Some physicochemical and interfacial properties of native and acetylated legumin from faba beans (Vicia faba L)

The influence of acetylation on adsorption kinetics, film compression behavior (air/water), emulsifying properties (n-decane/water emulsions), and conformation of legumin from faba beans was studied. These measurements involved the Wilhelmy plate method, film balance, turbidity measurements, centrifugation, and size exclusion and reversed phase HPLC, UV absorption, and fluorescence probes. While distinct changes in physicochemical properties only occurred above a ''critical degree of modification'' (approximately 60%) e.g. dissociation and denaturation of the molecule and increased surface hydrophobicity, emulsifying property parameters linearly improved with acetylation as indicated by an increase in the emulsifying activity index of the legumin, improved coalescence stability of the emulsions, and decreased droplet size distribution and protein load of the oil droplets. The measured contact angle due to adsorption of legumin at the Wilhelmy plate distinctly influenced parameters of the Gibbs adsorption isotherms. A correlation between the critical association concentration and the emulsifying activity of the protein samples was also found.