CHEMICAL COMPOSITION OF ACID AND ALKALINE SOAKED DEHULLED AFRICAN YAM BEAN SEEDS (Sphenostylis stenocarpa) SEEDS
DOI:
https://doi.org/10.51791/njap.vi.7854Abstract
African yam bean (AYB) (Sphenostylis stenocarpa) is an indigenous food legume crop in the tropics, but it is not as popular as food when compared with other major legumes. It is high in protein but it is under - utilized due to the presence of tannin, trypsin inhibitors, haemaglutinins, oxalates, phytates and saponins.. To improve its nutritional value as a protein source, AYB was subjected to dehulling, dehulled soaking in ogi liquor (acidic media) and dehulled soaking in wood ash (alkaline media) and its anti-nutritional contents analyzed. There were no significant (P>0.05) difference in tannin, phytate, saponin, and oxalate across the dietary treatments. However trypsin inhibitor and haemagglutinin showed significant (p<0.05) difference across the treatments. Raw AYB had the highest value for tannin (0.09/mg/g), phytate (0.67/mg/g), trypsin inhibitors (31.26/TIU/g), saponin (0.32mg/kg), haemaglutinnins (58.24HIU/g) and oxalates (0.25mg/g) followed by the dehulled seed with tannin (0.07/mg/g), phytate (0.49mg/g), trypsin inhibitor (11.34/TIU/mg), saponin (0.26/mg/kg) and haemmaglutinins (49.15/HIU/g). African yam bean soaked in alkaline media (pH 10) recorded the least value for tannin (0.05mg/g), phytates (0.05/mg/g), trypsin inhibitor (0.06/TIU/g), haemmaglutinins (6.35/HIU/g). The lowest value of oxalate was for AYB soaked in acidic medium (0.20mg/g). Soaking in alkaline medium (pH 10) was found to be more effective in reducing the levels of trypsin inhibitors activity and haemaglutinins by 99.8% and 89.1% respectively. However, soaking of AYB in (pH 3.9) resulted in 63.7% and 15.6% reduction in trypsin inhibitor activity and haemaglutinins respectively. It could be concluded that anti-nutritional factors present in African yam bean could easily be reduced when soaked in alkaline solution.