Water Activity

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 book presents the proceedings of the Tenth Basic Symposium sponsored by the Institute of Food Technologists and the International Union of Food Science and Technology. The key aim of the Symposium was to explore some basic principles relating to the influences of water activity on food quality.

Water Activity in Foods: Fundamentals and Applications is a one-of-a-kind reference text that brings together an international group of food scientists, chemists, and engineers to present a broad but thorough coverage of an important factor known to influence the attributes of foods – water activity. A team of experienced editors designed this book for lasting value as a sound introduction to the concept of water activity for neophytes and seasoned professionals in both academe and industry. Topics have been carefully selected to provide a comprehensive understanding of the mechanisms by which water activity influences the quality, shelf life, and safety of food products. Water Activity in Foods belongs on the shelves of all food science professionals for use in product development, quality control, and food safety. Students and newcomers to these areas will appreciate the instructional approach adopted by the experienced teachers and industry specialists who have contributed chapters to this comprehensive overview.

Low water activity (aw) and dried foods such as dried dairy and meat products, grain-based and dried ready-to-eat cereal products, powdered infant formula, peanut and nut pastes, as well as flours and meals have increasingly been associated with product recalls and foodborne outbreaks due to contamination by pathogens such as Salmonella spp. and enterohemorrhagic E. coli. In particular, recent foodborne outbreaks and product recalls related to Salmonella-contaminated spices have raised the level of public health concern for spices as agents of foodborne illnesses. Presently, most spices are grown outside the U.S., mainly in 8 countries: India, Indonesia, China, Brazil, Peru, Madagascar, Mexico and Vietnam. Many of these countries are under-developed and spices are harvested and stored with little heed to sanitation. The FDA has regulatory oversight of spices in the United States; however, the agency’s control is largely limited to enforcing regulatory compliance through sampling and testing only after imported foodstuffs have crossed the U.S. border. Unfortunately, statistical sampling plans are inefficient tools for ensuring total food safety. As a result, the development and use of decontamination treatments is key. This book provides an understanding of the microbial challenges to the safety of low aw foods, and a historic backdrop to the paradigm shift now highlighting low aw foods as vehicles for foodborne pathogens. Up-to-date facts and figures of foodborne illness outbreaks and product recalls are included. Special attention is given to the uncanny ability of Salmonella to persist under dry conditions in food processing plants and foods. A section is dedicated specifically to processing plant investigations, providing practical approaches to determining sources of persistent bacterial strains in the industrial food processing environment. Readers are guided through dry cleaning, wet cleaning and alternatives to processing plant hygiene and sanitation. Separate chapters are devoted to low aw food commodities of interest including spices, dried dairy-based products, low aw meat products, dried ready-to-eat cereal products, powdered infant formula, nuts and nut pastes, flours and meals, chocolate and confectionary, dried teas and herbs, and pet foods. The book provides regulatory testing guidelines and recommendations as well as guidance through methodological and sampling challenges to testing spices and low aw foods for the presence of foodborne pathogens. Chapters also address decontamination processes for low aw foods, including heat, steam, irradiation, microwave, and alternative energy-based treatments.

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.

Water Activity: Influences on Food Quality is a collection of papers presented at the 1978 International Symposium by the same title, held in Osaka, Japan. This book is a treatise on the influence of bound and free water on the quality and stability of foods and other natural products. This book is organized into seven sections encompassing 33 chapters. The first sections deal with the characterization of moisture sorption isotherms based on both theoretical and applied considerations, as well as the relationship of bound water to the physical and chemical properties of natural products, including foods. The succeeding sections consider the structure of water and the influence of solutes and solute mobility on water activity and the influence of water and water activity on the structural and functional characteristics of proteins, carbohydrates, and proteins. Other sections explore the influence of water activity and temperature on the rates of several important chemical reactions, such as lipid oxidation, vitamin decomposition, browning, and other reactions, which affect the chemical, physical, and nutritional properties of food. These sections also discuss the influence of water activity on food processing and storage practices from both theoretical and applied viewpoints, specifically the application of water activity principals to the processing and preservation of leafy vegetables, cheese, dried fish, and other products. The final section is devoted to the influences of water activity on the behavior of food-related microorganisms. This section emphasizes the role of solvents in controlling water activity and the related survival of certain microorganisms. This book will prove useful to food scientists and researchers.

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