Moisture dependent physico-mechanical properties of Iranian okra (Ablemoschus esculentus L.) seed

Physical and mechanical properties of mature okra (Hibiscus esculentus L.) seeds from Ahvaz in Iran were evaluated. The physical and mechanical properties were evaluated at four moisture content levels of 7.1, 10, 15 and 20% dry basis (d.b). In this moisture range, seed length, width, thickness, geometric diameter, mass of 1000 seeds increased from 5.096 to 5.677 mm, 4.476 to 4.878 mm, 4.239 to 4.608 mm, 4.585 to 5.035 mm and 56.615 to 65.779 g, respectively. The angle of repose, volume, surface area and sphericity increased from 21.2 to 24.3°, 5.367 to 6.396 mm3, 66.18 to 79.64 mm2 and 90.07 to 0.92, respectively. The true density, bulk density and porosity decreased from 1096.34 to 1002.16 kg/m3, 627.4 to 576.2 kg/m3 and 41.1 to 38.01%, respectively. The rupture force and coefficient of static friction on aluminum, rubber, plywood, iron and galvanized iron sheets increased with increasing moisture content.   Key words: Okra seed, physical properties, moisture content.