Quality characteristics of milled and cooked rice affected by hydrothermal treatment

A factorial design was used to determine the effects of hydrothermal process conditions on parboiled rice quality. The effect of temperature, heating time and tempering on head rice yield (HRY), translucence index (TI) and rupture force (RF) of milled grain was investigated. The effect of tempering and cooking time on texture profile analysis (TPA) of cooked parboiled rice was also studied. The quality indexes increased with tempering. A significant effect of heating time on RF and TI indexes was observed, while temperature affected mainly RF and TI quality indexes. The optimum conditions included tempering after soaking (24 h at 25 °C) and heating at 85 °C (174.4 min) or 93.7 °C (45 min). The rice presented intermediate values of textural properties between raw and traditional parboiled rice. It means less hard than traditional parboiled rice and less sticky than raw rice.