Abstract: Aiming to solve the problems of low juice yield and poor quality in the processing of Rhodomyrtus tomentosa fruit juice, the process conditions of ultrasonic-assisted enzymatic hydrolysis were optimized by response surface method, and then the quality of R. tomentosa fruit juice was evaluated. The results showed that the optimal processing conditions for R. tomentosa fruit juice were as follows: pectinase∶cellulase 1∶3, enzyme dosage 0.45%, enzymolysis temperature 50 ℃, enzymolysistime 1.5 h, ultrasonic power density 16 W/L. Under these conditions, the juice yield of R. tomentosa fruit was 75.13%, and the light transmission rate was 74.20%. Among the fruit juices prepared by four methods, namely the treatment without ultrasound wave and enzymes, enzymolysis treatment alone, ultrasound wave treatment alone, ultrasonic-assisted enzymatic hydrolysis treatment, the fruit juice prepared by ultrasonic-assisted enzymatic hydrolysis treatment had the highest juice yield, light transmission, soluble solids and nutrients, while the fruit juice prepared by enzymolysis treatment alone had the strongest antioxidant activity and the highest sensory score.

Key words: Rhodomyrtus tomentosa, fruit juice, enzymolysis, ultrasound wave, quality evaluation