Increasing Aureobasidium pullulans β-Glucan water solubility by carboxymethylation modification and its characterization study

β-glucan is a macromolecular polysaccharide with various biological activities. The β-glucan produced by Aureobasidium pullulans (A.pullulans) is ease separation and purification. However, the poor water solubility of A.pullulans β-glucan (A.pullulans β-G) hindered its subsequent processing and application. In this study, carboxymethylation modification was developed to improve the water solubility of A.pullulans β-G. The optimal conditions for carboxymethyl modification were as follows: alkalization temperature 50 °C, carboxymethylation time 3.0 h, and carboxymethylation temperature 65 °C. Under these conditions, the maximum carboxymethyl substitution degree is 0.662 and solubility was improved from 4.86 g/L to 28.70 g/L. The structure of carboxymethylated A.pullulans β-G (CM-A.pullulans β-G) were characterized. And also carboxymethylation modification improved the antioxidant and hypoglycemic activity of A.pullulans β-G.