Milk-fat globule membrane in homogenized cream

Abstract

SummaryThe proteins of the milk-fat globule membrane in homogenized cream have been studied using polyacrylamide-gel electrophoresis and electron microscopy. The effects of pasteurization and subsequent storage of the homogenized cream on the strength and composition of the membrane have also been investigated. Caseins and undenatured whey proteins are adsorbed to the fat–serum interface during homogenization; the caseins are the more dominant group, but with no apparent preference for any individual protein. After homogenization, but before pasteurization, whey proteins are more easily removed by washing than are the casein components. After subsequent pasteurization, and on storage, whey proteins become more tightly bound and are no longer readily removed by washing. Electron micrographs showed that the interfacial membrane between fat droplets and the serum phase consists of a protein composite material containing casein micelles, casein micellar sub-units and molecular, or non-micellar protein.