Design and Preliminary Evaluation of a Dry Cowpea Dehuller

Abstract

Cowpea dehulling is an important operation in the processing of cowpea. Traditional cowpea dehulling methods recognize the soaking of cowpea in water for a significant amount of time before manual abrasion is carried out either through the use of mortar and pestle, hands, or legs. Existing mechanical alternatives also require prolonged soaking of cowpea before dehulling occurs in addition to being expensive and beyond the reach of many rural populations. This study designed and fabricated a dry cowpea dehulling machine using engineering principles and with locally available materials. Components of the machine include the hopper, power transmission drive, dehulling chamber, polishing chamber, sieves, discharge chute, and agitator. Dry cowpea varieties of Brown Drum (15%Mc dB) and Oloyin (17.5%Mc dB) cowpea weighing 500 g each were fed into the machine at a constant speed of 358 rpm. Preliminary tests showed the “Brown Drum” cowpea variety recorded a maximum dehulling efficiency of 97.44% in 7 minutes while the Oloyin variety was completely dehulled in 7 minutes at 98.75% efficiency. The throughput capacity recorded was 450kg/hr and this machine raises the possibility of producing dry dehulled cowpea for domestic and industrial end-users.