Peptic partial hydrolysis of whey protein concentrate for modifying the surface properties of whey protein. II. Effects on the emulsifying and foaming properties

Effects of limited hydrolysis of reconstituted whey protein concentrate (WPC) by pepsin on surface properties of whey protein were studied. The functional properties were investigated in model systems. Surprisingly, the peptic whey protein hydrolysates (WPH) revealed two different optimal degrees of hydrolysis (DH) designed for emulsification and foaming applications. These optima were found to be at DH of 1-1.5% and DH 5.8%. The first was primarily related to molecular defolding of whey protein in the starting phase of hydrolysis by pepsin and the second to symbiotic effects of large peptides liberated during further proteolysis and P-lactoglobulin. The clear deterioration of surface properties with DH > 6.5% was due to very small peptides in connection with extremely increased surface hydrophobicity.