Chemical composition and functional properties of flour and protein isolate extracted from Bambara groundnut (Vigna subterranean)

Abstract

The objective of this research was to study the chemical composition of flour and protein isolate extracted from Bambara groundnuts. Protein, fat, ash, crude fiber and total carbohydrates were 17.70, 6.58, 4.22, 3.50 and 86.0% in flour and 85.97, 0.0, 3.37, 0.02 and 10.64% in protein isolate, respectively. Functional properties of Bambara groundnuts were also studied. Bambara groundnuts flour and protein isolate were high in water absorption, which recorded 281.35 and 221.83% dry sample, respectively. The highest foaming capacity was 210% at pH 9.0. The highest foaming stability was detected at pH 6.0 after 120 min. With protein isolate, foam stability (FS) was 40 min at different pH values (3.0 to 9.0). The highest emulsion stability (ES) was 70% after 48 h at pH 3.0 and 6.0. Data showed that gelation of Bambara flour and protein isolate were best at concentration of 20% (w/v), the gelation formation were 8 and 18%, respectively. The data revealed that bulking density (BD) in flour was higher than in protein isolate. Beside, protein solubility index (PSI) decreased as pH values increased until pH values 4.0 to 5.0 and then increased. Our results indicated that chemical and functional properties of Bambara groundnut may cause improvement in some food products when it is added to the foods. Key words: Bambara groundnut, chemical properties, functional properties, flour, protein isolate.