Optimization of shelling efficiency of a Moringa oleifera seed shelling machine based on seed sizes

Moringa oleifera seed is an oil bearing seed which contains substantial quantity of lipid acid. The seed is usually shelled before oil extraction. In this study the shelling efficiency of a moringa seed shelling machine was optimized based on seed sizes (small, medium and large). Response Surface Methodology was applied in the optimization of the shelling efficiency of the machine. Seed condition (moisture content), operation parameters (cylinder-concave clearance, cylinder speed and feed rate) and design parameter (cylinder bar inclination) were considered as the independent factors while the response variable was shelling efficiency. The experimental design adopted was five factors, five levels Central Composite Rotatable Design (CCRD) of second order polynomial model. The optimization of the moringa seed shelling machine has optimum moisture content, cylinder-concave clearance, cylinder speed, feed rate and cylinder bar inclination values of 13.75%,7.62 mm, 303.50 rpm, 30.00 kg/h, 42.76° for small moringa seed size; 11.75%,7.87 mm, 291.79 rpm, 29.80 kg/h, 40.0° for medium moringa seed size; 11.75%,8.00 mm, 248.65 rpm, 30 kg/h, 40.0° for large moringa seed sizes respectively. Shelling efficiencies for the three sizes (viz. small, medium and large seed sizes) have optimum values of 99.17%, 100% and 100% with desirability values of 0.73, 0.67 and 0.76 which indicated the nearness of the response to the predicted values and adequacy of models established in describing the observed values. The optimization of moringa seed shelling process showed the optimal processing conditions for small, medium and large sizes of moringa seed. The optimization of the moringa seed shelling machine would provide necessary information on combination of seed, operation and design parameters for enhanced shelling efficiency based on seed sizes.