The oxidation mechanism of phospholipids in Antarctic krill oil promoted by metal ions

Antarctic krill oil (AKO) is an emerging dietary supplement containing metal ions that influence oil oxidation. Thus, this study focuses on the effect and mechanism of metal ions on phospholipid oxidation in AKO. Firstly, AKO containing Mg2+, Mn2+, Cu2+, Fe2+ and Fe3+ (200 μmol/kg) were prepared separately and incubated at 60 °C for 6 days. Peroxide value (POV) and malondialdehyde (MDA) content showed that Fe3+ exhibited the most effective prooxidative activity, with the prooxidative activity of Fe2(SO4)3 (water-soluble) being stronger than that of ferric oleate (FeOl, fat-soluble). In addition, phosphatidylethanolamine (PE) oxidation degree (more than 90%) was considerably greater than phosphatidylcholine (PC) oxidation degree (about 15%) in AKO. Differences in the structure of head group hindered chelation of PC with metal ions than PE due to electrostatic repulsion and steric hindrance. Therefore, PC significantly inhibited, while PE promoted, the oxidation of polyunsaturated triacylglycerol (TAG), like fish oil (p < 0.01).