New insights into starch gelatinization by high pressure: Comparison with heat-gelatinization.

The effects of pressure and temperature on the gelatinization properties of wheat starch were investigated. The long-range crystallinity and short-range molecular order were gradually destroyed under both conditions as the degree of gelatinization (DG) increased. With increasing DG, differential scanning calorimetry (DSC) onset (To), peak (Tp) and conclusion temperatures (Tc) increased for the heat-gelatinized samples but did not change greatly for the pressure-gelatinized samples. At similar DG, pressure-gelatinization resulted in less granule swelling than heat-gelatinization. Lower degree of both heat- and pressure-gelatinization resulted in increased pasting viscosities and gel texture parameters, whereas the opposite was noted at higher DG. We conclude that pressure and heat induced starch gelatinization in different ways, resulting in different gel texture properties. Pressure-gelatinization disrupted both less stable and more stable crystallites, whereas less stable crystallites were preferentially disrupted during heat-gelatinization.