POLYMERIZATION OF WHEY PROTEINS IN WHEY PROTEIN-STABILIZED EMULSIONS

In emulsions stabilized by whey protein isolate, selective adsorption of beta-lactoglobulin (beta-Lg) and alpha-lactalbumin (alpha-La) over bovine serum albumin and immunoglobulins occurred at the oil-water interface. High molecular weight protein polymers were progressively formed at the oil-water interface with increasing time following emulsion preparation. The formation of the high molecular weight protein polymers correlated with the disappearance of beta-Lg (r = -0.98) and alpha-La (r = -0.97) over the 7-day storage period. The beta-Lg concentration decreased from 50.7 % of total whey proteins adsorbed at the interface immediately after emulsion preparation to 24.6 % after 24 h, and alpha-La decreased from 14.7 % initially to 10.3 % after 24 h. Polymerization involved the formation of intermolecular disulfide cross-links between the monomeric proteins.