Abstract: To systematically compare the differences in characteristic flavor metabolites between compressed black tea and raw black tea from Sichuan, high performance liquid chromatography (HPLC) was used for the quantitative detection of non-volatile metabolites such as tea polyphenols and caffeine. Furthermore, headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) was employed to quantitatively analyze volatile aroma components including alcohols and aldehydes. By applying chemometrics, a comparative analysis was conducted on the non-volatile metabolites and volatile aroma characteristics of two types of unaged compressed black tea (CBT-1 and CBT-2) and two types of raw black tea (RBT-1 and RBT-2) with similar raw material grades from Sichuan. The results indicated that compared with raw black tea, the grassy note and other undesirable aromas in compressed black tea were significantly weakened, while the sweet and aged aromas were more intense and long-lasting. Six non-volatile components—theanine, tea polyphenols, arginine, glutamic acid, aspartic acid, and theaflavin-3,3’-digallate (TFDG)—were identified as the key flavor compounds that could distinguish between the two types of tea. Seven volatile aroma components—myrcene, linalool, geranial, 2,4-di-tert-butyl-4-methylphenol, (E)-β-ionone, (E)-linalool oxide (pyranoid), and phenethyl alcohol—were found to be potential characteristic aroma components that could differentiate between Sichuan compressed black tea and raw black tea. These findings provide a reference for understanding the flavor characteristics of Sichuan black tea, conducting subsequent processing-related research, and developing related products.

Key words: Sichuan compressed black tea; raw black tea; headspace solid-phase microextraction; non-volatile compounds; volatile aroma substances; chemometrics