Physical Properties of White and Black Beans (Phaseolus vulgaris)

Abstract

Abstract. Physical properties including physical dimensions (length, width and thickness), 1000 kernel weight, bulk density, true density, angles of repose, and angles of friction against four structural surfaces of white beans (or navy beans) and black beans ( L.) were measured at 12.1 ±0.3%, 14.0 ±0.0%, 16.0 ±0.2%, and 18.0 ±0.4% moisture contents (wet basis). Physical dimensions of beans were measured using a Vernier caliper and a digital imaging system and the results were compared. Physical dimensions and 1000 kernel weight of beans increased with the increase in moisture content from 12% to 18%. Physical dimensions of both beans measured using the Vernier caliper and the digital imaging system were similar except the thickness of the black bean at 12%, 14%, and 18% moisture contents. Bulk densities and true densities of both beans linearly decreased with the increase in moisture content. Emptying angle of repose was larger than the filling angle of repose for both beans. The filling angles of repose of both beans at 14% moisture content was significantly higher than that at other moisture contents. The largest angle of friction was against the wood-floated concrete followed by the steel-troweled concrete, galvanized steel, and plywood surface for both beans. Angle of friction against galvanized steel and plywood for both beans increased with increase in moisture content, whereas, angle of friction against wood-floated concrete and steel-troweled concrete decreased with increase in moisture content. Keywords: White beans, Black beans, Physical dimensions, Digital imaging system.