Effect of moisture contant, rotational speed and duration of test on breakage susceptibility of rice bulk sample by a modifieid centrafugal tester

For determining the rationale of reducing strength of rice kernels during harvesting and postharvest operations and comparing the quality of rice bulk samples, specially for comercial proposes, a suitable device and method for rice quality measurment is necessary. Rice Breakage susceptible index for bulk samples, is a proposed index which could be determined by a centrifugal impact tester based on weight percent. Therefore, by modification of a laboratory mill, the effect of moisture content, blade rotational speed and duration of test were investigated on a fabricated apparatus performance, based on 50% breakage level and according to a completely randomize factorial test and by conducting 500 milling tests. The results showed that the three independent factors had a significant effect on BSI. According to the results, the speed of 1000rpm and less, and the speed of 5000rpm and more, are not suitable for this kind of test due to very low and very high rate of breakage, respectively. Finally, the speed of 4000 rpm, moisture content of 9% (wb) at 80 seconds of test duration was selected as the best condition for the test, according to 50% rate of breakage with minimum and maximum rate of 23 and 67%.