Hydrothermal treatment under pressure on head rice yield and other quality attributes of Indica and Japonica rice cultivars

In the present study, two popular rice varieties in China, Rong Youhua Zhan (RYZ), and Huaidao5 (H5) were selected for experimentation. Two initial soaking temperatures (40°C and 70°C) for 30, 90, and 180 min followed by steaming at elevated pressure 1 kg/cm2 (121°C) for 5, 10, and 15 min were used to parboil paddy. The head rice yield (HRY), hardness, cooking time, water absorption, whiteness, and color (b-value) were used as quality indicators in parboiling paddy. Furthermore, sensory analysis was performed to find optimum condition for both rice varieties and compared with their normal milled rice. It was observed that HRY was varied from 68.67% to 87.46% and 70.97% to 79.53% at 40°C soaking temperature, similarly, at 70°C soaking temperature, it varied from 82.89% to 95.76% and 83.99% to 94.48% for 5-15 min steaming at 1 kg/cm2 pressure in RYZ and H5 varieties respectively. Sensory analysis and other quality indicator showed that soaking at 70°C for 180 min followed by 15 min steaming and 70°C soaking for 90 min followed by 10 min steaming showed the best quality for Indica RYZ and Japonica H5 rice varieties respectively. Moreover, paddy treated at these conditions achieved the highest score in the sensory analysis by panelists. © 2018, Asian Association for Agricultural Engineering. All rights reserved.