Do antioxidants improve the oxidative stability of oil-in-water emulsions?

Oil-in-water emulsions were prepared with 30% stripped sunflower oil, stabilized by 20 g/L BSA and homogenized under high pressure to obtain a mean droplet size near 0.5 mum. The emulsions were shown to be physically stable during storage in a shaker at 47degreesC for 5 d. Such a medium was suitable to test the efficiency of different types of antioxidants. Oxidation of control emulsions appeared rapidly without a lag phase, and the contents of conjugated dienes and hexanal reached a plateau after around 20 h. in the presence of EDTA, the oxidation was strongly inhibited, suggesting that some metallic ions present in the oil or the protein solution act as inducers. Ascorbic acid and ascorbyl palmitate were inactive. Isoeugenol was found to be a powerful antioxidant, better than eugenol, alpha-tocopherol, and Trolox.