Effect of high pressure on some physicochemical properties of several native starches

The impact of high pressure treatments (HPT) on some physicochemical properties of normal corn, waxy corn, wheat, and potato starches were studied. Three high pressure treatments were applied: HPT1 (740–880 MPa from 5 min to 2 h), HPT2 (960–1100 MPa for 24 h) and HPT3 (1500 MPa for 24 h). Using differential scanning calorimetry (DSC), it was found that the gelatinization temperature of starch was lowered by 3.0–6.6 °C after high pressure treatment and the corresponding gelatinization enthalpy was also reduced. In addition, these changes were irreversible and maintained during storage at 25 °C for up to 6 months. However, the birefringence of native and high pressure treated starch was not visually different in polarized light. For starches of same biological origin, their X-ray diffraction patterns were also similar. Using scanning electron microscopy (SEM), it was revealed that the high pressure treatments altered the shape of starch granules and changed their surface appearance.