Study on the emulsifying stability and interfacial adsorption of pea proteins

Abstract

In order to expand the natural food emulsifier applications of pea proteins, the emulsifying stability and competitive relationship of interfacial adsorption were investigated. The protein extracted at 90 °C had the highest nitrogen solubility index and surface hydrophobicity. The molecular weight distributions analyzed by high-performance size exclusion chromatography demonstrated that over 60% of the protein had Mw > 500 kDa. The non-reducing SDS-PAGE results showed that the percentage of aggregates were about 37%, and the proportion of proteins were aggregates > vicilin > legumin > convicilin. Increasing the protein concentration from 1.0 to 30 mg/mL increased the emulsifying ability and stability of pea protein stabilized emulsions significantly. At the same time, the concentration of interfacial adsorbed proteins increased. However, the ratio of adsorbed protein to the protein in the initial dispersion (AP%) was decreased significantly from 84% to 21%. When the protein concentration was higher than 10 mg/mL, the interfacial adsorption of pea proteins would reach the saturated adsorption point. The content of aggregates adsorbed onto the interface at low concentration was higher than its proportion in the initial pea protein. With the increase of protein concentration at the interface, the proportion of adsorbed aggregates decreased, while the proportions of vicilin and legumin increased. At saturated adsorption, the contents of proteins on the interface were vicilin > legumin > aggregates > convicilin, and the proportion of aggregates was lower than its proportion in the initial pea protein extraction.