EFFECT OF COB SIZE AND MOISTURE CONTENT ON SHELLING PERFORMANCE OF LEVER OPERATED MAIZE COB SHELLER

Abstract

The operating factors were studied for different maize shelling methods (lever operated maize sheller, octagonal tubular maize sheller and conventional beating method) that affected losses and capacity of shelling methods. The factors comprised two levels of moisture content (16-20 % and 12-16 %) and three levels of cob size (< 30mm, 30-40 mm, and > 40 mm).  The results of this study indicated that the shelling force required to detach maize grains from the unshelled cob was dependent on the grain moisture content and cob size. Highest shelling force of 173.5 N was found at moisture content of 16-20% w.b. and cob diameter > 40 mm while the lowest shelling force of (133 N) was found at cob diameter <30 mm and moisture content of 12-16% w.b. Both moisture content and cob size significantly affected shelling capacity, shelling efficiency, grain breakage and unshelled grain. Increasing the moisture content increased both the grain breakage and unshelled grain but decreased shelling capacity and shalling efficiency, respectively. The cob size affected the shelling capacity but did not affect shelling efficiency and grain breakage. The optimised shelling capacity and shelling efficiency of the lever operated maize cob sheller was 30.50 kg/h and 91.37 % at 12-16% moisture content and 30-40 mm size of cobs, respectively which was  better than the conventional beating method which has been found to have 17.56 kg/h average shelling capacity and 73.0 % shelling efficiency.