Complex formation between starch and stearic acid: Effect of enzymatic debranching for starch

•Debranching enhanced the formation of starch/stearic acid complexes.•There was an optimum starch chain length for starch/stearic acid complexes.•The complex involving helices among amylopectin residue or amylose and stearic acid.•Complex yield of stearic acid could reach 89.31% by debranching process.

Effect of debranching for a high-amylose starch (∼70% amylose) on its V-complex formation with stearic acid was examined. Gel-permeation chromatograms showed that amylopectin was degraded to smaller molecules as the debranching time increased from 6 to 24 h. Increased formation of debranched starch/stearic acid complexes (recovery yield of stearic acid from 45.17 to 89.31% and starch from 39.92 to 55.43%) was observed with increased debranching time (from 6 to 24 h) and complexation time (from 6 to 24 h). The X-ray diffraction patterns of the debranched starch/stearic acid complexes displayed a mixture of B-type and V-type patterns, with 2θ peaks at 7.6°, 13.1°, 17.2°, 20°, 21.6°, and 23.4°. The melting temperature and enthalpy changes of the debranched starch/stearic acid complexes were gradually enhanced with increasing debranching time. These results suggest that starch can be modified by debranching to produce a significant amount of debranched starch/stearic acid complexes.