Influence of Moisture Content, Variety and Parboiling on Milling Quality of Rice Grains

The effects of moisture content (8%, 10% and 12%), variety (Tarom and Fajr) and parboiling on milling quality of rice as a function of milling recovery (MR), head rice yield (HRY), degree of milling (DOM) and whiteness were investigated. The parboiled grains was prepared with three soaking temperatures of 25 °C, 50 °C and 75 °C and three steaming times of 10, 15 and 20 min. As a result of parboiling, the increasing rates of MR and HRY values were 7.8% and 14.3% for Tarom and 9.8% and 10.0% for Fajr, respectively, and the decreasing rates for DOM and whiteness were 6.6% and 10.8% for Tarom and 6.8% and 10.5% for Fajr, respectively. Moreover, decreasing moisture content to 8% maximized MR (75.8% for Tarom and 74.3% for Fajr) and HRY (65.8% for Tarom and 57.0% for Fajr) while increasing that to 12% revealed maximum values of DOM (6.1% for Tarom and 6.2% for Fajr) and whiteness (24.8% for Tarom and 28.2% for Fajr).