Interfacial and emulsification properties of sono-emulsified grape seed oil emulsions stabilized with milk proteins

Emulsions were designed under low frequency ultrasound (20 kHz) at energy densities of 11.7–117.0 J/mL using grape seed oil and milk protein solutions containing different casein to whey protein ratios of 80:20, 60:40, 50:50 and 40:60. An increase in energy densities produced emulsions with a smaller droplet size and narrow size distribution at all milk protein ratios. However, the minimum sono-energy density required to produce stable emulsions varied depending on the ratio of caseins (CN) and whey proteins (WP) in the continuous phase. In addition, the composition of the interfacial layer was dependent on the composition of the milk proteins in the continuous phase. The interfacial layer was predominantly covered by the CN and CN-WP aggregates in the presence of equal or greater amounts of caseins than whey proteins (80:20, 60:40 and 50:50), while WP aggregates and CN-WP aggregates were the primary constituents of whey protein-rich emulsions (40:60).