Chemistry of Food Additives and Preservatives and Preservatives Chemistry of Food Additives Titus A

Chemistry of Food Additives and Preservatives and Preservatives Chemistry of Food Additives Titus A. M. Msagati Food additives are chemicals or ingredients that are added to food during processing to improve quality, flavour, appearance or nutritional value, or to prevent chemical or microbial spoilage. The most common types of additives are preservatives, colourants, sweeteners, flavourings, emulsifiers, thickeners and stabilisers. Adding new ingredients to a food has an effect upon its chemistry and structure as well as its sensory characteristics. Additives are usually characterised by where they come from (for example, whether they are natural or synthetic), by their purpose (such as improving shelf life) and the risks associated with them (such as their toxicity, and any side effects upon the consumer). Although in recent years the trend in consumer marketing has been to trumpet a lack of additives and preservatives, with ‘artificial ingredients’ commonly seen in a negative light, there nevertheless remains a wide variety of additives and preservatives that are crucial both to producers and consumers, without which the quality of the food would suffer. Chemistry of Food Additives and Preservatives is an up-to-date reference guide to the wide range of different types of additives used in the food industry today. It looks at the processes involved in adding preservatives and additives to foods, and the mechanisms and methods used. The book provides full details about the chemistry of each major class of food additive, showing the reader not just what kind of additives are used and what their functions are, but also how they work, and how they may have multiple functionalities. This book also covers numerous new additives currently being introduced, how the quality of these is ascertained, and how consumer safety is ensured. Chemistry of Chemistry of Food Additives and Preservatives is an ideal reference for food chemists, food safety specialists and agencies, food processors who are working with additives and preservatives, and food regulators and policy makers. Written in an accessible style and covering a broad range of food additives and preservatives, the book offers an in-depth analysis of the chemical interactions of food additives and preservatives with the natural composition of the foods to which they are added. It is a unique and ground-breaking Food Additives treatment of a topic vital to both the food industry and the researcher. About the Author Dr Titus A. M. Msagati is a Senior Lecturer in the Department of Applied Chemistry at the University and Preservatives of Johannesburg, South Africa. Msagati Titus A. M. Msagati Also available Food Additives Databook, 2nd edition Edited by J. Smith and L. Hong-Shum 978-1-4051-9543-0 Natural Food Flavors and Colorants M. Attokaran 978-0-8138-2110-8 Food Carbohydrate Chemistry Ronald E. Wrolstad 978-0-8138-2665-3 ISBN 978-1-118-27414-9 9 781118 274149 Msagati_Chemistry_9781118274149_hb.indd 1 31/08/2012 14:03 Chemistry of Food Additives and Preservatives Chemistry of Food Additives and Preservatives Titus A. M. Msagati, B.Sc. (Hons), MSc, Ph.D., CChem, MRSC Department of Applied Chemistry University of Johannesburg Republic of South Africa A John Wiley & Sons, Ltd., Publication This edition first published 2013 C 2013 by John Wiley & Sons, Ltd. Wiley-Blackwell is an imprint of John Wiley & Sons, formed by the merger of Wiley’s global Scientific, Technical and Medical business with Blackwell Publishing. Registered office: John Wiley & Sons, Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK Editorial offices: 9600 Garsington Road, Oxford, OX4 2DQ, UK The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK 2121 State Avenue, Ames, Iowa 50014-8300, USA For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at www.wiley.com/wiley-blackwell. The right of the authors to be identified as the authors of this work has been asserted in accordance with the UK Copyright, Designs and Patents Act 1988. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold on the understanding that the publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought. Library of Congress Cataloging-in-Publication Data Chemistry of food additives and preservatives / Titus A. M. Msagati. p. cm. Includes bibliographical references and index. ISBN 978-1-118-27414-9 (hardcover : alk. paper) 1. Food additives. 2. Food preservatives. 3. Food–Analysis. 4. Food–Composition. I. Msagati, Titus A. M. TX553.A3C455 2012 641.308–dc23 2012009754 A catalogue record for this book is available from the British Library. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. Cover image credit – Top: C iStockphoto.com/Pgiam; Bottom: C iStockphoto.com/mattjeacock Cover design by Meaden Creative Set in 10/12 pt Times by Aptara R Inc., New Delhi, India 1 2013 Contents Preface ix Introduction x List of Abbreviations xiii 1 Antioxidants and Radical Scavengers 1 1.1 Chemistry of free radicals and antioxidants 1 1.2 Types of antioxidants 4 1.3 Efficacy of different antioxidants 7 1.4 Action mechanisms of antioxidants 9 1.5 Structure–activity relationship of antioxidants 11 1.6 Factors affecting antioxidant activity 14 1.7 Quality assessment of dietary antioxidants 15 1.8 How safe are food antioxidants? 23 1.9 Summary 25 References 25 Further reading 31 2 Emulsifiers 33 2.1 Mechanisms of food emulsifiers 33 2.2 The role of emulsifiers in foods 35 2.3 Classification of emulsifiers 37 2.4 Types of food emulsifiers 38 2.5 Quality and analysis of food emulsifiers 58 2.6 Foods containing emulsifiers 60 References 62 Further reading 64 3 Stabilisers, Gums, Thickeners and Gelling Agents as Food Additives 67 3.1 Introduction to stabilisers, thickeners and gelling agents 67 3.2 Polysaccharides 68 3.3 Protein-based food stabilisers 77 3.4 Quality control of food stabilisers and thickeners 78 3.5 Analytical methods 78 References 80 Further reading 82 4 Sweeteners 83 4.1 Introduction to sweeteners 83 4.2 Properties of sweeteners 84 vi Contents 4.3 Intense sweeteners in foods 86 4.4 Bulk food sweeteners 92 4.5 Quality assurance and quality control 95 4.6 Analytical methods 98 References 98 Further reading 100 5 Fragrances, Flavouring Agents and Enhancers 102 5.1 Introduction to flavours and flavouring agents 102 5.2 Classification of food flavourings 103 5.3 Chemistry of food flavourings 105 5.4 Quality control of flavour compounds 119 5.5 Analytical methods for the analysis of food flavourings 120 References 121 Further reading 124 6 Food Acids and Acidity Regulators 125 6.1 What are food acids and acid regulators? 125 6.2 Types of food acids 126 6.3 Uses of food acids 128 References 129 Further reading 130 7 Food Colour and Colour Retention Agents 131 7.1 Why add colourants to foods? 131 7.2 Classification of food colourants 131 7.3 Overview of colourants 133 7.4 Chemistry of food colourants 143 7.5 Extraction from natural sources 143 7.6 Quality assurance of food colourants 144 7.7 Analytical methods 145 References 145 8 Flour Treatment/Improving Agents 148 8.1 What are flour treatment/improving agents? 148 8.2 Flour maturing agents 148 8.3 Flour bleaching agents 151 8.4 Flour processing agents 154 References 154 9 Anticaking Agents 155 9.1 The caking phenomena 155 9.2 Mechanisms of caking 156 9.3 Classification of anticaking agents 159 9.4 Anticaking agents in use 159 References 160 Further reading 161 Contents vii 10 Humectants 162 10.1 Humectants and moisture control 162 10.2 Classification of humectants 162 References 166 11 Antifoaming Agents 167 11.1 Sources of foam in food processing 167 11.2 Properties of antifoaming agents 168 11.3 Mechanisms of antifoaming and foam destabilisation 168 11.4 Synthetic defoamers 168 11.5 Natural defoamers 170 References 171 12 Minerals and Mineral Salts 172 12.1 The importance of minerals and mineral salts 172 12.2 Inorganic mineral salts 173 12.3 Organic mineral salts 175 References 176 13 Dietary Supplements 177 13.1 Introduction to dietary supplements 177 13.2 Classification of vitamins 178 13.3 Vitamin A (retinols) 179 13.4 Vitamin D (calciferol) 189 13.5 Vitamin E 194 13.6 Vitamin K 196 13.7 Vitamin B 199 13.8 Vitamin C (L-ascorbic acid) 210 13.9 Conclusions 212 References 213 14 Glazing Agents 218 14.1 Introduction to glazing agents 218 14.2 Mineral hydrocarbon glazes 218 14.3 Chemistry of MHCs 220 14.4 Conclusion 222 References 223 15 Preservatives 224 15.1 Preservatives: Past, present and future 224 15.2 Natural food preservatives 226 15.3

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