Aroma analysis on Nanlu Shuixian tea in different types

【Objective】 To explore the difference of sensory quality and aroma components of different aroma types of Nanlu Shuixian tea, and provide theoretical basis for quality inspection and processing of Nanlu Shuixian tea.【Method】 The aroma characteristics of 20 tea samples selected in the Nanya Nanlu Shuixian Tea King Competition in Jian'ou City in 2021 were evaluated by sensory evaluation, volatile compounds were detected by headspace solid phase microextraction combined with gas chromatography-mass spectrometry(HS-SPME-GC-MS), and odor activity value(OAV) analysis and partial least square discriminant analysis(PLS-DA) were carried out.【Result】 The 20 Nanlu Shuixian tea samples could be divided into three types:roasting aroma (5 samples), floral aroma (8 samples) and elegant aroma (7 samples). A total of 63 volatile substances were identified from the three aroma types of Nanlu Shuixian tea, including 12 alcohols, 7 aldehydes, 8 ketones, 11 terpenes, 5 alkanes, 5 esters, 5 aromatic compounds, 1 acid, 7 nitrogen-containing compounds and 2 others. Among which 44, 40 and 32 volatile substances were identified respectively from the roasting, floral and elegant samples.The content and composition of volatile components in tea samples of different aroma types were different. The total content of volatile components in floral type was the highest(478.0590 μg/kg), followed by roasting type(275.5390 μg/kg), and the total content in elegant type was the lowest(152.1710 μg/kg). Alcohols accounted for the highest proportion among the three aroma types. In addition, esters and aldehydes accounted for the highest proportion in the roasting aroma, ketones and terpenes accounted for the highest proportion in the floral aroma, and alkanes accounted for the highest proportion in the elegant aroma. Nine volatile compounds with OAV greater than 1 were calculated based on threshold, which were linalool, nerolidol, cedrol, saffron aldehyde, decanal, β-cyclocitral, β-ionone, D-limonene, p-cymene. In addition, decanal, linalool and cedrol were identified as the characteristic flavor components of Nanlu Shuixian tea in Jian'ou. Twenty-two differential volatiles, including p-xylene, theapyrrol, linalool, nerolidol, and eicosanoids, were identified by PLS-DA among the three aroma tea samples. Among them, roasting aroma, floral aroma and elegant aroma had 10, 10 and 2 prominent aroma components respectively.【Conclusion】 Jian'ou Nanlu Shuixian tea is mainly characterized by elegant aroma and floralaroma. Decanal, linalool, and cedrol are the main characteristic aroma components. The 22 volatiles such as p-xylene, teapyrrole, linalool, nerolidol, and eicosane are the main differences among tea samples of different aroma type.