Impact of oil phase concentration on physical and oxidative stability of oil-in-water emulsions stabilized by sodium caseinate and ultra-high pressure homogenization

In the present study, oil-in-water emulsions were formulated using 5.0% (w/v) of sodium caseinate (SC) and different oil concentrations (10–30%, v/v) by conventional homogenization (CH) and ultra-high pressure homogenization (UHPH, 200–300 MPa). The effect of oil concentration and pressure of treatment on emulsions characteristics and stability was studied. Emulsions were characterized assessing their microstructure, droplet size distribution, rheological properties, emulsifying activity index (EAI), creaming stability by Turbiscan®, and photo-oxidation. UHPH emulsions, especially those treated at 200 MPa, showed smaller droplet size and greater physical stability than CH emulsions. In addition, emulsions containing higher oil volume fractions (20 and 30%) exhibited greater physical and oxidative stability. UHPH emulsions treated at 200 MPa and containing 20% oil content were the most stable emulsions against physical separation and photo-oxidation. These results show that UHPH is a potential technology to enhance the physical and oxidative stability of emulsions containing sodium caseinate as emulsifier for several applications.