Moisture-dependent geometric, frictional and mechanical properties of cabbage (Brassica oleraceae L. var. capitata) seeds.

摘要

Selected geometric, frictional and mechanical properties of cabbage seeds were evaluated as a function of moisture content. The average length, width, thickness, geometric mean diameter and thousand-grain mass (TGM) ranged from 1.97 to 2.17 mm, 1.88 to 2.05 mm, 1.73 to 1.95 mm, 1.86 to 2.06 mm and 3.99 to 4.59 g, respectively, as the moisture content increased from 6.86 to 20.96% d.b. (dry basis). In the moisture content range, studies on rewetted cabbage seeds showed that the sphericity varied from 0.95 to 0.92, the seed volume from 3.73 to 4.51 mm3, the surface area from 10.87 to 13.34 mm2 and projected area from 3.02 to 3.76 mm2. Bulk density and true density were found to decrease from 653.4 to 622.2 kg m-3, and from 1071.00 to 1018.33 kg m-3, respectively. The effect of moisture content on porosity for cabbage seed was not significant (p<0.05). The terminal velocity increased from 7.18 m s-1 to 7.61 m s-1 with increase in specified moisture levels. The static coefficient of friction and the dynamic angle of repose on various surfaces, namely, rubber (0.366 to 0.422 and 12.41 degrees to 22.55 degrees ), aluminum (0.352 to 0.404 and 12.31 degrees to 19.71 degrees ), plastic (0.317 to 0.370 and 12.40 degrees to 21.24 degrees ), and stainless steel (0.294 to 0.366 and 11.12 degrees to 19.01 degrees ) increased with increase in moisture content. The static angle of repose increased linearly from 22.45 degrees to 26.16 degrees with increase in moisture content. The shelling resistance values ranged from 9.52 to 5.46 N. The coefficient of restitution decreased with increase in moisture content and drop height for various surfaces, namely, acrylic glass and galvanized iron sheet.