Effect of denaturants on the emulsifying activity of proteins

The relationship between protein flexibility and emulsifying activity was i nvestigated by disrupting disulfide bonds and/or noncovalent interactions o f the protein. Oil-in water emulsions using model proteins (apomyoglobin, b eta -casein, alpha -casein, lysozyme, bovine serum albumin, kappa -casein, and beta -lactoglobulin) were made in the presence of chemical denaturants (dithiothreitol and/or urea). In mast cases, the presence of denaturants en hanced emulsifying activity. The effect was protein-specific and depended o n the relative importance of disulfide bonds and noncovalent interactions i n stabilizing the native conformation of each protein. Implications for the design of novel protein emulsifiers are discussed.