Optimization of ultrasound-assisted compound enzymatic extraction and characterization of polysaccharides from blackcurrant

•An efficient UACEE procedure used to extract BCP was first investigated.•Based on single-factor experiments, the conditions were optimized by RSM further.•After preliminary purification, BCP I was characterized by HPLC, GC and IR.•BCP I showed notable α-amylase inhibitory activity. In the present study, an efficient procedure for ultrasound-assisted compound enzymatic extraction of polysaccharides from blackcurrant fruits was investigated using response surface methodology (RSM). The Box–Behnken design was applied to optimize the effects of enzyme concentration (X1), pH (X2) and ultrasonic time (X3). The statistical analysis indicated that the independent variables (X1) and the quadratic terms (X12 and X32) had significant effects on the yield of blackcurrant polysaccharides (BCP). The optimal conditions were: enzyme concentration 1.575%, pH 5.3, and ultrasonic time 25.6min. The experimental yield of BCP was 14.28±0.06%, which was closely matched with the predicted yield of 14.31%. After preliminary purification, BCP I was obtained and characterized by GC, HPLC, and IR. BCP I comprised rhamnose, arabinose, xylose, mannose, glucose, and galactose in a molar ratio of 1.818:1.362:0.377:0.501:1.581:1.722 and its molecular weight was 8146kDa. BCP I showed notable α-amylase inhibitory activity.