Comparative Evaluation of Antimicrobial Activity and Functional Properties of Native and Esterified Legume Proteins

Abstract

Tow legume proteins (cowpea and common bean proteins) were isolated and esterified with methanol in the presence of hydrochloric acid for 10 h at 4°C to give esterification extent 82% and 79%; respectively. Esterification raised the pIs (iso-electric points) of legume proteins from pH 4 for the native legume proteins, to pH 6 in the case of cowpea protein and pH 8 in the case of common bean. Applying methylated proteins at four different concentrations (0.5, 0.75,1 and 2 mg/ml) to Petri dishes containing nutrient agar infected with two pathogenic Gram-negative (Enterobacter cloacae and Serratia marcescens) and Gram-positive bacteria (Listeria monocytogenes) gave rise to concentrationdependent inhibition zones.