SEPARATION PROCESSES IN THE FOOD AND BIOTECHNOLOGY INDUSTRIES Principles and Applications Edited by A. S. GRANDISON and M. J. LEWIS Department of Food Science and Technology University of Reading, UK WOODHEAD PUBLISHING LIMITED Cambridge England Published by Woodhead Publishing Limited, Abington Hall, Abington, Cambridge CB 1 6AH, England First published 1996 0 1996, Woodhead Publishing Ltd Conditions of sale All rights reserved, No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording or any information storage and retrieval system, without permission in writing from the publisher. While a great deal of care has been taken to provide accurate and current information, neither the author, nor the publisher, 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. British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN I 85573 287 4 Typeset by Heather FitzGibbon, Christchurch, Dorset Printed by Galliard (Printers) Ltd, Great Yarmouth, England Preface This book concentrates on the more recent methods and techniques for separating food components and products of the biotechnology industry. Each chapter deals with a specific type or area of application and includes information on the basic principles, industrial equipment available, commercial applications and an overview of current research and development. The introductory chapter gives a brief overview of food composition and properties, and some of the heat and mass transfer considerations in batch and continuous processes. Separations from solids, liquids and gases are briefly discussed. A summary is provided of the more conventional separation techniques such as screening, filtration and centrifugation, and techniques for removing water, such as evaporation, freeze- concentration and dehydration. However, the main emphasis is on separation processes, which have received less attention in textbooks on food-engineering and food-processing operations. It is hoped that this book will complement and supplement many of these excellent texts. Chapter 2 deals with the use of supercritical fluids for extraction processes, with special reference to carbon dioxide. Chapter 3 deals with pressure- activated membrane techniques, and covers the general principles, reviews the applications of reverse osmosis, and serves as an introduction to Chapters 4 and 5, which deal specifically with the principles and applications of ultrafiltration and microfiltration respectively. The separation and recovery of charged particles by ion exchange and electrodialysis is covered in Chapter 6. Chapter 7 discusses innovative separation processes, and reviews some of the methods being actively investigated, some of which are now coming into industrial practice. Much of the emphasis in these chapters is on the separation and recovery of proteins and biologically active ingredients. Chapter 8 is specifically on the methods available for fractionating fat, and covers the upsurge in interest and recent developments in this area. The book concludes with a chapter on solids separation processes, with special reference to particulates. The physical properties which influence the separation are reviewed, together with sieving, screening and air classification. Wet processing methods for extraction are discussed, together with some miscellaneous applications such as dehulling, peeling and cleaning. xii Preface Much of the emphasis is on extraction of macromolecules, increasing the added value of foods and recovering valuable components from by-products and fermentation media. Many of the methods discussed are now in commercial practice, whilst others are being vigorously researched. A. S. Grandison and M. J. Lewis