Abstract:To detect the antioxidant activity in vitro of carboxymethyl glucan(CMG) with different degree ofsubstitution(DS),and the preparation technology of carboxymethyl yeast glucanwith best antioxidant activity invitro.The effect in degree of substitution on antioxidant activity of carboxymethyl glucan in vitro were investigatedby scavenging hydroxyl radicals,ABTS+ ·,and chelating Fe2+ .On the basis of single factor experiment,a mathematical model was established using Box-Behnken Design in response surface methodology to determinethe preparation process of carboxymethyl glucan with a degree of substitution of 0.8. Combined with the antioxidantactivity in vitro and the actual production situation,the results showed that carboxymethyl glucan witha degree of substitution of 0.8 was determined to optimize.The preparation process of carboxymethyl glucan)with the degree of substitution of 0.8 was that the mass ratio of sodium hydroxide to glucan was 3.2,the massratio of chloroacetic acid to sodium hydroxide was 1.5,carboxymethylation reaction time of 2.0 h,alkalizationreaction time of 1.5 h.Under the above conditions,the degree of substitution of carboxymethyl glucan was 0.784.