Influence of Process Variables on a Rice De-stoning Machine

Abstract

Investigation of the effect of processing factors on a rice de-stoner is necessary to address the major challenge of stone pebbles be introduced during harvesting and post-harvest handling of rice production. In this study, three process variables (moisture content, feed regulator, and machine speed) were investigated to determine their effects on a rice de-stoner. Design expert version 11 Response Surface Methodology (RSM) was used to identify the process variables levels yielding optimum rice tray loss, impurity level after separation rice separation efficiency, stone separation efficiency, and capacity of the machine. Feed regulator had a little effect on both the tray loss and impurity level after the separation of rice. Machine speed and moisture content had a little effect on both the rice separation efficiency and the stone separation efficiency while the feed regulator and moisture content in percentage had a little effect on the machine capacity. The rice de-stoner has the optimum machine speed, feed regulator, and moisture content of 189.654 rpm, 7.307 mm, and 11.88% respectively. The tray loss, impurity level after separation, rice separation efficiency, stone separation efficiency and machine capacity have optimum values of 9.366 %, 5.713 %, 90.629 %, 72.448 % and 133.024 kg/h with the corresponding R2 values of 0.71, 0.97, 0.71, 0.96, and 0.96 respectively at desirability value of 0.713 which indicates the nearness of the response to the predicted values and adequacy of models established in describing the observed values. The optimization of rice de-stoner showed an optimal processing condition for independent parameters and the machine response variables. This research is a contribution to the improvement of the quality of Nigerian rice.