Analysis of key aroma substances in Tongbai wild black tea using HS-SPME-GC-MS with ROAV

【Objective】 This study aimed to investigate the differences in volatile components between Tongbai wild black tea and conventionally cultivated black tea under the same processing techniques， and to identify their characteristic aroma substances， so as to provide a scientific reference for developing and utilizing tea plant resources in the Tongbai region and optimizing aroma quality of Tongbai black tea.【Method】 Fresh samples of one bud and two leaves of two wild tea varieties and four conventionally cultivated Tongbai tea varieties as raw materials， and six Tongbai black tea samples were made using the same processing techniques. Headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry （HS-SPME-GC-MS） was employed to analyze their volatile composition and identify key aroma substances.【Result】 A total of 115 volatile components were identified from the six Tongbai black tea samples， covering categories of esters （38）， alcohols （16）， aldehydes （20）， ketones （15）， terpenes （9）， heterocyclics （7）， acids （6）， phenols （3）， and others （1）. Comparative analysis revealed a greater diversity of volatile components was found in the Tongbai wild black tea （94） than in conventionally cultivated tea （89）， and the relative contents of volatile compounds in the Tongbai wild black tea were higher than those in cultivated tea. Multivariate statistical analysis identified 32 key differential compounds variable importance in projection （VIP）>1， P<0.05. By calculating the relative odor activity value （ROAV） of each compound， 16 aroma-active compounds （including hexanal， （E）-3,7- dimethyl-2,6-octadienal， and γ-nonanolactone） were determined as aroma-active substances （ROAV>1） leading to aroma quality differences between wild and cultivated Tongbai black tea. Methyl heptenone （fatty， green， citrus， with the max ROAV=103.13） and γ-nonanolactone （coconut-like， with a max ROAV=562.80） were major contributors in the conventionally cultivated tea； while hexanal （fruity， green， with the max ROAV=6785.00）， （E）-3,7-dimethyl-2,6-octadienal （lemon， with the max ROAV=1175.43）， and heptaldehyde （fruity， fatty， with the max ROAV=232.53） showed higher odor contributions in the wild tea.【Conclusion】 The growth environment significantly influences tea plants， leading to differences in volatile components and their relative contents between Tongbai wild black tea and the conventionally cultivated counterpart. Wild black tea contains more abundant aroma-contributing compounds with a greater contribution than conventionally cultivated tea. Its aroma profile， manifested as flowery， sweet， and fruity notes， is of higher quality， indicating potential for development.