Press FUNDAMENTAL FOOD. Bibek Ray Arun Bhunia EDITION FIFTH. Taylor & Francis Group. Taylor & Francis Group,

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1 FIFTH EDITION FUNDAMENTAL FOOD MICROBIOLOGY Bibek Ray Arun Press Taylor & Francis Group Boca Raton London NewYork CRC Press is an imprint of the Taylor & Francis Group, an informa business

2 Contents Preface to the Fifth Edition Preface to the Fourth Edition Preface to the Third Edition Preface to the Second Edition Preface to the First Edition Authors xxxv xxxvii xxxix xli xliii xlv SECTION I INTRODUCTION TO MICROBES IN FOODS 1 History and Development of Food Microbiology 3 Introduction 3 Discovery of Microorganisms 3 Where Are They Coming from? 4 What Are Their Functions? 4 Development of Early Food Microbiology (Before A.D. 1900) 5 Food Microbiology: Current Status 7 Food Fermentation/Probiotics 7 Food Spoilage 8 Foodborne Diseases 8 Miscellaneous 8 Food Microbiology and Food Microbiologists 9 Conclusion 9 References 10 2 Characteristics of Predominant Microorganisms in Food 11 Introduction 11 Classification of Microorganisms 12 Nomenclature 13 Morphology and Structure of Microorganisms in Foods 14 Yeasts and Molds 14 Bacterial Cells 16 Viruses 18 Important Microorganisms in Food 18 vii

3 viii Contents Important Mold Genera 18 Important Yeast Genera 19 Foodborne Protozoan Parasites 19 Important Viruses 20 Important Bacterial Genera 20 Gram-Negative Aerobes 22 Gram-Negative Facultative Anaerobes 23 Rickettsia 24 Gram-Positive Cocci 24 Gram-Positive, Endospore-Forming Rods 25 Gram-Negative, Endospore-Forming Rods 26 Gram-Positive, Nonsporulating Regular Rods 26 Gram-Positive, Non-Spore-Forming Irregular Rods 26 Some New Genera 27 Important Bacterial Groups in Foods 27 Lactic Acid Bacteria 27 Acetic Acid Bacteria 27 Propionic Acid Bacteria 27 Butyric Acid Bacteria 27 Proteolytic Bacteria 28 Lipolytic Bacteria 28 Saccharolytic Bacteria 28 Thermophilic Bacteria 28 Psychrotrophic Bacteria 28 Thermoduric Bacteria 28 Halotolerant Bacteria 28 Aciduric Bacteria 28 Osmophilic Bacteria 29 Gas-Producing Bacteria 29 Slime Producers 29 Spore Formers Aerobes Anaerobes Conclusion References Facultative Anaerobes Coliforms 29 Fecal Coliforms 30 Enteric Pathogens 30 3 Sources of Microorganisms in Foods 33 Introduction Predominant Microorganisms in Different Sources 34 Plants (Fruits and Vegetables) 34 Animals, Birds, Fish, and Shellfish 34 Air

4 Contents ix Soil Sewage and Manure 36 Water 36 Humans Food Ingredients 37 Equipment 37 Miscellaneous 38 Conclusion References 4 Normal Microbiological Quality of Foods and Its Significance 41 Introduction 41 Raw and Ready-to-Eat Meat Products 41 Raw and Pasteurized Milk 42 Shell Eggs and Liquid Egg 43 Fish and Shellfish 44 Vegetables, Fruits, and Nuts 44 Cereal, Starches, and Gums 45 Canned Foods 46 Sugars and Confectioneries 46 Soft Drinks, Fruit and Vegetable Drinks, Juices, and Bottled Water 47 Mayonnaise and Salad Dressings 47 Spices and Condiments 47 Conclusion 48 References SECTION II MICROBIAL GROWTH RESPONSE IN THE FOOD ENVIRONMENT 5 Microbial Growth Characteristics 53 Introduction Microbial Reproduction or Growth 53 Binary Fission 53 Generation Time (or Doubling Time) 54 Specific Growth Rate 55 Optimum Growth 56 Growth Curve 56 Nature of Microbial Growth in Food 57 Mixed Population 57 Sequence of Growth 58 Growth in Succession or Diauxic Growth 58 Symbiotic Growth 58 Synergistic Growth 59 Antagonistic Growth 59 Conclusion 59 References 60 53

5 x Contents 6 Factors Influencing Microbial Growth in Food 61 Introduction Intrinsic Factors or Food Environment 61 Nutrients and Growth 61 Carbohydrates in Foods 62 Proteins in Foods 63 Lipids in Foods 64 Minerals and Vitamins in Foods 64 Growth Factors and Inhibitors in Food 64 Water Activity and Growth 65 Principle 65 offood 65 Aw and Microbial Growth 66 ph and Growth 66 Principle 66 ph of Food 66 ph and Microbial Growth 67 Redox Potential, Oxygen, and Growth 67 Principle 67 Redox Potential in Food 68 Redox Potential and Microbial Growth 68 Extrinsic Factors 69 Temperature and Growth 69 Principle 69 Food and Temperature 69 Microbial Growth and Viability 69 Quorum Sensing and Bacterial Growth 70 Conclusion 71 References 72 7 Microbial Attachments and Biofilm Formation 73 Introduction 73 Mechanisms ofattachment 74 Influencing Factors 75 Assessment of Biofilm Formation 76 Control and Removal of Biofilms 77 Conclusion 77 References 78 8 Microbial Metabolism of Food Components 79 Introduction 79 Respiration and Fermentation During Growth 79 Metabolism of Food Carbohydrates 81 Degradation of Polysaccharides 81 Degradation of Disaccharides 82 Degradation of Monosaccharides 82 Fermentation 82 EMP Pathway 83 61

6 Contents xi HMP Pathway 83 Entner-Doudroff (ED) Pathway 83 Pentose Phosphoketolase Pathway 84 Hexose Phosphoketolase Pathway 84 Some Specific Pathways 84 Anaerobic Respiration 85 Aerobic Respiration 85 Synthesis of Polymers Metabolism of Food Proteins 86 Aerobic Respiration (Decay) 86 Fermentation (Putrefaction) 87 Metabolism of Food Lipids 88 Conclusion 88 References 89 9 Microbial Sporulation and Germination 91 Introduction 91 Mold Spores 91 Yeast Spores 92 Bacterial Spores Sporulation Dormancy 95 Activation 95 Germination 95 Outgrowth 95 Importance of Spores in Food 96 Conclusion 97 References Microbial Stress Response in the Food Environment 99 Introduction 99 Stress Adaptation Definition and Observations 100 Mechanisms of Stress Adaptation 101 Importance of Stress-Adapted Microorganisms Pathogens and Spoilage Bacteria Surviving in Low-pH Foods 102 Stress-Adapted Pathogens Surviving Stomach ph 102 Enhancing Viability of Starter Cultures and Probiotic Bacteria 103 Sublethal Stress and Injury in Food 101 Definition and Observations 103 Manifestation of Bacterial Sublethal Injury 103 Sites and Nature of Injury 105 Repair of Reversible Injury 106 Injury in Yeasts and Molds 108 Importance of Sublethally Injured Microorganisms in Food 108 Detection of Undesirable Microorganisms 108 Enhancing Shelf Life of Foods 108 Enhancing Viability of Starter Cultures 108

7 xii Contents Viable-but-Nonculturable 109 Definition and Terminologies 109 Proponent Views 109 Opponent Views Ill Current Views 111 of VBNC Cells 112 Physiological Properties Importance ofvbnc Microorganisms in Food 112 Conclusion 112 References 114 SECTION III BENEFICIAL USES OF MICROORGANISMS IN FOOD 11 Microorganisms Used in Food Fermentation 119 Introduction 119 Microbiology of Fermented Foods 119 Lactic Starter Cultures 120 Lactococcus 121 Streptococcus 122 Leuconostoc 122 Pediococcus 122 Lactobacillus 123 Oenococcus 124 Other Starter Cultures 124 Bifidobacterium 124 Propionibacterium 125 Brevibacterium 125 Acetobacter 125 Yeasts and Molds 125 Yeasts 126 Molds 126 Conclusion 127 References Biochemistry of Some Beneficial Traits 129 Introduction 129 Mechanisms of Transport of Nutrients 129 Transport and Metabolism of Carbohydrates 130 PEP-PTS System for Lactose Transport in Lactococcus lactis 131 Permease System for Lactose in Lactobacillus acidophilus 131 Carbohydrates Available Inside the Cells for Metabolism 131 Homolactic Fermentation of Carbohydrates 131 Heterolactic Fermentation of Carbohydrates 133 Metabolism of Pentoses 134 Hexose Fermentation by Bifidobacterium 135 Diacetyl Production from Citrate 135 Propionic Acid Production by Propionibacterium 136 Transport and Metabolism of Proteinaceous Compounds and Amino Acids 136

8 Contents xiii Transport and Metabolism of Lipid Compounds 137 Conclusion 137 References Genetics of Some Beneficial Traits 139 Introduction 139 Plasmids and Plasmid-Linked Traits in Starter-Culture Bacteria 139 Important Characteristics of Bacterial Plasmids 140 Some Characteristics of Small (ca. 10 kb) and Large (over 10 to ca. 150 kb) Plasmids 140 Presence of Plasmids in Some Starter-Culture Bacteria 141 Phenotype Assignment to a Plasmid 141 Plasmid-Linked Traits in Starter-Culture Bacteria 142 Cryptic Plasmids 143 Plasmid Replication 143 Plasmid Mapping and Sequencing 143 Gene Transfer Methods in Starter-Culture Bacteria 144 Transduction 144 Conjugation 144 Transformation 145 Protoplast Fusion 145 Electrotransformation 146 Conjugative Transposons 146 Gene Cloning 146 Cloning Vectors 147 Metabolic Engineering 148 Mixed Acid Fermentation by Lactococcus lactis 148 L(+)-Lactic Acid Production 148 Diacetyl Production by Lactococcus lactis 149 Alanine Production from Carbohydrates 149 Production of Mannitol and Other Polyols 149 Production of Folic Acid and Riboflavin 149 Enhancing Proteolysis by Cell Lysis 150 Protein Targeting 150 Expression of Interleukins 150 Drug-Delivery System 151 Production of Pediocin in Heterologous Hosts 151 Protein Engineering 151 Production of Hybrid Prepediocin 151 Bioengineered Bacteriocins 152 Genome Mapping and Sequencing 152 Lactic Acid Bacteria 152 Bacteriophages 154 The Lac and Las Genes 154 Conclusion 155 References 156

9 xiv Contents 14 Starter Cultures and Bacteriophages 159 Introduction 159 History 160 Concentrated Cultures 161 Starter-Culture Problems 162 Strain Antagonism Loss of a Desired Trait 162 Cell Death and Injury 162 Inhibitors in Raw Materials 163 Bacteriophages of Lactic Acid Bacteria 163 Morphology and Characteristics 163 Life Cycle 164 Host Specificity 164 Control Methods 165 Yeast and Mold Cultures 166 Conclusion References Microbiology of Fermented Food Production 169 Introduction 169 General Method of Production 170 Raw (or Starting) Materials 170 Microorganisms Used 170 Fermentation Process 171 Natural Fermentation 171 Back Slopping 171 Controlled Fermentation 172 Fermented Dairy Products 172 Milk Composition and Quality 172 Fermented Milk Products 173 Microbiology of Cultured Buttermilk Fermentation 173 Product Characteristics 173 Processing Starter (Controlled Fermentation) 174 Growth 174 Biochemistry 174 Genetics 174 Microbial Problems 175 Microbiology of Yogurt Fermentation 175 Characteristics 175 Processing Starters (Controlled Fermentation) 175 Growth 176 Biochemistry 176 Genetics 178 Microbial Problems 179 Cheeses

10 Contents xv Unripened Cheese 179 Ripened Cheese 179 Microbiology of Cottage Cheese 180 Characteristics 180 Processing (from Skim Milk) 180 Starters (Controlled Fermentation) 180 Growth, Biochemistry, and Genetics 180 Microbial Problems 180 Microbiology of Cheddar Cheese 181 Characteristics 181 Processing 181 Starters (Controlled Fermentation) 181 Growth 181 Biochemistry 181 Genetics 182 Microbial Problems 182 Microbiology of Swiss Cheese 183 Characteristics 183 Processing 183 Starters (Controlled Fermentation) 183 Growth 183 Biochemistry 183 Genetics 184 Microbial Problems 184 Microbiology of Blue Cheese 184 Characteristics 184 Processing 184 Starters and Growth (Controlled Fermentation) 184 Biochemistry, Genetics, and Problems 184 Accelerated Cheese Ripening 185 Curing at High Temperature 185 Addition of Enzymes 185 Slurry Method 185 Novel Methods 185 Fermented Meat Products 186 Types 186 Microbiology of Semidry Sausages 186 Characteristics 186 Processing 186 Starters (Controlled or Natural Fermentation) 187 Growth 187 Biochemistry 187 Genetics 187 Microbial Problems 188 Fermented Vegetable Products 188 Microbiology of Sauerkraut 189 Characteristics 189

11 xvi Contents Processing 189 Starters (Natural) and Growth 189 Biochemistry 189 Genetics 190 Microbial Problems 190 Conclusion 190 References Intestinal Bacteria and Probiotics 193 Introduction 193 Microbiology of the Human GI Tract 194 Gut Microbiota, Health, and Chronic Diseases 195 Important Characteristics of Beneficial Bacteria 196 Beneficial Effects of Probiotics 197 Lactose Hydrolysis 197 Reducing Serum Cholesterol Levels 198 Reducing Colon Cancer 198 Prevention and Control of Enteric Infections 199 Modulating Immune Response 199 Reducing Allergic Diseases 200 Bioengineered Probiotics 200 Probiotics as Vaccine Carriers for Infectious Agents 200 Some Aspects to Consider 201 Strain Variation 201 Sensitivity to Stomach Acids, Biles, and Pancreatin 202 Viability and Injury of Cells 202 Dose Level and Duration 202 Induced Lactase Trait 202 Antibacterial Substances 203 True Species and Strains 203 Expertise in Research Areas 203 Current Developments 204 Standard of Identity 204 Microorganisms Used as Probiotics 204 Safety of Probiotics 205 Probiotics, Prebiotics, and Synbiotics 206 Probiotics 206 Prebiotics 207 Synbiotics 207 Biogenics 207 Genome Sequence of Probiotic Bacteria 207 Conclusion 208 References Food Biopreservatives of Microbial Origin, Bacteriocin, and Nanotechnology 211 Introduction 211 Viable Cells of Lactic Acid Bacteria (LAB) as Preservatives 211

12 Contents xvii Organic Acids, Diacetyl, Hydrogen Peroxide, and Reuterine as Food Preservatives 212 Organic Acids 212 Diacetyl 213 Hydrogen Peroxide 214 Reuterine 214 Bacteriocins of Lactic Acid Bacteria as Food Preservatives 215 Bacteriocin-Producing Strains 215 Characteristics of Bacteriocins 216 Genetics and Gene Organization 220 Mode ofaction 221 Bioengineered Bacteriocin 222 Production and Purification 223 Applications 223 Encapsulation and Delivery of Bacteriocin 226 Food Packaging 226 Liposomes 227 Nanoencapsulation 227 Safety Concerns with Nanotechnology 228 Yeast Metabolites as Preservatives 228 Conclusion 228 References Food Ingredients and Enzymes of Microbial Origin 231 Introduction 231 Microbial Proteins and Food Additives 232 Single-Cell Proteins (SCPs) 232 Amino Acids 232 Nutraceuticals and Vitamins 232 Flavor Compounds and Flavor Enhancers 233 Colors 233 Exopolysaccharides (EPS) 234 Organic Acids 234 Preservatives 234 Microbial Enzymes in Food Processing 234 Enzymes Used 235 OC-Amylase, Glucoamylase, and Glucose Isomerase 236 Catalase 236 Cellulase, Hemicellulase, and Pectinase 236 Invertase 236 Lactase 236 Lipases 236 Proteases 236 Enzyme Production by Recombinant DNA Technology 237 Immobilized Enzymes 238 Adsorption on a Solid Support 238 Covalent Bonding 238

13 xviii Contents Entrapping 238 Crosslinking 238 Thermostable Enzymes 239 Enzymes in Food Waste Treatment 240 Conclusion 240 References 241 SECTION IV MICROBIAL FOOD SPOILAGE 19 Important Factors in Microbial Food Spoilage 245 Introduction 245 Sequence of Events 245 Significance of Microorganisms 246 Microbial Types 246 Microbial Numbers 246 Predominant Microorganisms 247 Food Spoilage Molds 248 Food Spoilage Yeasts 248 Some Important Food Spoilage Bacteria 248 Psychrotrophic Bacteria 248 Some Important Psychrotrophic Aerobic Spoilage Bacteria 249 Some Important Psychrotrophic Facultative Anaerobic Spoilage Bacteria 249 Some Important Thermoduric Psychrotrophs 249 Thermophilic Bacteria 249 Aciduric Bacteria 249 Significance of Foods 250 Food Types 250 Food Nutrients 250 Utilization of Food Nutrients 251 Microbial Growth in Succession 252 Conclusion 253 References Spoilage of Specific Food Groups 255 Introduction 255 Fresh and Ready-to-Eat Meat Products 255 Raw Meat 255 Ready-to-Eat Meat Products 257 Eggs and Egg Products 258 Shell Eggs 258 Egg Products 259 Fish, Crustaceans, and Mollusks 259 Fish 259 Crustaceans 260 Mollusks 260 Milk and Milk Products 261 Raw Milk 261 Pasteurized Milk 261

14 Contents xix Concentrated Liquid Products 262 Butter 262 Vegetables and Fruits 262 Vegetables 262 Fruits 263 Soft Drinks, Fruit Juices and Preserves, and Vegetable Juices 264 Cereals and Their Products 264 Grains and Seeds 265 Refrigerated Dough 265 Breads 265 Pastas 265 Pastries 265 Liquid Mayonnaise, Salad Dressings, Sweeteners and Confectioneries 266 and Condiments 266 Fermented Foods 266 Fermented Meat Products 267 Fermented Dairy Products 267 Fermented Vegetable and Fruit Products 268 Fermented Beverages 268 Canned Foods 268 Thermophilic Spore Formers 269 Flat Sour Spoilage 270 Thermophilic Anaerobe (TA) Spoilage 270 Sulfide Stinker Spoilage 270 Spoilage Resulting from Insufficient Heating 270 Spoilage Resulting from Container Leakage 270 Conclusion 270 References New Food Spoilage Bacteria in Refrigerated Foods 273 Microorganisms that Grow in Refrigerated Foods (Psychrotrophs) 273 Popularity of Refrigerated Foods 274 Microbiological Problems 275 Incidence of Spoilage of Vacuum-Packaged Refrigerated Food 276 Spoilage of Unprocessed (Fresh) Beef by Clostridium Species 276 Spoilage of Roasted Beef by Clostridium Species 278 Spoilage of Pork Chops by Clostridium algidicarnis 278 Spoilage of Tofu by Clostridium Species 278 Spoilage of Unripened Soft Cheese by Leuconostoc Species 279 Spoilage of Low-Heat-Processed Meat Products by Leuconostoc Species 279 Ammonia Odor in Turkey Roll 279 Yellow Discoloration of Luncheon Meat 280 Gray Discoloration of Turkey Luncheon Meat 280 Pink Discoloration of Sliced, Chopped, and Formed Roast Beef 280 Gas Distension and Pink Discoloration of Sliced Turkey Rolls 281 Gas Distension (Bloating) of Ground Beef Chubs 281 Egg Odor in Refrigerated Fresh Chicken Meat Products 282

15 xx Contents Conclusion Off-Odor in Frozen Chicken Meat Product 283 Gas and Slime Development in Vacuum-Packaged Smoked Salmon Products 284 References Food Spoilage by Microbial Enzymes 287 Introduction 287 Characteristics of Heat-Stable Enzymes of Psychrotrophic Bacteria 288 Spoilage of Foods with Heat-Stable Microbial Enzymes 289 Pasteurized Milk 289 Ultrahigh Temperature (UHT)-Treated Milk Products 290 Cheeses 290 Cultured Dairy Products 290 Cream and Butter 290 Milk Powder 291 Spoilage of Foods by Microbial Enzymes at Low Temperatures 291 Conclusion 292 References Indicators of Microbial Food Spoilage 295 Introduction 295 Microbiological Criteria 296 Enumeration of Colony-Forming Units (CFUs) 296 Phase-Contrast Microscopy 298 Chemical Criteria 298 Molecular Methods in Spoilage Microbe Detection 299 Assay of Heat-Stable Enzymes 299 Heat-Stable Proteinases in Milk 299 Heat-Stable Lipases in Milk 299 Conclusion 300 References SECTION V MICROBIAL FOODBORNE DISEASES 24 Important Facts in Foodborne Diseases 305 Introduction 305 Epidemiological Aspects 306 Investigation of a Foodborne Disease 306 Foodborne Disease Outbreak 307 Incidence of Foodborne Disease Outbreak 307 Cost of Foodborne Diseases 308 Predominant Etiological Agents 309 Types of Microbial Foodborne Diseases 310 Intoxication 312 Infection 312 Toxico-Infection 313 Predominant Food Types Associated with Foodborne Diseases of Bacterial and Viral Origin 313

16 Contents xxi Predominant Places of Food Consumption Associated with Confirmed Foodborne Disease Outbreaks of Bacterial and Viral Origin 313 Predominant Contributing Factors Associated with Confirmed Foodborne Disease Outbreaks from Pathogenic Bacteria and Viruses 316 Influence of Month (of the Year) to Number of Foodborne Disease Outbreaks Caused by Pathogenic Influence of Location on Foodborne Diseases of Pathogenic Bacterial and Bacteria and Viruses 316 Viral Origin 316 Human Factors in Foodborne Disease Symptoms 317 Acceptance Quality of Food Resulting from Growth of Pathogens 317 Sequence of Events in a Foodborne Disease 317 Current Trends 318 FoodNet 318 Estimated Foodborne Illnesses 320 Conclusion 320 References Foodborne Intoxications 323 Introduction 323 Staphylococcal Intoxication 323 Importance 323 Characteristics of Staphylococcus aureus 324 Organisms 324 Growth 324 Habitat 325 Toxins and Toxin Production 325 Disease and Symptoms 325 Food Association 326 Prevention (Reduction) of the Disease 327 Identification Methods 328 Analysis of an Outbreak 328 Botulism by Clostridium botulinum 329 Importance 329 Characteristics 329 Organisms 329 Growth 329 Habitat 329 Toxins and Toxin Production 330 Disease and Symptoms 331 Foodborne Botulism 331 Infant Botulism 331 Hidden Botulism 331 Wound Botulism 331 Inadvertent Botulism 332 Food Association 332 Prevention of Botulism 333 Identification Methods 333

17 xxii Contents Analysis of a Foodborne Botulism Case 334 Conclusion 334 References Foodborne Bacterial Infections 337 Introduction 337 Salmonella enterica 338 Importance 338 Current Nomenclature System 339 Predominant Serotypes in Salmonellosis 339 Characteristics 341 Habitat 341 Disease and Symptoms 341 Food Association 342 Prevention and Control 343 Detection Method 343 A Case Study 343 Listeria monocytogenes 344 Importance 344 Classification 345 Characteristics 345 Habitat 346 Virulence Factors 346 Disease and Symptoms 346 Febrile Gastroenteritis 346 Invasive Systemic Disease 347 Food Association 349 Prevention and Control 349 Detection Method 350 A Case Study 350 Pathogenic Escherichia coli 351 Importance 351 Enterotoxigenic Escherichia coli (ETEC) 352 Enteropathogenic Escherichia coli (EPEC) 352 Enteroinvasive Escherichia coli (EIEC) 352 Disease and Symptoms 353 Food Association 353 Prevention 353 Enteroaggregative Escherichia coli 353 Enterohemorrhagic Escherichia coli (EHEC), Shiga-Toxigenic Escherichia co/i (STEC) 353 Gastroenteritis Resulting from EHEC/STEC 354 Characteristics 354 Toxins 354 Disease and Symptoms 354 Food Association 355 Prevention 355

18 Contents xxiii Shigella Species 355 Importance 355 Characteristics 356 Habitat 356 Toxins 356 Disease and Symptoms 357 Food Association 357 Prevention 358 Campylobacter Species 358 Importance 358 Characteristics 358 Habitat 359 Pathogenic Factors and Toxins 359 Disease and Symptoms 359 Food Association 360 Prevention 360 Yersinia enterocolitica 360 Importance 360 Characteristics 361 Habitat 361 Virulence Factors 361 Disease and Symptoms 362 Food Association 362 Prevention 362 Vibrio Species 362 Vibrio parahaemolyticus 363 Importance 363 Characteristics 363 Habitat 363 Virulence Factors and Toxin Production 363 Disease and Symptoms 364 Food Association 364 Prevention 364 Vibrio vulnificus 365 Brucellosis 365 Streptococcal Infection 365 Q Fever 366 Conclusion 366 References Foodborne Toxico-Infections 371 Introduction 371 Clostridium perfringens 371 Importance 371 Characteristics 372 Habitat 372 Toxins and Toxin Production 372

19 xxiv Contents Disease and Symptoms 373 Food Association 373 Prevention 374 Detection Method 374 Analysis of Outbreak an 375 Bacillus cereus 375 Importance 375 Characteristics 375 Habitat 376 Toxins and Toxin Production 376 Disease and Symptoms 376 Food Association 377 Prevention 378 Detection Method 378 Vibrio cholerae 378 Importance 378 Characteristics 379 Habitat 379 Toxins and Toxin Production 379 Disease and Symptoms 380 Food Association 380 Prevention 381 Detection Method 381 Analysis of an Outbreak 381 Enterotoxigenic Escherichia coli (ETEC) 382 Importance 382 Characteristics 382 Habitat 382 Toxins and Toxin Production 382 Disease and Symptoms 383 Food Association 383 Prevention 383 Detection Methods 383 Conclusion 383 References Opportunistic Bacterial Pathogens, Molds and Mycotoxins, Viruses, Parasites, and Fish and Shellfish Toxins 387 Introduction 387 Opportunistic Bacterial Pathogens 387 Aeromonas hydrophila 387 Characteristics 387 Food Association 388 Disease-Causing Potential 388 Plesiomonasshigelloid.es 388 Characteristics 388 Food Association 388

20 Contents xxv Disease-Causing Potential 389 Non-Escherichia coli coliforms 389 Toxigenic Physchrotrophic Bacillus Species 390 Diseases Caused by Viruses and Prion 390 Importance 390 Food Association 390 Prevention 391 Detection Methods 391 Norovirus 391 Hepatitis A Virus 392 Bovine Spongiform Encephalopathy (BSE) 392 Molds and Mycotoxins 393 Importance 393 Characteristics 394 Organisms 394 Growth and Mycotoxin Production 395 Habitat 395 Toxins and Toxin Production 395 Food Association 396 Symptoms and Prevention of Mycotoxicosis 396 Detection Methods 397 Biogenic Amines 397 Toxins Associated with Fish and Shellfish 397 Scombroid Poisoning 397 Ciguatera Fish Poisoning (CFP) 400 Paralytic Shellfish Poisoning (PSP) 400 Neurotoxic Shellfish Poisoning (NSP) 400 Diarrhetic Shellfish Poisoning (DSP) 401 Azaspiracid Shellfish Poisoning (AZP) 401 Amnesic Shellfish Poisoning (ASP) 401 Puffer Fish Poisoning (PFP) 401 Parasites 401 Trichinella spiralis 402 Anisakis simplex 402 Taenia Species 402 Toxoplasma gondii 402 Giardia lamblia 403 Cryptosporidium parvum 404 Cyclospora cayetanensis 404 Conclusion 404 References New and Emerging Foodborne Pathogens 407 Introduction 407 Associated Factors 408 Better Knowledge of Pathogens 409 Improvement in Regulatory Actions 410

21 xxvi Contents Changes in Lifestyle and Food Habits 411 New Food-Processing Technology 414 Miscellaneous Factors 414 Genetic Exchange Antibiotic Resistance 415 Stress Adaptation Farming Practices 416 Aging and Immunocompromised Population 416 Other Emerging Foodborne Pathogens ofconcern 416 Cronobacter sakazaki 417 Clostridium difficile 417 Escherichia coli O104:H4 418 Hepatitis E Virus 418 Nipah Virus 419 Conclusion 420 References Indicators of Bacterial Pathogens 423 Introduction 423 Criteria for Ideal Indicators 424 Coliform Group 425 Colifbrms 425 Organisms and Sources 425 Occurrence and in Significance Food 425 Fecal Coliforms 426 Organisms and Sources 426 Occurrence and Significance in Food 426 Escherichia coli 426 Organisms and Sources 426 Occurrence and Significance in Food 427 Enterobacteriaceae Group 427 Enterococcus Group 429 Characteristics and Habitat 429 Occurrence and Significance in Food 429 Miscellaneous Indicator Organisms 429 Conclusion 430 References 431 SECTION VI CONTROL OF MICROORGANISMS IN FOODS 31 Control ofaccess of Microorganisms: Cleaning, Sanitation, and Disinfection 435 Introduction 435 Objectives of Sanitation 436 Factors to Consider 436 Plant Design 436 Quality of Water, Ice, Brine, and Curing Solution 436 Quality of Air 437

22 Contents xxvii Training of Personnel 437 Equipment 437 Cleaning of Processing Facilities 437 Sanitation of Food-Processing Equipment 438 Chlorine-Based Sanitizers 439 Iodophores 439 Quaternary Ammonium Compounds 439 H Decontamination and Sanitization of Fruits and Vegetables 440 Chlorine 441 Ozone 441 Microbiological Standards, Specifications, and Guidelines 442 Conclusion 442 References Control by Physical Removal 445 Introduction 445 Physical Methods 445 Centrifugation 445 Filtration 445 Trimming 446 Washing 446 Conclusion 447 References Control by Heat (Thermal Processing) 449 Introduction 449 Objectives 450 Mechanism of Thermal Inactivation 450 Influencing Factors 451 Nature of Food 451 Nature of Microorganisms 451 Nature of Process 452 Mathematical Expressions 452 Decimal Reduction Time (D Value) 452 Thermal Death Time (TDT), Z Value, and FValue 453 Methods 454 Low-Heat Processing or Pasteurization 454 High-Heat-Processed Foods 455 Microwave Heating 456 Conclusion 457 References Control by Low Temperature 459 Introduction 459 Objectives Mechanisms of Cold-Induced Inactivation 460 Influencing Factors

23 xxviii Contents Nature of Process 461 Nature of Food 462 Nature of Microorganisms 463 Methods 463 Ice Chilling 463 Refrigeration 463 Freezing 464 Conclusion 464 References Control by Reduced Water Activity and Drying 467 Introduction 467 Objectives 467 Mechanism of Action 468 Influencing Factors 468 Nature of Process 468 Nature of Foods 469 Nature of Microorganisms 469 Methods 471 Natural Dehydration 471 Mechanical Drying 471 Freeze Drying 472 Foam Drying 473 Smoking 473 Intermediate Moisture Foods 473 Conclusion 473 References Control by Low ph and Organic Acids 475 Introduction 475 Objectives 476 Mechanisms ofantimicrobial Action 476 Influencing Factors 477 Nature of Acids 477 Nature of Foods 478 Nature of Microorganisms 478 Acids Used 478 Acetic Acid 478 Propionic Acid 478 Lactic Acid 480 Citric Acid 480 Sorbic Acid 480 Benzoic Acid 480 Parabens (Esters of p-hydroxybenzoic Acid) 481 Conclusion 481 References 482

24 Contents xxix 37 Control by Modified Atmosphere (or Reducing O-R Potential) 483 Introduction 483 Objectives 485 Mechanism ofaction 485 Influencing Factors 485 Nature of Process 485 Nature of Foods 486 Nature ofmicroorganisms 486 Methods 486 Vacuum Packaging 486 Gas Flushing 487 Conclusion 487 References Control by Antimicrobial Preservatives and Bacteriophages 489 Introduction 489 Objectives 490 Influencing Factors 490 Examples of Antimicrobial Preservatives 491 Food-Grade Chemicals 492 Nitrates and Nitrites 492 Sulfur Dioxide (S02) and Sulfites (S03) 493 H Epoxides (Ethylene Oxide, Propylene Oxide) 494 Organic Acids 494 Parabens 494 Diacetyl 494 C Butylated Hydroxyanisol (BHA), Butylated Hydroxytoluene (BHT), and t-butyl Hydroquinone (TBHQ) 494 Monolaurin (Glycerol Monolaurate) 494 Ethylene-Diamine-Tetraacetate (EDTA) 495 Antimicrobials of Microbial Origin 495 Bacteriocins of Lactic Acid Bacteria 495 Natamycin 495 Tylosin 495 Polylysine 496 Antimicrobials ofanimal Origin 496 Chitosan 496 Lysozyme 496 Lactoferrin 496 Lactoperoxidase 497 Ovotransferrin 497 Protamine 497 Pleurocidin 497 Defensins 497 Antimicrobials of Plant Origin 497

25 xxx Contents Herbs and Spices 497 Wood Smoke 499 Bacteriophages 499 Bacteriophages to Control Pathogens in Food 500 Conclusion 502 References Control by Irradiation 505 Introduction 505 Irradiation (Radiation) and Radioactivity 505 Use of Irradiation in Food 506 Objectives 506 Mechanisms ofantimicrobial Action 507 Influencing Factors 507 Nature of Process 507 Nature of Foods 508 Nature of Microorganisms 508 Methods 508 Doses 508 Specific Terms 509 Radurization 509 Radicidation 509 Radappertization 509 Current Recommendations 509 UV Radiation 511 Conclusion 511 References Control by Novel Processing Technologies 513 Introduction 513 Summary of Processing Methods 514 Microwave and Radio-Frequency Processing 514 Ohmic and Inductive Heating 514 Infrared Heating 514 Pulsed Electric Fields 514 High-Pressure Processing 515 Pulsed Light Technology 515 Oscillating Magnetic Fields 515 Ultrasound 515 High-Voltage Arc Discharge 516 Pulsed X-Rays 516 Plasma Technology 516 Pulsed Electric Field 516 Hydrostatic Pressure Processing 518 History 518 Methods, Mechanisms of Microbial Inactivation, and Advantages 518 Destruction of Microbial Cells 520

26 Contents xxxi Bacterial Cells 520 Bacterial Endospores 520 Molds, Yeasts, Viruses, and Parasites 521 Application in Food Processing 521 Conclusion 524 References Control by a Combination ofmethods (Hurdle Concept) 527 Introduction 527 Mechanisms ofantimicrobial Action 527 Current Status 529 Low-Heat Processing 529 Low Storage Temperature 529 LowpH 529 LowiV 529 Modified Atmosphere 530 Preservatives 530 Hydrostatic Pressure Processing (HPP) 530 Conclusion 530 References 531 SECTION VII MICROBIAL DETECTION AND FOOD SAFETY 42 Conventional, Immunological, Molecular, and Biosensor-Based Detection Methods 535 Introduction 535 Methods Used 536 Standard and Recommended Methods 536 Sampling for Microbial Analysis 537 Sample and Sampling Plan 537 Sampling Procedure 538 Quantitative Methods for Microbial Enumeration in Foods 538 Direct Enumeration 538 Microscopic Counts 538 Colony-Forming Units (CFU) in Nonselective Agar Media 538 CFU in Nonselective Differential Chromogenic Media 539 CFU in Selective Agar Media 539 CFU in Selective-Differential Chromogenic Agar Media 539 Indirect Estimation 541 Dilution to Extinction in Nonselective Broths 541 Most Probable Number (MPN) in Selective Broth 541 Dye Reduction Test 541 Enumeration of Injured Microbial Groups by Selective Media 541 Dilution Scheme, Plating, Incubation, Selection of Plates for Counting CFU, and Reporting Results 542 Qualitative Methods to Isolate Microorganisms in Foods 542 Isolation of Pathogens 542

27 xxxii Contents Test for Bacterial Toxins in Foods 542 Rapid Methods and Automation 543 Metabolic Fingerprinting 543 Immunoassays for Rapid Detection of Pathogens 544 Immunomagnetic Separation (IMS) 544 Reverse Passive Latex Agglutination (RPLA) Method 545 Enzyme-Linked Immunosorbent Assay (ELISA) 546 Immunofluorescence Assay 547 Immunochromatographic Lateral Flow Assay 547 Flow Cytometry 548 Bacteriophage for Detection of Pathogens 548 Culture or Staining Methods 548 Reporter Phages 548 Phages for Capture and Detection Using Biosensors 549 Bioluminescence Methods 549 Nucleic Acid-Based Methods 549 Hybridization Method 549 Polymerase Chain Reaction (PCR) 550 DNA Fingerprinting 551 Whole Genome Sequencing 552 Microarrays and Mass-Spectrometry 552 Pathogenicity Assay 553 Biosensors for Pathogen Detection 553 Fiber-Optic Biosensors 554 Surface Plasmon Resonance Sensor 555 Electrochemical Immunosensor 556 Piezoelectric (PZ) Biosensor 556 Impedance-Based Biochip Sensor 556 Fourier Transform Infrared Spectroscopy (FTIR) and Raman Spectroscopy 557 Light Scattering 558 Cell-Based Sensors 558 Conclusion 559 References 560 Appendix A: Predictive Modeling of Microbial Growth in Food 563 Importance 563 Traditional Methods 564 Challenge Storage Studies 564 Studies 564 Accelerated Shelf Life Studies 564 Predictive Microbiology 564 Square Root Model 565 Sigmoidal Model (Gompertz: USDA Model) 565 Conclusion 565 References 566

28 Contents xxxiii Appendix B: Regulatory Agencies Monitoring Microbiological Safety offoods in the United States 567 Food Safety Regulations 567 The Agencies 568 Federal Agencies 568 State and Local Government Agencies 569 International Agencies 570 References 570 Appendix C: Hazard Analysis Critical Control Points 571 Introduction 571 HACCP Principle of the NACMCF 572 Seven Principles of HACCP 572 Brief Description of the Principles 572 Principle Principle Principle Principle Principle Principle Principle Conclusion 574 References 575 Index 577