Decoding lipid signatures and aroma characteristics of four Chinese traditional dark teas via integrative lipidomics, volatilomics, and quantitative descriptive analysis.

Dark tea is a microbially post-fermented tea whose aroma formation is closely associated with lipid degradation. In this study, integrated lipidomics and volatilomics were applied to characterize four Chinese dark teas: Anhua dark tea (AHDT), Qingzhuan dark tea (QZDT), Liupao dark tea (LPDT), and Pu-erh dark tea (PEDT). Lipidomic profiling identified 486 lipid species, including 186 differential lipids among the four tea varieties. Glycerophospholipids and glycoglycerolipids were relatively enriched in AHDT, fatty acyls in PEDT, and acylglycerolipids in QZDT and LPDT. Quantification of fatty acid esters of hydroxy fatty acids (FAHFAs) revealed more than ten-fold higher levels of FAHFA (18:1/O-26:0), FAHFA (18:2/O-26:0), and FAHFA (18:2/O-22:0) in PEDT than in AHDT. Volatilomic analysis identified 87 volatile compounds, among which fatty acid-derived volatiles (FADVs) were the predominant class. A total of 43 aroma-active compounds exhibited high aroma character impact (ACI > 0.1), including 26 FADVs. In addition, nine aroma attributes were quantified using quantitative descriptive analysis (QDA). Integrated lipidomic, volatilomic, and sensory analyses revealed distinct lipid-volatile-aroma signatures among the four tea varieties. AHDT was associated with membrane lipids and green, fungal aromas, PEDT with fatty acyls and stale, sweet, fruity notes, LPDT with triacylglycerols and woody, herbal, betelnut-like aromas, and QZDT with diacylglycerols and green, floral, woody characteristics. This study provides a valuable dataset for comparative investigations of flavor characteristics in post-fermented teas.