Assessment of Some Physical and Functional Properties of Two Species of Vigna subterranean – An Underutilised Hard-to-Cook Legume in South-West Nigeria

Abstract

Some physical and functional properties of two species of Vigna subterranean -- light cream smooth (VS1) and cream mottled with brown (VS2) varieties, were determined. The mean weight of 75.83 and 80.11 g was recorded for VS1 and VS2, respectively. Geometric mean diameter, surface area and degree of sphericity were significantly higher (p<0.05) for VS2 than for VS1. However, packed bulk density was higher for VS1 (0.758 g/cm3) than VS2 (0.627 g/cm3). Water absorption capacity of 18.38 and 13.07 % were recorded for VS1 and VS2, respectively while oil absorption was higher for VS2 (8.31%) than VS1 (6.20%). Foaming capacity of 3.92% was observed for VS1 while VS2 had 1.96%. Swelling capacity was higher for VS2 (80.00%) than for VS1 (75.71%). The protein solubility profiles of VS1 and VS2 are similar and at the highest in the alkaline medium. Solubility of each of the species decreased with increase in pH until isoelectric point was reached followed by increase in solubility with increase in pH.  Adoption of these lesser known legumes will foster industrial utility and strengthen dietary diversity.