Enzymes in Food Processing PDF
Preview Enzymes in Food Processing
Enzymes in Food Processing Enzymes in Food Processing Second edition Edited by G.A. TUCKER Reader in Applied Biochemistry University of Nottingham and L.F.J. WOODS Technical Manager Harris (Ipswich) Ud, Suffolk SPRINGER-SCIENCE+BUSINESS MEDIA, B.V. First edition 1995 © 1995 Springer Science+Business Media Dordrecht Origina11y published by Chapman & Hali in1995 Softcover reprint of the hardcover 2nd edition 1995 Typeset in 10/12 pt Times by AFS Image Setters Ltd, Glasgow ISNB 978-1-4613-5897-8 ISBN 978-1-4615-2147-1 (eBook) DOI 10.1007/978-1-4615-2147-1 Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the UK Copyright Designs and Patents Act, 1988, this publication may not be reproduced, stored, or transmitted, in any form or by any means, without the prior permission in writing of the publishers, or in the case of reprographic reproduction only in accordance with the terms of the Iicences issued by the Copyright Licensing Agency in the UK, or in accordance with the terms of licences issued by the appropriate Reproduction Rights Organization outside the UK. Enquiries concerning reproduction outside the terms stated here should be sent to the publishers at the Glasgow address printed on this page. The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. A catalogue record for this book is available from the British Library Library of Congress Catalog Card Number: 95-78762 00 Printed on acid-free text paper, manufactured in accordance with ANSIjNISO Z39.48-1992 (Permanence of Paper). Preface to first edition The use of enzymes is well established and widespread within the food industry. This is perhaps not surprising since the properties of enzymes make them ideal tools for the manipulation of biological material. However, considering the thousands of enzymes described so far by biochemists, it is surprising to find that only a mere handful are actually used commercially. This is due to a wide range of reasons including unsuitable reaction conditions, instability of the enzyme during processing, or the prohibitive cost involved in obtaining large amounts of sufficiently pure enzyme. Many of these problems may be overcome by the application of new biotechnological skills such as genetic and protein engineering. These will allow the design of novel enzymes which can operate under optimal conditions for processing, are more stable and can be produced efficiently using microbial fermentation. The scene may thus be set for a rapid expansion in the industrial use of enzymes in general, and, in particular, food processing. The first half of this book introduces the reader to the concept and properties of enzymes and to their general applications and limitations in food processing. The reader is then introduced at length to the new technologies and how these may be applied to expand the use of enzymes in food processing. The second half of the book concentrates on the current applications of enzymes in the food industry by considering individual groups of related commodities. Where possible, this section also speculates on the increased use of enzymes in the future. This book will prove useful to those in the food industry who wish to become aware of the potential for biotechnology, or who are just entering the industry and require an overview of the use of enzymes. The book could also be used by students of food science, either at advanced undergraduate or postgraduate level, to provide information on both the current uses of enzymes, and the potential for their increased use in the future. G.A.T. L.FJ.W. Preface to second edition During the five years since the first publication of enzymes in food processing the application of new areas of biotechnology to food processing has become more acceptable. In 1991 the use of food enzymes produced by genetic engineering techniques was being pioneered with the introduction of yeast derived chymosin for cheese manufacture. Since then this enzyme has become an accepted tool in the cheese industry. The genetic manipulation of enzymes within raw food material is also becoming more widespread and this is again having an impact on food processing. The first genetically manipulated food product (a tomato with improved flavour) was cleared for sale in the USA in 1994. This same tomato also has much improved processing qualities, pro- ducing much higher viscosity pastes, and ketchup made from this genetically manipulated fruit will be on sale in the UK sometime in 1995. The application of the new technologies to food processing is being enhanced by continuing advances in fundamental studies to relate enzyme structure and function. Thus our understanding of protein conformation, thermostability, substrate specificity and action in water lipid interfaces will no doubt lead to the more rational design of novel food processing enzymes in the future. In addition studies on enzymes responsible for key processing events, such as meat tenderisation, will again lead to novel ways of enhancing or controlling these events. The second edition of enzymes in food processing follows the same format as the first, i.e. the first three chapters deal with general aspects whilst the latter chapters cover more specific applications. The early chapters have been updated to take into account the rapid advances in the areas of protein- structure function relationships, the application of genetic engineering and the subsequent safety considerations. The latter chapters have also been updated to again take account of significant new findings over the past five years. G.A.T L.F.J.W. Contributors R.G. Bardsley Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington Campus, Lough- borough, Leics LEl2 5RD, UK. D.J. Etherington Former Head of Enzymology, IFR, Bristol, Present address: Southlea, Brent Street, Brent Knoll, Highbridge, Somerset T A9 4DT, UK. P.W. Goodenough Head of Protein Engineering Department, Institute of Food Research, Shinfield, Reading, Berkshire RG2 9AT, UK. R.J. Hamer Head of Biochemistry and Gene Technology Division, TNO Nutrition and Food Research Institute, PO Box 360, 3700 AJ Zeist, The Netherlands B.A. Law Head of Biochemistry and Enzymology Department, Institute of Food Research, Shinfield, Reading, Berkshire RG29AT, UK. A.G.H. Lea Reading Scientific Services Limited, The Lord Zucker- man Research Centre, The University, Whiteknights, PO Box 234, Reading RG6 2LA, UK. R.M. Leach Novo Nordisk Bioindustries UK Ltd, 4 St Georges Yard, Castle Street, Farnham, Surrey GU9 7LW, UK. P.D. Patel Leatherhead Food Research Association, Randalls Road, Leatherhead, Surrey RT 22 7PY, UK. S.J. Swinton MAFF Pesticides Safety Directorate (New Substances Branch), Mallard House, Kings Pool, 3 Peasholme Green, York YOl 2PX, UK. A.J. Taylor Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington Campus, Lough- borough, Leics LEl2 5RD, UK. M.P. Tombs Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington Campus, Lough- borough, Leics LEl2 5RD, UK. G.A. Tucker Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington Campus, Lough- borough, Leics LEl2 5RD, UK. L.F.J. Woods Technical Manager, Harris (Ipswich) Ltd, Hadleigh Road, Ipswich, Suffolk IP2 OHQ, UK. Contents 1 Fundamentals of enzyme activity 1 G.A. TUCKER 1.1 Introduction 1 1.2 What is an enzyme? 1 1.3 Enzyme nomenclature 5 1.4 Enzyme purification and assay 7 1.5 Enzyme kinetics 9 1.5.1 Enzyme concentration 9 1.5.2 Substrate concentration 12 1.5.3 Environmental conditions 17 1.5.4 Inhibitors, activators and co-factors 19 1.6 Enzyme immobilisation 21 1. 7 Genetic engineering 22 References 24 2 Enzymes in the food industry 26 A.J. TAYLOR and R.M. LEACH 2.1 Introduction 26 2.2 Commercialisation of enzyme processes 27 2.3 Alternative methods to the use of enzymes 29 2.4 Accessibility of substrate to enzyme 30 2.5 Types of reaction 31 2.6 Reaction conditions 33 2.7 Source of enzymes 34 2.8 Legal and safety implications 35 2.9 Use of enzymes 37 References 39 3 Food enzymes and the new technology 41 P.W. GOODENOUGH 3.1 Overview of the new technologies 41 3.1.1 Packaging of enzymes 41 3.1.2 Mutagenesis to provide 'tailored' enzymes 42 3.1.3 Solvent engineering to alter enzyme specificity 46 3.1.4 Abzymes 51 3.2 Understanding how protein structure controls function 59 3.2.1 Determining protein structure 59 3.3 Relating structure to function 71 3.3.1 Site-directed mutagenesis and early examples of protein engineering 73 3.3.2 Protein engineering to change thermal stability of enzymes 74 3.3.3 Protein engineering studies of protein folding 87 3.3.4 Design of ab initio proteins 88 3.3.5 Computational methods used to guide mutagenesis 94 3.3.6 Mutagenesis of genetic material to adjust protein structure 95 3.3.7 Expression of protein 98 3.3.8 Purification methods for recombinant, engineered and native protein used for food processing 101 x CONTENTS 3.4 A rational approach to reactions in organic solvents 104 3.5 Can abzymes become as efficient and economical as enzymes? 105 Acknowledgements 105 References 105 4 Enzymes in milk and cheese production 114 B.A. LAW and P.W. GOODENOUGH 4.1 Introduction 114 4.2 Enzymes in relation to milk production 114 4.2.1 Enzymes in milk preservation 114 4.2.2 Lactose hydrolysis 116 4.2.3 Use of enzymes for determining milk quality 118 4.2.4 The role of indigenous enzymes in the manufacturing quality of milk 122 4.3 Enzymes in relation to cheese manufacture 125 4.3.1 Endogenous microbial enzymes 125 4.3.2 Coagulant technology 125 4.3.3 Exogenous enzymes 127 4.3.4 Enzymes in cheese preservation 137 4.4 Concluding remarks 138 Acknowledgements 140 References 140 5 Enzymes in the meat industry 144 D.l. ETHERINGTON and R.G. BARDSLEY 5.1 Introduction 144 5.2 Development of rigor 145 5.3 Loss of rigor stiffness 147 5.4 Ultrastructural modifications in the myofibril 147 5.5 Connective-tissue weakening 151 5.6 Muscle proteinase 151 5.6.1 Proteinases active at neutral pH 152 5.6.2 Proteinases active at acid pH 159 5.7 Interaction of muscle proteinases in conditioning 163 5.8 Effect of age and growth rate on muscle proteinases and meat quality 168 5.9 Tenderising enzymes 170 5.10 Enzymic recovery processes 177 5.11 Conclusions 178 References 179 6 Enzymes in the baking industry 191 R.l. HAMER 6.1 Introduction 191 6.2 The need for problem solvers 192 6.3 Sources of technical enzymes 192 6.4 Regulations 193 6.5 The use of enzymes in the baking industry 194 6.6 Starch-degrading enzymes 195 6.6.1 Sources of starch-degrading enzymes 195 6.6.2 Analysis of starch-degrading enzymes 195 6.6.3 Application of starch-degrading enzymes 196 6.6.4 Summary 200 6.7 Proteinases 200 6.7.1 Sources of proteases 202 CONTENTS Xl 6.7.2 Analysis of proteases 202 6.7.3 Specific action of proteases on gluten 205 6.7.4 Application of proteases 206 6.7.5 Modification of wheat gluten by proteases 208 6.7.6 Summary 208 6.8 Pentosanases 209 6.8.1 Sources of hemicellulases used in the baking industry 210 6.8.2 Analysis of pentosanases 210 6.8.3 Applications of pentosanases 211 6.8.4 Summary 212 6.9 Lipases 213 6.10 Oxidoreductases 214 6.10.1 Lipoxygenase 214 6.10.2 Glucose oxidase, sulfhydryl oxidase 215 6.10.3 Summary 216 6.11 General considerations 216 6.11.1 Know your process 216 6.11.2 Keep your process constant 217 6.11.3 Know your enzymes 217 6.11.4 Keep your enzyme constant 217 References 218 7 Enzymes in the production of beverages and fruit juices 223 A.G.H. LEA 7.1 Introduction 223 7.2 Tea 223 7.3 Cocoa 227 7.4 Beer and whisky 228 7.5 Wine 230 7.6 Cider 232 7.7 Apple juice 235 7.8 Endogenous fruit enzymes 239 7.9 Other non-citrus fruits 242 7.10 Citrus juice processing 243 7.11 Citrus de-bittering 244 7.12 Other enzymic applications 246 7.13 Conclusion 247 References 247 8 Enzymes in the starch and sugar industries 250 L.F.l. WOODS and S.l. SWINTON 8.1 Introduction 250 8.2 Applications of hydrolytic enzymes in starch and sugar conversions 253 8.2.1 Introduction 253 8.2.2 Extensive starch hydrolysis-the enzymic liquefaction and saccharification processes 253 8.2.3 Partial starch hydrolysis-the enzymic production of low-dextrose-equivalent maltodextrins 257 8.3 Applications of non-hydrolytic enzymes in starch and sugar conversions 258 8.3.1 Glucose isomerase 258 8.3.2 Glucose oxidase 260 8.3.3 Branching enzyme 261 8.4 Production of fine chemicals by enzymic conversions of starch and sugars 262 8.4.1 Synthesis and applications of cyclodextrins 262 XlI CONTENTS 8.4.2 Synthesis of sugar esters 264 8.5 Conclusion 266 References 266 9 Enzymes in the processing of fats and oils 268 M.P. TOMBS 9.1 Introduction 268 9.2 Structure and function of lipases 269 9.3 Specificity of lipases 273 9.4 Stability of lipases 274 9.5 Lipases in the interface 275 9.6 Non-interfacial uses of lipases 277 9.7 Applications 277 9.7.1 Lipases and related enzymes in lipid sources 277 9.8 The dairy industry 279 9.9 Lipases as process aids 279 9.10 Hydrolysis of triglycerides 280 9.11 Interesterification and randomisation 281 9.12 Manipulation of fats other than by lipases 286 9.13 Lipoxygenases 286 9.14 Glycolipids 287 9.15 Phospholipids 287 9.16 Manipulation of raw materials 287 9.17 Conclusions 288 References 288 10 Enzymes as diagnostic tools 292 P.D. PATEL 10.1 Introduction 292 10.2 Enzyme kinetics in relation to diagnosis 293 10.3 Unlabelled enzymes in diagnosis 295 10.3.1 Non-microbiological applications 295 10.3.2 Applications in food microbiology 296 10.4 Enzymes as analytical aids 299 10.5 Enzyme conjugates used in diagnosis 300 10.5.1 Choice of enzymes 301 10.5.2 Enzyme conjugates 301 10.5.3 Choice of enzyme substrates 302 10.6 Applications of enzyme conjugates in microbiology 302 10.6.1 Performance characteristics of EIA 303 10.6.2 Enhanced EIA 304 10.7 Non-microbiological applications of enzyme conjugates 305 10.7.1 Protein analysis 305 10.7.2 Polysaccharide analysis 305 10.7.3 Vitamin analysis 306 10.7.4 Other potential applications 307 10.8 Future trends and perspectives 307 10.8.1 Analysis based on enzyme immunoassays 307 10.8.2 Nucleic acid probes for hybridisation assays 308 10.8.3 Catalytic antibodies (abzymes) 309 10.8.4 Neoglycoenzymes in pathogen detection 309 References 310 Index 315
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