MOISTURE MIGRATION IN IDEALIZED BILAYER SYSTEMS - RELATIONSHIPS AMONGWATER-ASSOCIATED PROPERTIES, STRUCTURE, AND TEXTURE

The effects of composition and thermal treatment on the water sorption and diffusional properties of idealized protein gels arranged in bila yer configurations were determined; these water binding/migration prop erties were related to the mechanical characteristics of the gels. Sam ples were prepared from whey protein concentrate (WPC), they consisted of water:WPC ratios of 1.5 to 5.67, and were thermally set for 20-60 min. Moisture migration rates from samples interfaced with filters wer e determined, as were moisture sorption capacities of samples immersed in water. The physical properties of the gels were assessed by uniaxi al compression and microscopy. Results showed that gel strength and co nsequent extent of protein interaction-as affected by thermal treatmen t-controlled the ability of the gel structure to absorb water. Sorptio n was exponentially correlated with gel modulus and linearly correlate d with a function of protein content, heating time, and immersion time . Rates of diffusion from interfaced gels were dependent solely on wat er content. It was concluded that the degree of protein interaction, w hether influenced by concentration or thermal treatment, affected netw ork extensibility and thus the capacity of the gels to act as receptor s of moisture. Results have implications for the functionality of shel f-stable sandwiches and other multicomponent foods. (C) 1998 Elsevier Science Ltd. All rights reserved.