Abstract: To clarify the differences in aroma quality among Congou black tea made from three major varieties grown in Chongqing and to evaluate their aroma characteristics, qualitative and quantitative evaluation of their volatile components were performed by sensory evaluation and gas chromatography-tandem mass spectrometry (GC-MS/MS), and key differential aroma compounds were identified by the combined use of orthogonal partial least squares-discriminant analysis (OPLS-DA), relative odor activity value (ROAV) and flavor annotation. The sensory evaluation showed obvious differences in aroma characteristics among the three black tea samples. Sichuan medium- and small-leaf group variety (SCB), Fuding Dabaicha (FDB) and Shuyong (SYB) presented elegant floral, sweet floral and citrus-like aromas, respectively. A total of 61 volatile components were detected, mainly including terpenoid, ester and heterocyclic aroma components. FDB differed significantly from SCB and SYB in terms of the content and composition of volatile compounds and the number of differential metabolites. Based on their ROAV and flavor annotation, 15 aroma components including methyl anthranilate, (E)-4-nonenal and phellandrene were identified as key contributors to the differences in aroma among the three varieties of Congou black tea. Methyl anthranilate and (6Z)-nonen-1-ol might be responsible for the elegant floral aroma of SCB. (E)-4-nonylaldehyde, δ-decanolactone, hexanoic acid-2-phenylethyl ester and (Z)-3-hexenyl acetate might play an important role in the sweet floral aroma of FDB, while phellandrene and p-cymene were crucial for the citrus-like aroma of SYB. The results provide a theoretical foundation for the aroma-oriented processing of Gongou black tea and for understanding the aroma composition of Gongou black tea from different varieties.

Key words: Congou black tea, tea variety, flavor quality, gas chromatography-tandem mass spectrometry, relative odor activity value