Decoding flavor precursors in channel catfish (Ictalurus punctatus): Lipidomics-guided discovery of phosphatidylcholine oxidation pathways under thermal processing

This original research integrated lipidomics and HS-SPME-GC-MS to unravel lipid-flavor interplay in channel catfish under steaming (ST) and roasting (RO) processing. 1085 kinds of lipids were identified using lipidomics, and phosphatidylcholine (PC) emerged as a critical flavor precursor, showing significant downregulation (Log2FC: −0.71 to −1.40) post-processing. Lipidomics revealed thermal-driven polarization, during which medium-chain fatty acids (C₈–C₁₀) declined, while long-chain species (C₁₆–C₂₂) increased. Correlation analysis highlighted PC's strong association with aldehydes (hexanal, nonanal), confirmed by chemical simulations where PC (C18:2/C16:0) oxidation generated key flavor compounds like hexanal, octanal, acetone, which were highly consistent with key VOCs from authentic channel catfish flesh. Dual degradation pathways were identified: (1) glycerol backbone cleavage yielding acetone and (2) linoleic acid autoxidation via radical-mediated β-scission, producing hexanal and trans-2-heptenal. RO intensified aldehyde formation due to higher thermal stress. Notably, 1-octen-3-ol was absent in PC oxidation products, suggesting alternative enzymatic or non-lipid pathways. This work established PC as a pivotal flavor precursor and mapped its oxidation routes, offering novel insights into lipid-driven flavor chemistry in thermally processed fishery foods.