Effects of Continuous Steaming on Milling Characteristics of Two Indica Rice Varieties

Parboiling improves milling characteristics of rice in a positive manner, which has been found to influence consumers demand and acceptability. A laboratory model of continuous steaming unit was fabricated and tested with two indica rice varieties, fine (ADT39) and coarse (CO43) rice, at three different soaking temperatures (50, 60 and 70 °C) for 4 h and five residence times of steaming (1.0, 1.5, 2.0, 2.5 and 3.0 min). The effects of continuous steaming on milling characteristics of rice were studied and compared with the values obtained from the control experiment (open steaming process under laboratory conditions). The favourable conditions for continuous parboiling of the fine variety ADT39 were identified as soaking at 70 °C for 4 h and 3.0 min residence time of steaming. These conditions showed head rice outturn of 74.0%. The favourable processing conditions for the coarse variety CO43 were found to be 4 h of soaking at 60 °C and steaming of 3.0 min residence time, and at these conditions the head rice outturn was 73.9%.