Abstract:
The need for an effective and complete mechanised system for peeling and washing cassava tubers is of high importance to post-harvest technological processing of cassava tubers. The studies of past works revealed that the problems faced by effective peeling of cassava tubers are yet to be eradicated. In other to reduce this problem, this research devised a unique and highly effective method to tackle the long persisting problems faced by mechanical peeling of cassava tubers. In line with this, a mechanised system for cleaning, peeling and washing cassava tubers was developed and evaluated in the department of Agricultural and Environmental Engineering, Federal University of Technology Akure, Nigeria. The machine consists of three sections, cleaning section, peeling and washing section. The cleaning section of the machine utilizes a belt conveying system that was set with stationary knives for the purpose of accumulated earth removal and pre-peeling of the tubers. The washing section utilizes gravitational and pressurized washing techniques. The washing system adopted recirculation techniques where the used water was filtered to ensure water conservation and quality control. The cleaning and the washing section of the machine were evaluated using harvested tubers at five different belt conveyor speeds 40, 45, 50, 55 and 60 rpm on day 1 to 3 after harvest with 1.0 hp electric motor. The mechanism of cleaning and washing techniques were described. Data collected from preliminary experiments on the basis of these principles were used to validate the expression. Result shows that cleaning efficiency of the belt conveying system and washing efficiency of gravitational and pressurised washing was significantly affected by machine rotational speed. The washing system assisted the cassava peeler to have <1% peel retention. The expression developed predicts washing efficiency of mechanised cassava peeling, cleaning and washing machine. The average washing and cleaning efficiency recorded on gravitational washing system were 98.10 % and 95.54 %. The average washing and
cleaning efficiency recorded on pressurised washing system were 98.90 % and 97.87 %. The average cleaning efficiency recorded on belt conveying system was 51.00 %. Moreover, the conveying and throughput capacity of the belt conveying systems at optimum designed velocity of 50rpm were found to be 428 kg/hr and 440.69 kg/hr respectively. Similarly, the gravitational and pressurised washing system discharge capacities were 1098.0 kg/hr and 1479.6 kg/hr respectively. Pressurised washing system washed 53.89 kg of tubers with 150 liters. The cost of a mechanised system for cleaning, peeling and washing cassava tubers was estimated at about #211000.
