The final stream of bran and polished rice mixture at the outlet passes through the bran separator where bran particles escape through the perforations and deposited in the outer chamber of the cylinder. Partially polished rice is collected at the bottom of the system. Due to less residence time of rice inside the polisher, required degree of polishing cannot be achieved in a single pass. The collected rice was recycled for 60 times and the broken content and degree of rice polisher was measured after every 10 passes. The air escaped at the top and carried very fine bran particles with it. Experiments were conducted with brown rice of 10, 11, 12, and 13% (wb) moisture content.
Parboiling is a hydrothermal pre-milling treatment is done in tree steps, viz., soaking, steaming and drying. The main factors involved in controlling the quality of parboiling rice are soaking time and temperature; steaming pressure time and stages, tempering time and drying time, temperature stages, these factors vary from mill to mill. Although, the equipments and steps followed in most of the mills are same, yet their energy management is different.
The key function of paddy separator is to remove paddy from rice. If rice contaminated with paddy, the consumer can get a negative impression that the rice is not clean. After the separation, brown rice is sent along the conveyor chain and down to the bucket elevator which shifts rice to a container above a polisher. When the polishing step begins, rice can be released to the machine immediately.