Competitive adsorption in oil-in-water emulsions containing α-lactalbumin and β-lactoglobulin

Abstract

Time-dependent changes in composition at the oil-water interface have been investigated in emulsion systems containing the whey proteins α-lactalbumin and β-lactoglobulin. Exchange experiments involving analysis of the serum phase by fast protein liquid chromatography show that the ability of one whey protein to displace another previously adsorbed at the interface is slow and limited in extent, in contrast to casein exchange which was shown previously to be rapid and essentially reversible in character. Of the two whey proteins, β-lactoglobulin is the more difficult to displace. This is confirmed by electrophoretic mobility measurements on whey protein emulsion droplets which are subsequently exposed to a solution of β-casein. Electrophoretic mobility measurements also show that neither whey protein will displace β-casein from the emulsion droplet surface, though both will displace gelatin, albeit to a limited extent.