Synergistic effects of lipid degradation and the Maillard reaction: Decoding the flavor formation of charcoal-grilled lamb skewers based on flavoromics, sensomics, metabolomics, and lipidomics.

This study aimed to investigate the dynamic changes associated with flavor formation in charcoal-grilled lamb skewers by integrating solvent-assisted flavor evaporation coupled with gas chromatography-mass spectrometry (SAFE-GC-MS), untargeted metabolomics, and lipidomics. An analysis was conducted to reveal the dynamic evolution of volatile compounds, metabolites, and lipids during the 0-12 min grilling period. Physicochemical analysis showed that thiobarbituric acid reactive substances (TBARS) and carbonyl content increased sharply after 8 min, confirming that the mid-to-late stages of grilling represent the peak period of lipid-protein co-oxidation. SAFE-GC-MS identified 118 volatile compounds. Through aroma extract dilution analysis, odor activity value calculation, and omission/recombination experiments, eight key aroma compounds were identified as playing decisive roles in the overall flavor profile including 2-methylpyrazine, 2,5-dimethylpyrazine, 1-octen-3-ol, 2-ethyl-6-methylpyrazine, nonanal, 3-ethyl-2,5-dimethylpyrazine, decanal, and (E,E)-2,4-decadienal. Untargeted metabolomics detected metabolites dominated by lipids (35%) and organic acids (25%). Topological analysis of differential metabolite pathways identified glycerophospholipid metabolism, linoleic acid metabolism, and alanine-aspartate-glutamate metabolism as the three core pathways potentially involved in flavor formation. Lipidomics identified 1611 lipid molecules, with glycerophospholipids accounting for 60.28% as the primary flavor precursor pool. Throughout the grilling process, lipid transformation was predominantly governed by high-temperature non-enzymatic reactions, with glycerophospholipid metabolism exhibiting a central perturbative role. A Transformer-based multi-omics integration strategy was further employed to prioritize the top 150 metabolites and lipids most responsive to the thermal processing trajectory, and correlation network analysis successfully established associations between these molecules and the eight key aroma compounds. In conclusion, integrated multi-omics indicates that three key molecular events, glycerophospholipid, selective oxidation of unsaturated fatty acids, and Strecker degradation of active carbonyl compounds with amino acids, are closely linked to flavor formation of grilled lamb skewers. The sequential synergy between lipid oxidation and the Maillard reaction appears to be a core driving force of flavor quality development.