Physicochemical, structural properties and in vitro digestibility of pea starch treated with high hydrostatic pressure†

The influence of high hydrostatic pressure (HHP) treatment at 150, 300, 450, 600 MPa for 25 min on the physicochemical, structural properties and in vitro digestibility of pea starch was studied. Compared to native and pea starch treated at 150-450 MPa, the morphology of pea starch at 600 MPa was completely destroyed and particle size became larger, indicating complete gelatinization. The X-ray diffraction results showed that the native pea starch was gradually changed from C-type into B-type pattern after 150-600 MPa HHP treatment. At 30-70 °C, pea starch treated at 600 MPa had higher water absorption index (p < 0.05), swelling power and solubility than other samples did, but opposite results were obtained at 90 °C. The RVA (Rapid Visco Analyzer) results indicated that pea starch treated with high pressure at 600 MPa showed lower values of peak viscosity, trough, breakdown, final viscosity and setback (p < 0.05), reflecting lower retrogradation. Gelatinization temperatures and enthalpy determined by DSC (Differential Scanning Calorimetry) decreased with increasing pressure. Furthermore, the in vitro digestibility of HHP treated pea starches was lower than native pea starch (p < 0.05). Therefore, it is an effective method for HHP treatment to modify the properties of pea starches.