Effect of moisture content, operating speed and mash quantity on the performance of a combined dewatered cassava mash lump pulveriser and sifter

Abstract

A combined dewatered cassava mash lump pulverising and sifting machine was developed to determine the effect of moisture content, operating speed, and mash quantity on the performance of the machine using historical data experimental design of response surface methodology. The independent variables of the experiments were moisture content, operating speed, and mash quantity, while the dependent variables were sifting efficiency, input capacity, and output capacity for both 3 and 5 mm aperture sieves. The results of the analysis revealed that sifting efficiency for 5 mm aperture sieve ranged from 78.8 to 89.0 %, sifting efficiency for 3 mm aperture sieve ranged from 62.8 to 79.9 %, input capacity ranged from 232.29 to 405.25 kg/hr, output capacity for 5 mm aperture sieve ranged from 56.2 to 97.4 kg/hr, while output capacity for 3 mm aperture sieve ranged from 45.10 to 87.8 kg/hr. Also, the independent variables were significant (p<0.05) on each dependent variable. In addition, from the model summary statistics, the adequacy of best fit of the model was obtained from the highest value of coefficient of determination (R²), and the least value of standard deviation (SD) and Predicted Residual Sum of Squares (PRESS) values. The respective R², SD, and PRESS values of 0.9759, 0.55, 13.44 for sifting efficiency for 5 mm aperture sieve; 0.9165, 1.52, 114.71 for sifting efficiency for 3 mm aperture sieve; 0.9828, 6.98, 2440.04 for input capacity; 0.9885, 1.57, 103.41 for output capacity for 5 mm aperture sieve; and 0.9847, 1.90, 155.91 for output capacity for 3 mm aperture sieve were obtained. Therefore, from the results obtained, the machine is recommended for small and medium scale gari processors.

Keywords: pulverising, sifting, model, input capacity, output capacity, efficiency, aperture sieve