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