Abstract: In this study,we applied enzymatic extraction technology to solve the problem of low recycling of Jerusalem artichoke pulp,which comes from waste in the industrial production of Jerusalem artichoke inulin,and then evaluated the antioxidant activity of inulin from Jerusalem artichoke pulp.The enzymatic extraction process was optimized by using response surface methodology,and the optimum parameters were as follows:pH4.5,extraction temperature 50 ℃,pectinase-substrate ratio 7.5 U/g,extracting time 2 h.The yield inulin from Jerusalem artichoke pulp was 35.30%±0.85% by using optimized enzymatic extraction process,which is 38.16% higher than that by traditional hot water extraction.Subsequently,we comparatively analyzed the chemical composition and antioxidant activity of primary water-extracted inulin (PWI) and secondary enzymatic-extracted inulin (SEI).The results showed that the total sugar and inulin contents of SEI were significantly higher than those of PWI (P< 0.05).Compared with PWI,SEI contained more inulin with six and higher polymerization,but less sugarcane trisaccharide and sugarcane tetrasaccharide.Furthermore,the antioxidant activity of SEI was superior to PWI,according to the total antioxidant capacity,DPPH,hydroxyl and superoxide anionradicals scavenging activity,Fe²⁺-chelating ability and reducing power assays.Therefore,pectinase-enzymatic extraction method has the potential to be a new solution for the problem on reutilization of inulin of Jerusalem artichoke pulp in the inulin industry.

Key words: Jerusalem artichoke pulp, enzymatic extraction, response surface methodology, chemical composition, antioxidant activity