Comparative study of the functional properties of bambarra groundnut ( Voandzeia subterranean), jack bean ( Canavalia ensiformis) and mucuna bean ( Mucuna pruriens) flours

Abstract

Functional properties of bambarra groundnut flour (BGF), jack bean flour (JBF) and mucuna bean (MBF) were determined. pH dependent protein solubility profile revealed that highest solubility in all flours was at pH 10, while minimum solubility was obtained at pH 4, which correspond to the isoelectric point. Gelation capacity was minimal at pH 4 for all of the flours. Increase in ionic strength of the medium at low salt concentration (⩽0.4 M) improved the gelation properties of the flours. Maltose, lactose, sucrose and starch when added to the flours enhanced the gelation capacity of all flours. Oil absorption capacity of JBF, MBF and BGF were 1.7, 1.6 and 1.3 ml g −1, respectively. Water absorption capacity of flours increased between ionic strength ranges of 0–0.2 M but reduced with further increase in ionic strength. Emulsifying activity (EA) decreased as the concentration of flour in solution increased. Maximum EA and emulsion stability (ES) were obtained at pH 10, while minimum values were read at isoelectric pH. EA and ES of flours increased in the ionic strength range 0–0.4 M but reduced afterwards with further increase in NaCl concentration. Foam stability (FS) of the flours increased as the concentration of flour solution increased and maximum values of 80.5%, 74.7% and 77.0% were observed for JBF, BGF and MBF at 10% flour concentration. MBF had highest foam capacity (FC) of 68% at pH 2, while JBF and BGF recorded highest value of 50% and 61%, respectively, at pH 10. Foam stability was maximal at pH 4 for all the fours. Low ionic strength ( μ⩽0.2 M) improved both foam capacity and stability of JBF while increases were recorded in FS and FC of BGF and MBF up to μ=0.4 M, after which further increase in ionic strength reduced the foaming properties of the flours.