Droplet-stabilized oil-in-water emulsions protect unsaturated lipids from oxidation

Droplet-stabilized emulsions use fine protein-coated lipid droplets (the shell) to emulsify larger droplets of a second lipid (the core). This study investigated the oxidation resistance of polyunsaturated fatty acid (PUFA) oil within droplet-stabilized emulsions, using shell lipids with a range of melting points: olive oil (low melting), trimyristin (high-melting), and palmolein oil (intermediate melting point). Oxidation of PUFA oil was accelerated with a fluorescent lamp in the presence of ferrous iron (100 μM) for 9 days, and PUFA oxidation was monitored via conjugated dienes, lipid hydroperoxides, and hexanal levels. Oxidation was slower in droplet-stabilized emulsions than in conventional emulsions or control emulsions of the same composition as droplet-stabilized emulsions but different structure, and trimyristin gave the greatest oxidation resistance. Results suggest the structured interface of droplet-stabilized emulsions limits contact between pro-oxidants and oxidation-sensitive bioactives encapsulated within, and this antioxidative effect is greatly enhanced with solid surface lipids.