Physico-chemical and functional properties of whey protein as affected by limited papain proteolysis and selective ultrafiltration

Limited proteolysis of whey protein by papain at pH 6.5 and subsequent thermal unfolding at acidic pH weve studied and correlations between physico-functional (solubility, foaming, emulsifying) and physico-chemical properties were determined. The optimal degree of hydrolysis (DH) for functionality was about 3.0%, characterized by a significant reduction of aggregated whey protein present in commercial ultrafiltered whey protein concentrates. From chromatographic and electrophoretic results it may by concluded that peptidic fragments ave derived from bovine serum albumin and molecular unfolded beta-lactoglobulin whereas alpha-lactalbumin remained unaffected. Liberated peptidic fragments were found to support foaming but not emulsification as determined by a selective ultrafiltration. The beneficial effects of proteolytic and thermal modification of proteins can be maximized with each protein requiring a particular protease to develop a desirable functionality at well-defined DH.