Physical Characterisation of Two Varieties of Bambara Groundnut Seeds

Abstract

Some physical attributes of two selected varieties of Bambara groundnut seeds grown in Nigeria were determined in this study. Standard methods were used to determine the selected properties which include linear dimensions, surface area, mass, volume, density, sphericity, porosity and coefficients of friction of the seeds on plywood, galvanized iron and aluminium surfaces. Length, width and thickness were within the ranges of 13.41-14.40 mm, 12.00-12.89 mm and 11.36- 11.99 mm, respectively for cream variety and 12.54-13.91 mm, 11.16-12.28 mm and 10.51-11.46 mm, respectively for light brown variety. Surface area of the seeds and volume were within the ranges of 507.94-588.45 mm2 and 1077.59-1351.79 mm3, respectively for cream variety, and 443.05-880.63 mm2 and 541.47-1191.18 mm3, respectively for light brown variety. The thousand seed mass ranged from 833.20 to 1116.93 g and 718.97 to 863.83 g for cream and light brown varieties respectively. Bulk density ranged from 0.71 to 0.79 g/cm3 and 0.71 to 0.77 g/cm3 for cream and light brown varieties respectively. The results showed that that the cream variety is larger and heavier than the light brown. Variations in true density and porosity of the seeds were sinusoidal in nature as moisture content increased for both varieties. Frictional coefficients on the three surfaces increased with moisture content. The investigated physical attributes were dependent on the amount of moisture in the seeds. The results from this study are useful in the development of handling and processing equipment for Bambara groundnut seeds.