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Rosana G. Moreira, Automatic Control for Food Processing Systems (2001). Javier Raso and Volker Heinz, Pulsed Electric Fields Technology for the Food ...
PULSED ELECTRIC FIELDS TECHNOLOGY FOR THE FOOD INDUSTRY Fundamentals and Applications

FOOD ENGINEERING SERIES Series Editor Gustavo V. Barbosa-Canovas, 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 Americas-Puebla

Food Engineering Series Jose M. Aguilera and David W. Stanley, Microstructural Principles of Food Processing and Engineering, Second Edition (1999) Stella M. Alzamora, Marfa S. Tapia, and Aurelio Lopez-Malo, Minimally Processed Fruits and Vegetables: Fundamental Aspects and Applications (2000) Gustavo Barbosa-Canovas and Humberto Vega-Mercado, Dehydration of Foods (1996) Gustavo Barbosa-Canovas, Enrique Ortega-Rivas, Pablo Juliano, and Hong Yan, Food Powders: Physical Properties, Processing, and Functionality (2005) PJ. 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 Treatmentsfor Food Stability, Safety, and Quality (2002) Michael J. Lewis and Neil 1. 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) Javier Raso and Volker Heinz, Pulsed Electric Fields Technology for the Food Industry (2006) 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) Jorge E. Lozano, Fruit Manufacturing (2006) R.B. Miller, Electronic Irradiation of Foods: An Introduction to the Technology (2005) S.D Holdsworth, Thermal Processing of Packaged Foods (1997)

PULSED ELECTRIC FIELDS TECHNOLOGY FOR THE FOOD INDUSTRY Fundamentals and Applications

Edited by

Javier Raso University ofZaragoza Zaragoza, Spain

Volker Heinz German Institute of Food Technology Quakenbrueck, Germany

~ Springer

Editors: Javier Raso Dpto. Producci6n Animal y Ciencia de los Alimentos Facultad de Veterinaria, Universidad de Zaragoza CI Miguel Servet, 17750013 Zaragoza Spain [email protected]

Volker Heinz German Institute of Food Technology P.O. Box 1165 49601 Quakenbrueck [email protected]

Library of Congress Control Number : 20059388 I I ISBN-IO: 0-387-31053-3 ISBN-13: 978-0387-31053-4 Printed on acid-free paper.

© 2006 Springer Science+Business Media, LLC All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer Science-Business Media, LLC, 233 Spring Street, New York, NY 10013, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden . The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. Printed in the United States of America. 9 87654 3 2 springer.com

PREFACE

In the last decade, in an attempt to improve, or replace, existing food processing methods , several novel technologies have been investigated. Some of these technologies, now known as "emerging technologies," have become, especially in highly competitive markets, a very interesting alternative for the food industry, as a means of developing new foods , or improving the safety and quality of existing ones, while reducing energy consumption. This book presents the information accumulated on Pulsed Electric Field technology (PEF) during the last 15 years, by experienced microbiologist, biochemists, food technologists, and electrical and food engineers with the object of offering to anyone interested in this subject a comprehensive knowledge in this field. PEF is a nonthermal food processing technology involving the application, to a food placed between two electrodes, of short duration high intensity electric fields. Such treatments cause, in cells, a phenomenon known as "electropermeabilization,' Electropermeabilization is a temporary or permanent permeabilization of the cell membrane. This permeabilization has shown to have very useful effects in food technology such are the inactivation of microorganisms or the extraction of cell components. In the food industry, processing operations seeking the stabilization of foods by microbial inactivation are of the outmost importance . Thus, the capability of PEF to inactivate microorganisms at temperatures that do not cause any deleterious effect on flavor, color or nutrient value of foods, opens very interesting possibilities. On the other hand, in some food processes, an essential and very common pretreatment step to improve mass transfer rates is the breakdown of cell membranes by different techniques such as grinding, or thermal or enzymatic treatments. Electroporation is also an alternative to these procedures, and it is more so in those processes where the complete disintegration of cell membranes is not desired. The contents of this book are presented in three sections. The first section, consisting of three chapters, includes the introduction and the fundamental aspects of PEF technology. In Chapter I, the historical evolution of PEF is reviewed and a general overview of the state of the art of this technology is given. In Chapter 2, a fundamental understanding of the electrical circuits of PEF generation systems is presented and the specifications of the major components is given. Chapter 3 revised theories proposed to explain "electroporation" in eukaryote cell membrane but it is mainly focused on recent discoveries on electroporation of cell membranes of prokaryotes. Second section is devoted to the effects of PEF on microorganisms, enzymes, main components responsible for food quality, and extraction of intracellular components. In Chapter 4, the effect of PEF on microorganisms is treated . The design of an adequate PEF inactivation treatment requires a prior knowledge on the influence of different factors on inactivation kinetics in order to be able to develop mathematical models that allow to calculate the effect of treatments. These are aspects covered in detail in this chapter as well as the most successful combination of PEF with other preservation technologies. v

vi

Preface

In Chapter 5, the influence of PEF treatments on some food spoilage enzymes and on different components responsible for nutritional and sensorial properties of foods are discussed. The last chapter of this section, Chapter 6, is devoted to an interesting application of PEF such is the extraction of cellular components: Fundamentals of this procedure, as well as possible industrial applications, are described in this chapter. In the lastsection, the possible applications of PEF in food technology, in general, are discussed and information on food processing equipment is given. Several potential applications of PEF are revised in Chapter 7 and an economical analysis is also included to help potential users of the PEF to estimate costs. Finally, in Chapter 8, the main characteristics of PEF processing equipment for the food industry are discussed to help to identify requirements for the correct design and construction of safe and reliable PEF equipment. Thanks are given to the collaborators in this book and to all the researchers of different disciplines who have contributed in the development of this technology for the food industry. With their efforts they deserve that this book becomes the comprehensive interdisciplinary reference source for researchers and industrials interested in the application of PEF technology. Francisco 1. Sala Trepat Professor of Food Technology University of Zaragoza

CONTENTS PART I: Introduction . . . . . . . • . . . . • . . . . . . . . • • . . . . . . . . . . . . . • . • . • .

1

1. Pulsed Electric Fields Processing of Foods: An Overview. . . . . . . . . . . • . . . . . . Gustavo V. Barbosa-Cdnovas and Bilge Altunakar I. Introduction 1.1. Historical Evolution and Chronological Developments in Pulsed Electric Field Processing 1.2. Present Status of Pulsed Electric Field Technology and Applications 2. Fundamental Aspects of Pulsed Electric Field Treatment 2.1. System Components 2.1.1. Power Supply 2.1.2. Treatment Chamber 2.2. Effectiveness of Pulsed Electric Field Treatment 2.2.1. Technological Factors 2.2.2. Biological Factors 2.2.3. Media Factors 2.2.4. Inactivation Kinetics and Modeling 3. Future Aspects and Economic Analysis of PEF Processing 3.1. Combination Studies 3.2. DrawbackslLimitations References

3

2. Generation and Application of High Intensity Pulsed Electric Fields . . . . . . . . . . Markus J. Loeffler 1. Introduction 2. Electric Load Requirements 2.1. Specific Power Consumption 2.2. Average Power 2.3. Voltage Waveforms 2.4. Pulse Lengths and Repetition Rates 2.5. Conclusion 3. Pulsed Power Systems 3.1. General Remarks About Switches in Pulsed Power Generators 3.2. PEF Treatment Chambers 3.3. High-Power Sources 3.3.1. Basic Pulsed Power Circuits 3.3.2. Circuits with Transformers or Other Voltage Multipliers

3 4 7 9 10 10 11 14 14 16 17 18 19 19 20 21 27 27 28 28 30 32 33 33 34 35 35 36 37 40

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Contents

3.3.3. Pulse Forming Networks 3.3.4. Networks with Pulse Forming Switches 3.3.5. Concluding Remarks 3.4. Components of High Power Sources 3.4.1. High-Power Capacitors 3.4.2. Switches 3.5. Low-Power Source 3.5.1. Basic Considerations 3.5.2. Typical Devices References

45 50 51 52 52 54 62 62 63 71

3. Fundamental Aspects of Microbial Membrane Electroporation . . . . . . . . . . . . .. Rafael Pagan and Pilar Mafias I. Introduction 2. Electroporation of Biomembranes 3. Electroporation of Microorganisms of Interest in Food Preservation 3.1. Electron Microscopy Examination 3.2. Leakage of Intracellular Material 3.3. Loss of Osmotic Response 3.4. Permeabilization to Nonpermeant Dyes 3.4.1. Effect of Process Parameters: Electric Field Strength, Treatment Time, and Specific Energy 3.4.2. Effect of Type of Microorganism 3.4.3. Effect of Product Characteristics 3.5. Occurrence of Sublethal Injury 4. Concluding Remarks References

PART II: Effects of Pulsed Electric Fields

73

73 74 77 77 78 78 79 79 81 84 86 90 91

. . ..

95

4. Microbial Inactivation by Pulsed Electric Fields . . . . . . . . . . . . . . . . . . . . . . . Ignacio Alvarez, Santiago Condon, and Javier Raso I. Introduction 2. Critical Factors Determining Microbial Inactivation by Pulsed Electric Fields 2.1. Processing Factors 2.1.1. Electric Field Strength 2.1.2. Pulse Shape 2.1.3. Pulse Width 2.1.4. Treatment Time 2.1.5. Frequency................................................... 2.1.6. Specific Energy 2.1.7. Temperature 2.2. Microbial Characteristics 2.2.1. Type of Microorganism 2.2.2. Cell Size and Shape 2.2.3. Culture Conditions

97

97 98 99 99 100 101 102 102 102 103 103 104 104 105

Contents 2.3. Treatment Medium Characteristics 2.3.1. Electrical Conductivity 2.3.2. pH 2.3.3. Water Activity 2.3.4. Composition of the Treatment Medium 3. Modeling Microbial Inactivation by Pulsed Electric Fields 3.1. Collecting Data for Modeling Microbial Inactivation by PEF 3.1.1. Strain and Culture Conditions 3.1.2. PEF Treatment 3.1.3. Treatment Medium 3.1.4. Recovery Conditions 3.2. Primary Models for Describing Microbial Inactivation by Pulsed Electric Fields 3.3. Secondary Models for Describing Microbial Inactivation Pulsed Electric Fields 4. Combination Treatments 5. Conclusions References

ix 105 106 106 108 108 110 110 III III 112 113 113 117 122 123 124

5. Effect of Pulsed Electric Fields on Enzymes and Food Constituents . . . . . . . . . .. Pilar Manas and Antonio Vercet 1. Introduction 2. Effect of PEF on Enzyme Activity 3. Effect of PEF on Food Constituents 3.1. Proteins 3.2. Fats and Emulsions 3.3. Vitamins 3.4. Pigments 4. Generation of New Compounds 5. Quality of PEF-processed Foods 5.1. Milk........... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5.2. Juices 5.3. Egg Products 5.4. Other Foods 6. Concluding Remarks References

131

6. Extraction of Intercellular Components by Pulsed Electric Fields . . . . . . . . . . .. Eugene Vorobiev and Nikolai I. Lebovka 1. Introduction 2. Theoretical Aspects of PEF Influence on The Biological Materials 2.1. Disintegration Index and Characteristic Damage Time 2.2. Selective Concentration of the Electric Fields on Membranes in Biological Materials 2.3. Main Mechanisms of Membrane and Cell Damage in External Electric Fields 2.3.1. Electroporation of Membrane 2.3.2. Joule Overheating of the Membrane Surface

153

131 131 137 138 139 142 143 143 144 144 145 147 148 149 149

153 154 154 155 156 156 157

Contents

x

2.3.3. Electroosmotic Transport Through the Membrane 2.3.4. Distinctness of the Cell Damage 2.4. PEF-Induced Structural Changes in a Cellular Tissue 2.4.1. Electrical Conductivity of PEF-Treated Tissues 2.4.2. Characteristic Damage Time and Optimization Criteria 2.4.3. PEF-Induced Secondary Effects in a Cellular Tissue 3. Application of PEF for Solidlliquid Expression 3.1. Example of a Laboratory Device for the Combined Pressing and PEF Treatment 3.2. Mechanism of SolidlLiquid Expression from Biological Tissue Treated by PEF 3.3. Effect of PEF on the Behavior of Constant Pressure Expression from Food Plants 3.3.1. Consolidation Behavior 3.3.2. SolidlLiquid Expression with Intermediate PEF Treatment 3.4. Effect of PEF on the Behavior of Constant Rate Expression from Food Plants 3.5. Combination of PEF with a Moderate Heating 3.6. Pilot Studies of SolidlLiquid Expression Combined with PEF 4. Effect of PEF-enhancing on Diffusion of Water and Soluble Substances From Tissues 4.1. Models for PEF Treatment Enhanced Diffusion 4.2. Influence of PEF Protocol, Temperature, and Fragmentation of Particles on the Extraction Kinetics References

158 158 159 159 161 163 165 165 166 168 168 171 172 176 179 182 183 185 190

PART III: Applications and Equipments

195

7. Applications of Pulsed Electric Fields Technology for the Food Industry . . . . . . ..

197

Stefan Toepji, Volker Heinz and Dietrich Knorr 1. Introduction 2. Permeabilization of Cell Membranes 3. Applications of PEF Technology For the Food Industry 3.1. Induction of Stress Response 3.2. Treatment of Plant or Animal Cellular Tissue 3.2.1. Juice Processing 3.2.2. PEF Treatment of Microalgae, Seaweed, and Other Aquatic Species 3.2.3. Plant Oil Extraction 3.2.4. Meat and Fish Treatment 3.2.5. Drying Enhancement 3.2.6. Sugar Processing 3.2.7. Energy Requirements for Tissue Disintegration 3.3. Microbial Decontamination 3.4. Wastewater Treatment 4. Cost Analysis 4.1. Fruit Mash Disintegration for Juice Winning 4.2. Cost Estimation for Beverage Pasteurization

197 197 199 199 199 199 201 202 203 204 204 205 206 209 210 211 212

Contents 5. Problems and Challenges 6. Research Needs , Conclusion s, and Outlook References 8. Pulsed Power Systems for Application of Pulsed Electric Fields in the Food Industry

xi 214 216 217 223

Hennie Mastwijk I. 2. 3. 4.

Introduction Peak Power Requirement s Continuous Power Requirements Power Supplies , Switches , and Treatment Devices 4.1. DC Power Supplies 4.2. Switches 4.3. Electrical Properties of Treatment Devices 4.3.1. Electrical Impedance 4.3.2. Comparison of Cell Resistance by Calculation and Measurement 4.4. Pulse Shapes 4.5. Measurement Under Pulsed Conditions 4.6. Partial Discharges, Electrical Breakdown , and Arcing 5. Electrochemical Properties of Pulsed Power Systems 5.1. Electrochemical Reactions 5.2. Electrode Degradation by DC Offset 5.3. Metal Release Under Pulsed Conditions 5.4. More Sources of AC Components 6. Process Assessment 6.1. Energy Input 6.2. Calorimetric Heat Output References

223 223 224 225 227 227 228 228 229 229 229 231 232 232 232 234 235 236 236 237 237

Index . . . • . . • . . . . . . . . . . . • . . . . • . . • . . . . . • . . . . . . . . • . . . . . . . . . . 239

CONTRIBUTORS BilgeAltunakar Center for Nontherrnal Process ing of Food Washington State University Pullman, Washington United States

Ignacio Alvarez Dpto. Produccion Animal y Ciencia de los Alimentos Facultad de Veterinaria Universidad de Zaragoza C/ Miguel Servet 177, 50013 Zaragoza Spain

Gustavo V. Barbosa-Canovas Center for Nontherrnal Proces sing of Food Washington State University Pullman, Washington United States

Santiago Condon Dpto. Producci6n Animal y Ciencia de los Alimentos Facultad de Veterinaria Universidad de Zaragoza C/ Miguel Servet, 177 50013 Zaragoza Spain

Volker Heinz German Institute of Food Technology Prof.-v.-Klitzing-Str. 7 4960 I Quakenbrueck Germany

Dietrich Knorr Department of Food Biotechnology and Food Process Engineering Berlin University of Technology

Koenigin-Luise-Str.22 14195 Berlin Germany

Nikolai I. Lebovka Institute of Biocolloidal Chemistry named after ED.Ovcharenko NAS of Ukraine 42, blvr. Vernadskogo, Kyiv 03142 Ukraine

Markus J. Loerner High Voltage and Pulsed Power Technology Energy Institute University of Applied Sciences Neidenburger StraBe 10 0-45877 Gelsenkirchen Germany

Pilar Mafias Dpto. Produccion Animal y Ciencia de los Alimentos Facultad de Veterinaria Universidad de Zaragoza C/ Miguel Servet 177, 50013 Zaragoza Spain

HennieMastwijk Wageningen UR, Agrotechnology and Food Innovations B.Y., P.O. Box 17,6700 AA Wageningen The Netherlands

Rafael Pagan Dpto. Produccion Animal y Ciencia de los Alimentos Facultad de Veterinaria, Universidad de Zaragoza C/ Miguel Servet 177, 500 13 Zaragoza Spain xiii

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Contributors

Javier Raso

Antonio Vercet

Dpto. Producci6n Animal y Ciencia de los Alimentos Facultad de Veterinaria, Universidad de Zaragoza C/ Miguel Servet, 177 50013 Zaragoza Spain

Dpto. Producci6n Animal y Ciencia de los Alimentos Facultad de Veterinaria Universidad de Zaragoza C/ Miguel Servet 177, 50013 Zaragoza Spain

Stefan Toepft

Eugene Vorobiev

Department of Food Biotechnology and Food Process Engineering Berlin University of Technology Koenigin-Luise-Str. 22 14195 Berlin Germany

Departement de Genie Chimique Universite de Technologie de Compiegne Centre de Recherche de Royallieu B.P. 20529-60205, Compiegne Cedex France