Functionality of native and succinylated Lablab bean ( Lablab purpureus) protein concentrate

Abstract

Lablab bean protein concentrate was acylated with succinic anhydride and resultant changes in some functional properties such as protein solubility index; oil absorption capacity, emulsifying properties and foaming properties were investigated. The result indicate that addition of succinic anhydride at 0.1, 0.25, 0.5, 0.75, and1.0 g/g of protein acylated 42.6, 61.3, 84.6, 89.1 and 92.4%, respectively of the ε-amino groups. Succinylation reduced solubility of native protein (nLPC) at pH values below its isoelectric point (4.5). However, marked improvement in solubility were observed at pH 4.5–10 following succinylation. Emulsifying activity (EA) increased with increase in concentration up to 4 and 6%, w/v for nLPC and succinylated protein (SLPC) respectively but further increase in concentration put the EA on the decline. Increase in ionic strength of the media to 0.2 M and 0.4 M significantly ( P<0.05) increased the EA of nLPC and SLPC respectively. Further increase in ionic strength however reduced the EA of protein solutions. Succinylation reduced the emulsion stability (ES) of nLPC at pH 2. However, in the pH 4–10, all succinylated protein concentrates showed improved ES over the native protein concentrate. A direct relationship was observed between increase in concentration of the protein concentrate and increase in foam capacity. Foam stability reduced after succinylation at all concentration studied. Succinylation improved foam capacity at pH 4–10 but reduced it at pH 2. Native lablab protein had better foam stability compared with the succinylated derivatives.