Effects of ferrous ions partitioning at the oil-water interface on the oxidative stability of Antarctic krill (Euphausia superba) oil: Reverse micelles alter the physical location of ferrous ions

This study investigates the role of ferrous ion partitioning in promoting lipid oxidation in Antarctic krill oil (AKO) containing reverse micelles. Cryogenic transmission electron microscopy and small-angle X-ray scattering confirmed the presence of reverse micelles in AKO. AKO with ferrous sulfate (FeSO 4 , water-soluble iron) and ferrous fumarate (C 4 H 2 FeO 4 , oil-soluble iron) were stored at 60 °C. Interestingly, compared with oil-soluble Fe 2+ , water-soluble Fe 2+ significantly enhanced oxidation. Confocal laser scanning microscopy (CLSM) showed that water-soluble Fe 2+ and lipid hydroperoxides (LOOHs) concentrated at the oil-water interface of reverse micelles, whereas ferrous fumarate was distributed in the oil phase. Meanwhile, water-soluble Fe 2+ significantly promote the oxidation of phospholipids at the oil-water interface, leading to the formation of LOOHs and free radicals that entered the oil phase, triggering glyceride oxidation. Overall, this characterization of the spatial distribution and pro-oxidant effects of metal ions in AKO provides valuable insights into the development of novel antioxidant technologies.