INFLUENCE OF MILK PROTEIN COMPOSITION ON PHYSICOCHEMICAL AND MICROSTRUCTURAL CHANGES OF SONO-EMULSIONS DURING IN VITRO DIGESTION

The influence of different milk protein compositions (casein to whey protein ratios - C:W) on the physicochemical and microstructural properties of sono-emulsions during in vitro digestion was determined. Emulsions were prepared using 10% (v/v) grape seed oil and 3.3% (w/v) milk protein solutions containing different C:W ratios of 60:40, 50:50 and 40:60 and milk protein isolate and whey protein isolate (as controls) using low frequency ultrasound. All the emulsions showed significantly different digestion behaviours at both stomach and intestinal digestion. The stomach digestion is influenced by the composition and nature (native, unfolded or aggregated) of milk proteins at the oil-water interface which was decided by the initial emulsifier composition in the emulsion. The intestinal digestion behaviour was governed by the outcome of stomach digesta: oil droplet size, microstructure and interfacial composition. Different C:W ratios had significant effects on in vitro digestion of and these suggestions may be useful during the fabrication of milk protein-based emulsions.