Food irradiation : principles and applications

Preface ................................................................................. xiii 1. Introduction .................................................................. 1 1.1 Historical Notes on Food Irradiation ................................ 1 1.1.1 Notes on the Development of the Food Irradiation Process and Applications ............. 1 1.1.2 Proving the Wholesomeness of Irradiated Foods ............................................ 12 1.2 Potential Social and Economic Benefits of Food Irradiation ......................................................................... 14 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 1.2.2 Social and Economic Benefits in Relation to Food Safety: Controlling Pathogenic Bacteria and Parasites in Foods ............................................................ 16 2. 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 viii Contents This page has been reformatted by Knovel to provide easier navigation. 2.5 Environmental Factors Affecting Radiation Sensitivity ......................................................................... 31 2.6 Other Issues .................................................................... 32 2.7 Conclusions ..................................................................... 32 3. Food Irradiation Chemistry ......................................... 37 3.1 Introduction ...................................................................... 37 3.1.1 Types of Ionizing Radiation and Their Sources ........................................................ 37 3.1.2 Background and Induced Radioactivity ......... 38 3.2 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 3.5 Conclusions ..................................................................... 68 4. 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 4.3 Current Disinfestation Methods and Their Drawbacks ....................................................................... 85 Contents ix This page has been reformatted by Knovel to provide easier navigation. 4.3.1 Chemical Methods ........................................ 86 4.3.2 Physical Methods .......................................... 87 4.4 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 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 5.6.1 Aspects of Importance in Conducting Radiation Quarantine Treatment Research ...................................................... 121 5.6.2 Research Needs ........................................... 124 5.7 Future Outlook for Irradiation as a Quarantine Treatment ........................................................................ 127 x Contents This page has been reformatted by Knovel to provide easier navigation. 6. Irradiation of Meats and Poultry ................................. 131 6.1 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 6.2 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 7. Irradiation Processing of Fish and Shellfish Products ....................................................................... 193 7.1 Introduction ...................................................................... 193 7.2 Irradiation for Shelf-Life Extension of Seafood Products ........................................................................... 195 Contents xi This page has been reformatted by Knovel to provide easier navigation. 7.2.1 Finfish Products ............................................ 195 7.2.2 Shellfish and Crustaceans ............................ 197 7.3 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 8. 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 xii Contents This page has been reformatted by Knovel to provide easier navigation. 8.4 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 8.5 Potential for Radiation Treatment of Vegetables ............ 230 9. Irradiation of Tuber and Bulb Crops .......................... 241 9.1 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 9.2 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 9.3 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 9.4 Effect of Ionizing Radiation on Technological Properties of Tubers and Bulbs ....................................... 254 9.4.1 Wound Healing and Storage Rot ................... 254 Contents xiii This page has been reformatted by Knovel to provide easier navigation. 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 xiv Contents This page has been reformatted by Knovel to provide easier navigation. 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 Contents xv This page has been reformatted by Knovel to provide easier navigation. 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 xvi Contents This page has been reformatted by Knovel to provide easier navigation. 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 Contents xvii This page has been reformatted by Knovel to provide easier navigation. 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 xviii Contents This page has been reformatted by Knovel to provide easier navigation. 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 Contents xix This page has been reformatted by Knovel to provide easier navigation. 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