Effects of milk protein type and pre-heating on physical stability of whipped and frozen emulsions

Various milk protein mixtures were used to manufacture complex emulsions differing by their total protein concentration (1, 2.25 and 3.5%) and by their weight proportion of casein (from 0 to 75%) or whey proteins (WP) (containing from 10 to 80% beta-lactoglobulin). Beside those changes in protein concentration and composition, impact of milk protein heat treatment, which was applied before emulsification, was also investigated. The resulting structuration effects on the corresponding emulsions were determined through changes in the particle size distribution and in the amount of adsorbed protein at the fat globule surface. Furthermore, fat destabilisation under a whipping and freezing steps was underlined as functions of the processing parameters (protein concentration and composition, and application or not of an additional heat treatment), and it was discussed in terms of the resulting amount of displaced protein from the oil-water interface. (C) 2003 Elsevier B.V. All rights reserved.