Different physicochemical properties of entirely alpha-glucan-coated starch from various botanical sources

Abstract

Amylosucrase from Neisseria polysaccharea (NpAS) synthesizes alpha-1,4 glucan polymer from sucrose. In this study, we coated various botanical sources of raw starch with an alpha-glucan layer generated by NpAS to improve physicochemical properties. Field-emission scanning electron microscopy demonstrated that all surfaces of the starch granules were successfully coated via the NpAS reaction. X-ray diffraction analysis revealed that the crystallinity decreased and the crystal pattern changed to C-type as an amylose layer formed around the surface of the starch granules. Based on rapid viscosity and differential scanning calorimetry analyses, the gelatinization resistance of the alpha-glucan-coated starch increased owing to decreased viscosity and increased melting temperature. Therefore, the alpha-glucans coated the starches by enzymatic reactions of various botanical sources; these have applicability in the food and starch industries owing to various physicochemical properties such as enhanced thermostability.