Multi-omics revealed the formation mechanism of flavor in salted egg yolk induced by the stages of lipid oxidation during salting

To explore the contribution of different lipid oxidation stages to flavor formation in salted egg yolk, potential pathways of flavor formation were characterized by multi-omics strategy and partial least squares structural equation model (PLS-SEM). 72 lipids, 135 metabolites and 5 volatiles related to lipid oxidation were screened out. The degradation of aldehydes and ketones, and the generation of tryptamine and elaidic acid, etc. were promoted by triglycerides (TG) (10:0 16:0 18:1), triglycerides (TG) (18:0 20:1 22:0), etc. at primary and secondary oxidation stage, respectively. The generation of acetophenone, thianaphthene, etc. through the pathway of 2-phenylacetamide, hexanoylcarnitine, etc. was facilitated by these triglycerides (TG) at primary oxidation stage. Furthermore, amino acid metabolisms, pentose phosphate pathway and linoleic acid metabolism occurred at secondary oxidation stage were key pathways to form distinctive flavor. In conclusion, secondary oxidation stage may be more important for the formation of unique flavor (taste) in salted egg yolk.