Moisture Dependent Physical Properties of Dragon’s Head Seeds (Lallemantia iberica)

Abstract

Physical properties of Dragon's head seed, and other grains, are necessary for the design of equipment handling, transporting, processing and storing of the crop. A range of physical properties of Dragon's head (Lallemantia iberica) were determined as a function of moisture content. As the moisture content increased from 7.18 to 48.46 % (d.b.), the average length, width, thickness and the geometric mean diameter varied from 4.48 to 4.97 mm, 1.69 to 1.85 mm, 1.16 to 1.35 mm and 1.97 to 2.31 mm, respectively. In the same moisture range, studies on Dragon's head showed that, sphericity, surface area, thousand seed mass and true density increased from 41.73 to 46.50 %, 12.16 to 16.79 mm² and 9.75 to 11.17 g and 837.2 to 1047 kg/m³, respectively. As the moisture content increased from 7.18 to 48.46 % (d.b.), bulk density decreased from 584.23 to 438.26 kg/m³ whereas the angle of repose and porosity increased from 27.16 to 43.33º and 30.17 to 58.12 %, respectively. The static coefficient of friction of Dragon's head seeds increased linearly against surfaces of three structural materials, namely, glass (0.25-0.63), plywood (0.42-0.70), and galvanized iron (0.32-0.64) as the moisture content increased from 7.18 % to 48.46 % (d.b.).