Physical Properties of Finola® Hemp Seeds: Clean and Containing Dockages

Abstract. Physical properties of hemp seeds (, L., cultivar Finola®) with 5%, 10%, and 15% foreign materials and dockages (FMD) at 9%, 12%, and 15% moisture contents (wet basis) were measured. The measured and determined physical properties include physical dimensions (length, width, thickness, kernel volume, sphericity, and average surface area), density (bulk and true density), porosity, weight of 1000 kernels, filling and empting angles of repose, and coefficients of friction on surfaces of plywood, galvanized steel, steel-troweled concrete, and wood-floated concrete. The mean value of the length, width, and thickness of the 50 kernels had a linear relationship with the increase of moisture content; however, this was not true for individual kernels. Bulk density of seeds at any FMD level decreased linearly or quadratically with the moisture content increase, while the true density had an opposite trend. Increasing FMD significantly increased the bulk density at any moisture content, and there were variations for the true density. There were gaps between the seed coat and cotyledon, and these gaps became smaller or disappeared when the seed moisture content was increased. This phenomenon resulted in the same average surface area, same volume, and exponential increase in porosity to 58.5% with the increase of moisture content. Increased FMD significantly decreased the porosity at any moisture content. Emptying angle of repose increased with the increase of moisture contents and percentage of FMD. Higher variability was observed in the filling angle of repose than in the emptying angle of repose. The coefficient of friction was the largest against wood-floated and steel-troweled concrete, followed by galvanized steel, and the smallest was against the plywood surface. Keywords: Angle of repose, Density, Foreign material and dockage (FMD), Friction against structural surface, Hemp seed, Physical dimensions.