LAUSR

Amylosucrase from Neisseria ploysaccharea (NpAS) was applied to modify waxy corn starch (WCS) and irradiated WCS, whose attenuated digestibility was studied. Herein, the mobility of the reaction mixture did not affect the enzyme catalytic efficiency, and the reaction kinetics suggests that the enzyme elongated the starch chain via a zipper reaction mode. The A-type crystalline structure of native and irradiated WCS was changed to B-type after NpAS treatment, and a longer chain length led to a further increase in gelatinization temperature. Chain elongation increased the content of resistant starch (RS) from 22.3% (native WCS) to be as much as 64.4% for NpAS-modified WCS, accordingly decreasing the contents of both rapidly and slowly digestible starches. Pearson correlation analysis implies that the RS content of NpAS-modified starches was positively and negatively correlated to the proportion of intermediate chains (13 ≤ DP ≤ 24) and short chains (DP ≤ 12), respectively.