Effect of paddy husked ratio on rice breakage and whiteness during milling process

Paddy husking operation is one of the most important stages during milling process, which effectively determines the quantitative and qualitative losses of rice. In this study, the effect of four levels of husked ratio (HR) of 0.6, 0.7, 0.8 and 0.9 on broken brown rice (BBR), broken milled rice (BMR) and rice whiteness (RW) was examined. Three common Iranian rice varieties, namely Binam, Khazar and Sepidroud were used as raw materials. A commercial rice milling system including rubber rolls husker and blade-type whitener was considered in the experiment. The results revealed that the BBR increased significantly (P<0.01) from 7.42 to 10.28%, 9.17 to 13.39% and 15.17 to 21.82% for Binam, Khazar and Sepidroud varieties, respectively as the HR increased from 0.6 to 0.9. The lowest BMR for varieties of Binam (17.83%), Khazar (23.35%) and Sepidroud (28.90%) were obtained at the HR of 0.8. By increasing the HR from 0.6 to 0.9, the RW decreased from 36.1 to 30.8, 36.5 to 30.1 and 35.4 to 29.8 for Bianm, Khazar and Sepidroud varieties.