Joint effects of enzymatic and high-intensity ultrasonic on the emulsifying propertiesof egg yolk

This study investigated the joint effect of the enzymatic and high-intensity ultrasonic (HIU) treatments on the emulsifying and structural properties of egg yolk (EY). The evaluation was performed under different HIU powers (i.e., 0, 240, and 480 W) and for different durations (10, 20, and 30 min). Results reveal that the emulsification activity and emulsification capacity at 240 W for 10 min significantly increase than that of the samples without HIU treatment (P < 0.05). The thermal stability reached a maximum of 90.33% in 480 W + 30 min. The HIU treatment under low power and for a short time (240 W + 10 min) reduced the average particle size of the EY to 224.77 nm. The combined treatment produced high zeta potential and total sulfhydryl contents. The highest hydrophobicity was 111.49 μg at 240 W for 20 min. The joint treatment enhanced the hardness and cohesiveness of the EY. Moreover, the α-helix content significantly decreased from 37.13% to 25.02% after the enzymatic treatment, while the β-sheet content increased with time in the 240 W treatment. The G' and G″ curves show an increasing tendency, and the highest G' and G″ were obtained in the 240 W + 30 min group, which is consistent with the dense microstructure. These results reveal that the combined treatment can improve the emulsifying characteristics, which could influence the structural properties of EY, expanding its application in the food industry.