The Effect of Moisture Content on Physical Properties of Wheat

Abstract

Physical properties often required for designing the equipments for planting, harvesting and postharvesting operations of seeds. Several physical properties of three popular wheat varieties (Shiraz, Karoun and Shiroudy) were determined and compared for moisture content in 8, 12 and 18% w.b in 2007 in University of Tehran. The average length, width and thickness were 6.75, 3.26 and 2.77 mm at a moisture content of 8% w.b., respectively. studies on rewetted wheat seeds showed that the thousand-kernel weight increased from 18.38 to 22.43g. The geometric and equivalent mean diameter, surface area, sphericity and aspect ratio at a moisture content of 8% w.b were 3.93, 3.94 mm, 48.68 mm², 0.58, 0.48, respectively. The porosity increased from 0.43 to 0.45 %. Whereas the bulk density decreased from 0.72 to 0.66kg m^-3 and the true density from 1.25 to 1.19 kg m^-3, with an increasing in the moisture content range of 8B18% w.b. The static and dynamic angle of repose varied from 37.28 to 47.33 and 29.89 to 36.5^o. The mean of static friction coefficient of three wheat varieties increased the linearly against surfaces of three structural materials, namely, compressed plastic (0.43 - 0.53), galvanized iron (0.33 - 0.53) and plywood (0.35 - 0.41) as the moisture content increased from 8 to 18% w.b.