Moisture-Dependent Physical Properties of Grape (Vitis vinifera L.) Seed

Some physical properties of grape (Vitis vinifera L.) seeds were determined as a function of seed moisture content varying from 16.55-5.21% (dry basis). The average values of seed length, width, thickness, geometric mean diameter, surface area filling angle of repose and terminal velocity decreased linearly with a decrease in the moisture content from 8.28-7.74 mm, 4.5-4.26 mm, 3.32-3.12 mm, 4.97-4.68 mm, 77.86-68.98 mm(2), 27.53-23.78 degrees and 6.8-6.3 m s(-1), respectively. The unit mass decreased nonlinearly from 0.056-0.049 g whereas the variation of sphericity was not statistically significant with a decrease in moisture content. The bulk density increased nonlinearly from 577.3-586.6 kg m(-3), while the true density and porosity decreased nonlinearly from 886.2-873.7 kg m(-3), and 34.85-32.86%, respectively, when the moisture content decreased from 16.55-5.21%. The static coefficient of friction decreased linearly from 0.38-0.18, 0.37-0.22, 0.5-0.41, 0.38-0.2 and 0.48-0.4 for glass, fiberglass, plywood, galvanized iron sheet and rubber, respectively. The static coefficient of friction of plywood surface was highest at all moisture contents investigated.