Abstract: In an effort to solve the problems of low yield and unstable quality during the processing of blackberry juice, response surface methodology was used to optimize the conditions for ultrasonic-assisted enzymatic processing of blackberry juice (with a mixture of pectinase and commercial enzyme preparation for juice processing). Moreover, the synergistic effect of ultrasonic and the enzymes on improving juice quality was analyzed. The results showed that the optimized process conditions were as follows: ultrasonic power, 200 W; enzyme concentration, 0.3%; hydrolysis time, 1.5 h; and temperature, 45 ℃. A higher juice yield of 80.89% and 68.21% transmittance were obtained under these conditions. The quality and stability analysis showed this juice had higher contents of anthocyanin and total phenols, and displayed a red color with better stability during storage as compared to enzymatic hydrolysis alone. Additionally, the results of scanning electron microscopy indicated that ultrasonic and the enzymes had a synergistic effect on destroying the cell structure of blackberries, thus increasing the efficiency of juice processing.

Key words: blackberry, ultrasonic-assisted enzymatic hydrolysis, synergistic effect, response surface methodology, anthocyanin