Physicochemical properties of partially α-glucan-coated normal corn starch formed by amylosucrase from Neisseria polysaccharea.

Amylosucrase (AS) is a glycosyltransferase that produces linear alpha-1,4 glucans using sucrose as the sole substrate. In this study, for various applications, alpha-glucan-coated starch (alpha-GCS) was produced by AS (20 U/L-reactant) from Neisseria polysaccharea to improve the physicochemical properties of raw normal corn starch (NCS) by applying different reaction conditions (i.e., varying the substrate concentration, pH, and temperature). Field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) showed that raw NCS was successfully coated by alpha-glucan. Differential scanning calorimetry (DSC) and rapid viscosity analyses (RVA) of the alpha-GCS confirmed that the alpha-glucan coating decreased the degree of retrogradation. Notably, compared to raw NCS as a control, starch retrogradation was significantly (p < 0.05) decreased by 13.7% after five weeks. Therefore, the novel alpha-GCS can be applied as a functional material for controlled retrogradation in the starch-based food industry for shelf-life extension. (C) 2019 Elsevier B.V. All rights reserved.