Enzymatic modification of corn starch with 4-α-glucanotransferase results in increasing slow digestible and resistant starch

In this study, partial 4-alpha-glucanotransferase (4 alpha GT) treatment was used to modulate the fine structure responsible for the slow digestion and resistant property of starch. Normal corn starch modified using 4aGT for 4 h showed an increase of slowly digestible starch from 9.40% to 20.92%, and resistant starch from 10.52 to 17.63%, respectively. The 4aGT treatment decreased the content of amylose from 32.6% to 26.8%. The molecular weight distribution and chain length distribution of 4 alpha GT-treated starch showed a reduction of molecular weight and a great number of short (DP < 13)and long (DP > 30) chains through cleaving and reorganization of starch molecules. Both the short and long chain fractions of modified amylopectin were attributed to the low in vitro digestibility. The viscosity was inversely related to the digestibility of the 4aGT-treated starch. These results suggested that the 4aGT modified starch synthesized the novel amylopectin clusters with slow digestible and resistant character. Crown Copyright (c) 2014 Published by Elsevier B.V. All rights reserved.