Nutritional value of African yambean (Sphenostylis stenocarpa L):: improvement by lactic acid fermentation

Tropical African yambean (Sphenostylis stenocarpa L) is an under-utilised hardy, protein-rich legume. Antinutrients and the excessively long cooking time (4-6 h), among other factors, limit the food use of African yambean seeds. To reduce these limitations, non-traditional, less energy-consuming processing methods are required. Seeds of different varieties were (i) examined for ingredients and (ii) fermented with Lactobacillus plantarum. Comparisons with traditionally cooked beans were made. Protein content and in vitro protein digestibility were increased slightly by fermentation or cooking. Reductions in trypsin and a-amylase inhibitor activity and tannin ranged from significant to complete. The contents of potentially very toxic cyanogenic glycosides and flatulence-causing alpha-galactosides were high in raw beans. Reduction by fermentation (by 85%) was clearly more effective than by traditional cooking (10-20%). The results demonstrate (i) that fermentation can substantially improve the nutritional quality and (ii) that the energy requirement to produce a basic consumable fermented food from African yambean is only 10% of that of traditional cooking. On these grounds, widespread application of lactic acid fermentation by individuals or small-scale industries would be advantageous in the context of small-household economy, environmental protection, health and long-term sustainable agriculture in Nigeria. (c) 2005 Society of Chemical Industry.