ABSTRACT

The effects of moisture content on some physical and mechanical properties of two varieties of Bambara kernel were investigated. Some compressive resistance (force, energy and deformation at rupture point) of two Bambara kernel (variety 1 and variety 2) kernels were investigated in terms of kernel sizes. The two varieties of bambara kernel used were the cream color with no eye (Vigna subterranea (L.) Verdc) and brown color (Vigna subterranea (L.) Verd). The selected engineering properties of bambara kernel were carried in the laboratory of Agricultural and Bioresources department and the National Centre for Agricultural Mechanization (NCAM), Ilorin, Kwara State, Nigeria. The geometric mean diameter, arithmetic mean diameter, sphericity, weight, true density and angle of repose of both varieties increased with increasing moisture content. The average length, width and thickness of the cream variety (Vigna subterranea (L.) Verdc) increases more than the brown variety (Vigna subterranea (L.) Verdc) at the determined moisture contents, Bulk density of the cream variety (Vigna subterranea (L.) Verdc decreased while brown variety (Vigna subterranea (L.) Verdc) increased with increase in moisture content. The cream variety (Vigna subterranea (L.) Verdc had bigger size kernel than the brown variety (Vigna subterranea (L.) Verdc and this has serious implication in packaging, handling and transportation issues. The mean force required for initiating the kernel rupture increased from 13 8.887 to 23 5.060 N for variety 1; and 115.185 to 190.487 N for variety 2, as the kernels size increased from small to large size. In addition, the energy absorbed by the kernel at rupture point increased from 0.19 1 to 0.401 Nm for Variety 1; and 0.062 to 0.165 Nm for Variety 2, for the small and large kernel, sizes respectively. Furthermore, the results showed that Variety I kernels had slightly higher compressive resistance values than the Variety 2 kernels and also as the moisture content increase the compressive parameter decrease. Data obtained from this research will help to design and fabricate equipment used in handling and processing of Bambara kernels