Attempts to provide safer and higher quality fresh and minimally processed produce have given rise to a wide variety of decontamination methods, each of which have been extensively researched in recent years.

Preface xvii List of Contributors xix SECTION I PRODUCE CONTAMINATION 1 1 Microbial ecology 3 Marilyn C. Erickson 1.1 Introduction 3 1.2 Sources of preharvest contamination 4 1.3 Fate of pathogen contamination in plant production systems 12 1.3.1 Experimental studies – field studies versus growth chamber studies 12 1.3.2 Rhizosphere and bulk soil systems 16 1.3.3 Phyllosphere 22 1.4 Molecular and biochemical responses of enteric pathogens and plant hosts 27 1.4.1 Mechanisms employed by enteric pathogens to survive as plant endophytes or epiphytes 27 1.4.2 Mechanisms employed by plant hosts to resist invasion by enteric pathogens 27 1.5 Cross-contamination of enteric pathogens to produce during harvest 28 1.6 Concluding comments 29 References 29 2 Surface characteristics of fresh produce and their impact on attachment and removal of human pathogens on produce surfaces 43 Hua Wang, Bin Zhou, and Hao Feng 2.1 Introduction 43 2.2 Produce surface characteristics 44 2.2.1 Surface topography 44 2.2.2 Surface hydrophobicity 46 2.3 Means to determine produce surface characteristics 47 2.3.1 Determination of surface roughness 47 2.3.2 Surface roughness determination with CLSM 48 2.3.3 Determination of hydrophobicity 51 2.4 Effect of surface characteristics on attachment and removal of human pathogens 51 2.4.1 Effect of surface roughness 51 2.4.2 Effect of hydrophobicity 54 2.4.3 Effect of hydrodynamics 55 References 55 3 Biofilms 59 Shin-Hee Kim and Cheng-i Wei 3.1 Introduction 59 3.2 Biofilm formation 60 3.3 Presence of biofilms on the produce surface 66 3.4 Antimicrobial resistance of biofilms versus planktonic cells 68 3.5 Perspective 71 References 71 4 Resistance and sublethal damage 77 Pascal Delaquis and Susan Bach 4.1 Introduction 77 4.2 Basic concepts 78 4.2.1 Definitions 78 4.2.2 Chemical interventions used in the produce industry 78 4.2.3 Physical interventions used in the produce industry 79 4.2.4 Mode of action of biocides, food antimicrobials, and physical treatments 79 4.3 Stress and resistance to biocides and antimicrobial physical treatments 81 4.4 Implications of stress, resistance, and sublethal damage in fresh produce decontamination 83 References 84 SECTION II DECONTAMINANTS 87 5 Produce washers 89 Steven Pao, Wilbert Long III, Chyer Kim, and D. Frank Kelsey 5.1 Basic concepts 89 5.2 Types of washers 91 5.2.1 Immersion washers 92 5.2.2 Non-immersion washers 95 5.3 Factors influencing the efficacy of washing 97 5.3.1 Time of contamination 98 5.3.2 Sanitation practices 98 5.3.3 Water quality 99 5.3.4 Surfactants and antimicrobials 99 5.3.5 Pathogen internalization 100 5.4 Conclusion 100 Acknowledgment 101 References 101 6 Minimal processing 105 Maria I. Gil and Ana Allende 6.1 Introduction 105 6.2 Effect of minimal processing on pathogenic bacteria 106 6.3 Effect of minimal processing on spoilage bacteria 108 6.4 Effect of minimal processing on vegetable physiology 110 6.5 Effect of minimal processing on quality and shelf life 113 6.6 Effect of minimal processing on nutritional and phytochemical composition 114 6.7 Conclusion 115 References 116 7 Chlorine 121 Cristóbal Chaidez, Nohelia Castro-del Campo, J. Basilio Heredia, Laura Contreras-Angulo, Gustavo González–Aguilar, and J. Fernando Ayala–Zavala 7.1 Definition 121 7.2 Inactivation mechanism 122 7.3 Effect of chlorine on pathogenic microorganisms 123 7.4 Effect of chlorine on spoilage microorganisms and shelf life 125 7.5 Effect of chlorine on vegetable physiology 125 7.6 Effect of chlorine on sensory quality 127 7.7 Effect of chlorine on nutritional and phytochemical composition 127 7.8 Chlorine residues and formation of toxic by-products 128 7.9 Regulatory status 129 References 131 8 Electrolyzed oxidizing water 135 Muhammad Imran Al-Haq and Vicente M. Gómez-López 8.1 Definition 135 8.2 Generation devices 138 8.3 Inactivation mechanism and factors affecting EO efficacy 142 8.4 Effect of EO water on pathogenic microorganisms 153 8.5 Effect of EO water on spoilage microorganisms and shelf life 153 8.6 Effects of EO water on vegetable physiology 154 8.7 Effect of EO water on sensory quality 155 8.8 Effect of EO water on nutritional and phytochemical composition 156 8.9 Residues and formation of toxic by-products 156 8.10 Regulatory status 157 References 157 9 Chlorine dioxide 165 Vicente M. Gómez-López 9.1 Definition and generalities 165 9.2 Inactivation mechanism 166 9.3 Effect of chlorine dioxide on pathogenic microorganisms 167 9.4 Spoilage and shelf life 169 9.5 Sensory quality 170 9.6 Effect of chlorine dioxide on vegetable physiology 171 9.7 Effect of chlorine dioxide on nutritional and phytochemical composition 171 9.8 Residues and toxic by-products 171 9.9 Legal framework 172 References 172 10 Ozone 177 Hülya Ölmez 10.1 Definition 177 10.2 Generation devices 178 10.3 Inactivation mechanism 179 10.4 Effect of ozone on pathogenic microorganisms 181 10.5 Effect of ozone on spoilage microorganisms and shelf life 185 10.6 Effect of ozone on vegetable physiology 185 10.7 Effect of ozone on sensory quality 187 10.8 Effect of ozone on nutritional and phytochemical composition 188 10.9 Ozone residues and formation of toxic by-products 188 10.10 Regulatory status 191 References 191 11 Hydrogen peroxide 197 Dike O. Ukuku, Latiful Bari, and Shinichi Kawamoto 11.1 Introduction 197 11.2 Definition of hydrogen peroxide 198 11.3 Inactivation mechanism 198 11.4 Effect of hydrogen peroxide on pathogenic microorganisms 201 11.5 Effect of hydrogen peroxide on spoilage microorganisms and shelf life 203 11.6 Effect of hydrogen peroxide on vegetable physiology 206 11.7 Effect of hydrogen peroxide on sensory quality 207 11.8 Effect of hydrogen peroxide on nutritional and phytochemical composition 209 11.9 Effect of hydrogen peroxide on residues and formation of toxic by-products 211 References 212 12 Peroxyacetic acid 215 Gustavo González-Aguilar, J. Fernando Ayala-Zavala, Cristóbal Chaidez-Quiroz, J. Basilio Heredia, and Nohelia Castro-del Campo 12.1 Definition 215 12.2 Inactivation mechanism 216 12.3 Effect of PAA on pathogenic microorganisms 217 12.4 Effect of PAA on spoilage microorganisms and shelf life 218 12.5 Effect of PAA on vegetable physiology 219 12.6 Effect of PAA on sensory quality 219 12.7 Effect of PAA on nutritional and phytochemical composition 220 12.8 PAA residues and formation of toxic by-products 220 12.9 Regulatory status 221 References 221 13 Essential oils for the treatment of fruit and vegetables 225 Catherine Barry-Ryan and Paula Bourke 13.1 Introduction to essential oils 225 13.1.1 Decontamination in the fruit and vegetable industry 225 13.1.2 Definition of essential oils 226 13.2 Inactivation mechanism of essential oils 226 13.2.1 The mechanisms of action of essential oils 226 13.2.2 Effect of essential oil profile on mechanism of action 228 13.2.3 Other factors that affect the mechanism of action of essential oils 229 13.3 Effect of essential oils on microorganisms 230 13.3.1 Effect of essential oils on pathogenic microorganisms 230 13.3.2 Effect of essential oils on spoilage microorganisms 231 13.3.3 Effect of essential oils on Gram-positive versus Gram-negative microorganisms 232 13.3.4 Effect of specific essential oils on microorganisms 233 13.4 Effect of essential oils on fruit and vegetable physiology 235 13.5 Effect of essential oils on sensory quality 235 13.6 Effect of essential oils on nutritional and phytochemical composition 237 13.7 Toxicity of essential oils 238 13.8 Regulatory status of essential oils 239 References 239 14 Edible fi lms and coatings 247 María Alejandra Rojas-Graü, Laura Salvia-Trujillo, Robert Soliva-Fortuny, and Olga Martín-Belloso 14.1 Definition 247 14.2 Composition and application of edible films and coatings 248 14.3 Edible films and coatings as antimicrobials 251 14.3.1 Edible films and coatings with antimicrobial properties 251 14.3.2 Antimicrobial agents incorporated into edible films and coatings 252 14.3.3 Methods to evaluate effectiveness of antimicrobial films and coatings 258 14.3.4 Effect of edible coatings on pathogenic microorganisms 259 14.3.5 Effect of edible coatings on microbial spoilage and shelf life 260 14.4 Effect of edible coatings on vegetable physiology 263 14.5 Effect of edible coatings on sensory quality 265 14.6 Effect of edible coatings on nutritional aspects 266 14.7 Toxicity 266 14.8 Regulatory status 267 References 267 15 Miscellaneous decontaminants 277 Vicente M. Gómez-López 15.1 Introduction 277 15.2 Acidified sodium chlorite 278 15.3 Lactic acid 279 15.4 Calcinated calcium 280 15.5 Levulinic acid 280 15.6 Benzalkonium chloride 280 References 281 SECTION III BIOLOGICAL DECONTAMINATION STRATEGIES 283 16 Bacteriophages 285 Manan Sharma and Govind C. Sharma 16.1 Introduction 285 16.2 Inactivation mechanism 286 16.3 Effect of bacteriophages on pathogenic microorganisms 288 16.3.1 Lytic bacteriophages and leafy greens 289 16.3.2 Lytic bacteriophages and tomatoes 290 16.3.3 Lytic bacteriophages and sprouts 290 16.3.4 Lytic bacteriophages and melons 291 16.3.5 Lytic bacteriophages and apples 291 16.3.6 Lytic bacteriophages and hard surfaces 292 16.4 Risks to human health 293 16.5 Regulatory status 293 16.6 Conclusions 294 References 294 17 Protective cultures 297 Antonio Gálvez, Rubén Pérez Pulido, Hikmate Abriouel, Nabil Ben Omar, and María José Grande Burgos 17.1 Basic concepts 297 17.2 Effect of protective cultures on pathogenic microorganisms 298 17.3 Effect of protective cultures on spoilage microorganisms and shelf life 305 17.4 Effect of protective cultures on sensory quality and nutritional and phytochemical composition 309 17.5 Risks to health 310 17.6 Regulatory status 311 References 312 18 Bacteriocins 317 Antonio Gálvez, Rosario Lucas, Hikmate Abriouel, María José Grande Burgos, and Rubén Pérez Pulido 18.1 Definition 317 18.2 Inactivation mechanism 318 18.3 Effect of bacteriocins on pathogenic microorganisms 319 18.4 Effect of bacteriocins on spoilage microorganisms and shelf life 323 18.5 Effect of bacteriocins on sensory quality and nutritional and phytochemical composition 324 18.6 Toxicity 325 18.7 Regulatory status 327 References 328 19 Quorum sensing 333 María S. Medina-Martínez and María Angélica Santana 19.1 Introduction 333 19.2 Quorum sensing: basic concepts 334 19.3 Quorum sensing and vegetable spoilage 336 19.4 Quorum sensing and biofilm formation 337 19.5 Quorum sensing interference and food industry 338 References 341 SECTION IV PHYSICAL METHODS 345 20 The use of mild heat treatment for fruit and vegetable processing 347 Catherine Barry-Ryan 20.1 Introduction to the use of mild heat treatment for fruit and vegetable processing 347 20.2 Definition of heat treatment 348 20.3 Mechanism of action of heat treatment 349 20.4 Effect of mild heat treatment on microorganisms 349 20.5 Effect of mild heat treatment on fruit and vegetable physiology 350 20.5.1 The responses of plant tissue to heat treatment 350 20.5.2 Effect of mild heat treatment on respiration and ethylene production 351 20.5.3 Effect of mild heat treatment on quality 352 20.5.4 Effect of mild heat treatment on weight loss 353 20.6 Effect of mild heat treatment on fruit and vegetable sensory quality 353 20.6.1 Effect of mild heat treatment on texture 353 20.6.2 Effect of mild heat treatment on color 354 20.6.3 Effect of mild heat treatment on other sensory characteristics 356 20.7 Effect of mild heat treatment on nutritional and phytochemical composition of fruit and vegetables 357 20.8 Safety and implications of heat treatment 357 References 358 21 Continuous UV-C light 365 Vicente M. Gómez-López 21.1 Definition 365 21.2 Inactivation mechanism 366 21.3 Effect of continuous UV light on pathogenic microorganisms 367 21.4 Effect of continuous UV light on spoilage microorganisms and shelf life 368 21.5 Effect of continuous UV light on vegetable physiology 369 21.6 Effect of continuous UV light on sensory quality 370 21.7 Effect of continuous UV-C light on nutritional and phytochemical composition 372 21.8 Toxicity 374 21.9 Regulatory status 375 References 375 22 Ionizing radiation 379 Xuetong Fan 22.1 Definition 379 22.2 Inactivation mechanism 380 22.3 Effect of ionizing radiation on pathogenic microorganisms 381 22.4 Effect of ionizing radiation on spoilage microorganisms and shelf life 385 22.5 Effect of ionizing radiation on physiology 386 22.5.1 Ethylene production and respiration 386 22.5.2 Enzymes involved in tissue browning 388 22.5.3 Enzymes involved in tissue softening 389 22.5.4 Other enzymes 389 22.6 Effects of ionizing radiation on sensory quality 390 22.6.1 Reduction of losses in quality 392 22.7 Effect of ionizing radiation on nutritional and phytochemical composition 392 22.7.1 Vitamin C 395 22.8 Toxicity 396 22.9 Regulatory status 397 Disclaimer 398 References 398 23 Miscellaneous physical methods 407 Vicente M. Gómez-López 23.1 Introduction 407 23.2 Pulsed light 407 23.3 Photosensitization 409 23.4 Low-temperature plasma 409 23.5 Steamer jet injection 411 23.6 Radio-frequency heating 412 23.7 Vacuum–steam–vacuum 412 23.8 Power ultrasound 413 References 414 24 Hurdle technology principles applied in decontamination of whole and fresh-cut produce 417 María S. Tapia and Jorge Welti-Chanes 24.1 Introduction 417 24.2 Mild technologies: whole and fresh-cut hurdles: Summing up steps for decontamination 419 24.3 “All that washing”: Washing and sanitizing treatments for the produce industry 420 24.4 To kill or not to kill: Safety without having a true kill step 434 24.5 Combination of whole and fresh-cut hurdles 439 24.6 Final remarks 442 Acknowledgments 443 References 443 SECTION V STORAGE STRATEGIES 451 25 Modified atmosphere packaging 453 Matteo Alessandro Del Nobile, Amalia Conte, Marianna Mastromatteo, and Marcella Mastromatteo 25.1 Basic concepts 453 25.2 Relevant case studies of passive and active MAP 457 25.2.1 Vegetables 457 25.2.2 Fruit 459 25.3 Mathematical models to optimize headspace conditions for packaging minimally processed food 460 25.3.1 Steady-state conditions 461 25.3.2 Transient conditions 462 References 463 26 Cold chain 469 Pramod V. Mahajan and Jesus Frías 26.1 Introduction 469 26.2 Cold chain 470 26.3 Sustainability of the cold chain 470 26.4 Cold chain and safety 471 26.5 Cold chain framework 472 26.6 Cold chain and quality 473 26.7 The cold chain and fresh produce distribution 474 26.7.1 Precooling 475 26.7.2 Convective-air and evaporative cooling 475 26.7.3 Contact or package icing 476 26.7.4 Hydrocooling 476 26.7.5 Forced-air cooling 476 26.7.6 Vacuum cooling 476 26.7.7 Cryogenic cooling 477 26.7.8 Freeze chilling 477 26.8 Transportation 477 26.9 Retail display 477 26.10 Compliance in the cold chain 478 26.11 Monitoring the cold chain 479 26.11.1 The use of sensors in cold chain assessment 479 26.12 Cold chain assessment 481 Acknowledgment 482 References 482 SECTION VI MODELING TOOLS 485 27 Modeling microbial responses during decontamination processes 487 Eva Van Derlinden, Astrid M. Cappuyns, Laurence Mertens, Jan F. Van Impe, and Vasilis P. Valdramidis 27.1 Introduction 487 27.2 Experiment design 488 27.2.1 Design of experiments (DOE) 489 27.2.2 Optimal experiment design for parameter estimation (OED/PE) 491 27.2.3 Implementations of OED/PE for microbial inactivation modeling 493 27.3 Model structure (selection) 494 27.3.1 Kinetic modeling 495 27.3.2 Probabilistic modeling 507 27.3.3 Dose–response modeling 509 27.3.4 Parameter estimation 513 27.4 Model validation 514 27.4.1 Model validation data 515 27.4.2 Graphical model structure and performance evaluation 515 27.4.3 Quantitative model structure and performance evaluation 516 27.5 Conclusions 519 References 519 28 Modeling microbial growth 529 Milena Sinigaglia, Maria Rosaria Corbo, and Antonio Bevilacqua 28.1 Introduction 529 28.2 Logistic model 532 28.3 Gompertz equation 532 28.4 Baranyi equation 533 28.5 Shelf life evaluation: the classical approach 535 28.6 The stability time 536 28.7 The risk time 537 28.8 Mathematical modeling: some key limitations 537 References 538 Index 541

Attempts to provide safer and higher quality fresh and minimally processed produce have given rise to a wide variety of decontamination methods, each of which have been extensively researched in recent years. Decontamination of Fresh and Minimally Processed Produce is the first book to provide a systematic view of the different types of decontaminants for fresh and minimally processed produce. By describing the different effects – microbiological, sensory, nutritional and toxicological – of decontamination treatments, a team of internationally respected authors reveals not only the impact of decontaminants on food safety, but also on microbial spoilage, vegetable physiology, sensory quality, nutritional and phytochemical content and shelf-life. Regulatory and toxicological issues are also addressed. The book first examines how produce becomes contaminated, the surface characteristics of produce related to bacterial attachment, biofilm formation and resistance, and sublethal damage and its implications for decontamination. After reviewing how produce is washed and minimally processed, the various decontamination methods are then explored in depth, in terms of definition, generation devices, microbial inactivation mechanisms, and effects on food safety. Decontaminants covered include: chlorine, electrolyzed oxidizing water, chlorine dioxide, ozone, hydrogen peroxide, peroxyacetic acid, essential oils and edible films and coatings. Other decontamination methods addressed are biological strategies (bacteriophages, protective cultures, bacteriocins and quorum sensing) and physical methods (mild heat, continuous UV light, ionizing radiation) and various combinations of these methods through hurdle technology. The book concludes with descriptions of post-decontamination methods related to storage, such as modified atmosphere packaging, the cold chain, and modeling tools for predicting microbial growth and inactivation. The many methods and effects of decontamination are detailed, enabling industry professionals to understand the available state-of-the-art methods and select the most suitable approach for their purposes. The book serves as a compendium of information for food researchers and students of pre- and postharvest technology, food microbiology and food technology in general. The structure of the book allows easy comparisons among methods, and searching information by microorganism, produce, and quality traits.