Novel polyglycerol-10 dialdehyde mediated cross-linking of sodium caseinate: Preparation, characterization, and improved emulsifying properties

Polyglycerol-10 dialdehyde , prepared by NaIO 4 oxidation of polyglycerol-10, was used as a novel cross-linking reagent for sodium caseinate (NaCas) modification, which can alter the emulsifying properties of proteins. The results revealed that cross-linking resulted in an approximately two-fold increase in the surface hydrophobicity and a 15° increase in the contact angle of NaCas. The emulsifying activity index, emulsion stability index, and oil-binding capacity of cross-linked NaCas also increased significantly. Furthermore, the stabilization of soybean oil-in-water emulsion demonstrated that cross-linked NaCas can prevent oil droplets from aggregating during storage; meanwhile, compared to the native protein, the cross-linked NaCas improved the stability of the emulsions under high ionic strength and temperatures. It is worth noting that the polyglycerol-integrated NaCas showed less adsorption on the glass surface. These findings clearly illustrate that renewable polyglycerol can be used as a novel cross-linking reagent for protein modification, which will provide proteins with promising features for use as emulsifiers in the food, pharmaceutical, and cosmetic industries.