In structure and in-vitro digestibility of waxy corn starch debranched by pullulanase

Abstract

Waxy corn starch (WCS) debranched by pullulanase was used to prepare starches with different debranching degrees. The effects of debranching degree on in vitro digestibility and structural properties of WCS were investigated. Pullulanase debranching of WCS decreased rapidly digestible starch (RDS), and increased slowly digestible starch (SDS; from 2% to 23%) and resistant starch (RS; from 13% to 19%) contents, with increase in debranching degrees. Weight-average molecular weights of debranched starches (determined using gel permeation chromatography) decreased from 450 kDa to 100 kDa, which were considerably smaller than WCS. X-ray diffraction patterns of debranched and B-type starches were almost similar, confirming that debranched starches contain partially ordered crystalline structures. SDS contents of debranched starches can be increased by increasing debranching degrees and provides useful information for the application of debranched starches in food industries.