Gelatinization of cassava, potato and wheat starches in supercritical carbon dioxide

The gelatinization of cassava, potato and wheat starches in supercritical carbon dioxide was investigated using light microscope. The starch was placed in a stainless steel chamber at atmospheric pressure and high CO2 pressures, 8 and 30 MPa as well as at 8 MPa N2 and the gelatinization degree observed by light microscopy. The results showed that both pressure and supercritical fluid affected the gelatinization degree. Cassava and potato starches showed a lowering of the gelatinization temperatures at 8 MPa and an increasing at 30 MPa as compared with the gelatinization degree at atmospheric pressure. For wheat starch, the decrease in the gelatinization temperature occurred in the same direction as the pressure increased, in comparison with the atmospheric pressure conditions. However, between the two applied pressures, there was a larger increase of the gelatinization temperature at 30 MPa than at 8 MPa. The effect of hydrostatic pressure component of the CO2 was evaluated by using N2 at 8 MPa. The replacement of CO2 by N2 at 8 MPa increased the gelatinization temperature for all the studied starches compared with the atmospheric conditions.