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A chestnut-like aroma is widely considered an important indicator of an excellent-quality green tea; however, the key odorants responsible for chestnut-like aroma have never been systematically studied and remain unknown. In this study, the aroma components of green teas and Chinese chestnuts were analyzed using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOFMS), and 58 compounds were identified as common aroma components among green teas, boiled Chinese chestnuts, roasted Chinese chestnuts and raw Chinese chestnuts. Subsequently, 17 volatiles, including 3-methylbutanal, ( E )-3-penten-2-one, ethylbenzene, heptanal, benzaldehyde, 2-pentylfuran, octanal, benzeneacetaldehyde, ( E )-2-octenal, ( E,E )-3,5-octadien-2-one, linalool, nonanal, ( E )-2-nonenal, decanal, ( Z )-hex-3-en-1-yl hexanoate, trans -β-ionone and ( E )-nerolidol, were identified as the key odorants responsible for chestnut-like aroma based on the odor activity value (OAV) calculation method. Besides, the comparison of OAVs of key odorants between fresh tea leaves and finished teas indicated that all key odorants were present in fresh tea leaves and that their contents increased or decreased during tea processing. Moreover, the comparison between results of OAV and gas chromatography-olfactometry (GC-O) methods showed that ethylbenzene, heptanal, benzaldehyde, 2-pentylfuran, ( E,E )-3,5-octadien-2-one, linalool, ( Z )-hex-3-en-1-yl hexanoate and trans -β-ionone were the common identified compounds between the two methods. The identification of chestnut-like aroma in green teas will provide a theoretical basis for further research on the directional adjustment and control of tea aroma quality. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel Es-GC×GC-TOFMS approach to separate chiral volatiles in tea was established. • Volatile enantiomers in Wuyi rock teas from four cultivars were firstly quantitated. • Limits of quantitation of linalool oxides A−B in teas were as low as 0.2 pg/mL. • R -α-Ionone, S -(E)-nerolidol etc. were the potential markers to distinguish cultivar. • 7 Volatile enantiomers were identified as aroma-active compounds in Wuyi rock teas. Chiral volatiles play important roles in the formation of aroma quality of foods. To date, enantiomeric characteristics of chiral volatiles in Wuyi rock tea (WRT) and their aroma contributions are still unclear. In this study, an efficient enantioselective comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (Es-GC × GC-TOFMS) approach to separate and precisely quantitate 24 pairs of chiral volatiles in WRTs was established, and the enantiomeric distribution and aroma contribution of chiral volatiles among WRTs from four representative cultivars were investigated. Enantiomeric ratio (ER) of R -α-ionone (80%) in Dahongpao (DHP), ER of S -α-terpineol (57%) in Jinfo (JF), ERs of R -γ-heptanolactone (69%), S -γ-nonanolactone (55%), (2 R , 5 S)-theaspirane B (91%), concentration of S -(E)-nerolidol (313.37 ng/mL) in Rougui (RG) and concentration of R -α-ionone (33.01 ng/mL) in Shuixian (SX) were unique from other types of WRTs, which were considered as the potential chemical markers to distinguish WRT cultivars. The OAV assessment determined 7 volatile enantiomers as the aroma-active compounds, especially R -α-ionone and R -δ-octanolactone in SX, as well as S -(E)-nerolidol and (1 R , 2 R)-methyl jasmonate in RG contribute much to aroma formation of the corresponding WRTs. The above results provide scientific references for discrimination of tea cultivars and directed improvement of the aroma quality of WRT. [ABSTRACT FROM AUTHOR]