Effect of moisture content on the engineering properties of African yam bean (Sphenostylis stenocarpa) seed

Purpose: This work was carried out to investigate the effect of moisture content on the engineering properties of African Yam Bean (Sphenostylis stenocarpa) seeds. Research method: Physical and mechanical properties of African Yam Bean seeds were evaluated. The physical and mechanical properties were evaluated at five moisture content levels of 8, 12, 16, 20 and 24% dry basis (d.b). Findings: From the physical properties, the average length, width, thickness, arithmetic mean diameter, geometric mean diameter and equivalent diameter were found to increase significantly (P≤0.05) with an increase in moisture content. The surface areas, volume, sphericity, aspect ratio, flakiness ratio, porosity, static angle of repose, dynamic angle of repose and static coefficient of friction of the seeds were also found to increase significantly (P≤0.05) with increasing seed moisture content. The mean results of seed densities showed a decrease in bulk density (0.840±0.045 to 0.806±0.074 g/cm3) and true density (1.268±0.083 to 1.238±0.079 g/cm3) with the increase in seed moisture content from 8% to 24 % (d.b). From the mechanical properties, the mean force, deformation, strain and energy for African yam bean seeds decreased significantly (P≤0.05) with the increase in moisture content. The mechanical properties evaluated showed a decrease in the force at peak (176.564±20.137 to 104.860±9.814 N), force at yield (168.548±24.049 to 84.694±53.464 N) and force at break (172.880±19.506 to 96.986±14.536 N) with the increase in seed moisture content from 8% to 24 % (d.b). Research limitations: No limitation to the report, yet, the study cannot claim to have exhausted all factors that influence engineering properties of African Yam Seed; thus, effects of other factors such as accessions, varieties, cultivars and species is recommended for further studies. Originality/Value: The results provide relevant data on efficient process handling and equipment design of the seeds to the engineers and designers.