Proximate, Anti-Nutritional Factors and Functional Properties of Processed African Yam Bean (Sphenostylis Stenocarpa) Residues

The study evaluated the proximate, anti-nutritional factors and functional properties of processed African yam bean residues. African yam bean seeds were processed using different methods - cracked and boiled for 60 min; sprouted for 72 h; toasted at 170 ℃ for 30 min; soaked for 12 h and then for 30 min. The seeds were milled and passed through a 250 µm mesh size sieve and the coarse particles were designated as the residue. Unprocessed African yam bean residue was used as the control. The proximate, anti-nutritional factors and functional properties of the residues were evaluated using standard methods of analysis. The results of the proximate composition of the residues revealed that processing affected the moisture, ash, crude protein, crude fibre and carbohydrate contents of the African yam bean residues. The fat content of the residues was not affected by processing. The sprouted African yam bean residue (SAR) had the highest contents of ash and crude protein, the toasted sample (TAR) had the highest contents of fat and fibre, the soaked and boiled residue (SBR) had the highest carbohydrate content while the unprocessed residue (UAR) had the highest moisture content. There were significant reductions in the oxalate, alkaloid, phytate and tannin contents of the processed African yam bean residues. The results of functional properties of the residues revealed that the bulk density and water absorption capacity increased with processing, oil absorption capacity did not vary significantly except for the sprouted residue that was slightly higher while dispersibility reduced with processing. The study revealed that sprouting improved the ash and protein contents of the residue while soaking prior to boiling was more effective in reducing the anti-nutritional factors. The inclusion of African yam bean residues in food formulations should be explored.