Beneficial and Adverse Effects of Water-Protein Interactions in Selected Dairy Products

Water-protein interaction is an important factor in the dehydration, rehydration, solubility, viscosity, gelation, heat stability, browning reaction, and other important properties of dairy products over a wide range of water activities. The ability of the major milk proteins, e.g., casein micelles and whey proteins, to interact with and immobilize water in dehydrated, solution, and gelled milk product systems is largely dependent upon their physicochemical state. This latter phenomenon is largely a function of pH; temperature; protein concentration; total solids concentration; ionic composition; addition of Ca-chelating compounds, stabilizer gums and sugars; and by thermal processing treatments that promote whey protein denaturation, aggregation, and interaction with casein micelles. Examples of the role of water and protein interactions in dairy products are illustrated by casein micelle solvation and voluminosity; whey protein aggregation in heated whey systems; casein micelle aggregation and syneresis in cheese manufacture; viscosity and gelation of sterile milk concentrates; rehydration, sotvation, solubility, and functionality of casein, caseinate, whey protein concentrate, and milk powder in formulated food products; viscosity, body, and texture of ice cream and frozen desserts; and viscosity and gelation of cultured dairy products.