Design and Development of a Cowpea Decorticator

Introduction: Cowpea decorticating is a crucial post-harvest process that involves removing the seed coats from the kernels to produce ready-to-use cowpea products such as flour, grits, and protein concentrates and food products such as Akara and Moinmoin in south western Nigeria.

Methodology: In this study, a locally developed cowpea decorticator was tested and evaluated using small oloka (a Nigerian local cowpea breed) cowpea grains. The machine was allowed to run empty for five minutes before the experiment commenced. Three samples of 1kg each were weighed and wetted with same quantity of water for 10, 20, and 30 minutes, respectively. The samples were then fed into the developed decorticator running at a speed of 420 rpm, and the operating speed and time taken were determined using a digital tachometer and stop watch, respectively. Samples of decorticated, undecorticated, and broken cowpea were collected and weighed to evaluate the efficiency of the machine based on the decorticating length and wetting time of cowpea grains.

Results: The study revealed that as the decorticating length increased from 44.5 to 178 mm and wetting time increased from 10 to 30 minutes, the decorticating efficiency increased from 55 to 92.1%. The highest average decorticating efficiency of 92.1% was obtained at 178 mm decorticating length and 30 minutes wetting time.

Conclusion: These findings showed that the decorticating efficiency of the machine depends on the wetting time and the decorticating length of the machine.