Interfacial Composition of Sodium Caseinate Emulsions

Oil‐in‐water emulsions stabilized by sodium caseinate were prepared and diluted with water or solutions of α sl ‐ or β‐casein. The emulsions were aged for 24 hr and the composition of the aqueous phase (and hence of the surface) was determined using Fast Protein Liquid Chromatography. There was no distinct preference for either α sl ‐ or β‐casein at the surface during homogenization, but on aging, β‐casein replaced some, but not all, of the surface α sl ‐casein. The exchange was stoichiometric, unless the initial surface concentration was low, in which case extra adsorption occurred to achieve a protein load of ‐ 1.2 mg m ‐2 . Build up of multilayers was not observed.