Properties of partially denatured whey protein products: Formation and characterisation of structure

Partially denatured whey protein (PDWPC) products have been manufactured using a controlled heating process that allows control of the degree of denaturation of the whey proteins. This is assessed by following the change in free sulphydryl content of the protein as heating progresses. This allows the formation of soluble whey protein aggregates of diverse particle size and morphology. The PDWPC's have been made using different manufacturing conditions (temperature, pH, degree of denaturation) to give aggregated PDWPC powders with a degree of denaturation in the range 45-98% and particle size 3-17 μm. Particle size analysis, scanning electron microscopy and density analysis show that the particles have aggregated structures that range from compact, particulate gel-like to fibrillar phase-separated structures, with intermediate structures formed under some conditions. These structures are consistent with the known gel structures formed in whey protein concentrate gels. The structure of the PDWPC particles differs from that of microparticulated whey proteins. The possibility of using PDWPC's as ingredients tailored to the needs of food manufacturers is discussed.