Effect of moisture content on some physical properties of safflower (var. Darab) seeds

Physical and engineering properties of agricultural grains are necessary for design of storage, handling and processing equipment. Physical properties of safflower seeds were investigated over moisture content range from 4 to 22% d.b. which covers the moisture range of safflower from harvesting to storage stages. As the moisture content increased from 4 to 22% d.b., the axial dimensions, mass of 1000 seeds, surface area, volume and static friction coefficient increased while bulk density, true density and porosity decreased. Length, width, thickness, effective mean diameter and arithmetic diameters increased from 7.6 to 7.95 mm, from 3.95 to 4.51 mm, from 3.37 to 3.77 mm, from 4.58 to 5.07 mm and from 4.97 to 5.47 mm, respectively. Mass of 1000 seeds increased from 32.2 to 40.7 g. Seed surface area, volume and sphericity were found to increase from 57.2 to 70.38 mm(2), from 34.83 to 47.43 mm(3) and from 0.603 to 0.635, respectively, and the angle of repose was increased from 42 to 51. As moisture content increased, bulk density, true density and porosity were found to decrease from 640 to 601 kg/m(3), from 940.2 to 850 kg/m(3) and from 31.91 to 29.29%, respectively. The coefficient of friction on compressed plastic, plywood and galvanized iron sheet surfaces increased from 0.36 to 0.55, from 0.38 to 0.57 and from 0.34 to 0.57, respectively, as the moisture content increased from 4 to 22% d.b.