Extraction and Polymerization Degree Distribution of Inulin from Jerusalem artichoke and Anti-Oxidation Activity Study

Abstract:

To compare the extraction rates，polymerization degree distribution and antioxidant properties，inulin was extracted from fresh Jerusalem artichoke via hot water，enzyme-assisted，ultrasound-assisted and microwave-assisted hot water respectively. Polymerization degree analysis of different the inulin extracts were assessed by Milipore with different molecular weight cut，and their own antioxidant activity were evaluated in vitro by radical scavenging assay such as DPPH、?OH and O2-?. The results of the experiment showed that the optimal process conditions were 1 g∶20 mL of Jerusalem artichoke and the microwave at 800 W for 6 min，before water at 80 ℃ for 120 min，and the highest extract ratio of inulin was 15.35% in these conditions. The average degrees of inulin extracted by ultrasound-assisted and microwave-assisted technology are lower than that extracted by the traditional hot water and enzyme-assisted technology. Specifically，the polymerization degrees from 30 to 60 had decreased from 32.5% to 28.6% and 16.5%，and the polymerization degrees above 60 had decreased from 13.6% to 6.8% and 3.6%. Experimental results suggested that inulin had some antioxidant ability in vitro and there is dose-effect relation. Especially it is important to note that the antioxidant capacity of inulin varies with different extraction techniques，and the inulin sample extracted by microwave-assisted technology had relatively strong scavenging capability to reactive oxygen species.