Dairy Chemistry and Biochemistry P.F. FOX and P.L.H. McSWEENEY Department of Food Chemistry University College Cork, Ireland BLACKIE ACADEMIC & PROFESSIONAL An Imprint of Chapman 8 Hall London 1 Weinheim . New York * Tokyo Melbourne . Madras Published by Blackie Academic & Professional, an imprint of Thomson Science, 2-6 Boundary Row, London SE1 SHN, UK Thomson Science, 2-6 Boundary Row, London SE18HN, UK Thomson Science, 115 Fifth Avenue, New York NY 10003, USA Thomson Science, Suite 750, 400 Market Street, Philadelphia, PA 19106, USA Thomson Science, Pappelallee 3, 69469 Weinheim, Germany First edition 1998 0 1998 Thomson Science Thomson Science is a division of International Thomson Publishing I@P* Typeset in 10/12pt Times by Doyle Graphics, Tullamore, Ireland Printed in Great Britain by St Edmundsbury Press Ltd, Bury St Edmunds, Suffolk ISBN 0 412 72000 0 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, without the prior written permission of the publishers. Applications for permission should be addressed to the rights manager at the London address of the publisher. 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: 97-77281 @ Printed on acid-free text paper, manufactured in accordance with ANSI/NISO 239.48-1992 (Permanence of Paper). Preface Milk has been the subject of scientific study for about 150years and, consequently, is probably the best characterized, in chemical terms, of our major foods. It is probably also the most complicated and serves as the raw material for a very large and diverse family of food products. Dairy science has existed as a university discipline for more than 100 years; it is the oldest sector of food science (and technology), with the exception of brewery science. Since dairy chemistry is a major facet of dairy science, it might be expected to have been the subject of numerous books. This is, in fact, not so. During the past 40years, as far as we are aware, only six books or series on dairy chemistry have been published in English, i.e. Principles of Dairy Chemistry (Jenness and Paton, 1959), Dairy Chemistry and Physics (Walstra and Jenness, 1984), Fundamentals of Dairy Chemistry (Webb and Johnson, 1964; Webb, Johnson and Alford, 1974; Wong et al., 19SS), Developments in Dairy Chemistry (Fox, four volumes, 1982, 1983, 1985, 1989), Advanced Dairy Chemistry (Fox, three volumes, 1992, 1995, 1997) and Handbook of Milk Composition (Jensen, 1995). Of these, Principles of Dairy Chemistry and Dairy Chemistry and Physics were written essentially for senior undergrad- uate students. The other four books/series were focused principally on lecturers, researchers, senior postgraduate students and senior production management. Thus, at present there is a lack of books written at senior undergraduate/junior postgraduate level specializing in dairy chemistry/ science. This book is intended to fill that gap and should be as useful to graduates working in the dairy industry as it is to those still studying. The book assumes a knowledge of chemistry and biochemistry but not of dairy chemistry. As the title suggests, the book has a stronger biochemical orientation than either Principles of Dairy Chemistry or Dairy Chemistry and Physics. In addition to a fairly in-depth treatment of the chemistry of the principal constituents of milk, i.e. water, lactose, lipids, proteins (including enzymes), salts and vitamins, various more applied aspects are also covered, e.g. heat-induced changes, cheese, protein-rich products and the applications of enzymes in dairy technology. The principal physical properties are also described. To facilitate the reader, the structure of various molecules mentioned frequently in the text are given in appendices but we emphasize that a good general knowledge of chemistry and biochemistry is assumed. The chemical composition of the principal dairy products is also included. xiv PREFACE The book does not cover the technology of the various dairy products, although brief manufacturing protocols for some products are included to facilitate discussion; however, a number of textbooks on various aspects of dairy technology are referenced. Neither are the chemical analyses, microbi- ology and nutritional aspects of dairy products covered, except in a very incidental manner. The effects of dairy husbandry on the composition and properties of milk are discussed briefly, as is the biosynthesis of milk constituents; in both cases, some major textbooks are referenced. We hope that the book will answer some of your questions on the chemistry and biochemistry of milk and milk products and encourage you to undertake more extensive study of these topics. The highly skilled and enthusiastic assistance of Ms Anne Cahalane and Ms Brid Considine in the preparation of the manuscript and of Professor D.M. Mulvihill and Dr N. O’Brien for critically and constructively review- ing the manuscript are gratefully acknowledged and very much appreciated. P.F. Fox P.L.H. McSweeney General references on dairy chemistry Alais, C. (1974) Science du Lait. Principes des Techniques Laitieres, 3rd edn, SEP Editions, Paris. Fox, P.F. (ed.) (1982-1989) Developments in Dairy Chemistry, Volumes 1, 2, 3 and 4, Elsevier Applied Science Publishers, London. Fox, P.F. (ed.) (1992-1997) Advanced Dairy Chemistry, Volumes 1, 2 and 3, Elsevier Applied Science Publishers and Chapman & Hall, London. Jenness, R. and Patton, S. (1959) Principles of Dairy Chemistry, John Wiley & Sons, New York. Jensen, R.G. (ed.) (1995) Handbook of Milk Composition, Academic Press, San Diego. Walstra, P. and Jenness, R. (1984) Dairy Chemistry and Physics, John Wiley & Sons, New York. Webb, B.H. and Johnson, A.H. (eds) (1964) Fundamentals of Dairy Chemis- try, AVI, Westport, CT, USA. Webb, B.H., Johnson, A.H. and Alford, J.A. (eds) (1974) Fundamentals of Dairy Chemistry, 2nd edn, AVI, Westport, CT, USA. Wong, N.P., Jenness, R., Keeney, M. and Marth, E.H. (eds) (1988) Funda- mentals of Dairy Chemistry, 3rd edn, Van Norstrand Reinhold, New York.