Characterisation of Bambara groundnut (Vigna Subterranean (L.) Verdc.) Non-starch polysaccharides from wet milling method as prebiotics
The aim of this study was to characterise the physicochemical, rheological, prebiotic and emulsion stabilising properties of four varieties (black-eye, brown-eye, brown and red) of Bambara groundnut (BGN) extracted using the modified wet milling method. A relatively high yield of BGN dietary fibres was obtained with soluble dietary fibres (SDFs) ranging from 15.4 to 17.1% and insoluble dietary fibres (IDFs) ranging from 12.0 to 15.6%. Black-eye and brown-eye dietary fibres showed superiority in terms of swelling capacities, water holding capacities, oil binding capacities, antioxidant properties as well as thermal stabilities than red and brown dietary fibres. In addition, black-eye and brown-eye dietary fibres were characterised by higher lightness (L*), redness (+a*), yellowness (+b*), chroma (C*) and hue. All four SDFs showed acceptable colour differences with ΔE < 8 ranging from 0.81 to 3.08. The hydrolysable polyphenolic (HPP) content of SDFs ranged from 6.89 to 20.86 mg/g GAE and that of IDFs ranged from 10.96 to 14.43 mg/g GAE. All four SDFs differed significantly (p < 0.05) in their HPP content. BGN IDFs were very low in tannins (< 2.2 mg/g).