THE INFLUENCE OF PROCESSING AND MEDIUM COMPOSITION ON THE THIOL AVAILABILITY OF WHEY PROTEIN CONCENTRATE

Abstract

Whey protein concentrates (WPC) play an important role in the development of functional foods with an increase in global demand. Whey proteins are highly soluble over a broad range of pH, a property that is important in their application as foaming, emulsifying, gelling, and water-binding agents in various types of food products. Denaturation of whey proteins is critical in modifying the functional behavior of dairy products. A knowledge of the thermal behavior of WPC occurring in different medium conditions, might allow to choose the most appropriate technology and to manipulate the thermal regime for a particular process or/and products, so that the final product possesses the optimal desirable properties. The objective of this study was to investigate the heat induced changes in whey protein concentrate solution at pH 7.5 and 6.6 in salt conditions (CaCl₂) on thiol availability. The results presented in this paper demonstrate that heat-induced changes in WPC greatly influence their degree in surface SH exposure. The exposure was more pronounced at higher temperatures.  However, above 80°C, the formation of disulfide bonds seems to be favored, resulting in a lower level of surface reactive SH groups after prolonged heating compared with the lower treatment temperatures. The increase was related to the intensity of applied temperature-time combination and medium composition. The thermal denaturation of WPC is regarded as a complex reaction involving several unfolding steps and ending in aggregation reactions.