Moisture-dependent physical properties of black grape (Vitis vinifera L.) seed

The physical properties of black grape seed were evaluated as a function of moisture content. The average length, width and thickness were 5.66, 3.46 and 2.61 mm, respectively, at 8.26% d.b. moisture content. In the moisture range from 8.26 - 26.14% dry basis (d.b.), studies on rewetted black grape seed showed that the thousand seed mass increased from 23.39 - 24.82 g, the projected area was 13.58 - 18.07 mm(2), the sphericity 0.656 - 0.692 and terminal velocity was 7.33 - 7.68 m s(-1). The static coefficient of friction of black grape seed increased linearly against surfaces of four structural materials, namely, rubber (0.340 - 0.393), aluminium (0.196 - 0.270), stainless steel (0.247 - 0.337) and galvanised iron (0.322 - 0.397) as the moisture content increased from 8.26 - 26.14% d.b. The bulk density decreased from 626.1 - 613.1 kg m(-3), true density from 1104.9 - 1052.6 kg m(-3) and porosity from 43.34 - 41.76%, respectively, with an increase in moisture content from 8.26 - 26.14% d.b.