Emulsifying properties of vicilins: Dependence on the protein type and concentration

The emulsifying and interfacial properties of vicilins from three selected Phaseolus legumes (kidney, red and mung beans; denoted as KV, RV and MV, respectively) at protein concentrations (c) of 0.25-2.5% (w/v) were investigated. The results indicated that the emulsifying ability and emulsion stability (against flocculation, coalescence and even creaming) of vicilins considerably varied with their type and c. In general, KV exhibited much better emulsifying ability than RV or MV. Increasing c basically facilitated formation of the fresh emulsions with less flocculated oil droplets, and enhanced their stability against coalescence. Increasing c progressively decreased the stability of KV and RV emulsions against flocculation and creaming, while in the MV case, least stability was observed at c = 1.0%. Besides the differences in conformational characteristics, the differences in emulsifying properties of these vicilins could be to a certain extent attributed to the differences in their interfacial properties, including zeta-potential and interfacial protein concentration, as well as unfolding, penetration and structural rearrangement at the interface. The findings are of great importance for extending the current knowledge about the emulsifying properties of vicilins, thus providing valuable information for the development of vegetable protein-stabilized emulsion products. (C) 2013 Published by Elsevier Ltd.