Food irradiation principles and applications

FOOD IRRADIATION:
PRINCIPLES AND
APPLICATIONS
Edited by

R. A. Molins
The National Academies

@ T T ILC I~
INTERSCIENCE
A JOHN WILEY & SONS, INC., PUBLICATION
NewYork

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Chichester

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This book is printed on acid-free paper. ©
Copyright © 2001 by John Wiley & Sons, Inc. All rights reserved.
Published simultaneously in Canada.
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Library of Congress Cataloging-in-Publication Data:
Molins, Ricardo A., 1948Food irradiation : Principles and applications / edited by Ricardo Molins.
p. cm.
Includes index.
ISBN 0-471-35634-4 (cloth : alk. paper)
1. Radiation preservation of food. I. Title.
TP371.8.M65 2001
664'.0288—dc21
Printed in the United States of America.
10

9 8 7 6 5 4 3 2 1

2001017629

In memory of George G. Giddings, Ph.D. Colleague, scholar, dear friend, and
indefatigable promoter of food irradiation. To you I say: Ignorance dies hard, and
progress sometimes comes slowly, but both are inevitable.


PREFACE

This book responds to the need of researchers, industry, and regulators to have a
single source of information comprising all aspects of food irradiation: historical,
technical, economic, and regulatory. Because food irradiation involves many disciplines within and outside the realm of food science, this book has general chapters
on radiation microbiology and chemistry as they apply to food as well as specific
chapters on irradiation of each of the major food groups. These are complemented
by additional chapters on process control, economics, and regulatory aspects of
food irradiation that are essential in planning the introduction or expansion of this
technology. The title of the book, therefore, is most appropriate in that principles
and applications of food irradiation are indeed extensively discussed. Twelve contributing authors from America, Asia, and Europe bring together the expertise
accumulated around the world on this promising food processing technique.
Although the contributing authors have striven to present and cite the most
recent information available on each topic covered in the book, there are notable
differences in the degree of success achieved by each one. These differences, to a
large extent, reflect the prevailing interest on particular applications of food irradiation at present and during the past decade as opposed to that in earlier years. Thus,
research into such applications of irradiation as microbial decontamination of meat,
poultry, and minimally processed foods, for example, has attracted more attention
in the 1990s than insect disinfestation of stored dried foods, which was studied
mainly during the 1960s and 1970s. Consequently, the information provided in each
chapter dealing with an application of food irradiation represents the state of the art
for that particular application.
A major departure this book has from other works in this field is that the
contributing authors, taking into consideration the massive scientific evidence gathered over more than half a century, concurred that food irradiation has been exhaustively proven to be safe and to result in wholesome food. Therefore, they

refused to continue to debate these issues. They believe that the unique potential
this technology has to increase the availability of food and to improve its quality
and safety will eventually lead to its acceptance.
I am grateful to my fellow co-authors for accepting my invitation to collaborate
in this book. It is a great honor to be here in their company.


Contents

Preface .................................................................................
1.

Introduction ..................................................................

1

1.1

1

Historical Notes on Food Irradiation ................................
1.1.1

Notes on the Development of the Food
Irradiation Process and Applications .............

1

Proving the Wholesomeness of
Irradiated Foods ............................................

12

Potential Social and Economic Benefits of Food
Irradiation .........................................................................

14

1.1.2
1.2

1.2.1

Social and Economic Benefits of Food
Irradiation in Relation to Food Security:
Preventing Postharvest Food Losses
and Extending the Shelf Life of
Perishable Foods ..........................................

15

Social and Economic Benefits in
Relation to Food Safety: Controlling
Pathogenic Bacteria and Parasites in
Foods ............................................................

16

Radiation Inactivation of Microorganisms .................

23

2.1

Introduction ......................................................................

23

2.2

Mechanisms of Inactivation .............................................

23

2.3

Mechanisms of Microbial Survival and Repair ................

24

2.4

Radiation Sensitivity of Specific Microorganisms ...........

25

2.4.1

Bacteria of Public Health Significance ...........

27

2.4.2

Viruses ..........................................................

27

2.4.3

Parasites .......................................................

31

1.2.2

2.

xiii

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viii

Contents
2.5

3.

Environmental Factors Affecting Radiation
Sensitivity .........................................................................

31

2.6

Other Issues ....................................................................

32

2.7

Conclusions .....................................................................

32

Food Irradiation Chemistry .........................................

37

3.1

37

Introduction ......................................................................
3.1.1

Types of Ionizing Radiation and Their
Sources ........................................................

37

Background and Induced Radioactivity .........

38

Basic Effects of Ionizing Radiation ..................................

39

3.2.1

Primary Effects .............................................

39

3.2.2

Secondary Effects .........................................

41

3.3

Water Radiolysis ..............................................................

43

3.4

Effects of Ionizing Radiation on Major Food
Components ....................................................................

46

3.4.1

Carbohydrates ..............................................

47

3.4.2

Proteins ........................................................

50

3.4.3

Lipids ............................................................

58

3.4.4

Vitamins ........................................................

64

Conclusions .....................................................................

68

Disinfestation of Stored Grains, Pulses, Dried
Fruits and Nuts, and Other Dried Foods ....................

77

4.1

Introduction ......................................................................

77

4.2

Radiation Effects on Insects ............................................

80

4.2.1

General Effects of Radiation on Insects ........

80

4.2.2

Feeding Behaviour of Irradiated Insects ........

82

4.2.3

Sterilizing Effects of Radiation ......................

83

Current Disinfestation Methods and Their
Drawbacks .......................................................................

85

3.1.2
3.2

3.5

4.

4.3

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ix

4.3.1

Chemical Methods ........................................

86

4.3.2

Physical Methods ..........................................

87

Irradiation Disinfestation ..................................................

88

4.4.1

Cereal Grains ................................................

88

4.4.2

Pulses ...........................................................

89

4.4.3

Dried Fruits and Nuts ....................................

90

4.4.4

Dried-Beverage Crops ..................................

92

4.4.5

Dried Foods of Animal Origin ........................

93

4.4.6

Other Dried Food Products ...........................

94

4.4.7

Irradiation in Combination with Other
Methods ........................................................

95

4.5

Preventing Reinfestation .................................................

97

4.6

Regulatory Approval and Potential Commercial
Application of Radiation Disinfestation of Stored
Dried Foods ..................................................................... 101

4.4

5.

Irradiation as a Quarantine Treatment ....................... 113
5.1

Need for Quarantine Treatment ...................................... 113

5.2

Types of Quarantine Treatment ...................................... 113

5.3

Comparison between Irradiation and Other
Quarantine Treatment ..................................................... 114

5.4

History of Irradiation Quarantine Treatment .................... 117

5.5

Radiation Quarantine Treatment ..................................... 118

5.6

Radiation Quarantine Treatment Research .................... 119

5.7

5.6.1

Aspects of Importance in Conducting
Radiation Quarantine Treatment
Research ...................................................... 121

5.6.2

Research Needs ........................................... 124

Future Outlook for Irradiation as a Quarantine
Treatment ........................................................................ 127

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Contents

6.

Irradiation of Meats and Poultry ................................. 131
6.1

6.2

7.

Introduction ...................................................................... 131
6.1.1

The Origins of Parasitic and Microbial
Contamination of Meats and Poultry ............. 131

6.1.2

Effectiveness of Nonlethal, Preventive
Measures to Control Microbiological
Contamination of Meats and Poultry ............. 132

6.1.3

Decontamination Methods of Raw Meats
and Poultry ................................................... 133

Irradiation of Meats and Poultry ...................................... 135
6.2.1

Microbiological Effects of Ionizing
Radiation on Meats and Poultry .................... 135

6.2.2

Combined Effects of Irradiation and
Other Treatments on Meats and
Poultry .......................................................... 159

6.2.3

Physical and Chemical Effects of
Ionizing Radiation on Meats and
Poultry .......................................................... 163

6.2.4

Effects of Irradiation on Nutrients in
Fresh Meats and Poultry ............................... 170

6.2.5

Packaging for Irradiation of Meat and
Poultry .......................................................... 172

6.2.6

Research Needs in Meat and Poultry
Irradiation ...................................................... 173

6.2.7

Outlook on the Future of Meat and
Poultry Irradiation .......................................... 174

Irradiation Processing of Fish and Shellfish
Products ....................................................................... 193
7.1

Introduction ...................................................................... 193

7.2

Irradiation for Shelf-Life Extension of Seafood
Products ........................................................................... 195
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Contents

7.3

8.

xi

7.2.1

Finfish Products ............................................ 195

7.2.2

Shellfish and Crustaceans ............................ 197

Potential Human Pathogens of Public Health
Concern in Seafood Products ......................................... 200
7.3.1

Indigenous Potential Pathogens
Associated with the Natural Aquatic
Environment .................................................. 200

7.3.2

Potential Pathogenic Microorganisms
Associated with Human and/or Animal
Fecal Pollution .............................................. 203

7.3.3

Potential Pathogenic Microorganisms
Associated with Processing and
Preparation ................................................... 204

7.4

Low- and Medium-Dose Irradiation for Pathogen
Control in Seafood Products ........................................... 205

7.5

Research Needs in Seafood Irradiation .......................... 208

7.6

The Future of Seafood Irradiation ................................... 208

Irradiation of Fruits and Vegetables ........................... 213
8.1

Introduction ...................................................................... 213

8.2

Physiology and Biochemistry of Fruit Ripening .............. 214

8.3

Effects of Ionizing Radiation on Ripening,
Senescence, and Shelf Life of Fruits .............................. 215
8.3.1

Tropical and Subtropical Fruits ..................... 215

8.3.2

Temperate Fruits .......................................... 218

8.3.3

Biochemical Mechanisms Involved in
Delay of Ripening in Fruits by
Irradiation ...................................................... 218

8.3.4

Effects of Irradiation on the Nutritional
Qualities of Fruits .......................................... 219

8.3.5

Effects of Irradiation on Sensory Quality
Attributes ...................................................... 225

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Contents
8.4

8.5

9.

Control of Postharvest Fungal Rot in Fruits by
Irradiation Alone or in Combination with Other
Treatments ....................................................................... 227
8.4.1

Heat Plus Irradiation ..................................... 228

8.4.2

Combination of Radiation, Heat, and
Chemicals ..................................................... 229

Potential for Radiation Treatment of Vegetables ............ 230

Irradiation of Tuber and Bulb Crops .......................... 241
9.1

9.2

9.3

9.4

Introduction ...................................................................... 241
9.1.1

Factors Contributing to Postharvest
Losses of Tuber and Bulb Crops ................... 242

9.1.2

Significance of Sprouting of Tuber and
Bulb Crops in Storage ................................... 243

9.1.3

Alternate Methods for Control of
Sprouting and Shelf Life Extension of
Tuber and Bulb Crops ................................... 244

Radiation Treatment for Control of Sprouting and
Shelf-Life Extension of Tuber and Bulb Crops ................ 245
9.2.1

Biochemical Mechanisms of Sprout
Control by Ionizing Radiation ........................ 245

9.2.2

Factors Determining the Efficacy of
Radiation Treatment ..................................... 246

Effects of Irradiation on Nutritional Components ............ 249
9.3.1

Carbohydrates .............................................. 249

9.3.2

Proteins and Amino Acids ............................. 250

9.3.3

Vitamins ........................................................ 251

9.3.4

Chlorophylls and Glycoalkaloids ................... 252

9.3.5

Flavor and Pungency .................................... 253

Effect of Ionizing Radiation on Technological
Properties of Tubers and Bulbs ....................................... 254
9.4.1

Wound Healing and Storage Rot ................... 254

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xiii

9.4.2

After-Cooking Darkening of Potatoes ............ 256

9.4.3

Other Types of Discoloration in
Potatoes ....................................................... 257

9.4.4

Inner-Bud Discoloration of Bulbs ................... 257

9.4.5

Processing Qualities ..................................... 258

9.5

Effect of Irradiation for Sprout Inhibition on the
Potato Tuber Moth ........................................................... 259

9.6

Commercial Irradiation for Sprouting Inhibition:
Current Status and Future Outlook ................................. 259

10. Irradiation of Minimally Processed Foods ................. 273
10.1 Introduction ...................................................................... 273
10.2 Irradiation of Minimally Processed Fresh Produce ......... 275
10.3 Irradiation of Cook – Chill Foods ..................................... 277
10.3.1 Irradiation of Packaged Conventional
Cook-Chill Meals ........................................... 279
10.3.2 Irradiation of Sous-Vide Foods ...................... 282

10.4 Research Needs on the Potential Use of
Irradiation on Minimally Processed Foods ...................... 284

11. Radiation Decontamination of Spices, Herbs,
Condiments, and Other Dried Food Ingredients ....... 291
11.1 Introduction ...................................................................... 291
11.1.1 Microbiological Contamination of Dried
Food Ingredients and Its Significance for
the Food Industry and Public Health ............. 291
11.1.2 Criteria for Microbial Quality of Dried
Food Ingredients ........................................... 293
11.2 Radiation Decontamination of Dried Food
Ingredients ....................................................................... 294
11.2.1 Spices, Herbs and Dried-Vegetable
Condiments ................................................... 296
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Contents
11.2.2 Herbal Teas and Dried Medicinal
Plants ........................................................... 300
11.2.3 Dried Fruits and Vegetables, Dry Soups,
and Cereal Products ..................................... 300
11.2.4 Texturizing Agents ........................................ 301
11.2.5 Protein and Enzyme Preparations ................. 301
11.2.6 Dried-Egg Products ....................................... 302
11.2.7 Cocoa Powder and Desiccated
Coconut ........................................................ 302

11.2.8 Other Dried Products .................................... 302
11.3 Economic Feasibility and Industrial Use of
Radiation Decontamination of Dried Food
Ingredients ....................................................................... 303
11.4 Acceptance and Commercialization of Radiation
Decontamination of Dried Ingredients ............................. 303

12. Combination Treatments Involving Food
Irradiation ..................................................................... 313
12.1 Introduction ...................................................................... 313
12.1.1 The Hurdle Concept ...................................... 315
12.2 Combination Treatments Involving Food
Irradiation ......................................................................... 316
12.2.1 Irradiation and Heat ...................................... 316
12.2.2 Irradiation and Low Temperatures ................ 319
12.2.3 Irradiation and Modified-Atmosphere
Packaging ..................................................... 320
12.2.4 Irradiation and Chemical Preservatives ......... 323
12.2.5 Irradiation and High Pressure ....................... 324

13. Development of Irradiated Shelf-Stable Meat
and Poultry Products .................................................. 329
13.1 Introduction ...................................................................... 329
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xv

13.2 History .............................................................................. 329
13.3 Atoms for Peace .............................................................. 330
13.4 Early Supporting Research ............................................. 330
13.5 Beef .................................................................................. 331
13.6 Pork .................................................................................. 332
13.7 Ham ................................................................................. 333
13.8 Bacon ............................................................................... 333
13.9 Frankfurters ..................................................................... 334
13.10 Fish .................................................................................. 334
13.11 Chicken ............................................................................ 335
13.11.1 Determination of 12D .................................... 335
13.11.2 Enzyme-Inactivated, Radiation-Sterilized
Chicken ......................................................... 335
13.12 Production of Radiation-Sterilized Food ......................... 337
13.13 U.S. Enzyme-Inactivated, Radiation-Sterilized
Products ........................................................................... 337
13.14 The South African Program ............................................. 338
13.15 Future of Irradiated Shelf-Stable Meat and Poultry
Products ........................................................................... 339

14. Detection Methods for Irradiated Foods .................... 347
14.1 Introduction ...................................................................... 347
14.2 Criteria for a Reliable Detection Method ......................... 348
14.3 Physical Methods ............................................................ 350
14.3.1 ESR Spectroscopy ........................................ 350
14.3.2 Luminescence Measurement ........................ 354
14.3.3 Viscosity Measurement ................................. 356
14.3.4 Electrical Impedance Measurement .............. 357
14.3.5 Other Physical Methods ................................ 358
14.4 Chemical Methods ........................................................... 358

14.4.1 Hydrocarbons ............................................... 358
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Contents
14.4.2 2-Alkylcyclobutanones .................................. 360
14.4.3 Ortho-Tyrosine .............................................. 362
14.4.4 Gas Evolution ............................................... 363
14.4.5 Other Chemical Methods .............................. 364
14.5 DNA Methods .................................................................. 364
14.5.1 DNA “Comet Assay” ...................................... 364
14.5.2 Agarose Electrophoresis of
Mitochondrial DNA ........................................ 366
14.5.3 lmmunologic Detection of Modified DNA
Bases ............................................................ 367
14.5.4 Other DNA Methods ...................................... 367
14.6 Biological Methods .......................................................... 368
14.6.1 Shift in Microbial Load ................................... 368
14.6.2 Direct Epifluorescent Filter Technique
Combined with Aerobic Plate Count
(DEFT/APC) .................................................. 369
14.6.3 Limulus Amoebocyte Lysate Test
Combined with Gram-Negative Bacterial
Count (LAL/GNB) .......................................... 370
14.6.4 Half-Embryo Test to Measure Inhibition
of Seed Germination ..................................... 371
14.6.5 Other Biological Methods .............................. 372
14.7 Conclusions ..................................................................... 372

15. Process Control and Dosimetry in Food
Irradiation ..................................................................... 387
15.1 Introduction ...................................................................... 387
15.1.1 Advisory Technological Versus Legal
Dose Limits ................................................... 389
15.1.2 Significance of the Dose-Effect
Relationship .................................................. 390

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15.2 General Control Considerations ...................................... 391
15.2.1 Gamma-Ray Facilities ................................... 392
15.2.2 Electron-Beam and X-Ray Facilities .............. 393
15.2.3 Product Variations ........................................ 395
15.3 Commissioning a Facility ................................................. 395
15.3.1 Description of lrradiators and Their
Design .......................................................... 395
15.3.2 Expected Dose Distribution in the
Product ......................................................... 397
15.4 Process Qualification ....................................................... 401
15.4.1 Initiating a Treatment .................................... 401
15.4.2 Changing a Treatment .................................. 402
15.4.3 Extreme Dose Homogeneity
Requirements ............................................... 402

15.4.4 Setting Process Limits .................................. 403
15.5 Dosimetry Used in Process Control ................................ 404
15.5.1 Dosimetry Guidelines .................................... 405
15.5.2 Dosimeter Selection Criteria ......................... 405
15.5.3 Dosimetry Systems ....................................... 407
15.5.4 Absorbed Dose and Its Measurement ........... 407
15.5.5 Traceability and Accuracy ............................. 408
15.6 Documentation and Recordkeeping ................................ 408
15.6.1 Auditing the Facility ....................................... 409
15.6.2 Auditing the Process ..................................... 409
15.6.3 Compliance with Customer and Legal
Requirements ............................................... 409
15.6.4 Inventory Control and Product Release ........ 409
15.6.5 Aspects of International Trade ...................... 410

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Contents

16. Economic and Technical Considerations in
Food Irradiation ........................................................... 415
16.1 Introduction ...................................................................... 415
16.2 Food Irradiation Parameters ............................................ 415
16.3 Food Irradiation Equipment ............................................. 416
16.3.1 Gamma lrradiators ........................................ 416
16.3.2 Machine Source lrradiators ........................... 419
16.4 Costs ................................................................................ 422

16.4.1 Capital Costs ................................................ 422
16.4.2 Operating Costs ............................................ 422
16.4.3 Total Processing Costs ................................. 422
16.4.4 Unit Processing Costs ................................... 422
16.5 Effect of Throughput on Costs ......................................... 433
16.6 Effect of Dose on Costs ................................................... 437
16.7 Effect of Packing Density on Cobalt-60 Utilization
Efficiency in Gamma Irradiators ...................................... 439
16.8 Summary ......................................................................... 441
16.9 Bibliographic Notes .......................................................... 442

17. Global Status of Food Irradiation in 2000 .................. 443
17.1 Global Developments Affecting the Introduction or
Expansion of Food Irradiation ......................................... 443
17.1.1 Developments in Health-Related Areas
Affecting the Introduction or Expansion
of Food Irradiation ......................................... 443
17.1.2 Developments in Environmentally
Related Areas Affecting the Introduction
or Expansion of Food Irradiation ................... 446
17.1.3 Developments in International Trade
Regulations Affecting the Introduction or
Expansion of Food Irradiation ....................... 446

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17.1.4 Developments in Food Irradiation
Regulations Affecting the Introduction or
Expansion of Food Irradiation ....................... 447
17.2 Current Commercial Application of Radiation
Processing to Foods and Future Outlook ....................... 450
17.3 Notes on Consumer Acceptance of Irradiated
Foods: The Myths and the Facts ..................................... 451

Index .................................................................................... 457

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CHAPTER 1

Introduction
RlCARDO A. MOLINS
Institute of Medicine, The National Academics, Washington, DC

1.1. HISTORICAL NOTES ON FOOD IRRADIATION
1.1.1. Notes on the Development of the Food
Irradiation Process and Applications
Although frequently termed "a new technology," food irradiation is anything but
new. As described in the excellent reviews on food irradiation history written by
Josephson (1983a) and Diehl (1990), the idea of using ionizing radiation to improve
the quality and shelf life of foods had already been expressed in the late 180Os.
The generic term, "irradiation," however, appears in the literature only until the
1940s, and it is safe to say that it constituted a most unfortunate occurrence because
it brought a direct and conceptually misleading association of a food processing

technique with the nuclear establishment (Kampelmacher 1983)—opposed by
certain groups because of political and/or environmental considerations beyond
the scope of this book—that persists today. Such an association was never made
with X-ray technology, for example, because the dreaded term "radiation" and its
post-war specter were not incorporated in its name. This association is specially
strong in certain languages in which the term "food irradiation" does, in fact,
contribute to public confusion. In Arabic, for example, "irradiated food" and
"radioactive food" are almost indistinguishable terms. Little did the originators
of the food irradiation name imagine that their choice of words would play such an
adverse role in the acceptance of this technology, and little was done later to
remedy the situation because pro-food irradiation scientists and authorities were
forced, for decades, into a defensive position. This resulted in the ironic situation of
having to keep an inappropriate name for the technology or being accused of
"trying to hide something."
The term "food irradiation" is inappropriate and generic because it does not
describe the actual process of applying ionizing radiation in ways that would set it
Food Irradiation: Principles and Applications, Edited by R. A. Molins
ISBN 0-471-35634-4 © 2001 John Wiley & Sons, Inc.


apart from other processes used in the food industry. Thus, microwaves and infrared
light—both of which generate heat—are also forms of radiation, and their use in
cooking, heating foods in a microwave oven, or simply keeping the food warm
under an infrared light—as is customary in many restaurants—could just as properly be termed "food irradiation." Indeed, shortly after World War II, there was
widespread distribution in the United States of pasteurized fluid milk labeled "irradiated" because it had been treated with infrared light to develop vitamin D from
precursors. This practice was later abandoned when milk was directly and routinely
fortified with vitamin D. Considering that we have reached an enlightened age,
perhaps it is time to do away with this absurd situation and either adopt the more
logical French term "ionization"—already adopted by French-speaking countries
that have or are developing regulations in this field—or reconsider the proposal of

the late E. Wierbicki to call irradiated foods "picowaved" in reference to the very
short wavelength of ionizing radiation, and quite in line with the currently common
term "microwaved." A first step in this direction may be the current increasingly
popular use of the term "electronic pasteurization" in the United States to describe
inactivation of pathogenic bacteria in food through irradiation.
In general, the early history of food irradiation (1890s-1940s) is inseparably
linked to that of radiation physics and to the development of the systems and
sources to be used in food irradiation. This was followed by a period of intensive
research and development (1940s-1970s) that overlapped with extensive studies on
the wholesomeness of irradiated foods (1970s). Since the 1970s, however, most
historical food irradiation events have been related to regulations. The following is
a chronological list of some of the most important dates and landmark events in
food irradiation history, or of events that had an impact on the development and
adoption of this technology:
1895
1896
1896

1898

1901
1902-1903

1904
1905

W. K. von Roentgen reported the discovery of X rays.
H. Becquerel reported the discovery of radioactivity.
H. Minsch (Germany) published a proposal to use ionizing
radiation to preserve food by destroying spoilage

microorganisms.
J. J. Thompson reported on the nature of cathode rays (i.e.,
that they are "electrons"). Pacronotti and Procelli observed
radiation effects on microorganisms.
Max Planck published the quantum theory proposal.
Rutherford and Soddy published a proposed theory of
radioactive disintegration. Marie Curie published her thesis
on the nature of alpha, beta, and gamma radiation.
S. C. Prescott published studies on the bactericidal effect
of ionizing radiation.
Albert Einstein published his theory of relativity. A British
patent was issued for use of ionizing radiation to kill bacteria
in foods through food irradiation. A separate U.S. patent


1906
1905-1920
1916
1918
1921

1923-1927

1920s-1930s

1930
1938
1942-1943

Late 1940s

1950

1953

1955
1958
1958-1959

was issued on mixing radioactive material with food for
preservation purposes.
The U.S. Pure Food and Drug Act became law.
This was a period of basic research on the nature and chemical,
physical, and biological effects of ionizing radiation.
Radiation processing of strawberries was evaluated in Sweden.
A U.S. patent on X-ray multiple-tube processing of food was
issued to Gillet.
B. Schwartz published on the lethal effects of X rays on
Trichinella spiralis in raw pork. Studies were conducted on
elimination of the tobacco beetle by irradiation.
Publications on the effects of ionizing radiation on enzymes first
appeared. First published results of animal feeding studies to
test the wholesomeness of irradiated foods appeared. The
rodent bioassay (essential in studying the toxicology of
irradiated foods) was developed.
Many important electron accelerator machine developments
took place. Atomic/nuclear fission was discovered and
demonstrated.
A French patent was issued to Otto Wiist (a German) for the use
of ionizing radiation to preserve foods.

The U.S. Food-Drug & Cosmetic (FDAC) Act became law.
The Massachusetts Institute of Technology (MIT) team (B. E.
Proctor and colleagues), under a U.S. Army contract,
demonstrated the feasibility of preserving ground beef
through irradiation using X rays.
Post-World War II era of food irradiation development by U.S.
government, industry, universities, and private institutions
began. Chronic animal feeding studies began by the U.S.
Army and by Swift & Company.
Beginning of the U.S. Atomic Energy Commission food
irradiation program. The United Kingdom began its food
irradiation development program (to be followed by many
countries).
President D. Eisenhower made his landmark "Atoms for Peace"
address at the United Nations General Assembly. Many
nations joined the research on peaceful uses of atomic energy,
including applications in food preservation. The U.S. Army
Quartermaster food irradiation program began.
The U.S. Army Medical Department 10-year wholesomeness
testing program began.
The U.S. Food Additives Amendment to the FDAC Act
classified food irradiation as an "additive."
The Soviet Union approved irradiation of potatoes and grains.


1960
1963-1964

1964
1965

1968

1970

1973

1976

1978

1979

1980

The first commercial food (spices) irradiation facility was
commissioned in the Federal Republic of Germany.
Canada approved potato irradiation. The Federal Republic of
Germany banned food irradiation.
The U.S. Food and Drug Administration (FDA) approved
irradiation of bacon, wheat, flour, and potatoes (the bacon
clearance was repealed in 1968).
The Joint FAO/IAEA Division of Nuclear Techniques in Food
and Agriculture was established.
The U.S. Army Surgeon General declared radiation-sterilized
foods in general "wholesome."
The U.S. FDA turned back a U.S. Army radiation-sterilized ham
petition and rescinded the 1963 bacon approval, alleging
insufficient data and experimental design/execution
deficiencies.
The U.S. Army began a new wholesomeness testing program

under revised protocols. The international irradiated foods
wholesomeness testing project (IFIP) was established at
Karlsruhe, Federal Republic of Germany by FAO, IAEA,
OECD, and 24 countries.
Japan began industrial-scale potato irradiation (the irradiator is
still in operation in Sapporo, making it the longest working
food irradiator in the world).
The Joint FAO/IAEA/WHO Expert Committee on the
Wholesomeness of Irradiated Food (JECFI) gave a clean bill
of health to several irradiated foods and recommended that
food irradiation be classified as a physical process.
The International Facility for Food Irradiation Technology
(IFFIT) was established at Wageningen, The Netherlands,
under the sponsorship of FAO, IAEA, and The Netherlands.
Until 1990, IFFIT trained hundreds of scientists from
developing countries in food irradiation and contributed to
develop many applications of radiation processing to foods.
The U.S. FDA Bureau of Foods formed an internal Irradiated
Foods Committee (final report submitted in July 1980). The
first Codex Alimentarius General Standard on Irradiated
Food was adopted (it included conditional and unconditional
clearances for a limited number of foods, based on the 1976
findings of the JECFI).
The Joint FAO/IAEA/WHO Expert Committee on the
Wholesomeness of Irradiated Food (JECFI) declared that
"irradiation of any food commodity up to an overall average
dose of 1OkGy presents no toxicological hazards; hence
toxicological testing of foods so treated is no longer
required." It also found that irradiation up to 1OkGy

1983

1984

1985

1986

1986-1989

1990
1992

1992

"introduces no special nutritional or microbiological
problems."
The Codex Alimentarius Commission adopted the Codex
General Standard for irradiated Foods and the Recommended
Code of Practice for the Operation of Radiation Facilities
Used for the Treatment of Foods (this was the first revision of
the standard of 1979, which made it valid for any food). Also
in 1983, the U.S. FDA and Health & Welfare Canada
approved irradiation of spices; Health & Welfare Canada
published a proposal to reclassify food irradiation as a
process, and to adopt the new international Codex General
Standard and Code of Practice', and the IFIP, founded in
1970, was terminated after achieving its goals; the foundation
of a successor organization was proposed.

The International Consultative Group on Food Irradiation
(ICGFI) was established under the aegis of
FAO/IAEA/WHO to evaluate global developments in
food irradiation, provide a focal point of advise on the
application of food irradiation to member states and the
three sponsoring organizations, and to furnish information
as required, through the organizations, to the Joint
FAO/IAEA/WHO Expert Committee on the
Wholesomeness of Irradiated Food, and the Codex
Alimentarius Commission. (See lists of ICGFI codes and
recommended dose limits in Tables 1.1 and 1.2.)
Final Canadian and U.S. food irradiation regulations were
published. The U.S. FDA approved irradiation of pork for
control of Trichinella spiralis.
The U.S. FDA approved irradiation to delay maturation, to
inhibit growth, and to disinfect food, including vegetables
and spices.
The European Community prepared the first draft to harmonize
the legislation in member states with regard to food
irradiation. The United States Department of Agriculture/
Food Safety Inspection System (USDA/FSIS) approved
irradiation for control of trichina in pork.
The U.S. FDA approved irradiation of poultry to
control Salmonella.
The USDA/FSIS approved irradiation of poultry. The first
commercial irradiation facility fully dedicated to food
processing in the United States was built.
At the request of Australia, the World Health Organization
(WHO) convened- an Expert Committee to reexamine the
safety of irradiated foods. WHO reaffirms the conclusion that

irradiated foods are safe.


TABLE 1.1. Codes of Good Irradiation Practice Published by the International
Consultative Group on Food Irradiation (ICGFI)
Code of Good Irradiation Practice for Insect Disinfestation of Cereal Grains (ICGFI
Document 3), IAEA, Vienna, 1991
Code of Good Irradiation Practice for Prepackaged Meat and Poultry (to control pathogens
and/or extend shelf-life) (ICGFI Document 4), IAEA, Vienna, 1991
Code of Good Irradiation Practice for the Control of Pathogens and Other Microflora in
Spices, Herbs and Other Vegetable Seasonings (ICGFI Document 5), IAEA, Vienna,
1991
Code of Good Irradiation Practice for Shelf-life Extension of Bananas, Mangoes and
Papayas (ICGFI Document 6), IAEA, Vienna, 1991
Code of Good Irradiation Practice for Insect Disinfe station of Fresh Fruits (as a quarantine
treatment) (ICGFI Document 7), IAEA, Vienna, 1991
Code of Good Irradiation Practice for Sprout Inhibition of Bulb and Tuber Crops (ICGFI
Document 8), IAEA, Vienna, 1991
Code of Good Irradiation Practice for Insect Disinfe station of Dried Fish and Salted and
Dried Fish (ICGFI Document 9), IAEA, Vienna, 1991
Code of Good Irradiation Practice for the Control of Microflora in Fish, Frog Legs and
Shrimps (ICGFI Document 10), IAEA, Vienna, 1991
Code of Good Irradiation Practice for the Control of Pathogenic Microorganisms in Poultry
Feed (ICGFI Document 19), IAEA, Vienna, 1995
Code of Good Irradiation Practice for Insect Disinfe station of Dried Fruits and Tree Nuts
(ICGFI Document 20), IAEA, Vienna, 1995

1996

1997

1998

The number of countries having clearances for irradiation of one
or more foods reaches 40, while 28 countries apply food
irradiation commercially. A new Study Group on High Dose
Food Irradiation is formed jointly by FAO, IAEA, and WHO
to examine the safety and wholesomeness of foods irradiated
at doses above 1OkGy.
A Joint FAO/IAEA/WHO Study Group on High Dose Food
Irradiation declared that foods irradiated at any dose are safe
and that there is no need for upper dose limits. Also in 1997,
the U.S. FDA approved irradiation of meats for pathogen
control, and the number of member states belonging to
ICGFI reached 45.
The U.S. FDA modified regulations on labeling of irradiated
foods such that the letter size indicating the treatment needed
to be equal in size only to the ingredients listed on the label.
The ICGFI initiated procedures to bring about a modification
of the Codex General Standard for Irradiated Foods to
remove all references to a 10-kGy maximum overall absorbed
dose, in accordance with the recommendation made in 1997
by the FAO/IAEA/WHO Study Group on High Dose Food
Irradiation.


1999

2000

A European Union Directive approved irradiation of spices,
herbs, and condiments; preparation of a final "positive list"
of food items permitted for radiation processing was
scheduled for the end of 2000. Construction of an electronbeam facility devoted to radiation processing of hamburger
patties was under way in the United States; further facilities
were in the planning stage at the time of writing. A coalition
of American food industry groups headed by the National
Association of Food Processors presented a petition to the
U.S. FDA to clear irradiation of ready-to-eat foods, as a result
of multiple outbreaks of listeriosis involving such products.
Also, the USDA cleared irradiation of meat for pathogen
control, and
The U.S. FDA cleared irradiation for control of Salmonella in
shell eggs, and for decontamination of seeds for sprouting.

Although the issuance of the Codex General Standard for Irradiated Foods in 1984
was determinant in moving many countries to enact food irradiation regulations,
other countries had approved various food processing applications of ionizing
radiation much earlier, as described in Chapter 17. Thus, the Soviet Union cleared
irradiation of potatoes and grains in 1958/59, followed by Canada (potatoes, 1960)
and the United States (bacon, wheat, flour and potatoes, 1963/64). However, it was
during the 1980s and 1990s that food irradiation clearances proliferated, possibly as
a result of recurrent outbreaks of foodborne illnesses described elsewhere in this
book. According to the database on food irradiation clearances maintained by the
International Consultative Group on Food Irradiation (ICGFI 1999), the latest
addition to the list of countries having them is the European Union (EU), which
approved irradiation of spices, condiments, and herbs in 1998 (Anonymous
1999a,b). The list of products approved by the European Union was expected to
increase after December 1999 according to the terms of the corresponding Directives.
Although there are historically important events and dates concerning irradiation

of various foods or groups of foods, the prominence that irradiation of meat and
poultry products have had from the toxicologically and regulatory standpoints is
well established. Furthermore, irradiation of meats and poultry may soon be the key
to a wider adoption of the technology the world over because of its unique potential
as a control measure of meat- and poultryborne bacterial diseases well known
to, and feared by, the public. A recapitulation of the history of food irradiation
published by Goresline (1982) attributed initial research on this technology, including the pioneering efforts in the area of meat irradiation, to scientists at the
Massachusetts Institute of Technology in the late 1930s and early 1940s. This
work was undertaken on behalf of the United States Army, which at the time
was seeking new food preservation methods that would allow improvements in
the diet of troops stationed abroad. By 1943, scientists had demonstrated that
ground beef could be preserved by exposing it to X rays. Various foods had been


TABLE 1.2. Advisory Technological Dose Limits for Good Irradiation Practice
Food Classes

Purpose

Class 1: bulbs, roots, and tubers

To inhibit sprouting
during storage
To delay ripening
Insect disinfestation
Shelf-life extension
Quarantine control"

Class 2: fresh fruits and vegetables
(other than class 1)

Class 3: cereals and their milled products,
nuts, oilseeds, pulses, dried fruits
Class 4:fish,seafood, and their products
(fresh or frozen)

Class 5: raw poultry and meat and their
(fresh or frozen)

Class 6: dry vegetables, spices, condiments,
animal feed, dry herbs, and herbal teas

Insect disinfestation
Reduction of microbial load
Reduction of pathogenic
microorganisms*7
Shelf-life extension
Control of infection by
parasites6
Reduction of pathogenic
microorganisms6
Shelf-life extension
Control of infection by
parasites6
Reduction of pathogenic
microorganisms6
Insect disinfestation

Dose Maxima (kGy)

ICGFr Document

0.2

8

1.0
1.0
2.5
1.0
1.0
5.0

6
3,7,17
6
7,13,17
3,20
3,20

5.0
3.0

10
10

2.0

10

7.0
3.0

4
4

2.0

4

10.0
1.0

5,19
5,19