Factors affecting fat droplet aggregation in whipped frozen protein-stabilized emulsions

Abstract

We studied four emulsions, stabilized by milk proteins, before and after application of whipping and freezing procedure. The emulsions were different in the whey protein/casein ratio and degree of heat-denaturation before mixing with the other ingredients. The supercooling needed for detection of crystalline fat was higher in emulsions than in bulk fat, and higher in emulsions containing casein or heat-denatured whey proteins than in emulsion containing non-pre-heated whey proteins. Furthermore, emulsions with high surface protein concentration and low crystalline fat content showed greater droplet aggregation under whipping and freezing. Our results indicated that differences in sensitivity to fat droplet aggregation was not caused by differences in resistance to protein displacement from the droplet surface in thawed whipped emulsions, but by low crystalline fat content prior to whipping and freezing. Data collected in this study were discussed in terms of effects of partial replacement of ‘native’ whey proteins by casein or heat-denatured whey proteins on partial coalescence of fat droplets in whipped-frozen emulsions.