Abstract:The effect of ultrasound-assisted high-pressure microfluidization on the quality of whey protein-inulin-based ginsenoside nanoemulsions was studied. With the encapsulation efficiency and average particle size of ginsenosides as evaluation indicators， response surface methodology was employed to optimize the preparation process including ultrasonic power， ultrasonic time， microfluidization pressure， and microfluidization cycles of ginsenoside nanoemulsions. Laser confocal microscopy was employed to observe the microstructure of the nanoemulsion. The antioxidant activity of the prepared nanoemulsion was assessed based on the DPPH and ABTS+ radical scavenging rates. The results indicated that the optimal conditions for preparing ginsenoside nanoemulsions were ultrasonic power of 450 W， ultrasonic time of 14 min， microfluidization pressure of 100 MPa，and 8 microfluidization cycles. Under these conditions， the average particle size of the nanoemulsion was（202.85±3.00） nm， and the encapsulation efficiency of ginsenosides was （69.32±2.21）%. Compared with the ultrasonic process alone， the combined method improved the encapsulation efficiency by 48% and reduced the average particle size by 32%. Compared with the high-pressure microfluidization alone， the combined method increased the encapsulation efficiency by 7% and decreased the average particle size by 5%. The microscopic analysis revealed that the emulsion had an O/W structure. The DPPH and ABTS+ radical scavenging rates suggested that ultrasound-assisted high-pressure microfluidization and the protein-polysaccharide composite nanocarrier system enhanced the antioxidant activity of the ginsenoside nanoemulsion. The whey protein-inulinbased ginsenoside nanoemulsion prepared by ultrasound-assisted high-pressure microfluidization exhibited superior quality. The findings suggested that ultrasound-assisted high-pressure microfluidization represented an effective method for producing nanoemulsions.