Physico-mechanical properties of rough rice (Oryza sativa L.) grain as affected by variety and moisture content

 M. Sadeghi, H. Ashtiani Araghi, A. Hemmat(Department of Farm Machinery, College of Agriculture, Isfahan University of Technology, Isfahan 84156-83111, Iran) Abstract: Rice varieties in Isfahan Province (central Iran) have high breakage losses during processing.  In order to optimize the design of machinery used for milling of these varieties it is quite important to determine their engineering properties.  In this study, physical and mechanical properties of Sorkheh and Sazandegi varieties were determined at three moisture content levels.  To determine the mechanical properties, compression and three-point bending tests were conducted.  It was observed that, by increasing moisture content, geometric mean diameter, sphericity, true density, and angle of repose were all increased, whereas bulk density decreased.  In contrary to the moisture content at the tested range, variety had a significant effect on rough rice mechanical properties.  For Sorkheh, the average fracture force, fracture energy, modulus of elasticity, and toughness obtained by compression test, were 169.1 N, 44.2 J×10-3, 996.1 MPa, and 1.88 MJ/m3, respectively.  The corresponding values for Sazandegi were 125.1 N, 24.4 J×10-3, 555.6 MPa, and 1.11 MJ/m3.  In three-point bending test, the average fracture force, fracture energy, and bending strength of Sorkheh were 24.2 N, 5.1 J×10-3, and 23.4 MPa, respectively.  For Sazandegi, these values were 19.1 N, 3.7 J×10-3, and 17.7 MPa, respectively.  Comparison of obtained mechanical properties with the literature revealed that the high milling losses of Isfahan province rice varieties could be due to the methods and devices used for their processing operations.Keywords: mechanical characteristic, milling, moisture content, physical property, Iran Citation: Sadeghi M, H. Ashtiani Araghi, A. Hemmat.  Physico-mechanical properties of rough rice (Oryza sativa L.) grain as affected by variety and moisture content.  Agric Eng Int: CIGR Journal, 2010, 12(3): 129-136. &nbsp