Abstract:Polysaccharides from Tremella fuciformis （TFP）was used as raw materials.TFP was acetylated by acetic anhydride to prepareacetylated polysaccharides from Tremella fuciformis（Ac-TFP）.Effect of reaction time，reaction temperature and the amount of acetic anhydrideon the substitution degree was investigated.Based on the single factor experiment，the acetylation modification process was optimized using response surface analysis.Antioxidant activity of TFP before and after acetylation modificationwas studied.The results revealed that the optimal conditions for the acetylation of TFP were as follows：the reaction time was 2.37 h，the reaction temperature was 61.04 ℃and the amount of acetic anhydride was 2.89 mL.The degree of substitution of Ac-TFP was 0.39 under the optimum modification conditions.Antioxidant studies showed that compared with TFP，the scavenging ability of Ac-TFP against DPPH free radicals was improved，but the scavenging abilities against hydroxyl free radicals and superoxide anion were weakened.