Ultraviolet light in food technology : principles and applications

The production of environmentally friendly, sustainable, chemical-free food continues to challenge the food industry, spurring on investigations into alternative food processing techniques that are more sophisticated and diverse than current practices. Exploring one of these emerging solutions, Ultraviolet Light in Food Technology: Principles and Applications incorporates the fundamentals of continuous and pulsed UV light generation and propagation; current food regulations; recommendations for optimal UV reactor design, selection, and validation; information on both commercially available and under-development UV sources; and the outlook for future food applications.

After reviewing essential terms, definitions, and current applications, the book emphasizes the need to properly assess the physical and chemical properties in foods that influence the effectiveness of UV treatment and impact inactivation kinetics. It also addresses the effects of UV processing on food quality, before considering the engineering aspects of UV light treatment, such as transport phenomena, process calculations, and continuous-flow reactor geometries. The book then describes the principles of validating UV reactors as well as the principles and applications of UV pulsed light, including microbial inactivation in water, meat, fruits, vegetables, and packaging materials.

For anyone working in food research, development, and operations, this resource provides broad, accessible information on the science and applications of UV light technology. It shows how UV light irradiation can be used as a physical preservation method in food processing.

Author Notes

Koutchma, Tatiana; Forney, Larry J.; Moraru, Carmen I.

Carmen I. Moraru and Aaron R. Uesugi

Preface to Contemporary Food Engineering Series	p. xi
Preface	p. xiii
Series Editor	p. xvii
Authors	p. xix
Chapter 1 Principles and Applications of UV Technology	p. 1
1.1 Basic Principles of UV-Light Technology	p. 1
1.1.1 Mechanisms of UV-Light Generation	p. 2
1.1.2 Gas Discharge	p. 3
1.2 Propagation of UV Light	p. 4
1.2.1 Basic Principle of Photochemistry	p. 5
1.2.2 Terms and Definitions	p. 6
1.2.3 UV Radiation Energy	p. 7
1.2.4 Absorbed Energy	p. 7
1.3 Application Guidance in Food Processing	p. 9
1.3.1 Disinfection of Surfaces	p. 9
1.3.1.1 RTE Meats	p. 9
1.3.1.2 Baguettes	p. 11
1.3.1.3 Shell Eggs	p. 11
1.3.1.4 Whole and Fresh-Cut Fruits	p. 11
1.3.1.5 Broiler Breast Fillets	p. 12
1.3.1.6 Pulsed UV Light for Foods	p. 12
1.3.2 UV Light for Liquid Foods and Beverages	p. 13
1.3.2.1 Fresh Apple Juice/Cider	p. 14
1.3.2.2 Juices with Pulp	p. 17
1.3.3 Liquid Sugars and Sweeteners	p. 20
1.3.4 Liquid Egg Products	p. 23
1.3.5 Milk	p. 24
1.4 Current Status of U.S. and International Regulations	p. 25
1.4.1 U.S. FDA: Continuous UV-Light Irradiation	p. 25
1.4.2 Pulsed UV Light in the Production, Processing, and Handling of Food	p. 26
1.4.3 Health Canada: Novel Food Information	p. 26
1.4.4 European Union Regulations	p. 27
1.4.5 Establishing the Equivalence of Alternative Methods of Pasteurization	p. 27
References	p. 28
Chapter 2 Sources of UV Light	p. 33
2.1 Introduction	p. 33
2.2 Mercury-Emission Lamps	p. 35
2.2.1 Low-Pressure Mercury Lamp Technologies	p. 36
2.2.2 Medium-Pressure Mercury Lamps	p. 38
2.2.3 Low-Pressure Mercury Lamp for Producing Ozone	p. 39
2.3 Amalgam UV Lamps	p. 40
2.3.1 UV-Lamp Breakage	p. 41
2.4 Special Lamp Technologies	p. 41
2.4.1 Excimer Lamps	p. 41
2.4.2 Broadband Pulsed Lamps	p. 44
2.4.3 Microwave UV Lamps	p. 46
2.4.4 UV-Light-Emitting Diodes	p. 47
2.5 Guidelines for Choice of Lamp Technology	p. 49
References	p. 50
Chapter 3 Characterization of Foods in Relation to UV Treatment	p. 53
3.1 Terms and Definitions	p. 53
3.2 Analytical Measurements	p. 54
3.3 Absorptive and Physicochemical Properties of Liquid Foods	p. 56
3.3.1 Apple Cider	p. 56
3.3.2 Apple Juices	p. 61
3.3.3 Tropical Fruit and Vegetable Juices	p. 62
3.3.4 UV Absorption of Major Apple Cider Components	p. 63
3.4 Food Solids and Surfaces	p. 64
3.5 Conclusions	p. 65
References	p. 66
Chapter 4 Microbial Inactivation by UV Light	p. 69
4.1 Mechanisms of Microbial Inactivation by UV Light	p. 69
4.2 UV Sensitivity of Pathogenic and Spoilage Food-Borne Microorganisms	p. 72
4.2.1 Definition of UV Dose	p. 72
4.2.2 Estimating UV Dose	p. 72
4.3 UV Sensitivity of Waterborne Pathogens	p. 73
4.4 UV Sensitivity of Food-Borne Pathogens	p. 74
4.5 UV Inactivation Kinetics and Competitive Effects in Foods: Absorbance, pH, Solids, and Other Components	p. 75
4.5.1 pH and Dissolved Solids	p. 76
4.5.2 Absorbance	p. 76
4.5.3 Suspended Solids	p. 77
4.5.4 Temperature	p. 81
4.5.5 Wavelength	p. 81
4.6 Methods to Measure, Quantify, and Mathematically Model UV Inactivation	p. 81
4.6.1 Collimated-Beam Tests	p. 81
4.6.2 Measurement of UV Inactivation Kinetics in Annular Reactors	p. 83
4.6.3 Modeling of UV Inactivation Kinetics	p. 86
4.6.3.1 First-Order Inactivation Model	p. 86
4.6.3.2 Series-Event Inactivation Model	p. 87
4.6.4 UV Inactivation Kinetics of E. coli	p. 88
4.6.4.1 First-Order Inactivation Model	p. 88
4.6.4.2 Series-Event Inactivation Model	p. 90
4.6.5 UV Inactivation Kinetics of Y. pseudotuberculosis	p. 90
4.6.5.1 First-Order Inactivation Model	p. 90
4.6.5.2 Series-Event Inactivation Model	p. 91
4.6.6 UV Inactivation of Bacillus subtilis Spores in the Annular UV Reactor	p. 92
4.7 Efficacy of Low-Pressure, High-Intensity Lamp for Inactivation of Food Pathogen	p. 94
4.8 Conclusions	p. 98
References	p. 99
Chapter 5 UV Processing Effects on Quality of Foods	p. 103
5.1 Basic Considerations	p. 103
5.2 Chemistry of the Photodegradation of Organic Compounds	p. 104
5.3 Shelf Life and Quality Changes in Fresh Juices	p. 105
5.4 Effects of UV Light on Degradation of Essential Vitamins	p. 107
5.5 Effect of UV Processing on Milk Quality	p. 113
5.6 Shelf Life and Quality Changes in Fresh Produce	p. 113
5.6.1 Lettuce	p. 113
5.6.2 Fresh-Cut Fruits	p. 114
5.6.3 Whole Fruits and Vegetables	p. 115
5.6.4 Meats, Poultry, Fish	p. 117
5.7 Degradation and Formation of Chemical Compounds in Foods	p. 117
5.7.1 Furan in Apple Cider	p. 117
5.7.2 Dioxins in Fish Meal	p. 119
5.7.3 Photolysis of Nitrates	p. 120
5.8 Conclusions	p. 120
References	p. 121
Chapter 6 Transport Phenomena in UV Processing	p. 125
6.1 UV Irradiance in Liquid Foods	p. 125
6.2 General Hydraulic Condition	p. 127
6.2.1 Hydraulic Diameter	p. 128
6.2.2 Channel Entrance Length	p. 128
References	p. 129
Chapter 7 UV Process Calculations for Food Applications	p. 131
7.1 Establishment of Specifications for Preservation	p. 132
7.2 Delivery of the Scheduled Process	p. 133
7.2.1 Reactor Performance	p. 134
7.3 Measurement of UV-Dose Delivery	p. 139
7.3.1 Biodosimetry	p. 139
7.3.1.1 Modified Biodosimetry Method	p. 139
7.3.2 Chemical Actinometry	p. 141
7.3.2.1 Effect of Chemical and Physical Properties of Apple Products on UV Dose	p. 143
7.3.2.2 Calibration of HHEVC against a Standard Biodosimeter	p. 147
7.3.3 Mathematical Modeling	p. 149
7.3.3.1 Flow Dynamics	p. 150
7.3.3.2 UV Fluence Rate Distribution	p. 150
7.4 Conclusions	p. 152
References	p. 153
Chapter 8 Reactor Designs for the UV Treatment of Liquid Foods	p. 155
8.1 Laminar Flow in Concentric Cylinders	p. 156
8.1.1 Thin-Film Annular Reactors	p. 156
8.1.2 UV Fluence Distribution	p. 156
8.1.3 UV Inactivation Kinetics	p. 159
8.1.4 UV Disinfection of E. coli	p. 160
8.1.5 Optimum Gap Width	p. 161
8.1.6 Correlation of UV Disinfection in Laminar Reactors	p. 162
8.2 Turbulent Flow in Concentric Cylinders	p. 164
8.2.1 Thin-Film Annular Reactor	p. 164
8.2.2 UV Fluence Distribution	p. 165
8.2.2.1 Numerical Modeling of Turbulent Flow	p. 165
8.2.3 UV Disinfection of Y. pseudotuberculosis	p. 166
8.2.4 Effect of Absorption Coefficient	p. 167
8.2.5 Effect of the Gap Width	p. 168
8.2.6 Optimum Gap Width	p. 170
8.2.7 Correlation of UV Disinfection	p. 171
8.3 Taylor-Couette Flow in Concentric Cylinders	p. 172
8.3.1 Thin-Film Annular Reactor	p. 173
8.3.2 UV Fluence Distribution	p. 174
8.3.2.1 Numerical Modeling of Taylor-Couette Flow	p. 175
8.3.3 UV Disinfection of E. coli	p. 176
8.3.4 Effect of Absorption Coefficient	p. 177
8.3.5 Optimum Gap Width	p. 177
8.3.6 Correlation of UV Disinfection	p. 180
8.3.7 Turbulent Taylor-Couette Flow	p. 181
8.3.8 Modified Taylor-Couette Flow	p. 182
8.4 Comparison of Disinfection in Concentric Cylinders	p. 185
8.4.1 UV Fluence Distribution in Concentric Cylinders	p. 185
8.4.2 Optimum UV Inactivation in Concentric Cylinders	p. 186
8.4.3 Microbe Mass Transfer	p. 187
8.4.3.1 Laminar Flow	p. 187
8.4.3.2 Turbulent Flow	p. 188
8.4.3.3 Taylor-Couette Flow	p. 188
8.4.4 Correlation of UV Inactivation in Concentric Cylinders	p. 189
8.5 Turbulent Channel Flow	p. 190
8.5.1 Turbulent Channel Reactor	p. 190
8.5.2 Effect of the Absorption Coefficient	p. 191
8.5.3 UV Disinfection of E. coli	p. 192
8.5.4 Correlation of UV Disinfection	p. 192
8.6 Dean Flow Reactor	p. 194
8.6.1 Dean Flow Reactor	p. 194
8.6.2 Active Microbe Distribution	p. 195
8.6.3 Effect of the Absorption Coefficient	p. 197
8.6.4 UV Inactivation of E. coli	p. 197
8.6.5 Correlation of UV Disinfection	p. 198
8.7 Evaluation of UV Reactor Design	p. 200
8.7.1 Segregation Model	p. 200
8.7.2 Dosage Distribution Model	p. 202
8.7.3 Comparison of Reactor Design Performance	p. 204
8.8 UDF Source C Codes	p. 206
8.8.1 Turbulent Flow between Concentric Cylinders	p. 206
8.8.2 Taylor-Couette Flow between Concentric Cylinders	p. 209
References	p. 212
Chapter 9 Principles of Validation of UV-Light Pasteurization	p. 215
9.1 Validation Concept	p. 215
9.2 Validation at Different Phases of Process Development-Scale-Up Process	p. 216
9.3 Key Components of Validation Procedures	p. 218
9.3.1 Microbiological Validation	p. 218
9.3.1.1 Pertinent Pathogen Selection	p. 218
9.3.1.2 Microbiological Methods	p. 220
9.3.1.3 Inoculum Levels	p. 220
9.3.2 Model Systems	p. 221
9.3.3 Microbial Validation in Scale-Up Process	p. 222
9.3.4 Generation of UV Dose Requirements for Test Microorganism	p. 222
9.3.5 Dose Delivery and Microbial Inactivation by UV Reactors	p. 223
9.3.6 Hydraulic Considerations	p. 225
9.3.7 UV Lamp Output	p. 228
9.3.8 Chemical and Physical Safety	p. 229
9.3.9 Quality Validation	p. 229
9.3.10 Equipment Validation	p. 230
9.3.11 UV-Intensity Sensors	p. 231
9.3.12 Cleaning Validation	p. 232
9.3.13 Testing Facility Requirements	p. 233
9.4 Conclusions	p. 233
References	p. 233
Chapter 10 Pulsed-Light Treatment: Principles and Applications	p. 235
10.1 Description of Pulsed-Light Treatment	p. 235
10.1.1 General Aspects of Pulsed-Light Treatment	p. 235
10.1.2 Pulsed-Light Equipment	p. 236
10.1.2.1 Flash Lamps: Design and Pulsed-Light Generation	p. 236
10.1.2.2 Design of Pulsed-Light Systems	p. 244
10.1.3 Alternative Technologies to Generate Pulsed Light	p. 246
10.1.3.1 Static-Discharge Lamps	p. 246
10.1.3.2 Sparkers	p. 246
10.1.3.3 Other Pulsed-Light Technologies	p. 246
10.2 Inactivation of Microorganisms by Pulsed-Light Treatment	p. 247
10.2.1 Mechanisms of Inactivation	p. 247
10.2.2 Factors that Influence the Efficiency of Pulsed-Light Treatment	p. 249
10.2.3 Inactivation Kinetics in Pulsed-Light Treatment	p. 252
10.3 Applications of Pulsed-Light Treatment	p. 254
10.3.1 Microbial Inactivation in Water and Other Liquids	p. 254
10.3.2 Microbial Inactivation in Food Systems	p. 254
10.3.2.1 Pulsed-Light Treatment of Meat Products	p. 254
10.3.2.2 Pulsed-Light Treatment of Fruits and Vegetables	p. 256
10.3.2.3 Pulsed-Light Treatment of Other Foods	p. 258
10.3.3 Pulsed-Light Treatment of Packaging Materials	p. 259
10.3.4 Other Applications of Pulsed-Light Treatment	p. 260
10.4 Future Prospects of Pulsed-Light Treatment in the Food Industry	p. 261
References	p. 261
Index	p. 267

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