Effects of protein concentration and degree of hydrolysis during heating on the aggregation of beta-lactoglobulin

Hydrolysis of whey protein isolate (WPI) solution prior to heat treatment induced preferential aggregation of beta-lactoglobulin, accompanied by oxidation of sulfhydryl to disulfide groups or sulfhydryl-disulfide exchange reactions. The degree of aggregation depended on the degree of hydrolysis (DH) and protein concentration of the hydrolysate on heating. Although beta-lactoglobulin could not be completely separated from alpha-lactalbumin, the optimum conditions to remove beta-lactoglobulin from WPI solution were a protein concentration of 5 % and a DH between 3.0 and 5.4 % prior to heat treatment.