Food Irradiation Research and Technology

The benefits of food irradiation to the public health have beendescribed extensively by organizations such as the Centers forDisease Control and Prevention in the USA and the World HealthOrganization. The American Medical Association and the AmericanDietetic Association have both endorsed the irradiation process.Yet the potential health benefits of irradiation are unknown tomany consumers and food industry representatives who are wary ofirradiated foods due to myth–information from consumer–advocate groups. 

This updated second edition of Food Irradiation Research andTechnology reviews the latest developments in irradiationtechnologies as they are applied to meat, seafood fish, fruits,vegetables and nuts. Experts from industry, government, andacademia define the basic principles and public health benefits ofirradiation.

New chapters in this edition address irradiation chemistry,including furan formation due to irradiation, irradiation ofpackaging materials, processing irradiation technologies andparameters, and ready–to–eat meat products. Coverage of safety andquality of fresh fruits and vegetables, phytosanitary applicationsand consumer acceptance has been expanded to address recentinterest and development.

The book is designed to appeal to a broad readership: industryfood scientists involved in the processing of meat and fish, fruitsand vegetables; food microbiologists and radiation processingspecialists; and government and industry representatives involvedin the import and export of food commodities.

List of Contributors xix

Preface xxv

Chapter 1 Introduction: Food Irradiation Moving On 1
Joseph Borsa

Introduction 2

Two Tracks Going Forward 3

The Food Safety Track 3

The Disinfestation Track 5

Bumps Still Remain on the Road Ahead 5

Summary 7

References 7

Chapter 2 Advances in Electron Beam and X–ray Technologiesfor Food Irradiation 9
Marshall R. Cleland

Introduction 10

Basic Irradiation Concepts 10

Definition and Units of Absorbed Dose 10

Absorbed Dose versus Emitted Radiation Power 11

Temperature Rise versus Dose 12

Electron Beam Facilities 13

Absorbed Dose versus Beam Current 14

Electron Beam Technologies 14

X–ray Facilities 21

Conclusion 24

References 25

Chapter 3 Gamma Ray Technology for Food Irradiation 29
Kevin O Hara

Introduction 29

Overview of Co–60 Gamma Technology 30

Basic Irradiation Concepts 32

Gamma Ray Facilities 32

Irradiator Categories 34

Criteria for Irradiator Design and Selection 35

Pallet Irradiator 38

Tote Box Irradiator 40

Independent Dose Delivery Carrier and Stationary Irradiations41

Gray Star GenesisTM Underwater Irradiator 42

Gamma Ray Facilities for Radiation Research 43

Comparison of Irradiation Technologies 45

References 46

Chapter 4 Regulation of Irradiated Foods and Packaging47
George H. Pauli

Introduction 48

References 52

Notes 52

Chapter 5 Toxicological Safety of Irradiated Foods 53
Christopher H. Sommers, Henry Delincee, J. Scott Smith, andEric Marchioni

Introduction 54

Food Irradiation 54

Benzene, Formaldehyde, and Amines 56

Formation and Levels of 2–ACBs in Foods 57

Toxicological Safety of 2–ACBs 63

2–ACBs and Tumor Promotion 66

Diet and Tumor Promotion 67

Conclusions 67

References 68

Chapter 6 Radiation Chemistry of Food Components 75
Xuetong Fan

Basic Radiation Effects 76

Radiolysis of Water 76

Radiation Chemistry of Major Food Components 77

Radiation Chemistry of Lipids 77

Radiolysis of Proteins 80

Radiolysis of Carbohydrates 83

Reduction of Undesirable Compounds by Irradiation 88

Reduction of Furan and Acrylamide 88

Reduction of Mycotoxins 89

Antinutritional Compounds 92

Acknowledgments 93

References 93

Chapter 7 Dosimetry for Food Processing and ResearchApplications 99
Kishor Mehta and Kevin O Hara

Importance of Dosimetry 99

Introduction 100

Some Fundamentals of Dosimetry 101

Absorbed Dose 101

Dosimetry System 102

Measurement Management System 103

Selection and Characterization of a Dosimetry System 103

Types of Dosimetry Systems 103

The Selection of an Appropriate Dosimetry System 104

Dosimetry System Characterization 106

The Use of a Dosimetry System 107

Dosimetry in Food Research 108

Dosimetry at a Commercial Facility 109

General 109

Process Validation 110

Operational Qualification (OQ) 110

Performance Qualification (PQ) 114

Routine Process Monitoring and Control 117

References 120

Chapter 8 Detection of Irradiated Foods 123
Eric Marchioni

Introduction 124

Free Radicals and Electronic Excited States 126

ESR Spectroscopy 126

Luminescence 129

Stable Radiolytic Products 131

Radiolytic Products from Proteins 131

Volatile Compounds 131

Radiolytic Products from Carbohydrates 132

Radiolytic Products from Nucleic Acids 132

Radiolytic Products from Lipids 134

Modification of Macroscopic Physico–Biological Parameters of theFood 137

Gas Evolution 138

Cellular Wall Modifications 138

Bacteriological Modifications 138

Germination Inhibition 139

Irradiated Ingredients and Low–Dose Irradiated Plants 139

Conclusion 140

References 140

Chapter 9 Irradiation of Packaging Materials in Contact withFood: An Update 147
Vanee Komolprasert

Introduction 148

Current Authorizations of Packaging Materials for Irradiation ofPrepackaged Food 149

Radiation–Induced Chemical Changes in Packaging Materials157

Role of AOs 158

Evaluating Packaging Materials Irradiated in the Presence ofOxygen 159

Irradiation Effects 160

Analysis for RPs 161

Dietary Exposure to RPs 162

Safety Assessment of RPs 164

Approaches to Testing 165

Conclusions 167

Acknowledgment 168

References 168

Chapter 10 Consumer Acceptance and Marketing of IrradiatedFoods 173
Ronald F. Eustice and Christine M. Bruhn

Introduction 174

What Is Food Irradiation? 174

Why Is Food Irradiated? 174

Marketing of Irradiation Foods 176

Commercial Acceptance of Irradiation Foods 177

Resistance to New Technology 178

Risks versus Benefits 179

World s Safest Food Supply, But Not Safe Enough 179

Irradiation: A Powerful and Effective Tool to Improve FoodSafety 181

Education: The Key to Consumer Acceptance 182

Effect of Unfavorable Information 185

Can Unfavorable Information Be Counteracted? 186

Effects of Gender, Income, and Children 188

Barriers to Acceptance 188

The Minnesota Model of Consumer Acceptance 189

A Defining Moment in Food Safety 191

Is It Farm to Fork, or Turf to Tort? 192

Conclusion 192

References 193

Chapter 11 Irradiation of Ready–To–Eat Meat Products197
Christopher H. Sommers and William J. Mackay

Introduction 198

Materials and Methods 198

RTE Meats 198

Processing of Beef Bologna 199

Bacterial Isolates 199

Preparation of Inoculum 200

Inoculation of RTE Meats 200

Gamma Irradiation 200

Enumeration of Bacteria 201

Storage Study 201

D10 Values 201

Statistical Analysis 202

Results and Discussion 202

Acknowledgment 205

References 205

Chapter 12 Mechanisms and Prevention of Quality Changes inMeat by Irradiation 209
Doug U. Ahn and Eun Joo Lee

Introduction 209

Food Irradiation 210

Microcidal Effect 211

Quality Changes in Meat by Irradiation 213

Lipid Oxidation 213

Sources and Mechanisms of Off–Odor Production 214

Color Changes in Meat by Irradiation 216

Control of Off–Odor Production and Color Changes 220

Additives 220

Packaging 221

Packaging and Additive Combinations 221

Future Research 222

References 222

Chapter 13 Phytosanitary Irradiation for Fresh HorticulturalCommodities: Research and Regulations 227
Peter A. Follett and Robert L. Griffin

Introduction 228

Developing Irradiation Quarantine Treatments 228

Insect Radiotolerance 228

Methodology 231

Varietal Testing 234

Probit 9 Efficacy and Alternatives 234

Generic Radiation Treatments 236

Regulatory Aspects of Irradiation 240

USDA Regulations 242

Regional and International Harmonization 244

Trade 245

References 249

Chapter 14 Antimicrobial Application of Low–Dose Irradiationof Fresh and Fresh–Cut Produce 255
Brendan A. Niemira

Introduction 256

Produce Microbiology and Irradiation Treatment 257

Internalization of Bacteria 258

Biofilm–Associated Pathogens 260

Postirradiation Recovery and Regrowth 261

Treatment Parameters for Irradiation of Produce 262

Influence of Plant Variety 264

Combination with Sanitizers 264

Irradiation Plus Mild Thermal Treatment 265

Summary 266

Acknowledgments 266

References 266

Chapter 15 Irradiation of Fresh and Fresh–Cut Fruits andVegetables: Quality and Shelf Life 271
Xuetong Fan

Introduction 272

Ethylene and Respiration 273

Appearance 274

Texture 276

Flavor/Taste 278

Nutrients 281

Vitamin C 281

Other Nutrients 282

Combination of Irradiation with Other Postharvest Techniques284

Chemical Sanitizers 284

Hot–Water Treatment 284

Calcium and Calcium Ascorbate 285

MAP 286

Shelf–Life Extension 287

References 288

Chapter 16 Irradiation of Seeds and Sprouts 295
Kathleen T. Rajkowski and Md. Latiful Bari

Introduction 295

Outbreaks Associated with Sprouts 296

Potential Source of Contamination 301

Pathogens of Concern for Sprouts 302

Salmonella 302

Enterohemorrhagic E. coli 302

L. monocytogenes 302

B. cereus 303

Yersinia enterocolitica 303

Shigella 303

Klebsiella 303

Pathogen Decontamination Overview 304

Seed and Sprout Evaluation after Treatment 305

Radiation Dose to Reduce Microbial Pathogens on Seeds 305

Combination Treatments 308

Radiation Dose to Reduce Microbial Pathogens on Sprouts 308

Other 309

Conclusions 310

References 310

Chapter 17 Irradiation of Nuts 317
Anuradha Prakash

Introduction 317

Farming and Harvesting 318

Insect Disinfestation 318

Microbial Contamination 319

Contamination with Pathogens 320

Irradiation Treatment of Nuts 323

Insect Disinfestation 323

Molds and Aflatoxins 324

Pathogen Inactivation 325

Chemical and Sensory: Irradiation Can Catalyze or Induce LipidPeroxidation, and Lipid and/or Protein Radiolysis 325

Nonoxidative Radiolytic Reactions 329

Effect of Irradiation on Nut Allergenicity 329

Advantages of Using Irradiation to Treat Nuts 330

Research Needs 330

References 331

Chapter 18 Irradiation of Seafood with a Particular Emphasison Listeria monocytogenes in Ready–To–Eat Products 337
Denise M. Foley

Introduction 338

Listeria monocytogenes Is a Significant Contaminant of Seafood338

Stress Adaptation of the Organism 339

Irradiation Is an Effective Postprocessing Treatment for FishProducts 340

Physical, Chemical, and Sensory Changes of Irradiated Seafood344

Competing Microflora 345

Comments Regarding Irradiation and the Risk for Botulism 346

Conclusion 346

References 346

Chapter 19 Ionizing Radiation of Eggs 351
Ignacio Alvarez, Brendan A. Niemira, Xuetong Fan, andChristopher H. Sommers

Introduction 352

Ionizing Radiation of Shell Eggs 353

Microbial Lethal Effect of Ionizing Radiation on Shell Eggs353

Internal Quality of Ionizing Radiated Shell Eggs 356

Physicochemical Properties of Ionizing Radiated Shell Eggs358

Functional Properties of Ionizing Radiated Shell Eggs 358

Ionizing Radiation of Refrigerated Liquid Egg 359

Ionizing Radiation of LWE 359

Ionizing Radiation of Liquid Egg White 361

Ionizing Radiation of Liquid Egg Yolk 362

Ionizing Radiation of Dried Egg 363

Microbial Lethal Effect of Ionizing Radiation in Dried Egg363

Quality of Ionizing Radiated Dried Egg 363

Physicochemical Properties of Ionizing Radiated Dried Egg363

Functional Properties of Ionizing Radiated Dried Egg 364

Ionizing Radiation of Frozen Egg 365

Microbial Lethal Effect of Ionizing Radiation in Frozen Egg365

Physicochemical Properties of Ionizing Radiated Frozen Egg365

Functional Properties of Ionizing Radiated Frozen Egg 365

Strategies to Increase the Quality of Irradiated Egg Products366

Areas for Future Research 368

Conclusion 369

Acknowledgments 370

References 370

Chapter 20 Irradiated Ground Beef for the National SchoolLunch Program 373
Xuetong Fan

Introduction 374

Foodborne Illnesses in School 374

Regulatory Allowance and Specifications of Irradiated Foods forSchools 376

Sensory Properties of Irradiated Ground Beef 378

Conclusion 382

Acknowledgments 383

References 383

Chapter 21 Potential Applications of Ionizing Radiation385
Ju–Woon Lee, Jae–Hun Kim, Yohan Yoon, Cheorun Jo, andMyung–Woo Byun

Introduction 386

Reduction of Food Allergies by Ionizing Radiation 386

Volatile N–nitrosamine and Residual Nitrite Reduction 387

Biogenic Amines Reduction 390

Reduction of Phytic Acid and Increase in Antioxidant Activity391

Chlorophyll b Breakdown 393

Color Improvement of Plant Extracts without Change of BiologicalFunctions 393

Control of Enterobacter sakazakii in Infant Formula 394

Use of Irradiation to Control Food–Related Bacteria in MeatProducts 394

Application of Irradiation for Sea Food Safety 396

Use of Irradiation on Fresh Produces and Dairy Products 396

Application of Irradiation for the Development of TraditionalFermented Foods 397

Use of Boiled Extracts from Cooking 398

Improvement of Nutritional Conditions and Food Quality byIrradiation 399

Conclusion 399

Acknowledgments 399

References 400

Chapter 22 A Future Uncertain: Food Irradiation From a LegalPerspective 407
Denis W. Stearns

Introduction 408

Liability for the Manufacture of a Defective Food Product409

The Origins of Strict Liability in Tainted Food Cases 409

The Modern Rule of Strict Liability 410

Defining Products and Defects 410

Proving the Existence of a Defect in Food 411

Strict Liability Creates Few If Any Legal Incentives in Favor ofFood Irradiation 412

A Possible Existing Legal Duty to Use Irradiated Food: TheChallenge of Highly Susceptible Populations 414

Negligence: Failing to Avoid a Known and Avoidable Risk 414

The Eggshell Plaintiff: Irradiation, Liability, and SusceptiblePopulations 416

The Prospect of Punitive Damages as a Stronger Incentive 417

The Possibility of Liability Arising from Irradiated Foods418

Conclusion 419

Notes 420

Chapter 23 Technical Challenges and Research Directions inElectronic Food Pasteurization 425
Suresh D. Pillai, Les Braby, and Joe Maxim

Introduction 426

Target Pathogens 427

Enteric Viruses 427

Protozoan Pathogens 428

Bacterial Pathogens 428

Radiation Physics and Chemistry 428

Chemical Environment 428

Standardized Protocols 429

Electronic Pasteurization in Conjunction with Microbial RiskAssessment 430

Low Dose Electronic Pasteurization and Dosimetry 431

Product Packaging 431

Electronic Pasteurization of Complex–Shaped Packages 432

Acknowledgments 433

References 433

Index 435

Christopher H. Sommers, Ph.D., a research microbiologist and lead scientist, and Xuetong Fan, Ph.D., a research food technologist, both work for the Food Safety Intervention Technologies Research Unit, USDA–ARS–Eastern Regional Research Center, Wyndmoor, PA. Drs. Sommers and Fan were co–moderators of the IFT symposium from which this book arose and have over thirty years combined experience in food irradiation, food technology, chemistry, microbiology and toxicology.