Physicochemical properties and in vitro digestibility of high hydrostatic pressure treated waxy rice starch.

Waxy rice starch slurry (10%, w/w) was treated with high hydrostatic pressure (HHP) (100-600 MPa) for 20 min and morphology, gelatinization property, X-ray diffraction pattern, semi-crystalline structure, and in vitro digestibility was determined. The morphology analysis showed that HHP treatment significantly affected the shape of starch granules. The thermal properties indicated an increase in gelatinization temperatures and decreased enthalpy with increasing pressure. However, compared with lower pressure, a complete gelatinization of starch was induced by 600 MPa. The lamellar repeat distance increased with increased pressure, while scattering peak disappeared at 600 MPa as a result of starch gelatinization. Based on the in vitro digestibility results of slowly digestible starch, HHP treatment at 400 MPa could be beneficial for improving the functionality of the waxy rice starch.