Abstract:The effect of three different methods, including ultrasonic extraction,enzymatic extraction and ultrasound-assisted enzymatic extraction, and the extraction of sour jujube juice was optimized. Moreover, the total phenol, total sugar content and antioxidant activity of the extracts were compared. The response surface method was used to optimize the extraction process, and the antioxidant activity of jujube juice was evaluated by ABTS scavenging, DPPH scavenging and hydroxyl radical scavenging test. The results demonstrated that under the control of the optimal conditions, the extraction rates of ultrasonic method, enzymatic method and ultrasonic-assisted enzymatic hydrolysis were 67.37%, 69.47% and 74.49%. The optimal ultrasonic-assisted enzymatic hydrolysis extraction technology was: liquid-solid ratio 131 (mL/g), enzyme amount 2.1% (based on the total weight of pulp powder), enzymolysis time 1.2 h, ultrasonic time 29 min, and ultrasonic power 146 W. Different extraction methods had no significant effect on the total phenolic content in jujube juice. Compared with ultrasonic and enzymatic methods, ultrasonic assisted enzymatic method could significantly increase the total sugar content in jujube juice. The antioxidant test showed that the jujube juices of different extraction methods had high antioxidant activity, and the antioxidant capacity of the jujube juice extracted by ultrasound-assisted enzymatic method was higher than the other two ones. This indicated that the ultrasonic assisted enzymatic hydrolysis method could be used as a method for efficiently extracting water-soluble substances from jujube pulp.