Displacement of native and thiolated β-casein from oil—water interfaces—effect of heating, ageing and oil phase

Abstract

Tetradecane- and soya oil-in-water emulsions stabilized by native and chemically thiolated β-casein were prepared using a microfluidizer. Displacement of adsorbed protein by addition of the non-ionic detergent Tween 20 after 2 and 28 days storage at 20°C, and before and after heating to 80°C for 30 min, was determined colorimetrically. Adsorbed protein was displaced more readily from the 2-day-old tetradecane emulsion than from the soya oil. Heating reduced displacement from the soya oil emulsion, but not from the tetradecane. Thiolated protein was displaced less readily than native β-casein. Storage decreased displacement of both forms of β-casein from the soya oil emulsions and heating had very little effect on the stability of the adsorbed protein in these aged emulsions.