Effect of Rotor Speed and Output Rate of Modified Blade Whitener on Breakage Percentage and Degree of Milling of Sazandegi Variety

Improvement and optimization of the processing machines, including blade-type whitener, is one of the factors that could decrease in rough rice milling process. In this study, a rotor equipped with screw conveyor was used. The effect of rotor speed (in four levels: 600, 700, 800 and 900 rpm) and output rate (in three levels: 400, 500 and 600 kg/h) on losses of the Sazandegi rice variety were examined by using a factorial experiment based on randomized complete block design (RCBD) with three replications. In each test, the breakage percentage and degree of milling were measured. The results showed that the main and interaction effects of rotor speed and output rate on the breakage percentage were significant at the 1% level and the main effect of output rate and interaction of rotor speed and output rate on degree of milling were significant at the 1% level. Based on results, the highest of breakage percentage (38.25%) occurred at the rotor speed of 800 rpm with an output rate of 600 kg/h and the lowest of breakage percentage (20.79%) occurred at rotor speed of 700 rpm with an output rate of 400 kg/h (on the average of four rotor speeds). In addition, the highest degree of milling (6.45%) occurred at the rotor speed of 900 rpm with an output rate of 400 kg/h and the lowest degree of milling (2.15%) took place at rotor speed of 600 rpm with an output rate of 600 kg/h. However, in practice the rotor speed of 700 rpm with 400 kg/h output rate was recommended to be an optimum setting.