DESIGN MODIFICATION AND PERFORMANCE EVALUATION OF CASSAVA MASH FRYING MACHINE WITH RECIPROCATING PADDLES

Abstract

A machine for gari frying was designed, fabricated and tested. The major component of the machine include the base fryer, hopper, wooden paddle, shaft, frame, driving mechanism, and discharge outlet. The machine is powered by a three-phase (20rpm-100rpm) 1.41kw electric motor (variable speed reduction gear motor) connected to the mains through a control box which controls the movement of the wooden paddles to a reciprocating system. Electricity was used as a source of heat energy required for the gari frying. The time of frying sieved cassava mash was evaluated at four different operating speeds of wooden paddles (10rpm, 20rpm, 40rpm, 60rpm), and three different quantity of mash (5kg, 7.5kg, 10kg). Also, change in mash temperature and trough temperature with time was evaluated. The optimum speed for the fryer was 20rpm which gave gari of 12.2% final moisture content from the initial moisture content of 40.2% at the twenty four minutes of frying while frying temperature was 118oC using electricity as source of heat energy. The throughput capacity and functional efficiency evaluated at an optimum operating speed of 20rpm were 71.6% and 19.7kg/hr respectively. The product (that is gari) obtained at the end of operation was good for human consumption. The two main aims of frying gari (called Garrification) were achieved, that is the safe cooking and the reduction of moisture content (MC) to a storage level. The machine can be used by the small and medium scale farmers and it can complement emerging mechanized methods of cassava processing which include: washing, peeling, grating, dewatering, fermenting, press and sieving.