Oxidation patterns and stability mechanisms of marine oils revealed by oxidized triglyceride and phospholipid...

Marine oils are rich in polyunsaturated fatty acids and are highly susceptible to oxidation, resulting in complex oxidized lipids that deteriorate their quality. This study aims to explore the dynamic profiles of these oxidized species and elucidate the molecular mechanisms governing their oxidative stability. By utilizing RPLC-Q-TOF oxidized lipidomics combined with molecular dynamics (MD) simulations, this work provided a pioneering molecular-level analysis of oxidized marine oils, identifying 47 oxidized triacylglycerol (oxTG) and 45 oxidized phospholipid (oxPL) molecular species, including 14 oxTG and 6 oxPL isomers. Temporal tracking revealed divergent oxidation kinetics among the samples. In highly unsaturated TG-type oils, multi‑oxygenated TGs exhibited a dramatic "rise-then-fall" cleavage pattern, characterized by a rapid peak of 4.5 mg/g as early as day 2. Conversely, phospholipid (PL)-rich oil demonstrated remarkable macroscopic stability via preferential PL oxidation, suppressing oxTG accumulation to below 0.6 mg/g. At 40% PL addition, MD simulations confirmed that PC provides a better physical barrier against O₂ than PE due to its bulkier headgroup and lower free volume. When applied at trace PL level (0.5%), a crucial acyl-chain trade-off emerged. While marine PUFA-PLs autoxidized and compromised their physical barrier, fully saturated PC (16:0_16:0) effectively blocked radical initiation, restricting specific deep oxidation products (TG (22:6_22:6_22:6 < +3O>)) to 0.86 mg/g. By profiling oxidized molecular species and bridging PL spatial conformation to oxidation trajectories, this study provides precision theoretical strategies for stabilizing marine oil systems.