Abstract:
In Uganda, cassava plays a major role' in food security contributing up to 60% of the basic food requirements nationally. It is mostly grown by small scale farmers cultivating about 1-3 acres of land. Cassava being highly perishable, it is urged to process it immediately after- harvesting because physiological postharvest deterioration (PPD) starts within 48 to 72 hours after harvest. PPD turns the cassava tubers to brown or black which reduces the products' acceptance by the people who want purely white dry cassava hence lowering its market. Cassava processing involves peeling, chipping, drying, roasting, crisps and chips making and flour. In Uganda, these processes are done using traditional methods and tools for example local knives, machetes, and stones. These methods produce large sized slices which still are subjected to PPD since they take long to dry, In. addition. these traditional processing methods are tedious and also expose the operators to a high risk of injuries.
To reduce tediousness and drudgery, a pedal operated cassava chipper was developed for small scale cassava growers. This produces chips about 2 to thick which dry 6-8 hours. The pedal operated cassava chipper operates using: a. local -bicycle •mechanism which is familiar 10 the biggest percentage of the rural population hence it. does not require any special training to be operated. Due to the fact that pedal power is greater than the power output by hand. the pedal operated cassava chipper has a higher output: capacity than -the hand operated chipper.
The development of pedal operated cassava chipper was achieved in the following steps/processes; design of the different components, selection appropriate materials for the Components, fabrication and assembly of the prototype and finally testing or the prototype.
The prototype-was tested for efficiency and capacity; the highest chipping efficiency of 95% Was obtained at a speed of 40rpm while the highest machine capacity was 205kg/hr at a speed of 80rpm. Analysis of values showed that at high speeds; the capacity is high but low efficiency. The overall mean of the chipping efficiency was 90.27 + 4.75% and machine capacity was 142.986 + 74.25kg/hr, The. chipping efficiency and uniformity of chips were -affected- by the age, size, shape, orientation, feed rate and pressure of the tuber contact with the chipping
Keywords; Cassava, Chipping; Pedal Machine, Capacity, Efficiency
