Structure, composition and functional properties of storage proteins extracted from bambara groundnut (Vigna subterranea) landraces

Bambara groundnut is a protein-rich traditional legume. In this study, storage proteins were isolated from three bambara landraces. Bambara protein revealed four major protein bands: one broad band at 55 kDa, two medium bands at 62 kDa and 80 kDa and a high molecular weight (HMW) protein at 141 kDa. The vicilin (7S) subunits with molecular weight of 55 kDa and 62 kDa were major fractions in bambara storage proteins. Bambara proteins showed two endothermic peaks ranging from 64 to 69 degrees C and 76 to 90 degrees C, respectively. Bambara protein isolates had well-defined tertiary and secondary structures, respectively, at pH 3.0, and this well-defined structure decreased slightly at higher pH values. The isolates revealed a strong secondary structure dominated by alpha-helical conformation. Foaming capacities of bambara proteins were dependent on pH with maximum percentage FC observed at pH 3.0, while the emulsion activity increased with increasing pH for all the isolates. Vicilin (7S) fraction seems to be the major storage protein fraction of bambara. Bambara proteins could serve as excellent ingredients for the formulation of food foams and emulsions.