The moisture-dependent physical properties are important to investigate for designing the post harvest equipments of the product.  The physical properties of black cumin were evaluated as a function of moisture content in the range of 5.1% to 18.75% w.b.  The average length, width, thickness and 1,000 seed mass were 3.11 mm, 1.59 mm, 1.09 mm and 2.76 g, respectively, at moisture content of 5.1% w.b.  The geometric mean diameter and sphericity increased from 1.75 mm to   1.79 mm and 56.34% to 56.98% as moisture content increased from 5.1% to 18.75% w.b., respectively.  In the same moisture range, the bulk density decreased from 539.3 kg/m³ to 486.4 kg/m³, whereas the corresponding true density and porosity increased from 1,009.4 kg/m³ to 1,071.2 kg/m³ and 46.5% to 54.59%, respectively.  As the moisture content increased from 5.1% to 18.75% w.b., the angle of repose, terminal velocity and surface areas were found to increase from 32.5° to 33.3°,    5.6 m/s to 5.92 m/s and 8.14 mm² to 8.46 mm², respectively.  The static coefficient of friction increased on four structural surfaces namely, galvanized iron sheet (0.37-0.41), mild steel (0.36-0.39), aluminum (0.32-0.34) and plywood (0.53-0.58) in the moisture range from 5.1%-18.75% w.b.

Key words: black cumin, Nigella sativa, engineering properties, moisture content

Citation: Gharib-Zahedi S. M. T., S. M. Mousavi, A. moayedi, A. T. Garavand, and S. M. Alizadeh.  Moisture-dependent engineering properties of black cumin (Nigella sativa L.) seed.  Agric Eng Int: CIGR Journal, 2010, 12(1): 194－202.