Effect of Speed Variations in Abrasive Rice Whitening on Milling Properties of Two Varieties of Rice in Fars Province

In this study, the effect of the speed of the mill-rotor during the whitening process was evaluated for the milling properties of two varieties of rice in Fars province. A split plot design with five replications and the Duncan test were used for statistical analysis. Two varieties of paddy rice, Amol-3 and Kamfiruzi, and five mill-rotor speeds, 550, 600, 650, 700 and 750 rpm, were selected as main plot and sub-plot, respectively. The samples were milled at different speeds and the milling-output parameters of percentage of breakage and cracking, break strength and whiteness degree of rice kernels was measured. The results showed that the speeds of 600 and 600-650 rpm are the most proper mill-rotor speeds for the Kamfiruzi and Amol-3 varieties, respectively. Furthermore, the percentage of breakage and degree whiteness of the Amol-3 rice was 6.36% and 3.46%, respectively, more than for the Kamfiruzi variety. The percentage of cracking andbreak strength were 13.31% and 17.22 kgf more in the Kamfiruzi variety compared to the Amol-3 variety.