Competitive adsorption of alpha(s1)-casein and beta-casein in oil-in-water emulsions

Competitive adsorption of alpha(s1)-casein and beta-casein at the emulsion droplet surface and the planar oil-water interface has been investigated. Analysis of the aqueous phase after centrifugation of fresh emulsions made with a mixture of alpha(s1)-casein + beta-caseinshows that beta- casein predominates at the interface. Exchange experiments indicate that beta-casein will rapidly displace alpha(s1)-casein from the emulsion droplet surface; alpha(s1)-casein will also displace beta-casein, but to a much lesser extent. Surface viscosity measurements at a planar oil-water interface are consistent with the view that the alpha(s1)-casein displaced by beta-casein is removed from the interfacial region.