Performance Study of Modified Rice Parboiler

A small-scale rice parboiling system, developed in the National Cereals Research Institute (NCRI), was modified by a combined team of engineers of NCRI, Japan International Cooperation Agency (JICA), DESFABENG Co. Ltd and the Federal Ministry of Agriculture and Natural Resources, Nigeria. The system has a capacity to parboil 1000kg of rice per batch of over 8hours process time. This process duration is a combination of 6hours soaking, 1 hour 45 minutes steaming and 30 minutes packing. The equipment is comprised of a boiler and steaming sections, which are interconnected by a network of pipes to allow hot water and steam to soak and steam the paddy. The original design of the system had problems of uneven steaming and over-steaming, which usually results in variations in the coloration of processed rice, thereby making it unattractive to buyers. Also, longer cooking durations with attendant loss in flavor of the rice were observed. In order to solve this problem, the parboiling system was modified by incorporating additional steaming pipes at half of the height of the original design to reduce the distance travelled by the steam to get to the top of the system. The modified model drastically reduced the steaming duration of paddy from 1 hour 45 minutes to 45 minutes, thereby eliminating the problems of variations in coloration and longer cooking duration.