Water Activity in Foods: Fundamentals and Applications (Institute of Food Technologists Series)

"Understand how water activity can determine food quality with this exhaustive guide This second edition of Water Activity in Foods furnishes those working within food manufacturing, quality control, and safety with a newly revised guide to water activity and its role in the preservation and processing of food items. With clear, instructional prose and illustrations, the book's international team of contributors break down the essential principles of water activity and water--food interactions, delineating water's crucial impact upon attributes such as flavor, appearance, texture, and shelf life. The updated and expanded second edition continues to offer an authoritative overview of the subject, while also broadening its scope to include six newly written chapters covering the latest developments in water activity research. Exploring topics ranging from deliquescence to crispness, these insightful new inclusions complement existing content that has been refreshed and reconfigured to support the food industry of today. This essential text: Helps to build a full understanding of water activity as it relates to the production of food Spans both the theoretical and practical dimensions of water activity Features six new chapters detailing current progress in water activity research Includes frequent illustrations to clearly demonstrate water activity process Food science students, engineers, and industry professionals alike will find Water Activity in Foods a practical and informative work that makes understanding this core aspect of food manufacturing an engaging and accessible process. Water activity (or aw) is a measure of the extent to which water is "available" to interact with other, non-aqueous materials. The concept of water activity is crucial in food science. William James Scott showed in 1953 that microorganisms have a limiting aw level for growth. It is now generally accepted that aw is more closely related to the microbial, chemical, and physical properties of foods and other natural products than is total moisture content. Specific changes in color, aroma, flavor, texture, stability, and acceptability of raw and processed food products have been associated with relatively narrow aw ranges. Next to temperature, aw is considered one of the most important parameters in food preservation and processing. It has a pivotal effect upon the physical and chemical stability of foods"-- Provided by publisher Cover......Page 1 Title Page......Page 5 Copyright Page......Page 6 Contents......Page 9 Dedication......Page 7 Preface to the Second Edition......Page 11 Preface to the First Edition......Page 13 List of Contributors......Page 15 Chapter 1 Introduction: Historical Highlights of Water Activity Research......Page 19 References......Page 25 Chapter 2 Water Activity: Fundamentals and Relationships......Page 31 Temperature......Page 36 References......Page 44 Introduction......Page 45 Water Activity......Page 46 Water Activity and Time......Page 47 Importance of Water Activity......Page 49 Glass Transition......Page 50 Glass Transition and Water Relations......Page 53 Relaxation Times......Page 55 Time-Dependent Changes......Page 57 Overall Stability......Page 59 References......Page 60 Introduction......Page 63 Anhydrous Materials......Page 65 Water Plasticization......Page 66 Ice in Binary Solutions......Page 69 Development of Supplemented Phase Diagrams......Page 72 Characterization of Foods......Page 75 References......Page 77 Introduction......Page 79 Water Structure......Page 80 Types of Molecular Motions......Page 81 Principles of NMR......Page 85 A Basic NMR Experiment......Page 90 Longitudinal Relaxation......Page 94 Transverse Relaxation......Page 96 Relaxation Time Comparison......Page 99 Connecting NMR Relaxation Times and Molecular Mobility......Page 100 NMR Relaxation Time Measurement Factors and Considerations......Page 103 NMR Pulse Sequences for Measuring Water Diffusion......Page 108 NMR Imaging for Water Mobility Mapping......Page 110 General Advantages and Disadvantages of NMR......Page 111 Examples of Using NMR to Probe Water Relations in Foods......Page 113 Relationship Between NMR Relaxation Rates and aw......Page 120 Future Needs and Directions......Page 127 Notes......Page 131 References......Page 133 Introduction......Page 141 Water–Solid Intermolecular Interactions......Page 142 Adsorption......Page 146 Capillary Condensation......Page 148 Deliquescence......Page 151 Crystal Hydrate Formation......Page 160 Absorption......Page 164 Water–Solid Interactions in Multicomponent Systems......Page 169 Acknowledgments......Page 171 References......Page 172 Chapter 7 Water Activity Prediction and Moisture Sorption Isotherms......Page 179 Water Activity Prediction......Page 180 Thermodynamics......Page 181 Models for Predicting Water Activity......Page 190 Electrolyte Solutions......Page 194 Moisture Sorption Isotherms......Page 199 Theoretical (Kinetic Based) Models......Page 202 Empirical Models......Page 208 Effects on Isotherms......Page 209 Hysteresis......Page 216 Theories of Sorption Hysteresis......Page 217 Final Remarks......Page 219 References......Page 220 Calibration/Validation......Page 225 Temperature......Page 227 Sample Preparation......Page 228 Hygrometers......Page 230 Electric Hygrometer......Page 232 Freezing Point Depression......Page 238 Moisture Sorption Isotherm Determination......Page 239 Moisture Content Determination......Page 240 References......Page 241 Chapter 9 Moisture Effects on Food’s Chemical Stability......Page 245 Modeling Chemical Stability Data......Page 246 Temperature Effects on Chemical Stability......Page 249 Moisture Content......Page 251 Water Activity......Page 252 Dielectric Properties......Page 254 Water and Temperature Sensitivity......Page 255 Mechanism of Aspartame Degradation......Page 256 Effect of Water on Aspartame Degradation......Page 257 Ascorbic Acid Stability......Page 258 Riboflavin Stability......Page 259 Reaction Overview......Page 260 Effect of Water on the Maillard Reaction......Page 261 Effect of Water on Lipid Oxidation......Page 264 Enzymatic Reactions......Page 265 Enzyme Activity......Page 266 General Requirements for Conducting a Shelf‐life Test......Page 267 Summary......Page 268 References......Page 269 Chapter 10 Water Activity and Physical Stability......Page 273 Plasticization–Antiplasticization: Influence of Water on Mechanical Properties......Page 274 Water and Crispness......Page 275 Water Activity and Softness......Page 278 Stickiness, Caking, and Collapse......Page 279 Crystallization......Page 282 Conclusion......Page 284 References......Page 285 Water Activity......Page 289 Glass Transition......Page 290 Enthalpy Relaxation......Page 291 Enthalpy Relaxation and Food Stability......Page 295 References......Page 300 Chapter 12 Diffusion and Sorption Kinetics of Water in Foods......Page 305 Diffusion of Water......Page 307 Factors Affecting Moisture Migration......Page 308 Rate of Diffusion......Page 310 Diffusion of Water in Polymers......Page 313 Film Moisture Diffusivities......Page 314 Nuclear Magnetic Resonance and Magnetic Resonance Imaging in Diffusion of Water in Foods......Page 317 Packaging Predictions......Page 318 Moisture Gain and Loss in Packaging......Page 319 References......Page 325 Dynamic Moisture Sorption......Page 329 Comparing the Dynamic and Static Methods......Page 330 The Value of Dynamic MSPs......Page 331 Dynamic MSPs and Glass Transition......Page 332 Dynamic MSPs and Crystalline Deliquescence......Page 337 Dynamic MSPs and Texture Changes......Page 338 Final Remarks......Page 339 References......Page 340 Chapter 14 Effects of Water Activity (aw) on Microbial Stability as a Hurdle in Food Preservation......Page 341 Water Activity and Metabolic Activities of Microorganisms – Minimal Water Activity for Growth, Toxin Production, and Sporulation......Page 342 The Challenge of Minimal aw Limits for Growth......Page 345 The Safety of Water Activity Adjustment/Measurement for the Control of Bacterial Growth in Foods......Page 346 Effects of aw on Thermal Resistance of Microorganisms......Page 347 Osmotic and Specific Solute Effects......Page 350 Microbial Growth in Reduced‐Moisture Foods: Water Activity and “Mobility”......Page 356 Water Activity as a Hurdle in Combined Preservation Techniques......Page 359 Predictive Microbiology in Assessing the Effects of aw in Combination with Other Hurdles......Page 366 References......Page 369 Chapter 15 Baroprotective Effect from Reduced aw......Page 375 High Hydrostatic Pressure: Fundamentals and Applications......Page 0 Factors Influencing Microbial Inactivation by HHP......Page 376 Inactivation of Microbial Vegetative Cells and Spores......Page 377 Vegetative Cells......Page 379 Effect of Water Activity......Page 381 Baroprotective Effect of Different Solutes......Page 383 Non-ionic Solutes......Page 384 Ionic Solutes......Page 387 Low-Moisture and High-Fat Foods......Page 389 Barotolerance of Pathogens in Low and High aw Foods......Page 390 High-Pressure Process Combined with Other Hurdles......Page 391 Mathematical Models for Barotolerance......Page 394 Conclusion......Page 397 References......Page 398 Water Activity and Stability of Foods......Page 403 Intermediate-Moisture Foods: Definition......Page 405 Water Activity Reduction......Page 407 Production of Intermediate‐Moisture Food Products......Page 415 Microbial and Chemical Quality of Intermediate‐Moisture Food Products......Page 416 Commercial Development of Intermediate-Moisture Foods......Page 421 Military Development of Intermediate-Moisture Foods......Page 425 References......Page 435 Some Definitions......Page 443 Mechanisms of Mass and Heat Transfer......Page 446 Psychrometrics......Page 449 Mass and Energy Balances......Page 450 Dehydration Kinetics......Page 451 Dehydration Curves......Page 452 Constant Rate Period......Page 454 Falling Rate Periods......Page 455 Drying Resistance......Page 457 Sorption Isotherms and Drying Process Characterization......Page 459 Temperature Effect on Sorption......Page 460 Drying Process Representation and Energy Changes in Sorption Isotherms......Page 462 Conventional Air Drying......Page 464 Spray Drying......Page 465 Vacuum Dehydration and Freeze Drying......Page 466 Dielectric Drying Methods......Page 467 References......Page 468 Chapter 18 Humidity Caking and Its Prevention......Page 471 Humidity Caking......Page 472 Unpredictability in Humidity Caking......Page 473 Effect of Moisture, Temperature, and Particle Size......Page 474 The Sticky Point and Glass Transition......Page 475 Anticaking Agents......Page 477 Concluding Remarks......Page 480 References......Page 481 Chapter 19 Selected Applications of Water Activity Management in the Food Industry......Page 483 Water Activity in Estimations of Food Safety and Quality......Page 484 Incorporation of aw Concept in International and Domestic Food Regulations......Page 486 Dried Foods and the Monolayer Value......Page 490 Formulation of Products with Multiple Ingredients......Page 491 Final Remarks......Page 494 References......Page 495 Introduction......Page 501 Gummies and Jellies......Page 502 Fondants and Creams......Page 503 Caramel and Fudge......Page 506 Marshmallow......Page 508 Nougat......Page 509 Hard Candy and Brittle......Page 510 Chewing and Bubble Gum......Page 511 Compressed Tablets and Wafers......Page 512 Sugar Panned Confections......Page 513 Chocolate......Page 514 Acknowledgments......Page 516 References......Page 517 Chapter 21 Applications of Probabilistic Engineering in Food Moisture Management to Meet Product Quality, Safety, and Shelf-Life Requirements......Page 519 Probabilistic Engineering......Page 521 Monte Carlo Approach to Probabilistic Engineering......Page 522 Equilibrium aw for Multiple Ingredients with Different Initial aw......Page 524 Shelf-Life of Moisture-Sensitive Products......Page 526 Estimation of the Required Packaging Moisture Permeance......Page 528 Moisture Barrier Measurements to Estimate Moisture Gain in Packaged Foods......Page 530 Application of the Concept of Glass Transition Temperature (Tg) in Shelf‐Life Estimations......Page 532 Application of Information Theory Criteria for Predictive Model Selection......Page 533 Application of Isotherm and Tg Models Assessed by Information Theory Criteria and Use in the Assessment of Product Stability......Page 534 Conclusions......Page 535 References......Page 536 Water Potential......Page 539 Energy Status of Water......Page 541 Soil–Plant Applications......Page 542 Seed Viability......Page 544 Seed Coating......Page 545 Seed Priming......Page 546 Medical Applications......Page 547 Pharmaceutical Applications......Page 548 References......Page 550 Developments in Risk Management......Page 553 Performance, Process, and Product Criteria......Page 554 Nonthermal Processing Technologies and Impact of Water Activity......Page 559 High‐Pressure Processing......Page 560 Pulsed Electric Fields......Page 562 Irradiation......Page 563 Physiological Actions of Osmotic Stress......Page 564 Osmoregulation......Page 565 Conclusions......Page 566 References......Page 567 Appendix A Water Activity of Saturated Salt Solutions ......Page 571 Appendix B Water Activity of Unsaturated Salt Solutions at 25°C......Page 575 Nonelectrolytes Solution......Page 579 Electrolyte Solution......Page 582 Multi-component Mixtures......Page 583 Isotherm Equations......Page 584 Glass Transition Equations......Page 585 Glass Transition and Water Activity Relationships......Page 586 References......Page 587 Appendix D Minimum Water Activity Limits for Growth of Microorganisms......Page 589 Appendix E Water Activity Values of Select Food Ingredients and Products......Page 591 References......Page 608 Appendix F Water Activity Values of Select Consumer and Pharmaceutical Products......Page 611 References......Page 612 Index......Page 613 EULA......Page 635

This second edition of Water Activity in Foods furnishes those working within food manufacturing, quality control, and safety with a newly revised guide to water activity and its role in the preservation and processing of food items. With clear, instructional prose and illustrations, the book's international team of contributors break down the essential principles of water activity and water–food interactions, delineating water's crucial impact upon attributes such as flavor, appearance, texture, and shelf life.

The updated and expanded second edition continues to offer an authoritative overview of the subject, while also broadening its scope to include six newly written chapters covering the latest developments in water activity research. Exploring topics ranging from deliquescence to crispness, these insightful new inclusions complement existing content that has been refreshed and reconfigured to support the food industry of today.