Effects of Machine Operating Parameters on the Grating Time of a Double-Action Cassava Grater with Automated Contact Plate: A Response Surface approach

Processing time needs to be considered as an essential attribute of an agricultural product processing system. Therefore, the effect of machine operating parameters on the grating time of a double-action cassava grater with automated contact plate was studied. A 2 × 5 central composite rotatable design of response surface methodology was adopted for the experiments. The machine operating parameters were conveying time and contact plate control timing, at grating speeds of 765 , 865 and 965 rpm . The grating time at each grating speed and the minimum overall grating time were evaluated. Data obtained were analyzed using multiple linear regression at p = 0.05. The grating time ranged from 211–412, 188–383 and 158–353 s at grating speeds of 765, 865 and 965 rpm, respectively, while the minimum overall grating time of 158 s was obtained at conveying time, contact plate control timing and grating speed of 3.19 s, 5.85 s and 965 rpm, respectively. The numerical optimization employed, with the aim to minimize the grating time revealed optimal values of conveying time of 6.67 s, contact plate control timing of 5.85 s and grating speed of 865 rpm for the optimum grating time of 158.74 s at the desirability of 0.9289. The mathematical models relating machine operating parameters to grating time were developed. Coefficient of determination ( R^2 ) for the grating time at 765, 865 and 965 rpm was 0.99 , 0.99 and 0.99 , respectively. The deviation between experimental and predicted values ranged from 0.01–0.66, 0.01–0.48 and 0.01–0.69 for grating time at grating speeds of 765, 865 and 965 rpm, respectively. The result obtained from this study will provide a worthwhile machine operating variables capable of controlling the overall processing time for satisfactory production yield in a cassava processing industry.