Pasting, rheology, and fine structure of starch for waxy rice powder with high-temperature baking.

Abstract

The pasting and rheological properties of waxy rice powder (WRP) with high-temperature baking (140-180 °C) and the fine structure of its starch were investigated. Rapid visco-analysis showed that the viscosity and breakdown value of baked WRP decreased obviously compared to its native counterpart, and this trend was greatly increased under higher temperature. Rheological analysis indicated that the baked WRP had relatively more elastic component compared to viscosity component but was less thixotropic than native WRP, suggesting the swelling of starch granules and the leaching of starch molecules were retarded when the WRP was baked at high temperature. Additionally, WRP was severely degraded and further re-associated and interacted with other granules during high-temperature baking. Changes in starch fine structure contributed to the alteration of pasting and rheological properties of WRP. These findings suggest that high-temperature baking induced structural changes of starch and thus reduced the viscosity of WRP.