Amylosucrase (AS), a glycosyltransferring enzyme, produces linear α-1,4 glucans from sucrose as a donor molecule. In this study, the α-glucan-coated starch (α-GCS) was produced by AS (20 U/Lreactant) from Neisseria polysaccharea to improve the physicochemical properties of raw normal corn starch (NCS) under various reaction conditions (substrate concentration, pH, and temperature). The field-emission scanning electron microscopy and X-ray diffraction showed that the raw NCS was successfully coated by α-glucan without breaking the starch granule. Differential scanning calorimetry and rapid viscosity analyses of the α-GCS confirmed that the α-glucan coating decreased the degree of retrogradation in the initial stage, and the starch retrogradation was significantly decreased to 23.1% after 5 weeks compared to the control. The results clearly suggested that physicochemical properties of raw NCS were improved by the α-glucan coating by the AS treatment on the surface. Thus, the newly synthesized α-GCS can be utilized as a functional material in the starch-based food industry for shelf-life extension via controlled retrogradation.
