Effects of heat-moisture treatment on physicochemical properties of wheat starch

Heat-moisture treatment is a physical method for starch modification to improve its functional properties depending on the application. The functional characteristics of the heat-moisture treated starch depend upon the source of starch and treatment conditions including time and temperature. The main objective of this study was to determine the functional properties of heat-moisture treated wheat starch under different conditions. Therefore, wheat starch was heat-moisture treated at 105 °C for 14 and 16 h and the physicochemical properties of the starch were studied. The results showed that the heat-moisture treatment caused the formation of some cracks and spots on the surface of the starch granules, while preserving the whole integrity of the granules. The water solubility of the samples increased after modification while increasing the treatment time had negative effects on it. The x-ray diffraction pattern of the samples remained unaffected but the degree of crystallinity increased significantly. The gelatinization temperature increased while the enthalpy of gelatinization decreased as a result of modification. Gel texture became harder, less adhesive and elastic after modification. Increasing the treatment time dramatically enhanced all these properties.