Physical principles of food preservation.

Foreword v Preface to the Second Edition vii Preface to the First Edition ix PART I. PRINCIPLES 1. Thermodynamics 1 I. Introduction 1 II. Thermodynamic Fundamentals 1 A. Definition of Systems 2 B. First Law of Thermodynamics 2 C. Second Law of Thermodynamics 5 D. Thermodynamic Potential: Gibbs Free Energy 6 III. Solution Properties 9 A. Partial Molar Quantities 9 B. Chemical Potential 10 C. Ideal Mixtures 11 D. Nonideal Mixtures 14 IV. Phase Equilibria 15 xiii A. Liquid–Vapor Equilibria 17 B. Solid–Liquid Equilibria 18 C. Solid–Vapor Equilibria 18 D. Phase Rule 19 E. Pressure-Composition Diagram 20 V. Colligative Properties 22 A. Vapor Pressure Lowering 23 B. Boiling Point Elevation 23 C. Freezing Point Depression 24 D. Osmotic Pressure 25 Symbols 26 References 27 2. Reaction Kinetics 28 I. Introduction 28 II. General Considerations 29 A. Concept of Rate-Limiting Step 29 B. Basic Chemical Kinetics 30 C. Order of Reaction 31 III. First-Order Rate Processes 32 IV. Determining Kinetic Parameters 35 A. General Considerations 35 B. Differential Methods 38 C. Integral Methods 39 D. Accuracy of Rate Constants 40 V. Temperature Dependence of Reaction Kinetics 41 A. Arrhenius Model 41 B. Thermal Death Time Model 42 C. Q10 Model 42 VI. Kinetic Parameter Values Important in Food Processing 43 VII. Enzyme-Catalyzed Reactions 45 A. Introduction 45 B. Michaelis–Menten Analysis 45 VIII. Summary 48 References 49 3. Heat Transfer in Food 50 I. Introduction 50 II. Mechanisms of Heat Transfer 51 A. Conduction 58 B. Convection 60 xiv Contents C. Radiation 65 D. Dielectric and Microwave Heating 68 III. Steady-State Heat Transfer 70 A. Conduction Heat Transfer in Series 70 B. Convection Heat Transfer Coefficient 73 C. Free or Natural Convection 74 D. Forced Convection 75 IV. Unsteady-State Heat Transfer 76 A. General Principles 76 B. Unaccomplished Temperature Change 80 C. Generalized Solution for Unsteady-State Heat Transfer 81 D. Negligible Internal Resistance to Heat Transfer (Well-Mixed Fluid) (Bi , 0.1) 82 E. Finite Internal Resistance to Heat Transfer (Bi . 0.1) 83 F. Example 87 G. Finite Objects 89 H. Other Conditions 90 Symbols 90 References 91 4. Mass Transfer in Food Preservation Processes 92 I. Introduction 92 II. Phase Equilibria 93 A. The Phase Rule 93 B. Gas–Liquid Equilibria 93 C. Solutions 95 D. Representation of Equilibrium Relationships for Binary Systems with Two Volatile Components 95 E. Colligative Properties Related to Vapor Pressure 97 F. Liquid–Liquid Equilibria 98 G. Gas–Solid Equilibria 99 III. Mass Transfer Between Phases 101 A. Interface Between Phases 101 B. Diffusion Within a Homogeneous Phase 102 C. Nonideal Diffusion Behavior 108 D. Film Coefficients for Mass Transfer 111 E. Transport in Porous Solids 113 F. Simultaneous Heat and Mass Transfer 114 Symbols 114 References 115 Contents xv 5. Water Activity and Food Preservation 117 I. Introduction 117 II. Water Activity 118 III. Sorption of Water by Foods 120 IV. Indicators of the State of Water in Foods 124 V. Causes of Water Vapor Depression in Foods 126 VI. Sorption Hysteresis 130 VII. Water Activity of Mixtures 134 VIII. Water and Glass Transitions in Food Materials 136 IX. Overview of Effects of Water Activity on Shelf Life of Foods 142 X. Water Activity and Physical Changes in Foods 143 XI. Effects of Water on Microbial Growth 152 XII. Water and Chemical Reactions in Foods 156 Symbols 166 References 167 PART II. PRESERVATION PROCESSES 6. Heat Processing 170 I. Introduction 170 II. Application of Heat Energy to Foods 170 A. Cooking 171 B. Blanching 171 C. Pasteurization 173 D. Sterilization 174 III. Interaction of Heat Energy and Food Components 178 A. Introduction 178 B. Reaction Kinetics 179 C. Temperature Dependence on Kinetics 180 D. Thermal Destruction of Microorganisms 184 E. Thermal Destruction of Enzymes 191 F. Thermal Destruction of Nutrients and Quality Factors 192 IV. Heat Penetration into Foods 197 A. Introduction 197 B. Determination of Time–Temperature Profile for Thermal Process Calculations 198 C. Evaluation of Heat Penetration Data 199 V. Methods of Determining Lethality of Thermal Processes 203 A. Introduction 203 B. Improved General Method 204 xvi Contents C. Formula Method 207 D. Aseptic Processing 214 VI. Process Application 219 A. Optimization of Thermal Processes for Nutrient Retention 220 B. Process Equipment 223 Symbols 233 References 234 7. Storage at Chilling Temperatures 237 I. Introduction 237 II. Considerations 238 A. Normal Behavior of Food Stored at Chilling Temperatures 238 B. Causes of Quality Loss 242 C. Temperature 244 D. Relative Humidity 252 E. Air Circulation and Purification 252 F. Adjuncts to Chilling Temperature 252 G. Summary of Product Characteristics That Influence Conditions Selected for Chilling Storage 259 III. Applications and Procedures 259 A. Precooling 259 B. Conditions Recommended for Storage of Food in Ordinary Air at Chilling Temperatures 261 C. Conditions Recommended for Storage of Food in Chilled Atmospheres of Modified Composition 263 D. Handling of Food Following Removal from Chilling Storage 273 References 273 8. Freezing 276 I. Introduction 276 A. Objectives of Freezing of Foods 276 B. Size of the Food Industry 277 II. Physicochemical Principles of the Freezing Process 277 A. Introduction 277 B. Water and Ice 278 C. Nucleation in Pure Water 283 D. Freezing Point Depression in Solutions, Biological Systems, and Foods 287 Contents xvii E. Crystal Growth 292 F. Recrystallization 293 III. Glassy State and Preservation by Freezing 297 IV. Biological Aspects of Freezing 300 A. Cryopreservation of Cells and Other Biomaterials 300 B. Biological Ice Nucleation 304 C. Antifreeze Proteins 305 V. Freezing Technology 307 A. Air Freezers 308 B. Indirect Contact Freezers 309 C. Immersion Freezing 311 D. Cryogenic Freezing 311 E. High Pressure Applications in Freezing Technology 312 VI. Design Calculations 314 A. Heat to Be Removed 315 B. Calculation of Freezing Time 315 C. Illustrative Examples 317 VII. Effects of Freezing, Storage, and Thawing on Food Properties 322 A. Effects of Freezing 323 B. Effects of Storage in the Frozen State 324 C. Effects of Thawing 326 Symbols 327 References 327 9. Concentration 330 I. Introduction 330 II. Evaporation 331 A. Principles of Evaporator Operation 331 B. Boiling Point Estimation 333 C. Food Properties and Evaporator Performance 334 D. Types of Evaporators 337 E. Evaporation with Feed Preheating 342 F. Multiple-Effect Evaporators 343 G. Evaporators with Vapor Recompression 345 H. Principles of Operation of Equipment Used in Evaporators 349 I. Examples of Evaporator Systems in Industry 354 III. Freeze Concentration 355 A. Introduction 355 B. Principle of the Process 355 C. Freeze Concentration and Freeze Desalination 358 xviii Contents D. Principles of Equipment Used in Freeze Concentration 358 E. Normal Freezing 360 F. Problems Caused by Precipitation of Solids Other than Ice 363 G. Concentration by Gas Hydrate Formation 363 H. Applications in the Food Industry 364 IV. Membrane Processes for Concentration 364 A. Introduction 364 B. Driving Forces for Membrane Processes 365 C. Membranes 367 D. Reverse Osmosis 370 E. Applications of Reverse Osmosis 371 F. Ultrafiltration 372 G. Electroosmosis 373 H. Thermoosmosis and Pervaporation 374 V. Cost of Food Concentration 374 Symbols 375 References 377 10. Dehydration 378 I. Introduction 378 II. Principles of Dehydration Processes 379 A. Introduction 379 B. Equilibrium Relations in Air–Water Mixtures 379 C. Humidity Charts 382 D. Energy and Material Balance on an Air Dryer 385 E. Transport of Water in Foods 386 III. Air-Drying of a Slab Under Constant Conditions 389 A. Idealized Mechanisms of Drying of a Slab 389 B. Calculation of Drying Rates Using Experimental Results 395 C. Characteristics and Significance of the Slab Model 398 D. Shrinkage During Drying 399 IV. Drying Technology 402 A. Introduction 402 B. Classification of Drying Processes 403 C. Convective Dryers 403 D. Flash Dryers and Fluidized Bed Dryers 413 E. Spray Drying 417 F. Drum Dryers 424 G. Infrared and Solar Dryers 427 Contents xix V. Freeze-Drying 429 A. Introduction 429 B. Heat and Mass Transfer in Freeze-Drying 431 VI. Quality Aspects of Dehydrated Materials 444 A. Changes Due to Chemical Reactions Occurring During Drying 446 B. Retention of Volatile Organic Compounds—Flavor Compounds 451 Symbols 456 References 457 11. Nonthermal Methods 461 I. Nonthermal Physical Processes for Food Preservation 461 II. Radiation Preservation of Foods 462 A. Introduction 462 B. Properties of Ionizing Radiations 463 C. Dosimetry of Ionizing Radiations 468 D. Chemical Effects of Ionizing Radiations 471 E. Effects of Radiation on Living Organisms 472 F. Technological Aspects of Food Irradiation 476 G. Organoleptic Acceptability and Safety of Irradiated Foods 485 H. Status of Commercial Application of Food Irradiation 488 III. High-Pressure Processing 489 A. Principles 489 B. Physicochemical Effects of Pressure 490 C. Effects of High Pressure on Living Systems 491 D. Technological Aspects of HPP 494 IV. High-Intensity Pulsed Electric Fields (PEF) 497 A. Principles 497 B. Effects of PEF on Microorganisms 499 C. Applications to Food Products 502 V. High-Voltage Arc Discharge 503 VI. Ultraviolet Light 503 A. Effects of Ultraviolet Light on Biological Systems 503 B. Applications and Considerations in Process Control and Validation 504 VII. Pulsed-Light Technology 505 VIII. Oscillating Magnetic Fields (OMF) 507 xx Contents IX. Ultrasound 508 A. Applications of Ultrasound in Food Technology 508 B. Mechanism of Inactivation of Microorganisms by Ultrasound 509 C. Application of Ultrasound in Combination with Heating 510 X. Status and Prospects of Nonthermal Food Preservation Processes 510 Symbols 511 References 512 12. Protective Packaging 514 I. Protection of Product as a Major Function of Packaging 514 A. Functions of Packaging 514 B. Protective Packaging 515 II. Nature of Packaging Materials 517 A. Glass 517 B. Metals 519 C. Paper 523 D. Plastics 523 E. Biodegradable and Edible Films and Coatings 526 F. Combinations 527 III. Effect of Environment on Food Stability and the Need for Protective Packaging 528 A. Light 528 B. Oxygen 529 C. Water 533 D. Temperature 534 E. Sensitivity to Mechanical Damage 534 F. Sensitivity to Attack by Biological Agents 534 IV. Properties of Materials That Determine the Degree of Protection Against Environmental Factors 535 A. Light-Protection Characteristics 535 B. Permeability to Gases and Vapors 537 C. Temperature Control by Packaging 561 D. Control of Biological Attack by Packaging 562 E. Protection from Mechanical Damage 563 V. Calculation of Shelf Life and of Requirements for Packaging 570 A. General Approach 570 B. Analysis of Storage Requirement of Moisture-Sensitive Foods 572 Contents xxi C. Accelerated Storage Stability Testing 576 D. Packaging Requirements of Fresh Fruits and Vegetables 578 E. Oxygen-Sensitive Foods 582 VI. Interaction Between Product and Package 584 A. Extraction of Packaging Material Components 584 B. Active Packaging 585 Symbols 587 References 588 Index 593