FOOD POWDERS Physical Properties, Processing, and Functionality FOOD ENGINEERING SERIES Series Editor Gustavo V. Barbosa-C´anovas, Washington State University Advisory Board Jose Miguel Aguilera, Pontifica Universidad Catolica de Chile Pedro Fito, Universidad Politecnica Richard W. Hartel, University of Wisconsin Jozef Kokini, Rutgers University Michael McCarthy, University of California at Davis Martin Okos, Purdue University Micha Peleg, University of Massachusetts Leo Pyle, University of Reading Shafiur Rahman, Hort Research M. Anandha Rao, Cornell University Yrjo Roos, University College Cork Walter L. Spiess, Bundesforschungsanstalt Jorge Welti-Chanes, Universidad de las Am´ericas-Puebla Food Engineering Series Jose M. Aguilera and David W. Stanley, Microstructural Principles of Food Processing and Engineering, Second Edition (1999) Stella M. Alzamora, Mar´ıa S. Tapia, and Aurelio L´opez-Malo, Minimally Processed Fruits and Vegetables: Fundamental Aspects and Applications (2000) Gustavo Barbosa-C´anovas and Humberto Vega-Mercado, Dehydration of Foods (1996) Gustavo Barbosa-C´anovas, Enrique Ortega-Rivas, Pablo Juliano, and Hong Yan, Food Powders: Physical Properties, Processing, and Functionality (2005) P.J. Fryer, D.L. Pyle, and C.D. Rielly, Chemical Engineering for the Food Industry (1997) Richard W. Hartel, Crystallization in Foods (2001) Marc E.G. Hendrickx and Dietrich Knorr, Ultra High Pressure Treatments of Food (2002) Lothar Leistner and Grahame Gould, Hurdle Technologies: Combination Treatments for Food Stability, Safety, and Quality (2002) Michael J. Lewis and Neil J. Heppell, Continuous Thermal Processing of Foods: Pasteurization and UHT Sterilization (2000) Rosana G. Moreira, M. Elena Castell-Perez, and Maria A. Barrufet, Deep-Fat Frying: Fundamentals and Applications (1999) Rosana G. Moreira, Automatic Control for Food Processing Systems (2001) M. Anandha Rao, Rheology of Fluid and Semisolid Foods: Principles and Applications (1999) George D. Saravacos and Athanasios E. Kostaropoulos, Handbook of Food Processing Equipment (2002) FOOD POWDERS Physical Properties, Processing, and Functionality Gustavo V. Barbosa-C´anovas Washington State University Pullman, Washington Enrique Ortega-Rivas Autonomous University of Chihuahua Chihuahua, Mexico Pablo Juliano Washington State University Pullman, Washington Hong Yan Washington State University Pullman, Washington Kluwer Academic/Plenum Publishers New York, Boston, Dordrecht, London, Moscow Library of Congress Cataloging-in-Publication Data ISBN 0-306-47806-4 C 2005 by Kluwer Academic/Plenum Publishers, New York 233 Spring Street, New York, New York 10013 http://www.kluweronline.com 10987654321 A C.I.P. record for this book is available from the Library of Congress. All rights reserved No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Permissions for books published in Europe: [email protected] Permissions for books published in the United States of America: [email protected] Printed in the United States of America To our families PREFACE Food powders represent a large fraction of the many food products available in the food industry, ranging from raw materials and ingredients, such as flours and spices, to processed products like instant coffee or powdered milk. Food powders can be distinguished not only by their composition and microstructure, but also by particle size, size distribution, chemical and physical properties, and functionality. Historically, a number of unit operations have been developed and adopted for the production and handling of different food powders. Information on the physical properties, production, and functionality of food powders has been published, mainly through research and review articles, reports in trade magazines, and symposia presentations. This is likely the first book ever authored that addresses key aspects of food powder technology. This book was designed and developed as a useful reference for individuals in both the food industry and academia interested in an organized and updated review, from an engineering perspec- tive. The book consists of twelve chapters including several tables, figures, diagrams, and extensive literature citation, and covers as thoroughly as possible a fascinating field of study and practical applications. The first section of the book (Chapters 1–3) deals with food powder characterization. Chapter 1 presents statistical concepts related to powder sampling as well as techniques, equipment, and procedures for optimal sampling. Single particle-related properties and their evaluation are cov- ered in Chapter 2, which includes particle size and shape, density, size distribution, surface area, and moisture. Chapter 3 describes in detail the bulk powder properties, giving special attention to flow, handling, packing, strength, and instant properties. The second part of the book describes, analyzes, and provides tools needed for the design of a typical unit operation, as related to production, handling, and processing of food powders. Chapter 4 includes useful information about storage alternatives for food powders, as well as flow patterns, together with the analysis of natural and assisted discharge from bins. Chapter 5 covers typical food powder transportation systems utilized during processing, which includes belts, chain, screw and pneumatic conveyors, among other conveying systems. Size reduction, and conversely, size enlargement processes are covered in Chapters 6–8. Reduction of larger food pieces or particles, including energy requirements and equipment used, is described in Chapter 6. Particle enlargement methods, fundamentals, and other design aspects are described in Chapter 7. A specific case on particle size enlargement, i.e., particle encapsulation, can be found in Chapter 8 with focus on the methods used for the production of different food capsules. Chapter 9 analyzes in depth fundamental aspects and the design of food particle mixing systems, while Chapter 10 deals with dry powder separation and classification technology. The most widely encountered process in food particle production is drying, a subject covered in Chapter 11 that includes relevant drying systems commonly used in the food industry. Last but not least, in Chapter 12 four key undesirable phenomena occurring during food particle handling, processing and testing— namely particle attrition, segregation, bulk caking, and dust explosion—are addressed. A thorough description of each phenomenon is given, including evaluation tests, methods for minimization, and mechanisms of action. vii viii Preface We truly hope this book will be a valuable addition to the food powder technology literature and will promote additional interest in advancing food powders research, development, and imple- mentation. Gustavo V. Barbosa-C´anovas Enrique Ortega-Rivas Pablo Juliano Hong Yan CONTENTS PART I: Food Powders Characterization . .......................... 1 1. Sampling .............................................. 3 1.1 Theory and Statistical Aspects ....................................... 3 1.1.1 Introduction: Importance of Sampling .......................... 3 1.1.2 Sampling Variation Sources .................................. 4 1.1.3 Minimum Sample Size ...................................... 5 1.1.4 Standard Sampling Deviation ................................. 7 1.2 Sampling Techniques and Procedures ................................. 10 1.3 Samplers and Sample Dividers ....................................... 12 1.4 Sample Dispersion ................................................ 16 References ............................................................ 17 2. Particle Properties ........................................ 19 2.1 Particle Size and Shape ............................................. 19 2.1.1 Introductory Definitions ..................................... 19 2.1.2 Selection of Relevant Characteristic Particle Size ................. 20 2.1.3 Shape of Particle Related to Sphericity .......................... 22 2.1.4 Evaluation of Shape Outline .................................. 25 2.2 Particle Density ................................................... 27 2.2.1 Density Expressions ........................................ 27 2.2.2 Liquid Pycnometry ......................................... 28 2.2.3 Air Pycnometry ............................................ 28 2.2.4 Aerodynamic Particle Density ................................ 32 2.3 Particle Size Distribution ........................................... 33 2.3.1 Relevance of Particle Size Distribution .......................... 33 2.3.2 Types of Particle Size Distribution ............................. 33 2.3.3 Particle Size Distribution Tendencies ........................... 34 2.3.4 Presentation of Data ........................................ 36 2.3.5 Size Distribution Functions ................................... 37 2.3.6 Analytical Techniques for Size Measurement ..................... 39 2.3.6.1 Sieving .......................................... 39 2.3.6.2 Microscopy Techniques ............................. 42 2.3.6.3 Sedimentation ..................................... 43 2.3.6.4 Stream Scanning ..................................