The Technology of Extrusion Cooking

Transcription

1 The Technology of Extrusion Cooking

2 The Technology of Extrusion Cooking Edited by N.D. FRAME Process Development Manager APV Baker Ltd Peterborough SPRINGER-SCIENCE+BUSINESS MEDIA, B.V.

3 First edition Springer Science+Business Media Dordrecht Originally published by Chapman & Hali in 1994 Softcover reprint of the hardcover 1 st edition 1994 Typeset in 10/12 pt Times New Roman by Acorn Bookwork, Salisbury, Wiltshire ISBN 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 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 Cataloguing-in-Publication data The Technology of extrusion cooking / edited by N.D. Frame.-1st ed. p. cm. Includes bibliographical references and index. ISBN ISBN (ebook) DOI / Food-Extrusion. 1. Frame, N.D. TP370.5.T '.02-dc CIP 8 Printed on permanent acid-free text paper, manufactured in accordance with ANSIINISO Z (Permanence of Paper)

4 Preface Extrusion cooking is a specialist area of food technology because of the complexity of the interactive effects which are inherent in the system. General predictive modelling is very difficult because ingredients are diverse and can vary considerably. Modelling tends to be product specific - new product development tends to be by experimental designs and good fortune. The emphasis of this book is on the latest and potential applications of twin screw extrusion in food production, specifically co-rotating intermeshing screw extruders. Of course, in order to develop products and maximise the extruder potential in terms of energy, product quality and output, an overall understanding of the material flow mechanism, barrel fill length and rheology is essential. The book aims to give explanations and general guidance with examples of screw design, configuration and operating parameters for a variety of product categories. It is also intended to help production operators diagnose the symptoms of particular problems such as temperature control, quality variation, raw material inconsistency, etc. For the product development technologist there is more than one way to make a similar product. For example, equipment manufacturers recommend difficult methods for producing flaked corn. In addition, their machines may differ from each other in terms of screw design, power/ volume ratio, screw tip/barrel clearance, etc., making scale-up more problematic. Extruders generate mixing or shear forces in relatively short residence times which make them highly energy efficient in producing, at high outputs, the direct expanded products found in snack and RTE breakfast cereal categories. Unfortunately these shear forces can generate significant heat and physical degradation of ingredients which may be detrimental to quality parameters such as palatability, water absorption, texture or chemical reaction. These factors are especially important to petfood and brewers' hop extrusion. The advantages and limitations of the twin screw extruder are clearly outlined for different categories and the examples provide the necessary information on the practicalities of setting up a new process or widening a current product range. NDF

5 Contents 1 Operational characteristics of the co-rotating twin-screw extruder 1 N.D. FRAME 1.1 Types of extruders Single screw Co-kneaders Counter rotating Co-rotating 1.2 Process characteristics of the t.s.e Feeding Screw design Screw speed Screw configurations Die design Barrel temperature and heat transfer Scale-up Process flow charts 1.3 Ancillary processes Preconditioning Devolatilisation 1.4 Raw materials 1.5 Practical operation of the t.s.e.-start up, shut down and control 1.6 Glossary References Raw materials for extrusion cooking processes R.C.E. GUY 2.1 Introduction 2.2n Structure-forming raw materials Structure-forming raw materials based on starch Protein-rich raw materials 2.3 Raw materials acting as fillers in the extrudates Proteins Starches Fibrous materials 2.4 Raw materials as plasticisers and lubricants Water Oils and fats Emulsifiers 2.5 Raw materials acting as nucleants for gas bubble formation 2.6 Raw materials acting as flavours Salt Sugar References

6 Vlll CONTENTS 3 Breakfast and cereal extrusion technology 73 R.c. MILLER 3.1 Introduction What is a breakfast cereal? A closer look at the products Breakfast cereal processes Principles of cooking Overview of cooking processes Boiling water cookers Steam cookers Adiabatic extrusion High shear cooking extrusion Low shear, high pressure cookers Low shear, low pressure cookers Continuous steam pre-cooking Breakfast cereal processes: traditional and extrusion methods Flaked cereals Extrusion puffed breakfast cereals Oven puffed cereals Gun puffed cereals Shredded products Pre-cooked hot cereals Conclusion 108 References Snack food extrusion 110 G. MOORE 4.1 Introduction Ingredients Cereals Root crops Process aids Equipment review Mixing equipment Feeders Conditioning cylinders Extruders Dryers Fryers Coaters Direct expanded products Process description Fried collets Baked collets Co-extruded snacks Process description Formulation Miscellaneous Indirect expanded products Pellets Fabricated chips Die and cutter design Die plates Die holes 140

7 CONTENTS IX Effect of expansion forces Effect of viscoelastic forces 140 References Petfood and fishfood extrusion 144 G.J. ROKEY 5.1 Introduction Raw material characteristics and selection Protein sources Starch sources Fat, fibre and ash consideration Minor ingredients Typical formulations Raw material preparation Selection of hardware Feeding devices Preconditioning considerations Extruder barrel selection Die/knife design Ancillary process equipment Processing variables Preconditioning Extrusion Process control Final product specifications Quality control Troubleshooting techniques Evaluation of operational costs Conclusion 188 References Confectionery extrusion 190 E.T. BEST 6.1 Introduction Processing Pre-extrusion processes Cooker extruder profiling Addition and subtraction of materials Shaping and forming at the die Post -extrusion processes Flavours and other special ingredients for confectionery extrusion Liquorice Toffees, caramels and fudges Boiled sweets Sugar crust liqueurs Pressed tablets Creams, pastes and lozenges Gums Jellies Cocoa and crumb Chocolate Reaction chamber products Aerated confections Chewing gum Frozen confectionery 226

8 x CONTENTS 6.18 Croutons 6.19 Three-dimensional confections 6.20 Confections by half products 6.21 Other areas 6.22 Conclusion Acknowledgements References 7 Extrusion of brewers' hops K.T. WESTWOOD Introduction Application of extrusion technology to the production of bitterness in beer Background Development of extrusion technology in hop processing Process chemistry-choice of alkaline salt Composition and quality of extruded hops Experimental brewing studies with extruded hops Process development to commercial scale production Conclusion 250 References 250 Index 251

9 Contributors Mr E.T. Best Westreco Inc., Missouri Development Centre, 3916 Pettis Road, St Joseph, M064593, USA Mr N.D. Frame Dr R.C.E. Guy Mr R.C. Miller Mr G. Moore APV Baker Ltd, Manor Drive, Paston Parkway, Peterborough PE4 7 AP, UK Flour Milling and Baking Research Association, Chorleywood, Herts WD3 5SH, UK RD2 Box 413, Auburn, New York 13021, USA 3200 Fruit Ridge Avenue, NW, Grand Rapids, Michigan 49504, USA Mr G.J. Rokey Wenger Manufacturing, Sabetha, Kansas 66534, USA Dr K.T. Westwood Brewing Research Foundation, Lyttel Hall, Nutfield, Redhill RH14HY, Surrey, UK