Effect of high hydrostatic pressure and retrogradation treatments on structural and physicochemical properties of waxy wheat starch

•Waxy wheat starch treated with HHP of 600MPa had the maximum SDS content of 31.12%.•HHPR treatment decreased gelatinization temperatures of waxy wheat starch.•HHPR treatment decreased gelatinization enthalpy of waxy wheat starch.•HHPR treatment decreased relative crystallinity and peak viscosity of waxy wheat starch.•HHPR treatment destroyed the structure of waxy wheat starch granules. In this study, the effects of high hydrostatic pressure and retrogradation (HHPR) treatments on in vitro digestibility, structural and physicochemical properties of waxy wheat starch were investigated. The waxy wheat starch slurries (10%, w/v) were treated with high hydrostatic pressures of 300, 400, 500, 600MPa at 20°C for 30min, respectively, and then retrograded at 4°C for 4d. The results indicated that the content of slowly digestible starch (SDS) in HHPR-treated starch samples increased with increasing pressure level, and it reached the maximum (31.12%) at 600MPa. HHPR treatment decreased the gelatinization temperatures, the gelatinization enthalpy, the relative crystallinity and the peak viscosity of the starch samples. Moreover, HHPR treatment destroyed the surface and interior structures of starch granules. These results suggest that the in vitro digestibility, physicochemical, and structural properties of waxy wheat starch are effectively modified by HHPR.