Decontamination of Fresh and Minimally Processed Produce

Attempts to provide safer and higher quality fresh and minimallyprocessed produce have given rise to a wide variety ofdecontamination methods, each of which have been extensivelyresearched in recent years. Decontamination of Fresh andMinimally Processed Produce is the first book to providea systematic view of the different types of decontaminants forfresh and minimally processed produce. By describing the differenteffects microbiological, sensory, nutritional andtoxicological of decontamination treatments, a team ofinternationally respected authors reveals not only the impact ofdecontaminants on food safety, but also on microbial spoilage,vegetable physiology, sensory quality, nutritional andphytochemical content and shelf–life. Regulatory and toxicologicalissues are also addressed.

The book first examines how produce becomes contaminated, thesurface characteristics of produce related to bacterial attachment,biofilm formation and resistance, and sublethal damage and itsimplications for decontamination. After reviewing how produce iswashed and minimally processed, the various decontamination methodsare then explored in depth, in terms of definition, generationdevices, microbial inactivation mechanisms, and effects on foodsafety. Decontaminants covered include: chlorine, electrolyzedoxidizing 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 quorumsensing) and physical methods (mild heat, continuous UV light,ionizing radiation) and various combinations of these methodsthrough hurdle technology. The book concludes with descriptions ofpost–decontamination methods related to storage, such as modifiedatmosphere packaging, the cold chain, and modeling tools forpredicting microbial growth and inactivation.

The many methods and effects of decontamination are detailed,enabling industry professionals to understand the availablestate–of–the–art methods and select the most suitable approach fortheir purposes. The book serves as a compendium of information forfood researchers and students of pre– and postharvest technology,food microbiology and food technology in general. The structure ofthe book allows easy comparisons among methods, and searchinginformation by microorganism, produce, and quality traits.

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 systems12

1.3.1 Experimental studies field studies versus growthchamber 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 andplant hosts 27

1.4.1 Mechanisms employed by enteric pathogens to survive asplant endophytes or epiphytes 27

1.4.2 Mechanisms employed by plant hosts to resist invasion byenteric pathogens 27

1.5 Cross–contamination of enteric pathogens to produce duringharvest 28

1.6 Concluding comments 29

References 29

2 Surface characteristics of fresh produce and their impacton attachment and removal of human pathogens on produce surfaces43
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 removalof 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 cells68

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, andphysical treatments 79

4.3 Stress and resistance to biocides and antimicrobial physicaltreatments 81

4.4 Implications of stress, resistance, and sublethal damage infresh produce decontamination 83

References 84

SECTION II DECONTAMINANTS 87

5 Produce washers 89
Steven Pao, Wilbert Long III, Chyer Kim, and D. FrankKelsey

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 life113

6.6 Effect of minimal processing on nutritional andphytochemical composition 114

6.7 Conclusion 115

References 116

7 Chlorine 121
Cristóbal Chaidez, Nohelia Castro–del Campo, J. BasilioHeredia, Laura Contreras–Angulo, GustavoGonzález Aguilar, and J. FernandoAyala 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 life125

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 phytochemicalcomposition 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 efficacy142

8.4 Effect of EO water on pathogenic microorganisms 153

8.5 Effect of EO water on spoilage microorganisms and shelf life153

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 phytochemicalcomposition 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 microorganisms167

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 phytochemicalcomposition 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 life185

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 phytochemicalcomposition 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 microorganisms201

11.5 Effect of hydrogen peroxide on spoilage microorganisms andshelf 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 andphytochemical composition 209

11.9 Effect of hydrogen peroxide on residues and formation oftoxic by–products 211

References 212

12 Peroxyacetic acid 215
Gustavo González–Aguilar, J. Fernando Ayala–Zavala,Cristóbal Chaidez–Quiroz, J. Basilio Heredia, and NoheliaCastro–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 life218

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 composition220

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 vegetables225
Catherine Barry–Ryan and Paula Bourke

13.1 Introduction to essential oils 225

13.1.1 Decontamination in the fruit and vegetable industry225

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 action228

13.2.3 Other factors that affect the mechanism of action ofessential oils 229

13.3 Effect of essential oils on microorganisms 230

13.3.1 Effect of essential oils on pathogenic microorganisms230

13.3.2 Effect of essential oils on spoilage microorganisms231

13.3.3 Effect of essential oils on Gram–positive versusGram–negative microorganisms 232

13.3.4 Effect of specific essential oils on microorganisms233

13.4 Effect of essential oils on fruit and vegetable physiology235

13.5 Effect of essential oils on sensory quality 235

13.6 Effect of essential oils on nutritional and phytochemicalcomposition 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 coatings248

14.3 Edible films and coatings as antimicrobials 251

14.3.1 Edible films and coatings with antimicrobial properties251

14.3.2 Antimicrobial agents incorporated into edible films andcoatings 252

14.3.3 Methods to evaluate effectiveness of antimicrobial filmsand coatings 258

14.3.4 Effect of edible coatings on pathogenic microorganisms259

14.3.5 Effect of edible coatings on microbial spoilage and shelflife 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 microorganisms288

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, HikmateAbriouel, Nabil Ben Omar, and María José GrandeBurgos

17.1 Basic concepts 297

17.2 Effect of protective cultures on pathogenic microorganisms298

17.3 Effect of protective cultures on spoilage microorganismsand shelf life 305

17.4 Effect of protective cultures on sensory quality andnutritional 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 PérezPulido

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 shelflife 323

18.5 Effect of bacteriocins on sensory quality and nutritionaland phytochemical composition 324

18.6 Toxicity 325

18.7 Regulatory status 327

References 328

19 Quorum sensing 333
María S. Medina–Martínez and MaríaAngélica 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 vegetableprocessing 347
Catherine Barry–Ryan

20.1 Introduction to the use of mild heat treatment for fruitand 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 vegetablephysiology 350

20.5.1 The responses of plant tissue to heat treatment 350

20.5.2 Effect of mild heat treatment on respiration and ethyleneproduction 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 vegetablesensory 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 sensorycharacteristics 356

20.7 Effect of mild heat treatment on nutritional andphytochemical 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 microorganisms367

21.4 Effect of continuous UV light on spoilage microorganismsand shelf life 368

21.5 Effect of continuous UV light on vegetable physiology369

21.6 Effect of continuous UV light on sensory quality 370

21.7 Effect of continuous UV–C light on nutritional andphytochemical 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 microorganisms381

22.4 Effect of ionizing radiation on spoilage microorganisms andshelf 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 andphytochemical 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 ofwhole 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 upsteps for decontamination 419

24.3 All that washing : Washing and sanitizingtreatments for the produce industry 420

24.4 To kill or not to kill: Safety without having a true killstep 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, MariannaMastromatteo, 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 forpackaging 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 decontaminationprocesses 487
Eva Van Derlinden, Astrid M. Cappuyns, Laurence Mertens, JanF. 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 inactivationmodeling 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 evaluation515

27.4.3 Quantitative model structure and performance evaluation516

27.5 Conclusions 519

References 519

28 Modeling microbial growth 529
Milena Sinigaglia, Maria Rosaria Corbo, and AntonioBevilacqua

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

Dr. Vicente M. Gómez–López is a Senior Researcher at the Centro de Edafología y Biología Aplicada del Segura (CEBAS–CSIC, Murcia, Spain) and a former Associate Professor at the Instituto de Ciencia y Tecnología de Alimentos, Facultad de Ciencias, Universidad Central de Venezuela