The structure of high molecular weight dextrins obtained from potato starch by treatment with Bacillus macerans enzyme

Abstract

Bacillus macerans enzyme (BME)-derived high molecular weight dextrins, which are by-products in the course of the industrial production of cylodextrins, were isolated and their chemical structures were characterized.

Dextrin I was obtained in a yield of about 24% from BME-hydrolyzate (a mixture of dextrin and cylodextrins, 50% each) of potato starch by fractionation with an ultrafiltrator having a membrane of cut-off molecular weight 2.0 × 10⁴. Dextrin II was obtained in a yield of about 15% from BME-hydrolyzate (a mixture of dextrins and cyclodextrins, 70 : 30) of Dextrin I by the same method.

Dextrin I and II consisted of dextrin having molecular weights over 20 × 10⁶ and dextrins having molecular weights 4 × 10³−1 × 10⁵ in the ratio of 80 : 12 and 66: 15, respectively.

The results of hydrolysis by β-amylase and methylation analysis indicated that the average, exterior and interior chain lenghts of the dextrins having molecular weights over 20 × 10⁶ and 4 × 10³−1 × 10⁵ from Dextrin I were 16.5, 8.2 and 7.3, and 11.5, 6.9 and 3.6, respectively, than those from Dextrin II were 13.6, 4.7 and 9.9, and 10.4, 5.1 and 4.3, respectively.