Food Irradiation Research and Technology E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Serie: Institute of Food Technologists Series
• Sprache: Englisch

Seitenzahl: 778

Veröffentlichungsjahr: 2012

Beschreibung

The benefits of food irradiation to the public health have been described extensively by organizations such as the Centers for Disease Control and Prevention in the USA and the World Health Organization. The American Medical Association and the American Dietetic Association have both endorsed the irradiation process. Yet the potential health benefits of irradiation are unknown to many consumers and food industry representatives who are wary of irradiated foods due to myth-information from "consumer-advocate" groups. This updated second edition of Food Irradiation Research and Technology reviews the latest developments in irradiation technologies as they are applied to meat, seafood fish, fruits, vegetables and nuts. Experts from industry, government, and academia define the basic principles and public health benefits of irradiation. New chapters in this edition address irradiation chemistry, including furan formation due to irradiation, irradiation of packaging materials, processing irradiation technologies and parameters, and ready-to-eat meat products. Coverage of safety and quality of fresh fruits and vegetables, phytosanitary applications and consumer acceptance has been expanded to address recent interest and development. The book is designed to appeal to a broad readership: industry food scientists involved in the processing of meat and fish, fruits and vegetables; food microbiologists and radiation processing specialists; and government and industry representatives involved in the import and export of food commodities.

Leseprobe

Contents

Cover

IFT Press

Title Page

Copyright

Series Page

List of Contributors

PREFACE

Chapter 1: INTRODUCTION: FOOD IRRADIATION MOVING ON

Introduction

Two Tracks Going Forward

Bumps Still Remain on the Road Ahead

Summary

References

Chapter 2: ADVANCES IN ELECTRON BEAM AND X-RAY TECHNOLOGIES FOR FOOD IRRADIATION

Introduction

Basic Irradiation Concepts

Electron Beam Facilities

X-ray Facilities

Conclusion

References

Chapter 3: GAMMA RAY TECHNOLOGY FOR FOOD IRRADIATION

Introduction

Overview of Co-60 Gamma Technology

Basic Irradiation Concepts

Gamma Ray Facilities for Radiation Research

Comparison of Irradiation Technologies

References

Chapter 4: REGULATION OF IRRADIATED FOODS AND PACKAGING

Introduction

References

Notes

Chapter 5: TOXICOLOGICAL SAFETY OF IRRADIATED FOODS

Introduction

Food Irradiation

Benzene, Formaldehyde, and Amines

Formation and Levels of 2-ACBs in Foods

Toxicological Safety of 2-ACBs

2-ACBs and Tumor Promotion

Diet and Tumor Promotion

Conclusions

References

Chapter 6: RADIATION CHEMISTRY OF FOOD COMPONENTS

Basic Radiation Effects

Radiation Chemistry of Major Food Components

Reduction of Undesirable Compounds by Irradiation

Acknowledgments

References

Chapter 7: DOSIMETRY FOR FOOD PROCESSING AND RESEARCH APPLICATIONS

Importance of Dosimetry

Introduction

Selection and Characterization of a Dosimetry System

The Use of a Dosimetry System

Dosimetry in Food Research

Dosimetry at a Commercial Facility

References

Chapter 8: DETECTION OF IRRADIATED FOODS

Introduction

Free Radicals and Electronic Excited States

Stable Radiolytic Products

Germination Inhibition

Conclusion

References

Chapter 9: IRRADIATION OF PACKAGING MATERIALS IN CONTACT WITH FOOD: AN UPDATE

Introduction

Current Authorizations of Packaging Materials for Irradiation of Prepackaged Food

Radiation-Induced Chemical Changes in Packaging Materials

Evaluating Packaging Materials Irradiated in the Presence of Oxygen

Conclusions

Acknowledgment

References

Chapter 10: CONSUMER ACCEPTANCE AND MARKETING OF IRRADIATED FOODS

Introduction

What Is Food Irradiation?

Why Is Food Irradiated?

Marketing of Irradiation Foods

Commercial Acceptance of Irradiation Foods

Resistance to “New” Technology

Risks versus Benefits

World's Safest Food Supply, But Not Safe Enough

Irradiation: A Powerful and Effective Tool to Improve Food Safety

Education: The Key to Consumer Acceptance

Effect of Unfavorable Information

Can Unfavorable Information Be Counteracted?

Effects of Gender, Income, and Children

Barriers to Acceptance

The “Minnesota Model” of Consumer Acceptance

A Defining Moment in Food Safety

Is It Farm to Fork, or Turf to Tort?

Conclusion

References

Chapter 11: IRRADIATION OF READY-TO-EAT MEAT PRODUCTS

Introduction

Materials and Methods

Results and Discussion

Acknowledgment

References

Chapter 12: MECHANISMS AND PREVENTION OF QUALITY CHANGES IN MEAT BY IRRADIATION

Introduction

Food Irradiation

Microcidal Effect

Quality Changes in Meat by Irradiation

Control of Off-Odor Production and Color Changes

Future Research

References

Chapter 13: PHYTOSANITARY IRRADIATION FOR FRESH HORTICULTURAL COMMODITIES: RESEARCH AND REGULATIONS

Introduction

Developing Irradiation Quarantine Treatments

Varietal Testing

Probit 9 Efficacy and Alternatives

Generic Radiation Treatments

Regulatory Aspects of Irradiation

USDA Regulations

Regional and International Harmonization

Trade

References

Chapter 14: ANTIMICROBIAL APPLICATION OF LOW-DOSE IRRADIATION OF FRESH AND FRESH-CUT PRODUCE

Introduction

Produce Microbiology and Irradiation Treatment

Internalization of Bacteria

Biofilm-Associated Pathogens

Postirradiation Recovery and Regrowth

Treatment Parameters for Irradiation of Produce

Influence of Plant Variety

Combination with Sanitizers

Irradiation Plus Mild Thermal Treatment

Summary

Acknowledgments

References

Chapter 15: IRRADIATION OF FRESH AND FRESH-CUT FRUITS AND VEGETABLES: QUALITY AND SHELF LIFE

Introduction

Ethylene and Respiration

Appearance

Texture

Flavor/Taste

Nutrients

Combination of Irradiation with Other Postharvest Techniques

Shelf-Life Extension

References

Chapter 16: IRRADIATION OF SEEDS AND SPROUTS

Introduction

Outbreaks Associated with Sprouts

Potential Source of Contamination

Pathogens of Concern for Sprouts

Pathogen Decontamination Overview

Seed and Sprout Evaluation after Treatment

Radiation Dose to Reduce Microbial Pathogens on Seeds

Combination Treatments

Radiation Dose to Reduce Microbial Pathogens on Sprouts

Other

Conclusions

References

Chapter 17: IRRADIATION OF NUTS

Introduction

Farming and Harvesting

Insect Disinfestation

Microbial Contamination

Contamination with Pathogens

Irradiation Treatment of Nuts

Insect Disinfestation

Molds and Aflatoxins

Pathogen Inactivation

Chemical and Sensory: Irradiation Can Catalyze or Induce Lipid Peroxidation, and Lipid and/or Protein Radiolysis

Effect of Irradiation on Nut Allergenicity

Advantages of Using Irradiation to Treat Nuts

Research Needs

References

Chapter 18: IRRADIATION OF SEAFOOD WITH A PARTICULAR EMPHASIS ON LISTERIA MONOCYTOGENES IN READY-TO-EAT PRODUCTS

Introduction

Listeria monocytogenes Is a Significant Contaminant of Seafood

Stress Adaptation of the Organism

Irradiation Is an Effective Postprocessing Treatment for Fish Products

Physical, Chemical, and Sensory Changes of Irradiated Seafood

Competing Microflora

Comments Regarding Irradiation and the Risk for Botulism

Conclusion

References

Chapter 19: IONIZING RADIATION OF EGGS

Introduction

Ionizing Radiation of Shell Eggs

Ionizing Radiation of Refrigerated Liquid Egg

Ionizing Radiation of Dried Egg

Ionizing Radiation of Frozen Egg

Strategies to Increase the Quality of Irradiated Egg Products

Areas for Future Research

Conclusion

Acknowledgments

References

Chapter 20: IRRADIATED GROUND BEEF FOR THE NATIONAL SCHOOL LUNCH PROGRAM

Introduction

Foodborne Illnesses in School

Regulatory Allowance and Specifications of Irradiated Foods for Schools

Sensory Properties of Irradiated Ground Beef

Conclusion

Acknowledgments

References

Chapter 21: POTENTIAL APPLICATIONS OF IONIZING RADIATION

Introduction

Reduction of Food Allergies by Ionizing Radiation

Volatile N-nitrosamine and Residual Nitrite Reduction

Biogenic Amines Reduction

Reduction of Phytic Acid and Increase in Antioxidant Activity

Chlorophyll b Breakdown

Color Improvement of Plant Extracts without Change of Biological Functions

Control of Enterobacter sakazakii in Infant Formula

Use of Irradiation to Control Food-Related Bacteria in Meat Products

Application of Irradiation for Sea Food Safety

Use of Irradiation on Fresh Produces and Dairy Products

Application of Irradiation for the Development of Traditional Fermented Foods

Use of Boiled Extracts from Cooking

Improvement of Nutritional Conditions and Food Quality by Irradiation

Conclusion

Acknowledgments

References

Chapter 22: A FUTURE UNCERTAIN: FOOD IRRADIATION FROM A LEGAL PERSPECTIVE

Introduction

Liability for the Manufacture of a Defective Food Product

Strict Liability Creates Few If Any Legal Incentives in Favor of Food Irradiation

A Possible Existing Legal Duty to Use Irradiated Food: The Challenge of Highly Susceptible Populations

Negligence: Failing to Avoid a Known and Avoidable Risk

The Possibility of Liability Arising from Irradiated Foods

Conclusion

Notes

Chapter 23: TECHNICAL CHALLENGES AND RESEARCH DIRECTIONS IN ELECTRONIC FOOD PASTEURIZATION

Introduction

Target Pathogens

Radiation Physics and Chemistry

Product Packaging

Electronic Pasteurization of Complex-Shaped Packages

Acknowledgments

References

INDEX

The IFT Press series reflects the mission of the Institute of Food Technologists – to advance the science of food contributing to healthier people everywhere. Developed in partnership with Wiley-Blackwell, IFTPress books serve as leading-edge handbooks for industrial application and reference and as essential texts for academic programs. Crafted through rigorous peer review and meticulous research, IFT Press publications represent the latest, most significant resources available to food scientists and related agriculture professionals worldwide. Founded in 1939, the Institute of Food Technologists is a nonprofit scientific society with 18,000 individual members working in food science, food technology, and related professions in industry, academia, and government. IFT serves as a conduit for multidisciplinary science thought leadership, championing the use of sound science across the food value chain through knowledge sharing, education, and advocacy.

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This edition first published 2013 © 2013 by Blackwell Publishing and the Institute of Food Technologists

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Library of Congress Cataloging-in-Publication Data

Food irradiation research and technology / edited by Xuetong Fan, Christopher H. Sommers. – 2nd ed. p. cm. Includes bibliographical references and index. ISBN 978-0-8138-0209-1 (hardback : alk. paper) 1. Radiation preservation of food–Research. 2. Irradiated beef. I. Fan, Xuetong. II. Sommers, Christopher H. TP371.8.F676 2013 664′.0288–dc23 2012015387

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Cover image: © iStockphoto.com/mattjeacock

Cover design by Meaden Creative

Titles in the IFT Press series

Accelerating New Food Product Design and Development (Jacqueline H. Beckley, Elizabeth J. Topp, M. Michele Foley, J.C. Huang, and Witoon Prinyawiwatkul)Advances in Dairy Ingredients (Geoffrey W. Smithers and Mary Ann Augustin)Bioactive Proteins and Peptides as Functional Foods and Nutraceuticals (Yoshinori Mine, Eunice Li-Chan, and Bo Jiang)Biofilms in the Food Environment (Hans P. Blaschek, Hua H. Wang, and Meredith E. Agle)Calorimetry in Food Processing: Analysis and Design of Food Systems (Gönül Kaletunç)Coffee: Emerging Health Effects and Disease Prevention (YiFang Chu)Food Carbohydrate Chemistry (Ronald E. Wrolstad)Food Ingredients for the Global Market (Yao-Wen Huang and Claire L. Kruger)Food Irradiation Research and Technology (Xuetong Fan and Christopher H. Sommers)Foodborne Pathogens in the Food Processing Environment: Sources, Detection and Control (Sadhana Ravishankar, Vijay K. Juneja, and Divya Jaroni)High Pressure Processing of Foods (Christopher J. Doona and Florence E. Feeherry)Hydrocolloids in Food Processing (Thomas R. Laaman)Improving Import Food Safety (Wayne C. Ellefson, Lorna Zach, and Darryl Sullivan)Innovative Food Processing Technologies: Advances in Multiphysics Simulation (Kai Knoerzer, Pablo Juliano, Peter Roupas, and Cornelis Versteeg)Microbial Safety of Fresh Produce (Xuetong Fan, Brendan A. Niemira, Christopher J. Doona, Florence E. Feeherry, and Robert B. Gravani)Microbiology and Technology of Fermented Foods (Robert W. Hutkins)Multiphysics Simulation of Emerging Food Processing Technologies (Kai Knoerzer, Pablo Juliano, Peter Roupas and Cornelis Versteeg)Multivariate and Probabilistic Analyses of Sensory Science Problems (Jean-François Meullenet, Rui Xiong, and Christopher J. Findlay)Nanoscience and Nanotechnology in Food Systems (Hongda Chen)Natural Food Flavors and Colorants (Mathew Attokaran)Nondestructive Testing of Food Quality (Joseph Irudayaraj and Christoph Reh)Nondigestible Carbohydrates and Digestive Health (Teresa M. Paeschke and William R. Aimutis)Nonthermal Processing Technologies for Food (Howard Q. Zhang, Gustavo V. Barbosa-C´novas, V.M. Balasubramaniam, C. Patrick Dunne, Daniel F. Farkas, and James T.C. Yuan)Nutraceuticals, Glycemic Health and Type 2 Diabetes (Vijai K. Pasupuleti and James W. Anderson)Organic Meat Production and Processing (Steven C. Ricke, Ellen J. Van Loo, Michael G. Johnson, and Corliss A. O'Bryan)Packaging for Nonthermal Processing of Food (Jung H. Han)Preharvest and Postharvest Food Safety: Contemporary Issues and Future Directions (Ross C. Beier, Suresh D. Pillai, and Timothy D. Phillips, Editors; Richard L. Ziprin, Associate Editor)Processing and Nutrition of Fats and Oils (Ernesto M. Hernandez and Afaf Kamal-Eldin)Processing Organic Foods for the Global Market (Gwendolyn V. Wyard, Anne Plotto, Jessica Walden, and Kathryn Schuett)Regulation of Functional Foods and Nutraceuticals: A Global Perspective (Clare M. Hasler)Resistant Starch: Sources, Applications and Health Benefi ts (Yong-Cheng Shi and Clodualdo Maningat)Sensory and Consumer Research in Food Product Design and Development (Howard R. Moskowitz, Jacqueline H. Beckley, and Anna V.A. Resurreccion)Sustainability in the Food Industry (Cheryl J. Baldwin)Thermal Processing of Foods: Control and Automation (K.P. Sandeep)Trait-Modified Oils in Foods (Frank T. Orthoefer and Gary R. List)Water Activity in Foods: Fundamentals and Applications (Gustavo V. Barbosa-Cánovas, Anthony J. Fontana Jr., Shelly J. Schmidt, and Theodore P. Labuza)Whey Processing, Functionality and Health Benefits (Charles I. Onwulata and Peter J. Huth)

List of Contributors

Doug U. Ahn

Animal Science Department

Iowa State University

Ames, USA

Ignacio Alvarez

Tecnología de los Alimentos

Facultad de Veterinaria

University of Zaragoza

Zaragoza, Spain

Md. Latiful Bari

Food Analysis and Research Laboratory

Center for Advanced Research in Sciences

University of Dhaka

Dhaka, Bangladesh

Joseph Borsa

MDS Nordion

Ottawa, Canada

Les Braby

National Center for Electron Beam Food Research

Institute of Food Science & Engineering

Texas A&M University

College Station, USA

Christine M. Bruhn

Center for Consumer Research

Department of Food Science & Technology

University of California

Davis, USA

Myung-Woo Byun

Radiation Food Science & Biotechnology Team

Korea Atomic Energy Research Institute

Daejeon, Republic of Korea

Marshall R. Cleland

IBA Industrial, Inc.

Edgewood, USA

Henry Delincée

Department of Physiology and Biochemistry of Nutrition

Max Rubner-Institut

Karlsruhe, Germany

Ronald F. Eustice

Minnesota Beef Council

Minneapolis, USA

Xuetong Fan

Eastern Regional Research Center

Agricultural Research Service, US Department of Agriculture

Wyndmoor, USA

Peter A. Follett

Pacific Basin Agriculture Research Center

Agricultural Research Service, US Department of Agriculture

Hilo, USA

Denise M. Foley

Department of Biological Sciences

Chapman University

Orange, USA

Robert L. Griffin

Plant Epidemiology and Risk Analysis Laboratory

US Department of Agriculture, APHIS

Raleigh, USA

Cheorun Jo

Radiation Food Science & Biotechnology Team

Korea Atomic Energy Research Institute

Daejeon, Republic of Korea

Jae-Hun Kim

Radiation Food Science & Biotechnology Team

Korea Atomic Energy Research Institute

Daejeon, Republic of Korea

Vanee Komolprasert

Division of Food Contact Substance Notification Review

Center for Food Safety and Applied Nutrition

US Food and Drug Administration

College Park, USA

Eun Joo Lee

Department of Food and Nutrition

University of Wisconsin-Stout

Menomonie, USA

Ju-Woon Lee

Radiation Food Science & Biotechnology Team

Korea Atomic Energy Research Institute

Daejeon, Republic of Korea

William J. Mackay

Department of Biology and Health Services

Edinboro University of Pennsylvania

Edinboro, USA

Eric Marchioni

Equipe de Chimie Analytique des Molécules BioActives (IPHC-UMR 7178)

Faculté de Pharmacie

Illkirch, France

Joe Maxim

National Center for Electron Beam Food Research

Institute of Food Science & Engineering

Texas A&M University

College Station, USA

Kishor Mehta

Senior Scientist Emeritus

IAEA

Vienna, Austria

Brendan A. Niemira

Eastern Regional Research Center

Agricultural Research Service, US Department of Agriculture

Wyndmoor, USA

Kevin O'Hara

Nordion

Ottawa, Canada

George H. Pauli

Division of Product Policy

FDA Office of Premarket Approval

Washington, USA

Suresh D. Pillai

National Center for Electron Beam Food Research

Institute of Food Science & Engineering

Texas A&M University

College Station, USA

Anuradha Prakash

Department of Physical Sciences

Chapman University

Orange, USA

Kathleen T. Rajkowski

Eastern Regional Research Center

Agricultural Research Service, US Department of Agriculture

Wyndmoor, USA

J. Scott Smith

Department of Animal Sciences and Industry

Kansas State University

Manhattan, USA

Christopher H. Sommers

Eastern Regional Research Center,

Agricultural Research Service, US Department of Agriculture

Wyndmoor, USA

Denis W. Stearns

Marler Clark Attoneys at Law

Seattle, USA

Yohan Yoon

Radiation Food Science & Biotechnology Team

Korea Atomic Energy Research Institute

Daejeon, Republic of Korea

Chapter 1

INTRODUCTION: FOOD IRRADIATION MOVING ON

Joseph Borsa

MDS Nordion, Ottawa, Canada

Abstract: This chapter discusses the applications of irradiation technology for a wide variety of food products. Irradiation has been widely used for spices and other food ingredients for many years; but for perishables (meat and produce), it is just now emerging into a significant commercial reality. Two major separate driving forces are moving adoption of food irradiation forward. One is the need to effect microbial reduction, primarily for purposes of food safety enhancement. The second major driver is the need for an effective and environmentally friendly technology to disinfest fruits and vegetables for quarantine security purposes associated with interregional trade. These two main driving forces translate into two distinct business opportunities on which the current implementation activities are centered. Irradiation with ionizing energy is very effective in killing many of the common microbial pathogens such as Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., and Vibrio spp. that are significant contributors to foodborne illness. A major advantage of irradiation for this purpose is that the food can be processed after it has been sealed in its final packaging, thereby reducing or entirely eliminating the possibility of recontamination following this treatment. Irradiation is increasingly being recognized as an excellent agent for disinfestation purposes. There is considerable interest around the world in bringing this potential into reality. USDA-APHIS is playing a leading role in the effort to put in place the regulatory infrastructure needed to allow its use for products imported into the United States, as well as for export of American horticultural products.

Keywords: microbial food safety; disinfestations; phytosanitation; fruits and vegetables; USDA-APHIS

Introduction

There is an old Chinese proverb that says, “May you live in interesting times.” With respect to food irradiation (Borsa 2000), today's proponents and other observers of this technology have good reason to feel that indeed these are interesting times in this unfolding story. Studied intensively for more than half a century, and approved in some 50 countries around the globe for a wide variety of food products (ICGFI 2005), irradiation has been widely used for spices and other food ingredients for many years, but for perishables (meat and produce) it is just now emerging into a significant commercial reality. This chapter focuses primarily on these emerging applications, in which just in the past half dozen years or so the changes in what we might call the food irradiation landscape have been dramatic, and at times go well beyond that. These changes have been most pronounced in the United States but the effects are beginning to be felt in other countries around the globe as well. In the United States from basically a standing start at the beginning of this recent period, but powered by a high level of entrepreneurial energy and zeal, commercialization of irradiation technology in the food industry accelerated rapidly to reach heights far beyond anything previously achieved. Almost overnight, irradiated products appeared in literally thousands of retail and foodservice outlets (SureBeam 2001). Investors took notice (Titan Corp 2001) and millions of dollars were raised for ventures targeting the opportunity presented by the very real needs recognized in food safety (Osterholm and Norgan 2004) and quarantine security (IAEA 2004). The fact that those needs are evident all over the world added to the investment appeal. In these positive circumstances, interest in food irradiation rapidly escalated, giving rise to an exciting play in the investment world.

Unfortunately, in 2004 a major business miscalculation intervened and this nascent industry suffered a significant setback just as it appeared to be getting over the hurdles associated with its launch. Not surprisingly, and to the great satisfaction of the skeptics and antitechnology activists, unreasonable expectations had exceeded the actual pace of adoption, especially by the major food processors, and the simple but inexorable math of the business world led SureBeam™, the most prominent player in the field, to declare bankruptcy (Egerstrom 2004). This failure caused considerable consternation and uncertainty in the fledgling industry, raising concerns as to whether it would survive the setback. Now, more than a year later and with the dust largely settled, it appears that emerging from this uncertainty is a restructured food irradiation industry that is gradually regaining momentum. The fundamental benefits offered by the technology remain the same (Olson 2004) and the new path forward, although lacking the brash boldness and dash of the SureBeam approach, offers prospects for a more sustainable long-term future.

Two Tracks Going Forward

Two major separate driving forces are moving adoption of food irradiation forward. One is the need to effect microbial reduction, primarily for purposes of food safety enhancement. This need is associated especially with those foods that are derived from animals, although similar food safety needs are increasingly being recognized for fresh fruits and vegetables (Sewall and Farber 2001). Shelf-life extension constitutes a significant additional incentive for adoption of this technology, and in some specific applications it may serve as the primary benefit being sought.

The second major driver is the need for an effective and environmentally friendly technology to disinfest fruits and vegetables for quarantine security purposes associated with interregional trade (NAPPO 2003). These two main driving forces translate into two distinct business opportunities on which the current implementation activities are centered.

The Food Safety Track

Irradiation with ionizing energy is very effective in killing many of the common microbial pathogens such as Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp. and Vibrio spp., among others, that are significant contributors to foodborne illness. A major advantage of irradiation for this purpose is that the food can be processed after it has been sealed in its final packaging, thereby reducing or eliminating entirely the possibility of recontamination following this treatment. This unique operational capability makes irradiation particularly suitable for (cold) pasteurization of ready-to-eat foods, such as hot dogs and other deli items, that are at risk of contamination with L. monocytogenes during postprocess slicing and packaging operations.

How does irradiation fit into the overall food safety strategy, based on Hazard Analysis Critical Control Point (HACCP), which is now the dominant food safety paradigm in the food industry? Although the incidence of positive samples for both E. coli O157:H7 (USDA 2005) and L. monocytogenes (USDA 2003) has declined significantly since HACCP was made mandatory in the late 1990s, the need for further improvement remains. A simple calculation puts this into useful perspective. The latest sampling statistics from USDA-FSIS indicate that the incidence of ground beef samples testing positive for contamination with E. coli O157:H7 stands at 0.17% (USDA 2004). This translates into roughly 17 million pounds of such contaminated ground meat presumably randomly interspersed through the approximately 10 billion pounds of this product consumed annually in the United States. Expressed in terms of commonly consumed units of ground beef, this amount represents some 68 million average-size hamburger patties that are contaminated by this pathogen and which therefore have the potential to cause illness in consumers. Of course, this scenario is for only one pathogen; there are others, including some newly emerging ones, which multiply the risk.

In the present situation eating such product with the documented levels of contamination becomes a statistical game of chance as to whether one gets exposed to this pathogen or not. Although the probability of falling ill due to consumption of a randomly selected hamburger borders on the infinitesimally small, this is one of those situations in which a very small probability multiplied by the very large number of people at risk amounts to a significant number of seriously sick people, as attested to by CDC statistics (Mead et al. 1999). Of course, for those unlucky enough to actually become sick, or whose child gets hemolytic uremic syndrome (HUS), the talk of probabilities becomes irrelevant (STOP 2003). Thus the need for further improvement is still very real. The “zero tolerance” regulatory policy in effect for this pathogen (USDA 1999) reflects the seriousness of the hazard.

In the context of HACCP irradiation is an excellent CCP (Molins et al. 2001) for E. coli O157:H7 and other bacterial pathogens in ground beef and similar products. Its use would reduce the probability of contamination in the finished product by several orders of magnitude, depending on the specifics of any particular application. No other technology exists that can offer the convenience of processing in the final shipping cases, and even on pallets, while still treating every last gram of product to a standard that essentially guarantees absence of the target pathogen. Irradiation can offer to solid and semisolid foods such as meat, poultry, and fish the same benefits that thermal pasteurization has brought to milk and other liquid products.

In the past two years, since SureBeam's failure, two new irradiation plants for processing food for the purpose of microbial reduction have been commissioned in the United States. Of course, the ultimate success of these ventures will be decided in the market place, subject to all the realities, scrutiny, and judgments of the business world. On this basis it seems safe to predict that the days ahead will continue to provide “interesting times.”

The Disinfestation Track

Growth in international trade of agricultural products, especially tropical fruits and vegetables, is seen as a foundation component of the economic development strategy of many underdeveloped countries (World Trade Organization 2001). Disinfestation technology for quarantine security purposes is a critical enabler for such trade in agricultural products (Henson and Loader 2001). Currently, fumigation with methyl bromide is the predominant technology used for this purpose. However, the continuing availability of methyl bromide for this purpose is an open question, due to its ozone depleting potential. An international agreement (Montreal Protocol) is in effect to phase out the use of this chemical because of this negative effect on the environment (UNDP 2002). In addition, methyl bromide is phytotoxic to some commonly traded fruits and vegetables (Hallman 1998), bringing further pressure to bear to find a suitable alternative. Irradiation is increasingly being recognized as an excellent agent for disinfestation purposes, and there is considerable interest around the world in bringing this potential into reality. USDA-APHIS is playing a leading role in the effort to put in place the regulatory infrastructure needed to allow its use for products imported into the United States, as well as for export of American horticultural products. Success has already been achieved for irradiated products routinely being shipped from Hawaii to mainland United States (Hawaii Pride 2005). Efforts currently under way should lead, in the relatively short term, to expansion of the list of US trading partner countries for which irradiation will be accepted as a suitable disinfestation measure for products shipped between them. It can be anticipated that successful establishment of irradiation as a quarantine security technology for trade involving the United States will rapidly lead to its use for this purpose in trade involving other trading partners. The recent commencement of shipment of irradiated Australian fruit to New Zealand (TVNZ 2004) represents a first step along this path.

Currently, besides the Hawaiian and Australian/New Zealand examples, there is interest in and movement toward implementation of irradiation disinfestation as part of a trade-enabling infrastructure in several countries in different regions around the world, including the Asia Pacific group and Latin America. The future for irradiation in this application looks bright indeed.

Bumps Still Remain on the Road Ahead

Although implementation of food irradiation has taken great strides forward and is building momentum, it has not yet reached a condition of clear sailing. Several troublesome hindrances remain, which need to be addressed.

On the regulatory front, much remains to be done, even in the United States, where most of the implementation progress to date has taken place. Specifically, petitions for clearance of irradiation for several categories of food that could benefit from this treatment continue to languish somewhere in the evaluation process. These include petitions for ready-to-eat foods and for seafood. Elsewhere, an encouraging sign is that in some parts of the world, as in Brazil (ICGFI 2005), the authorities have granted blanket approval for irradiation of all foods, consistent with Codex Alimentarius recommendations (Codex 2003). Perhaps this will encourage other member states of Codex Alimentarius to base their national regulations for food irradiation on the international standard to which they are party. It seems likely that as food irradiation registers more and more successes, countries currently on the sidelines will join the growing movement toward greater acceptance and utilization of this powerful technology.

Regulatory requirements for the labeling of foods that have been irradiated remain a deterrent to some processors who would otherwise use it on their products. This issue has been under review for several years now, but to date no suitable alternative has been put forth that would satisfy both the needs of industry to inform but not alarm consumers, and the consumers' right to know. Also very important is the need to extend the list of clearances for irradiation of food packaging materials, to include more of the common modern polymers and films (ICGFI 2005).

At present there is a major logistical impediment, stemming from the scarcity of processing capacity within reach of many food manufacturers that are interested in using irradiation. This difficulty can be alleviated only by building new capacity in strategic locations to provide easy access for those wishing to use it. Installation of contract service irradiators in distribution centers and cold storage warehouses that serve many clients would be a logical and cost-effective approach to meeting this logistical need. Such locations have the advantage of easy and convenient access for their clients without incurring any additional transportation costs. New irradiation systems currently available (Stichelbaut and Herer 2004) that can process fully loaded pallets of food allow seamless interfacing between the irradiation facility and the existing warehouse, distribution, and transportation networks that use pallets as the basic unit of product handling.

Another challenge is that with some products the maximum dose that can be tolerated without sensory degradation is low enough that it can be difficult to effect the wanted benefit to the extent desired. Excellent research progress in improving the effectiveness of irradiation in such difficult cases is being made. Different approaches involve one or more of increasing the product tolerance to radiation (Kalsec 2005), increasing the sensitivity of pathogens to radiation so that lower doses can effect the needed kill (Chiasson et al. 2004), and improvements to irradiator design permitting the delivery of more uniform dose distributions in product stacks (Stichelbaut and Herer 2004), thereby reducing the regions of overdose wherein the sensory degradation is most likely to occur. These and other technical issues will undoubtedly serve as the focus of research at universities and other institutions for some time to come.

Summary

Implementation of food irradiation continues to move forward. The biggest gains are happening in the United States, but progress is being made in other parts of the world as well. Both the food safety and the disinfestation applications are growing, with the disinfestation application being especially active. It seems likely that this expansion will continue for an extended period of time, perhaps decades.

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Chapter 2

ADVANCES IN ELECTRON BEAM AND X-RAY TECHNOLOGIES FOR FOOD IRRADIATION

Marshall R. Cleland

IBA Industrial, Inc., Edgewood, USA

Abstract: Irradiation of materials and commercial products with ionizing energy is widely used to improve their physical, chemical, or biological properties. Gamma rays from radioactive nuclides, energetic electrons from particle accelerators, and X-rays emitted by high-energy electrons are suitable kinds of radiant energy for such purposes. This chapter describes the relevant characteristics of these energy sources, methods for generating sufficient emitted power to support industrial applications, including food irradiation, and some examples of radiation processing facilities. Cobalt-60 (Co-60), the predominant nuclide for gamma ray facilities, is produced in a nuclear reactor. Industrial electron accelerators can provide electron energies from less than 100 keV to more than 10 MeV, and with beam power ratings extending up to 700 kW. A variety of accelerating methods are needed to cover this wide energy range. Techniques for irradiating full pallet loads of products are presented, including data on absorbed dose distributions and processing rates obtained by Monte Carlo simulations.