Digestion properties of corn starch modified by α-D-glucan branching enzyme and cyclodextrin glycosyltransferase

Corn starch was modified using alpha-D-glucan branching enzyme (GBE) and cyclodextrin glucosyltransferase (CGTase), and their in vitro digestibility were investigated. Compared to native corn starch and single-enzyme treated starch, dual-enzyme modified starch had higher amount of slowly digestible starch (SDS) and resistant starch (RS) contents. The chain length distributions and the ratio of alpha-1,6 linkages of the dual-enzyme modified starch indicated an increase in short side-chains (DP < 13) as well as branching degree, compared with control starch (corn starch treated without enzyme). Cyclodextrins formed in starch modified reaction was found to complex with branched amylopectin clusters by hydrogen bonding and other intermolecular forces, showing V-type X-ray diffraction pattern. The presence of the crystalline regions of dual-enzyme modified starch favored digestion rate reduction, which may give some useful reference for the development of modified starch with slow digestion property.