Water Activity and Food

1st Edition - May 28, 1978
Author: John Troller
Language: English
eBook ISBN:
9 7 8 - 0 - 3 2 3 - 1 5 9 0 1 - 2

Water Activity and Food explores the role of water activity in the water relations of microorganisms and in food processing, packaging, and storage. It reviews the literature and… Read more

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Water Activity and Food explores the role of water activity in the water relations of microorganisms and in food processing, packaging, and storage. It reviews the literature and provides numerous examples demonstrating the use of water activity to predict the reactions of microorganisms or the stability of food components. It also highlights cases where water activity is not a reliable predictor of events and considers some interesting interactions with other environmental parameters. Comprised of 11 chapters, this volume begins with an overview of water in foods and solutions, water activity values for foods, and water relations of enzyme activity. It then discusses lipid oxidation, enzyme reactions and non-enzymatic browning, and several other food-related factors. The reader is also introduced to water relations of microbial growth; the effects of water on microbial survival; the spoilage and preservation of foods at various levels of water activity; the water relations of food-borne pathogens such as Salmonella and toxigenic molds; the importance of water activity in non-microbiological aspects of food processing and storage; and the influence of atmospheric relative humidity on sanitation and the protection of food products. This book is an important source of information for researchers in food microbiology and microbial water relations.

ForewordPreface1 Water Activity—Basic Concepts Water in Foods Properties of Solutions Water Binding Water Sorption Isotherms Temperature Effects Hysteresis Frozen Foods Nonequilibrium Conditions Applications Water Activity Values for Foods References2 Methods Desired Characteristics Water Activity Methods Relative Humidity Methods Total Moisture Methods Calibration Control of aw References3 Enzyme Reactions and Nonenzymatic Browning Effect of Water Activity on Enzymatic Reactions Effect of Water Activity on Nonenzymatic Browning Reactions References4 Lipid Oxidation, Changes in Texture, Color, and Nutritional Quality Effect of aw on Lipid Oxidation Effect of aw on Food Texture Effect of aw on Food Pigments Effect of aw on Nutrients References5 Microbial Growth Bacteria Fungi Interactions with Water Activity Sporulation, Germination, and Outgrowth Solute Effects Hysteresis Effects Physiological Basis of Tolerance of Reduced Water Activity References6 Food Preservation and Spoilage Cereals and Legumes Fish Meat Milk Products Vegetables Fruit Confectionery References7 Microbial Survival Survivor Curves Survival at Freezing Temperatures Survival at Moderate Temperatures Survival at Elevated Temperatures Sublethal Impairment References8 Food-Borne Pathogens Staphylococcus aureus Toxigenic Molds Salmonella Clostridium perfringens Clostridium botulinum Vibrio parahaemolyticus Bacillus cereus Parasites References9 Control of aw and Moisture Dehydration Concentration by Water Removal Intermediate Moisture Foods References10 Packaging, Storage, and Transport Bulk Storage of Commodities Transport Refrigerated Storage of Bulk Products Packaged Foods Measurement of Water Vapor Permeability Permeability of Packaging Materials Unrefrigerated Packaged Foods Refrigerated Packaged Foods References11 Food Plant Sanitation Process Equipment Cleaning Food Storage Sanitation Effect of Relative Humidity on Insects and Insect Control Effect of Relative Humidity on Fumigants and Antimicrobial Agents Effect of Relative Humidity and aw on Bacterial Survival on Surfaces Effect of Relative Humidity on Airborne Microorganisms ReferencesAppendix AAppendix BIndex