Surface properties of the fat globule in treated creams

Surface properties and susceptibility to lipolysis by a generic lipase were studied on raw cream, pasteurized cream and UHT-treated, homogenized cream. Heat treatments did not modify extensively the structure of the fat globule membrane, either in terms of its surface properties or of the nature of the associated proteins. Homogenization of cream resulted in markedly increased susceptibility to the lipolytic action of added enzymes, and was accompanied by extensive modifications of the surface properties. The protein composition of the milk fat globule membrane in treated cream was different from that reported when cream was isolated from treated milk. Attempts at discriminating commercial creams on the basis of lipolysis and surface hydrophobicity indicated that measuring the susceptibility to lipolytic action could discriminate pasteurized, non-homogenized cream from UHT-treated, homogenized cream, while estimating surface properties did not allow such differentiation.