Divergent roles of phospholipids and triacylglycerol in flavor formation and trimethylamine generation in Antarctic krill oil

Phospholipids (PL) and triacylglycerol (TAG) are the major lipid components of Antarctic krill oil (AKO), yet their distinct roles in undesirable flavor formation remain unclear. This study compared the volatile profiles of purified PL and TAG fractions from AKO during accelerated storage. Results showed that PL contained significantly higher levels of polyunsaturated fatty acids than TAG and generated a more diverse array of volatile compounds. A total of 42 and 37 volatiles were identified in PL and TAG, respectively, with amines—especially trimethylamine (TMA)—being the key discriminatory compounds exclusive to PL. Model systems further suggested that TMA is produced via a non-enzymatic pathway: phosphatidylcholine is hydrolyzed to release choline, which is subsequently oxidized under metal ion (Fe 3+ ) catalysis to form TMA. These findings provide novel insights into the origin of the characteristic ammonia odor in oxidized AKO and establish a theoretical foundation for flavor control in AKO products.