has been reformatted by Knovel to provide easier navigation.

70

Index Terms

Links

I ice slush

91

interesterification

74

inulin

211

invert syrup

141

isomalt

219

95

K keyholing

68

knocking-back the dough

122

knowledge-based systems

23

L L-cysteine

80

L-cysteine hydrochloride

80

lactic acid

64

lactitol

219

lactobacilli

204

lactose

167

175

67

lactulose

211

laminated products effect of re-work on lift in laminated products

8

key ingredient and process factors affecting product quality processing pattern on laminated pastes

30 182

This page has been reformatted by Knovel to provide easier navigation.

181

Index Terms

Links

laminated products (Cont.) role of dough and batter temperature

158

variation in product lift

181

lecithin

78

lignin

50

lipase

71

lipids

38

loaf shape

138

loaf-style cakes

135

loaves

112

breaking on one side of the pan

112

crumb softness and collapse of sides

126

external appearance

110

internal appearance

111

joining of loaves baked in rack ovens

124

167

72

stains around fruit pieces and darker crust colour touching loaf from new straps

201 124

M Madeira Maillard reactions

135 67

141

220

222

malted grains

48

malting process

48

maltitol

219

maltose

55

67

201

70

This page has been reformatted by Knovel to provide easier navigation.

218

Index Terms

Links

man-t'ou

198

mannitol

219

metallised polypropylene

215

micro-encapsulated baking acid

189

microwave

76

Milton Keynes Process

207

minerals and vitamins

38

Mixograph times

53

modified atmosphere packaging

205

moisture-impermeable film

184

Moisture Vapour Transpiration Rate

215

208

mono-glyceride

71

72

mono-saccharides

67

121

6

221

73

muffin, see cake muffin Munsell colour chip-based system MVTR, see Moisture Vapour Transpiration Rate

N neutralising value

144

new harvest effect

40

new product development

ix

concept

24

launch

27

on-going product maintenance/handover

27

pre-launch trials

26

24

This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

new product development (Cont.) product development investigation– prototype product

25

prototype trials on the plant

26

scale-up to commercialisation assessment

26

nitrogen

205

non-starch polysaccharides

50

non-wheat fibres

50

nondiastatic malt powders

68

O oats

49

oil

73

oligosaccharides

211

osmotic pressure

121

osmotolerance

121

oven break

112

oven lift

121

oven spring

112

oxidases

71

oxygen

71

121

P palate cling palm oil

183 73

This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

pan bread air occlusion in dough pancake at curling stage

104

hole formed by the un-zipping of air pockets

107

holes

102

open-top

107

potential site of trapped air pocket from curling stage in single and four-piece bread

104

smooth sided hole

102

stranded holes

105

trapped air pockets following dough moulding lines

105

par-baked products

88

part bake products

86

partial defrosting

86

partial hydrogenation

74

pastries

169

butter

177

croissant

170

184

effect of processing temperatures of 12°C and 19°C on puff pastry lift using butter

170 177

factors to consider in using pastry trimmings age and condition

174

level of addition 174 This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

pastries (Cont.) temperature fat level reduction

174 178

key ingredient and process factors affecting product quality

29

processing variation of short and puff paste products

169

influence of ingredient temperature

169

influence of processing temperature

170

product lift variation of laminated products

181

role of rest periods in manufacture of savoury short pastry products shape distortion

175 181

shell, see pastry shell short pastry products

183

surface cracks on custard tarts

180

water temperature calculation method

176

185

pastry shell discoloration

179

pale colour

180

refrigerated, dark marks on base

179

patent flour

36

pentosans

38

perforated film

215

pH meter

214

phenol red

214

41

46

phosphate aftertaste 143 This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

pizza

193

plain sheeted biscuits

159

polish

109

polyhydric alcohols

218

polymorphism polyols

74 218

effect on cake crumbliness

218

negative features

219

potassium bicarbonate

54

potassium bromate

217

potassium chloride

52

potassium sorbate

61

prebiotic

203

211

preservative

52

chemically based, alternatives

61

63

64

common preservatives for bread and fermented products

61

effect of sorbic acid on shelf-life of cakes of different pHs pro forma probiotic

62 5 211

problem solving

ix

analysis

8

guide

1

how to problem solve

2

keyholing

3

low bread volume

2

This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

problem solving (Cont.) information sources

13

constructing knowledge trees and knowledge fragments

20

knowledge (computer)-based systems

21

personal

14

the Web

23

written

14

23

20

knowledge fragment related to ascorbic acid oxidation in CBP

22

level 1 checklists identifies ingredients that may have an effect or not on manufacture

15

impact of processing steps applied in manufacture of bakery product

16

varying ingredient level impact on paste characteristics and final product quality

16

level 2 checklists changes in ingredient level

18

ingredient specific content characteristic

17

process conditions

19

matching patterns and visualising changes modelling techniques new product development

11 9 24

This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

problem solving (Cont.) part of knowledge tree identifying factors that contribute to pastry lift record

20 4

divider record sheet

6

product scoring sheet

7

some key ingredient and process factors affecting product quality

27

bread

27

cakes and sponges

28

laminated products

30

pastries

29

proteases

71

protein

38

proteinases

71

proteolytic activity

48

proteolytic enzymes

68

43

46

71

153

175 puff biscuits, savoury

154

punching the dough

122

R radiofrequency heating ragged break

76 118

re-freezing

86

reducing agent

80

regrinding

129

This page has been reformatted by Knovel to provide easier navigation.

167

Index Terms

Links

resilience

223

resistant oligosaccharides

50

resistant starch

50

types

51

rest period

175

retarding phase

201

roller-milled wholemeal flour rolls

44 117

fruited

201

lean on one side and lose weight during retarding in retarder-prover

202

rotary moulded biscuit lines potential reasons for occurrence of wedging thickness variation

160 160

rye

48

rye flours

46

S Saccromyces cerivisii

55

Saccromyces rosei

59

Saccromyces rouxii

59

56

salt, see sodium chloride salt-replacers

54

sandwich bread characteristics

114

control points

115

This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

sandwich bread (Cont.) crumb characteristics

114

finer cell structure

127

most common forms of assessment

114

crumb softness

115

moisture content

114

shape

114

satiety

210

saturated fats

73

scald

119

scones carbon dioxide evolution during refrigerated storage

189

retarding unbaked scones

189

sensory qualities improvement

188

variations in using fresh fruits

186

Scottish Oatcake

190

self-raising flour

47

129

semi-sweet biscuits blistering on the surface

163

cavities and hollow bottoms

163

intermittent problems with shrinkage

161

role of dough and batter temperature

156

sheeting

97

shelling

86

shift change effect short-dough biscuits

100

127

8 164

role of dough and batter temperature 157 This page has been reformatted by Knovel to provide easier navigation.

161

Index Terms

Links

short pastry products flour characteristics

185

waxy eating character

183

Shrewsbury biscuits

152

skinning

113

122

slab cake

138

141

149

soda crackers

214 141

143

sodium bicarbonate

54 189

sodium chloride

52

alternatives

54

sodium metabisulphite

80

64

153

167

61

64

217

sorbitol

141

219

sourdough

109

spiral mixer

127

192

85

109

sodium stearoyl-2-lactylate

167

soft-eating cookies

150

sorbic acid

sponge cake

119

143

key ingredient and process factors affecting product quality

28

preparation and usage with CBP dough making

120

recipe and method

120

SSL Stable Micro Systems

167 6

223

Staffordshire oatcakes 190 This page has been reformatted by Knovel to provide easier navigation.

159

Index Terms

Links

staling

38

starch

38

steamed bread

198

stock syrup

197

stoneground wholemeal flour

44

sucrose

67

alternatives

165

sucrose hydrate

195

sugar

38

88

183

180

65

133

key requirements in different baked product groups

65

biscuit and cookies

66

bread

65

fermented products

65

fruited cakes

66

other bakery products

66

pastries

66

sponges and cakes

66

main features of alternative sugars

67

main groups

67

relative sweetness

67

types

65

see also specific sugars sugar xylose

70

sulphur dioxide

64

Swiss roll

200

syneresis

180

synergy 217 This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

T tagatose Taguchi method

219 11

tartaric acid

143

TA.XTPlus Texture Analyser

223

tempering process Texture Profile Analysis TexVol instruments

75 223 6

theory cube ice

93

top patent flour

36

Torulaspora

59

Torulaspora delbrueckii

59

total titratable acidity

204

trans fats

74

trehalose

219

triglyceride tristimulus instruments

71

73

6

220

tunnel holes

136

twin-arm type mixer

127

U UK-style bloomers

42

This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

V vacuum-cooling principles vinegar

208 60

see also acetic acid VolScan Profiler

6

W wafer role of dough and batter temperature

156

sheets

168

water absorption capacity

44

flours and grains

41

Water Vapour Transpiration Rate wheat

215 48

mixed with oats or oat products starch

49 135

wheat berry

43

wheat flour

133

wheat gluten

44

wheaten farl

191

wheatmeal

191

199

white bread characteristics

83

flour treatments and additives

84

Hagberg Falling Number

84

level of bran particles

83

This page has been reformatted by Knovel to provide easier navigation.

Index Terms

Links

white bread (Cont.) protein content

83

protein quality

84

water absorption capacity

83

white farl

191

wholemeal bread flour characteristics and specifications

44

vs white flour protein content and bread volume World Wide Web

43 23

X xylanases

70

xylitol

219

xylose

70

Y yeast

10

118

123

This page has been reformatted by Knovel to provide easier navigation.

201