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 int erface. High molecular weight protein polymers were progressively form ed at the oil-water interface with increasing time following emulsion preparation. The formation of the high molecular weight protein polyme rs 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 concentratio n decreased from 50.7 % of total whey proteins adsorbed at the interfa ce immediately after emulsion preparation to 24.6 % after 24 h, and al pha-La decreased from 14.7 % initially to 10.3 % after 24 h. Polymeriz ation involved the formation of intermolecular disulfide cross-links b etween the monomeric proteins.