Abstract: In order to obtain dextran with specific molecular mass, dextranase was used to hydrolyze dextran and compared with the traditional acid hydrolysis method. The experimental results showed that both enzymatic hydrolysis and acid hydrolysis could control the molecular mass of dextran, the distribution coefficients of the products were within a reasonable range, with good homogeneity. The enzymatic hydrolysis occurred fast under mild reaction conditions at about 50 ℃, and the products had no chloride ion residue. At about 90 ℃, the acid hydrolysis was carried out at a high reaction rate, but it needed a large amount of acid and alkali, with high energy consumption and serious pollution, and the level of chloride ion residue in the products was 5.89%. Therefore, compared with the acid hydrolysis, the enzymatic hydrolysis had the advantages of lower energy consumption, less pollution and no chloride ion residue, which provides a strong basis for the potential of the enzymatic method as an alternative to the acid method to produce dextran with specific molecular mass.

Key words: dextran, dextranase, acid hydrolysis, enzymatic hydrolysis, weight average molecular mass