Elucidation of soaking and steaming duration in parboiling: effects on the physical quality and appearance of local rice cultivars

Enhancing the quality of rice grains is essential to meet consumer demand and boost farmers' income. Various factors, such as processing techniques and parboiling methods, play a crucial role in influencing the overall quality of rice grains. In this study, the effects of soaking and steaming durations on the parboiling process were studied on rice grains' physical quality and appearance. The 10 kg of paddy grains of the two most consuming cultivars (Surkha Zurati and Barah) were soaked in natural water and then steamed for 15, 20, and 25 min under two covering methods: cloth + lid and cloth. The parboiled grains were dried (12-13%) and milled for a physical quality test. The results revealed that cloth + lids increased the amount of head rice and decreased broken and chalky grain production. The maximum head rice rate was recorded for 25 min, followed by 20 and 15 min of steaming for all treatments and cultivars. The lower broken and chalky grains were recorded after 25 min of steaming (cloth + lid), and the highest values were observed after 15 min (cloth) for both cultivars. The cloth + lid method produced darker yellow grains after parboiling compared to the cloth treatments only in both cultivars. Furthermore, the rice grain darkness increased with increasing steaming duration. Hence, head rice, chalkiness, broken grains, and discoloration can be managed through parboiling. This method can be useful for rice processors to improve rice grain quality using adequate parboiling technology.