www.ccsenet.org/mas Modern Applied Science Vol. 5, No. 1; February 2011 Published by Canadian Center of Science and Education 139 Moisture-Depend some Postharvest Properties of Two Varieties of Safflower (Darab and Goldasht) Javad Tarighi (Corresponding author) Department of Agricultural Machinery Engineering, Faculty of Agricultural Engineering and Technology College of Agricultural and Natural Resources, University of Tehran P.O. Box 4111, Karaj 31587-77871, Iran Tel: 98-935-211-2286 E-mail: Javad_tarighi63@yahoo.com Asghar mahmoudi Department of Agricultural Machinery Engineering, Faculty of Agricultural Engineering University of Tabriz, Iran Meysam Karami Rad Department of Agricultural Machinery Engineering, Faculty of Agricultural Engineering and Technology College of Agricultural and Natural Resources, University of Tehran Abstract The moisture-dependent physical properties are important to investigate for designing the post harvest equipments of the product .This study was carried out to determine the effect of moisture content on some physical properties. Four levels of moisture content ranging from 4-22% d.b (wet basis) and 4-22% d.b. for Darab and Goldasht, respectively was used. The average length, width, thickness, geometric mean diameter, equivalent diameter, arithmetic diameter, sphericity, thousand grain mass, angle of repose, grain volume, surface area and aspect ratio ranged from 7.52 to 7.89 mm, 3.95 to4.48 mm, 3.36 to 3.70 mm, 4.51 to 4.99 mm and 4.52 to5.00 mm, 4.89 to 5.36 mm, 60% to 63%, 32.2 to40.7 gr, 43º to 51º, 34.83 to 47.43 mm 3 , 57.28 to 70.38 mm 2 , 52.57% to 56.74% as the moisture content increased from 4 to 22% d.b. for Darab and from 7.41 to 7.67 mm, 4.59 to 4.74 mm, 3.57 to 3.84 mm, 4.93 to 5.18 mm, 4.88 to 5.12 mm, 5.17 to 5.41 mm, 66.37% to 68.56%, 50.50 to 59.2 gr, 47° to 56°, 40.76 to 53.12 mm 3 , 62.27 to 72.38 mm 2 , 64.22% to 62.95% with increase in moisture content from 4 to 22% d.b. for Goldasht. Goldasht has higher static angle of repose than Darab in all moisture content levels. As the moisture content increased, the bulk density was found to decrease from 547 to 520 kgm -3 and from 640 to 601 kgm -3 for Goldasht and Darab, respectively whereas true density and porosity were found to decrease from 1070 to 1010 kgm -3 and 48.87% to 48.51% for Goldasht and from 940 to 850 kgm-3, 31.91% to 29.29% for Darab. The static coefficients of friction on various surfaces, namely, galvanized metal, plywood and plastic also increased linearly with an increase in moisture content. For galvanized metal and plastic Darab was higher correlated with moisture content than Goldasht. Keywords: Safflower, Physical properties, Moisture content, Darab variety, Goldasht variety Introduction The safflower is a plant that has the scientific name of Carthamus tinctorius L. The safflower which belongs to the Composite family is cultivated in several parts of the world due to its adaptability at different environmental conditions. In the past, safflower was planted in order to provide the pigment for using in dyeing machine. Today, in addition to that application, its seed is used for the production of seed oil. In order to design equipment for the handling, conveying, separation, drying, aeration, storing and processing of safflower grains, it is necessary to determine their physical properties as a function of moisture content. The knowledge of some important physical properties such as shape, size, volume, surface area, thousand grain weights, density, porosity, angle of repose, of different grains is necessary for the design of various separating, handling, storing and drying systems (Sahay and Singh, 1994). The size and shape are, for instance, important in their electrostatic separation from undesirable materials and in the development of sizing and grading machinery (Mohsenin, 1986). The shape of the material is important for an analytical prediction of its drying behavior. (Esref and Halil, 2007).