Integrated volatile profiling and metabolomics reveal changes in volatile compounds  during low‐temperature smoking of sea bass ( Lateolabrax maculatus )

BACKGROUND: Low-temperature smoking is increasingly used as a mild processing approach to develop the characteristic aromas of fish products; however, the origins and stage-dependent changes in volatile compounds during processing remain insufficiently understood. This study investigated volatile changes in sea bass (Lateolabrax maculatus) during low-temperature smoking using an integrated strategy combining gas chromatography-ion mobility spectrometry (GC-IMS), gas chromatography-mass spectrometry (GC-MS), multivariate analysis, and untargeted metabolomics. RESULTS: Gas chromatography-ion mobility spectrometry detected 31 volatile compounds and GC-MS detected 39, showing pronounced stage-dependent shifts in volatile profiles. Multivariate analysis, specifically orthogonal partial least squares discriminant analysis (OPLS-DA), clearly discriminated early stage samples (S1-S3) from smoked and matured samples (S4-S5) and identified stage-discriminant volatiles. Metabolomics-based pathway enrichment indicated that representative lipid-related volatiles, including hexanal, (E)-2-octenal, and 1-octen-3-ol, were associated with linoleic and α-linolenic acid oxidation pathways. After smoking, phenolic and furanic compounds commonly associated with wood thermal decomposition (e.g., guaiacol and 5-methylfurfural) increased markedly and were retained after maturation, supporting substantial smoke-derived contributions to the final volatile profile. In addition, aldehyde-alcohol associations, together with odor-threshold and relative odor activity value results, suggested progressive softening of sharp green oxidized notes during low-temperature smoking and maturation. CONCLUSION: The results support a process-dependent aroma development pattern in which endogenous lipid-related reactions and smoke-derived constituents jointly shape volatile profiles during low-temperature smoking. This work provides a practical basis for volatile-marker selection, process optimization, and flavor quality control for smoked fish products.