Abstract:Auricularia auricula polysaccharide was obtained by water extraction and alcohol precipitation，and degraded by trifluoroacetic acid（TFA）.The degradation conditions were optimized by single factor and response surface tests.After purification，the polysaccharide was purified by high performance gel permeation chromatography，infrared spectroscopy，and high performance liquid chromatography.The molecular weight，infrared spectrum，and monosaccharide composition were determined，and the antioxidant activities of the degraded polysaccharide in vitro were determined.At a TFA concentration was 0.8 mol/L，temperature of 78.2 ℃，and degradation time of 2.1 h，the DPPH radical scavenging rate of polysaccharide was 70.37%.The yield of TFA degradation was 73.89%.After degradation，the molecular weight of A.auricula polysaccharide changed from 148.2 kDa to 37.5 kDa.There were no significant changes in the structure of characteristic functional groups and monosaccharide composition.The data provided an experimental basis for molecular modification of A.auricula polysaccharide.