GC–O–MS-Guided Volatilomics and Microbiome Profiling Prioritize Candidate Odorants and Associated Microbial Taxa during Flowering-Driven Aroma Remodeling of Tibetan Dark Tea

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Solid-state fermentation can generate diverse aroma profiles, but the outcomes are often difficult to predict and standardize, which limits scalable production and intelligent quality control in fermented foods. Tibetan dark tea provides a relevant model because pile fermentation followed by flowering can produce distinct aroma styles. In this study, we compared four processing regimes to examine flowering under different pile fermentation levels: short piling (S1), tea stem decoction assisted flowering after short piling (S2), long piling (S3), and long piling followed by stem-decoction-assisted flowering (S4). Sensory evaluation revealed clear differences among regimes. S3 showed balanced woody and sweet notes, whereas S4 exhibited stronger medicinal notes together with fungal and floral impressions. GC-O-MS (gas chromatography-olfactometry-mass spectrometry), untargeted volatilomics, and ROAV (relative odor activity value) analysis identified nine key odorants with distinct trends across processes. Correlation analysis suggested that thermophilic fungi such as Thermomyces lanuginosus and heat-tolerant bacteria including Saccharopolyspora gregorii and Staphylococcus gallinarum were positively associated with woody-associated volatiles. In contrast, Leuconostoc, Weissella , and several proteobacteria taxa were negatively associated with grassy aldehydes such as hexanal. Overall, this study integrates sensory profiling, odorant prioritization, and microbiome association analysis to identify candidate odorant markers and associated microbial signatures, providing a basis for future process optimization and aroma quality control in flowering Tibetan dark tea. The framework may also inform aroma design and quality control for other solid-state fermented foods.