Shelling and characterisation of the technical parameters of a shea nut (Vitellaria paradoxa) shelling machine in Cameroon

Abstract

Producers of shea kernels encounter difficulties in processing the nuts. This leads to greater losses of raw material and a reduction in the yield of shea butter, as processing is generally done manually by smallholders, who produce more shea kernels in local areas. Added to this is the arduous work involved in shelling, due to the lack of a shelling machine adapted to their level of production. This study was, therefore, carried out to improve local shea butter production capacity. The huller was designed using data on the physical, gravimetric, geometric and frictional properties of shea nuts, before being built and tested. The hopper has an angle of inclination of 62.64°, a concave clearance of 3.6 cm and a winnowing air flow rate of 0.53 m³/s. The machine has an hourly capacity of 136 kg/h. The performance test showed that moisture content had a significant influence on hulling efficiency, cracking rate and machine output. The best cracking rate of 3.68±0.74% was obtained with a moisture content of 10.24%. The hulling efficiency obtained with the above
content is 92.43±1.05%, a cleaning efficiency of 78.30±0.55% and a machine yield of 88.83±0.38%. Water contents of < 10.24% are ideal for better shelling efficiency.