Development, Testing and Optimization of a Screw Press Oil Expeller for Moringa (Moringa oleifera) Seeds

A screw press moringa oil expeller was developed and evaluated in terms of oil expression efficiency (OEE), material balance efficiency (MBE) and expression loss (EL). Four different models were fitted to the output variables. Maximum OEE of 81.66% was obtained at moisture content of 11% wet basis, heating temperature of 80 degrees C, heating time of 30 min and applied pressure of 20 MPa. The coefficient of determination (R-2) for the OEE was 0.77. Predicted optimum OEE of 80.62% at moisture content of 11.30% wet basis, temperature of 85.55 degrees C, time of 27.17 min and pressure of 19.64 MPa was obtained with a desirability of 0.867. Under these optimal conditions, the experimental value was 80.74%. Deviations between experimental and predicted values were low and statistically insignificant which implies the model chosen can effectively predict the OEE. Maximum MBE and EL were 95.47 and 4.53%, respectively, which shows a better conversion of input (seeds) to output (oil and cake) materials with minimal losses along the production line. However, it was observed that the mean is a better predictor for the MBE and EL than any of the models considered as the experimental values obtained were very close and statistically insignificant.