Emulsion stability as affected by competitive adsorption between an oil-soluble emulsifier and milk proteins at the interface

The effect of an oil-soluble emulsifier upon adsorption properties of beta-casein and beta-lactoglobulin at the oil-water interface was studied. Addition of emulsifier improved the emulsification properties,but Towered emulsion stability, Higher concentrations decreased emulsification capacity, due to an increase in oil phase viscosity, and interfered with several protein assays, except the o-phthaldialdehyde (OPA) assay. Depletion measurements revealed that the emulsifier displaced beta-casein more readily than beta-lactoglobulin from the surface of droplets, which correlated with emulsification and stability measurements. Displacement of proteins was not complete due to emulsifier-induced formation of a multiple w-o-w emulsion, which accounted for the missing protein in the continuous phase.