COMPETITIVE ADSORPTION BETWEEN SODIUM CASEINATE AND OIL-SOLUBLE AND WATER-SOLUBLE SURFACTANTS IN OIL-IN-WATER EMULSIONS

Competitive adsorption between sodium caseinate and either a water-sol uble surfactant, Tween 60 (polyoxyethylene sorbitan monostearate-PSM) or an oil-soluble surfactant, Span 60 (sorbitan monostearate-SM) was s tudied in oil-in-water emulsions. Surfactants were present during homo genization. Surface concentration of protein in freshly prepared emuls ions decreased as concentration of PSM or SM increased. However, only partial displacement of protein was observed with either surfactant. T he reduction in protein surface concentration was greater in the prese nce of PSM. Interfacial protein composition was independent of surfact ant type. In the absence of surfactant, preferential adsorption of bet a-casein occured in emulsions containing less than or equal to 1.0 wt % protein. On addition of surfactant preference for beta-casein at the interface was reduced.