Natural Food Colorants JOIN US ON THE INTERNET VIA WWW, GOPHER, FTP OR EMAIL: WWW: http://www.thomson.com GOPHER: gopher.thomson.com A service of lOOP FTP: ftp.thomson.com EMAIL: Natural Food Colorants Second edition Edited by G.A.F. HENDRY Honorary Senior Lecturer NERC Unit of Comparative Plant Ecology University of Sheffield and l.D. HOUGHTON Lecturer Department of Biochemistry and Molecular Biology University of Leeds SPRINGER-SCIENCE+BUSINESS MEDIA, B.V. First edition 1992 Second edition 1996 Reprinted 1997 © 1996 Springer SciencetBusiness Media Dordrecht Originally published by Chapman & Hall in 1996 Softcover reprint ofthe hardcover 2nd edition 1996 'JYpeset in 10/12 TImes by Photoprint, Torquay, Devon ISBN 978-1-4613-5900-5 ISBN 978-1-4615-2155-6 (eBook) DOI 10.1007/978-1-4615-2155-6 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 licences 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 conceming reproduction outside the terms stated here should be sent to the publishers at the London 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 maybemade. A catalogue record for this book is available from the British Library Library of Congress Catalog Card Number: 95-78251 Printed on acid-tree text paper, manufactured in accordance with ANSIINlSO Z39, 48-1992 (Performance of Paper) Preface to the second edition In this second edition of Natural Food Colorants two new chapters have been added and we have taken the opportunity to revise all the other chapters. Each of the original authors have brought up to date their individual contributions, involving in several cases an expansion to the text by the addition of new material. The new chapters are on the role of biotechnology in food colorant production and on safety in natural colorants, two areas which have undergone considerable change and development in the past five years. We have also persuaded the publishers to indulge in a display of colours by including illustrations of the majority of pigments of importance to the food industry. Finally we have rearranged the order of the chapters to reflect a more logical sequence. We hope this new edition will be greeted as enthusiastically as the first. It remains for us, as editors, to thank our contributors for undertaking the revisions with such thoroughness and to thank Blackie A&P for their support and considerable patience. G.A.F.R. J.D.R. Contributors Dr G .. Brittori Department of Biochemistry, University of Liverpool, PO Box 147, Liverpool L69 3BX, UK Professor F.J. Francis Department of Food Science, College of Food and Natural Resources, University of Massa- chusetts, Amherst, MA 01003, USA Dr G.A.F. Hendry NERC Unit of Comparative Plant Ecology, Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK Mr B.S. Henry Phytone Limited, Third Avenue, Centrum 100, Burton-on-Trent, Staffordshire DE14 2WD, UK Dr J.D. Houghton Department of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, UK Professor R.L. Jackman Department of Food Science, Ontario Agricul- tural College, University of Guelph, Guelph, Ontario N1G 2W1, Canada Dr M.C. O'Caliaghan Mary O'Callaghan & Associates, Castledowns, Boycestown, Carrigaline, Co. Cork, Ireland Professor J.L. Smith Ault Foods Ltd., 75A Bathurst Street, London, Ontario N6B 1N8, Canada Contents 1 Natural pigments in biology 1 G.A.F. HENDRY 1.1 Summary 1 1.2 Introduction 1 1.3 Definitions 1 1.4 Colour and colour description 2 1.5 Colour perception 4 1.6 Colour and chemical name 6 1.7 Electronic structure of pigments 7 1.8 Classification of biological pigments 9 1.9 Classification based on structural affinities 9 1.9.1 Tetrapyrroles 9 1.9.2 Tetraterpenoids 12 1.9.3 O-Heterocyclic compounds 12 1.9.4 Quinoids 15 1.9.5 N-Heterocyclic compounds (other than tetrapyrroles) 17 1.9.6 Metalloproteins 23 1.9.7 Miscellaneous 25 1.10 Colourless compounds in perspective 25 1.11 Pigment classification by natural distribution 26 1.11.1 Plants including algae 27 1.11.2 Vertebrates 28 1.11.3 Invertebrates 28 1.11.4 Fungi 29 1.11.5 Lichens 33 1.11.6 Bacteria 37 1.12 Biological systems as sources of pigments for commercial exploitation 38 Acknowledgements 39 References 39 2 Natural food colours 40 B.S. HENRY 2.1 Summary 40 2.2 The role of colour in food 40 2.3 Classification of food colours 41 2.3.1 Synthetic colours 42 2.3.2 Nature-identical colours 42 2.3.3 Natural colours 42 2.4 Legislation 42 2.5 Factors affecting colour choice 44 2.6 Factors affecting colour application forms 45 2.6.1 Solubility 45 2.6.2 Physical form 45 2.6.3 pH 46 2.6.4 Microbiological quality 46 2.6.5 Other ingredients 46 viii CONTENTS 2.7 Performance and consumption of natural colours 46 2.8 Annatto 47 2.8.1 Source 47 2.8.2 Extracts and their application forms 49 2.8.3 Legislation 50 2.8.4 Factors affecting stability 50 2.8.5 Applications 51 2.9 Anthocyanins 53 2.9.1 Source 53 2.9.2 Legislation 55 2.9.3 Factors affecting stability 56 2.9.4 Applications 57 2.10 Beetroot 59 2.10.1 Source 59 2.10.2 Extracts and their application forms 60 2.10.3 Legislation 61 2.10.4 Factors affecting stability 62 2.10.5 Applications 63 2.11 Cochineal and carmine 64 2.11.1 Source 64 2.11.2 Extracts and their application forms 66 2.11.3 Legislation 67 2.11.4 Factors affecting stability 67 2.11.5 Applications 67 2.12 Curcumin 69 2.12.1 Source 69 2.12.2 Extracts and their application forms 70 2.12.3 Application forms 71 2.12.4 Legislation 71 2.12.5 Factors affecting stability 71 2.12.6 Applications 72 2.13 Other colours 74 2.13.1 Chlorophyll 74 2.13.2 Copper complexes of chlorophylls and chlorophyllins 75 2.13.3 Carotenoids 76 2.13.4 Caramel 77 2.13.5 Carbon black 78 2.14 Conclusions 78 References 79 3 Biotechnology in natural food colours: The role of bioprocessing 80 M.C. O'CALLAGHAN 3.1 Summary 80 3.2 Introduction 80 3.3 Definitions 82 3.4 Plant biotechnology 83 3.4.1 Genetic engineering 83 3.4.2 Plant tissue culture 83 3.5 Fermentation 90 3.5.1 Fermentation development 91 3.5.2 Solid state (surface) fermentation 92 3.5.3 Algal fermentation 93 3.5.4 Submerged fermentation 97 3.6 Bioprocessing 98 3.6.1 Bioprocessing of j3-carotene 99 3.6.2 Bioprocessing of annatto 101 CONTENTS ix 3.6.3 Bioprocessing of astaxanthin 101 3.6.4 Bioprocessing of marigolds 102 3.6.5 Bioprocessing of betanin 103 3.7 Future perspectives 103 3.7.1 Biotechnology and carotenoid production 105 3.7.2 The influence of legislation 106 3.7.3 Commercial developments 107 Acknowledgements 108 References 108 4 Safety of food colorants 112 F.J. FRANCIS 4.1 Introduction 112 4.2 Toxicity testing 112 4.3 Acceptable daily intake (ADI) 114 4.4 Regulatory approaches 116 4.4.1 The European Union (EU) 116 4.4.2 The USA 117 4.4.3 The Delaney Clause 117 4.5 Safety of individual colorants 119 4.5.1 Beneficial aspects 119 4.5.2 Anthocyanins 120 4.5.3 Carotenoids 120 4.5.4 Canthaxanthin 121 4.5.5 Apocarotenol 121 4.5.6 Lycopene 122 4.5.7 Annatto 122 4.5.8 Paprika 122 4.5.9 Algae 122 4.5.10 Turmeric and curcumin 123 4.5.11 Cochineal and carmine 123 4.5.12 Lac 124 4.5.13 Caramel 124 4.5.14 Monascus 124 4.5.15 Iridoids 125 4.5.16 Betalains 125 4.5.17 Cocoa 125 4.5.18 Chlorophyll 125 4.5.19 Titanium dioxide 125 4.5.20 Carbon black 126 References 126 5 Chlorophylls and chlorophyll derivatives 131 G.A.F. HENDRY 5.1 Summary 131 5.2 Introduction 131 5.2.1 Nomenclature 133 5.3 Chlorophylls under natural conditions 135 5.3.1 Function 135 5.3.2 Structure of chlorophylls and chlorophyll-protein complexes 136 5.3.3 Biosynthesis of chlorophyll a and other natural porphyrin pigments 138 5.3.4 Types of naturally-occurring chlorophylls 140 5.3.5 Turnover and degradation of chlorophylls in biology 141 5.3.6 Natural, and some unnatural, chlorophyll derivatives 142 X CONTENTS 5.4 Chlorophyll derivatives as food colorants 146 5.4.1 Sources of chlorophylls for food colorants 146 5.4.2 Alternatives to chlorophyll a 147 5.4.3 Extraction, isolation and derivatization 149 5.4.4 Structure of the derivatives 150 5.4.5 Stability and instability 151 5.4.6 Economics of chlorophyll derivatives 152 5.5 Future prospects 153 Acknowledgements 155 References 155 6 Haems and bilins 157 J.D. HOUGHTON 6.1 Summary 157 6.2 Haems 157 6.2.1 Introduction 157 6.2.2 Haems in nature 158 6.2.3 Free haems 165 6.3 Phycobilins 170 6.3.1 Introduction 170 6.3.2 Phycobilins in nature 173 6.3.3 Free phycobilins 182 References 193 7 Carotenoids 197 G. BRI1TON 7.1 Summary 197 7.2 Introduction 197 7.2.1 General publications 197 7.2.2 Structure and nomenclature 198 7.3 Distribution, natural functions and actions 200 7.3.1 Distribution 200 7.3.2 Natural functions 202 7.3.3 Actions of carotenoids in human health 202 7.4 Biosynthesis 203 7.4.1 Regulation of biosynthesis 208 7.5 Absorption, transport and metabolism 209 7.6 Natural and synthetic carotenoids as colorants 211 7.6.1 Natural carotenoids and extracts 211 7.6.2 Synthetic carotenoids 212 7.7 General properties and stability 213 7.8 General procedures for carotenoid work 213 7.9 Extraction and purification 215 7.10 High-performance liquid chromatography (HPLC) 217 7.10.1 Normal-phase (adsorption) HPLC 217 7.10.2 Reversed-phase HPLC 218 7.10.3 HPLC of apocarotenoids 219 7.10.4 Resolution of optical isomers 219 7.11 UV-visible light absorption spectroscopy 219 7.11.1 Position of the absorption maxima 220 7.11.2 Spectral fine structure 221 7.11.3 Geometrical isomers 221 7.12 Quantitative determination 221 7.12.1 Spectrophotometry 221 7.12.2 Quantitative determination by HPLC 224