Journal of Agricultural Technology 53 Moisture-Depend Physical Properties of Wheat (Triticum aestivum L.) K. Kheiralipour * , M. Karimi, A. Tabatabaeefar, M. Naderi, G. Khoubakht, K. Heidarbeigi Department of Agricultural Machinery Engineering Faculty of Bio-System Engineering, University college of Agricultural and Natural Resource, University of Tehran, Karaj, Iran. Kheiralipour, K., Karimi, M., Tabatabaeefar, A., Naderi, M., Khoubakht, G. and Heidarbeigi, K. (2008). Moisture-Depend Physical Properties of Wheat (Triticum aestivum L.). Journal of Agricultural Technology 4(1): 53-64. Physical properties of wheat grains (Shiraz variety) were determined as a function of moisture content in the range of 8-18 % wet basis (w.b.) using standard techniques. The average length, width and thickness were 6.78 mm, 3.45 mm and 2.84 mm, at a moisture content of 8% w.b., respectively. In the moisture range from 8 % to 18% w.b., studies on rewetted wheat grains showed that the thousand kernel weight (TKW) increased from 20.13 to 24 g, the surface area from 43.43 to 44.66 mm 2 , the porosity from 0.42 to 0.44 %. Whereas the sphericity decreased from 0.6 to 0.58, the bulk density from 708.4 to 664 kgm -3 and the true density from 1222.4 to 1177.2 kg m -3 with an increase in the moisture content range of 8 –18 % w.b. The static coefficient of friction of wheat grains increased linearly against surfaces of three structural materials, namely, glass (0.33–0.4), plywood (0.46–0.55), and galvanized iron (0.34–0.54) and the static and dynamic angle of repose increased from 30.83 to 36.33 and from 37.33 to 47.33º, respectively as the moisture content increased from 8 % to 18% w.b. Key words: Wheat, Physical properties, Moisture content, Equipment design, Shiraz variety Angle of repose Introduction In Iran, wheat is cultivated on 6.41 million hectares with an annual production of 13.44 million tons (Anonymous, 2003). In order to design equipment for the handling, conveying, separation, drying, aeration, storing and processing of wheat 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 * Corresponding author: K. Kheiralipour; e-mail address: kamrankheiralipour@gmail.com