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• Volatiles in baked green teas with different tenderness were examined thoroughly. • cis -Linalool oxide (furanoid) and methyl salicylate were abundant in mature leaves. • Most chiral odorants had significantly higher contents in mature tea samples. • Enantiomeric ratios of most odorants were unaffected by tenderness and processing. • Evident variation on ERs of limonene, α-terpineol etc. occurred after processing. Suitable picking tenderness is an essential prerequisite for manufacturing tea. However, the influence of picking tenderness of fresh tea leaves on the aromatic components is still unclear. In this study, aromatic profiles and chiral odorants in fresh tea leaves and corresponding baked green teas with five levels of tenderness of two representative cultivars were analysed using stir bar sorptive extraction-gas chromatography-mass spectrometry. cis -Linalool oxide (furanoid) and methyl salicylate exhibited significantly increasing trends as samples of all series matured. The content of most chiral odorants was significantly high in the mature samples, and significant content variations of all enantiomers during baked green tea processing could be observed with different trends according to their precursors. In particular, the enantiomeric ratios of most chiral odorants were less influenced by the picking tenderness and processing, while drying (limonene), spreading and fixation (α-terpineol), and spreading (dihydroactinidiolide) influenced the chiral distribution of the aforementioned odorants. [ABSTRACT FROM AUTHOR]

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]

Linalool is a major volatile component of tea aroma. It occurs naturally as R -(−)- and S -(+)-linalool enantiomers, which exhibit entirely different sensorial properties. Using headspace solid-phase microextraction with chiral gas chromatography, we quantitated R -(−)- and S -(+)-linalool in teas. Optimal extraction conditions were as follows: CAR–DVB–PDMS fiber, 60 min at 60 °C, and tea/water ratio of 1:6 (w(g)/v(mL)). We measured linalool levels in five different teas, in fresh leaves of 14 different cultivars, and in samples collected during processing of green and black teas. Enantiomeric distributions of linalool were significantly different among the different teas and among the different tea cultivars. R -(−)-Linalool and S -(+)-linalool reached maximum levels during the rolling of black tea, with the levels declining drastically during green tea processing. Although tea germplasm was an important factor in determining the enantiomeric distribution of linalool in tea products, the processing steps also had a large impact on linalool levels. [ABSTRACT FROM AUTHOR]

Aroma is one of the most important determinants of tea quality; thus, the precise characterization of the chemical composition of tea aroma is of significant value. In this study, aroma components of the most famous Chinese green tea, Xihu Longjing tea, were first systematically analyzed using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOFMS) combined with simultaneous distillation extraction (SDE). 478 volatile compounds were identified as common constituents of fifty-five Xihu Longjing tea samples based on standard mass spectra in available databases, retention times, retention indices, structured chromatograms and standards. Subsequently, the aroma qualities of Xihu Longjing tea samples were discriminated by sensory evaluation combined with multivariate analysis. The study results indicated that 37 compounds were positively correlated with aroma quality, and 65 compounds were negatively correlated with aroma quality. The above compounds with various odor characteristics were considered as the key components to affect the aroma quality of Xihu Longjing tea. [ABSTRACT FROM AUTHOR]