Influence of Moisture Content to the Physical Properties of Unhusk Rice Grain

Determination physical properties of rice grain are important for design of harvesting, conveying and processing equipment. Size, sphericity, bulk density, a hundred grain seed mass, angle of repose and angle of friction against different surfaces were evaluated for five varieties of unhusk rice grain (Junjungan, Mundam, SokanPulau, Simaung and Bakwan) as a function of moisture content in the range of 9 to 25 (w.b.%). The objective of this study is to determine the influance of moisture content on the physical properties of local varieties of grain and rice from West Sumatra, Indonesia. Among the varieties, Junjungan had the highest values for geometric mean diameter, sphericity and thousand seed mass at all moisture levels. Geometric Mean Diameter (GMD) and sphericity increased significantly from 3.11 to 3.76 and 0.37 to 0.42 variety in a moisture content range of 9 to 25% w.b. Maximum values of bulk density and a thousand grain mass were obtained for Sokan Pulau (0.55-0.63g/cm3) and for Bakwan (29.99- 35.21 g). The angle of repose and angle of friction ranges for Mundam increased from 27.36 to 38.75˚and 27.33 to 37˚, respectively as increasing moisture content levels.