Concentration of resveratrol at the oil-water interface of corn oil-in-water emulsions

Accumulation of polyphenolic antioxidants at the oil-water interfaces of lipid-based emulsions is crucial to improve their oxidative stability. Polyphenolic antioxidants are added to lipid-based emulsions to minimize the lipid peroxidation reaction, a radical reaction that produces harmful products and undesirable off-flavors, and because of their benefits in human health. Antioxidants react with the lipid radicals at the oil-water interface of emulsions, inhibiting or minimizing the lipid oxidation reaction, increasing the oxidative stability of the emulsion, and their efficiency in inhibiting the oxidation of lipids strongly depends on their interfacial concentration. In this work we have evaluated the accumulation of trans-resveratrol (3,4,5-trihydroxystilbene, TRES) in the interfacial region of a model food-grade emulsion composed of stripped corn oil, acidic water and Tween 20 and analyzed its variation with the surfactant concentration. Results show that TRES distributes between the three regions, but more than 85% of TRES is located in the interfacial region and only a small fraction in the oil and aqueous regions. An increase in emulsifier concentration promotes the incorporation of TRES into the interfacial region, however, its interfacial concentration, which is much higher than the stoichiometric concentration, decrease because of the increase of the interfacial volume. Results obtained should contribute to a better understanding of the antioxidant efficiency in inhibiting lipid oxidation and to the development of new strategies to prepare healthier and more nutritional foods with longer shelf-lives.