Abstracts

Parboiling is a common rice processing operation, particularly in West Africa. Current traditional parboiling practices have high energy and labour demands leading to environmental and health problems. The objectives of this study were to design and build improved rice parboiling pilot plant for operation in a rural context and to characterize the operational efficiency of the system. The system consists of an improved heating stove, perforated soaking baskets, steaming/parboiling vessels and a mechanical hoist. The soaking baskets are placed in a circular setting such that the central mechanical hoist can lift and manoeuvre them around a circle that includes the stove with parboiling vessel. The system is designed to operate successively in order to manage operation efficiently. Batches of rice paddy are processed consequently reducing the time and fuel it takes to fire-up the stove. The use of a hoist avoids the necessity for manual handling and keeps the hoist operator away from the heated stove. Only one stove that is maintained at high temperature is used to do multiple tasks: parboil rice paddy, boil water for soaking and cleaning. To characterize the soaking process, different initial soaking temperatures (70, 80 and 90C) were tested. Moisture content and temperature of the soaked paddy were monitored hourly throughout a 12 hr period. During the parboiling process, temperature readings were recorded at 5 min intervals to assess uniformity of steaming. Because the stove ran continuously throughout the day, it consumed 40% less wood during a high-power phase hot start than a cold start and took 60% less time (~40 mins) to boil water than a cold start. Overall, the improved rice parboiling pilot plant reduces high energy use and manual labour by mechanization and creating opportunities for employment and local investment. L'tuvage est une opration courante de transformation du riz, en particulier en Afrique de l'Ouest. Les pratiques traditionnelles d'tuvage ont une forte demande en nergie et en main-d'uvre entranant des problmes d'environnement et de sant. Les objectifs de cette tude taient de concevoir et de construire un systme pilote amliore d'tuvage du riz pour l'exploitation en milieu rural et de caractriser l'efficacit oprationnelle du systme.Le systme se compose d'un foyer de chauffage amlior, passoire de trempage perfors, marmites de trempage/tuvage et un levier mcanique. Les paniers de trempage sont placs dans un arrangement circulaire tel que le levier central peut les soulever et les manuvrer autour d'un cercle qui inclut le foyer avec le rcipient du riz tuv. Le systme est conu pour fonctionner successivement afin de grer efficacement l'exploitation. Des lots de riz sont traits en consquence rduisant le temps et le combustible qu'il faut pour le feu. L'utilisation d'un levier vite la ncessit d'une manipulation manuelle et maintient l'oprateur du levier hors du foyer rchauff. Un seul foyer qui est maintenu haute temprature est utilis pour faire deAdvisors/Committee Members: Michael O Ngadi (Internal/Supervisor), Robert Kok (Internal/Cosupervisor2).