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 ۸, ۱۲, ۱۶, ۲۰ and ۲۴% 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≤۰.۰۵) 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≤۰.۰۵) with increasing seed moisture content. The mean results of seed densities showed a decrease in bulk density (۰.۸۴۰±۰.۰۴۵ to ۰.۸۰۶±۰.۰۷۴ g/cm۳) and true density (۱.۲۶۸±۰.۰۸۳ to ۱.۲۳۸±۰.۰۷۹ g/cm۳) with the increase in seed moisture content from ۸% to ۲۴ % (d.b). From the mechanical properties, the mean force, deformation, strain and energy for African yam bean seeds decreased significantly (P≤۰.۰۵) with the increase in moisture content. The mechanical properties evaluated showed a decrease in the force at peak (۱۷۶.۵۶۴±۲۰.۱۳۷ to ۱۰۴.۸۶۰±۹.۸۱۴ N), force at yield (۱۶۸.۵۴۸±۲۴.۰۴۹ to ۸۴.۶۹۴±۵۳.۴۶۴ N) and force at break (۱۷۲.۸۸۰±۱۹.۵۰۶ to ۹۶.۹۸۶±۱۴.۵۳۶ N) with the increase in seed moisture content from ۸% to ۲۴ % (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.