International Agricultural Engineering Conference, Bangkok, Thailand, 7 – 10 December, 2009 1 Determination of Some Physical, Mechanical, Chemical and Thermal Attributes of Black Seed (Nigella oxypetala Boiss.) (IAEC Ref. No. 197) Seyed Mohammad Taghi Gharib-Zahedi 1 , Seyed Mohammad Mousavi 1 , Manochehr Hamedi 1 and Amin Taheri Garavand 2 1 Department of Food science, Engineering and Technology, Faculty of Biosystems Engineering, University of Tehran, Karaj, Iran, 2 Department of Agricultural Machinary Engineering, Faculty of Biosystems Engineering, University of Tehran, Karaj, Iran. ∗ Corresponding author: E-mail: gharibzahedi@ut.ac.ir ABSTRACT Several physical, mechanical, nutritional and thermal properties of black seed at a moisture content of 5.1% (w.b.) were determined. The average seed length, width, thickness, the geometric mean diameter, the effective mean diameter, sphericity index, volume and surface area of the seed were 3.11 mm, 1.59 mm, 1.09 mm, 1.75 mm, 1.93 mm, 56%, 2.92 mm 3 and 8.14 mm 2 , respectively. One hundred seed mass, bulk density, true density and porosity were 2.54 g, 539.3 kg m -3 , 1009.4 kg m -3 and 46.5%, respectively. Mean values for angle of repose and terminal velocity were 5.6 m s -1 and 32.5°, respectively. Static friction coefficient on plywood, mild steel, aluminum and galvanized iron sheet were 0.53, 0.36, 0.32 and 0.37, respectively. The results of mechanical test showed that the force required for initiating seed rupture decreased from 55.70 to 30.24 N and 57.36 to 39.13 N, and the energy absorbed at seed rupture decreased from 39.13 to 27.94 mJ and 26.90 to 7.12 mJ, with increase in loading rate from 1 to 10 mm min -1 , for vertical and horizontal orientations, respectively. This showed that black cumin seeds are more flexible in vertical orientation. Furthermore, seed deformation amount decreased from 0.938 to 0.182 mm for horizontal orientation, while this parameter increasing from 1.13 to 1.84 mm, for vertical orientation, with increase in loading rate from 1 to 10 mm min -1 . Dry matter, oil, protein and nitrogen contents were 95.4%, 24.4%, 22.43% and 3.59%, respectively. Moreover, the amount of potassium, calcium, magnesium, phosphorus and iron were 706, 548, 202, 42.5 and 9.2 mg kg -1 of dry matter, respectively. Specific heat, thermal conductivity and thermal diffusivity varied from 1642 to 2035 J kg -1 K -1 , 0.17 to 0.22 W m -1 K -1 , 9.3 to 10.4 × 10 -8 m 2 s -1 , respectively. Keywords: Black seed, Engineering properties, Composition, Thermal conductivity; Nutritional properties. 1. INTRODUCTION Black seed (Nigella oxypetala Boiss.) is an annual herbaceous plant belonging to the Ranunculaceae family (Al-Gaby, 1998; Atta, 2003) growing in countries around the Mediterranean Sea (Gad et al., 1963). It tastes slightly bitter and peppery with a crunchy texture. Seeds are angular, of generally small size (1–5 mg), grey or black color. Seeds are presently used in traditional medicine and culinary preparations because of their health- promoting benefits (D’Antuono et al., 2002). Black seeds are used for edible and medicinal purposes in many countries, including Egypt, Syria, Jordan and Iran. Moreover, they are used as a condiment in bread and other dishes (Aboutabl et al., 1986; Merfort et al., 1997). They are also used in the preparation of a traditional sweet dish, composed of black seed paste, which is sweetened with honey or syrup, and in flavoring of foods, especially bakery products and cheese. Black seed oil or extract has protective and curative actions. Black seed