EMULSIFYING PROPERTIES OF WHEY PROTEIN

Abstract

ABSTRACT The effects of variables on the properties of the emulsion prepared from a whey protein dispersion and coconut oil were studied. Adsorption of the protein on to the fat globule surface was also investigated. A stable emulsion was obtained at the protein concentrations more than 2%. The creaming stability was minimal and the viscosity was maximum at pH 5 over the range of pH 3‐9. Addition of sugar ester, monostearate, and lecithin rather depressed the creaming stability. The emulsion was heat stable in the absence of salt, but became a gel on heating in the presence of CaCl 2 , The fat globule size and the amount of protein adsorbed on to the fat globule surface were highest at pH 5. SDS‐electrophoresis of the protein recovered from the surface revealed that β‐lactoglobulin, immunoglobulin, and lactoferrin were selectively adsorbed at pH 7. The adsorption of α‐lactalbumin markedly increased and that of β‐lactoglobulin decreased with the decrease in pH to 5 or 3. The importance of electrostatic nature and conformation of the proteins in the adsorption was suggested.