Analysis of Key Aroma Components in Five High-Fragrance Black Teas Using Electronic Nose and Headspace Solid-Phase Microextraction Coupled with Gas Chromatography-Mass Spectrometry

To investigate the differences in aroma among five high-fragrance black teas (Tieguanyin, Jinguanyin, Jinmudan, Huangdan and Meizhan), an electronic nose, headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS) and sensory evaluation were used to investigate their key aroma components. The sensory evaluation results showed that all black teas had obvious aroma characteristics. Jinmudan black tea had a prominent fruity and floral aroma with a faint milky note. Jinguanyin black tea had a rich floral aroma with elegant fragrance. Tieguanyin black tea had a tender, sweet and milky aroma. Huangdan black tea had a sweet aroma with floral notes. Meizhan black tea had an obvious fresh and sweet aroma. Orthogonal partial least squares-discriminant analysis (OPLS-DA) performed on the electronic nose data showed a clear separation among different black teas. By HS-SPME-GC-MS, a total of 834 aroma components were identified, and 272 differential aroma compounds were selected using the cutoff of variable importance in projection (VIP) > 1 with a P value < 0.05. According to odor activity value (OAV) and relative odor activity value (ROAV), benzenemethanethiol, 3-mercapto-3-methylbutyl formate, dimethyl trisulfur compounds, 3-octen-2-one, (Z)-6-nonenal and 2-thiophenemethanethiol were identified as key aroma components in the five black teas, which contributed to their clean, sweet, floral and fruity aroma characteristics. Among them, 1-(2-thienyl)-ethanone, 3-octen-2-one and 3-mercapto-3-methylbutyl formate were important volatile substances to discriminate between different black teas. The findings of this study help to elucidate the aroma characteristics of different varieties of black tea and also provide a scientific basis for the research and development of high-fragrance black tea.