Characterization of the Key Aroma-Active Compounds Responsible for the Rice Cruse-like Aroma of Large-Leafed Yellow Tea (Camellia sinensis)

Comparative analysis of aroma-active compounds in large-leaf yellow tea and rice crust was carried out via headspace solid phase micro-extraction (HS-SPME) combined with gas chromatography-olfactometry-mass spectrometry (GC-O-MS) to elucidate the material basis of the rice crust-like aroma of large-leaf yellow tea. The results revealed that 72 and 45 volatile compounds were identified in large-leaf yellow tea infusion and rice crust, respectively. In total, 15 aroma-active components were found in both large-leaf yellow tea and rice crust. Among them, five pyrazines responsible for a roasted aroma were common to both, which made a key contribution to the characteristic rice crust-like aroma of largeleaf yellow tea. 2-Ethyl-3,5-dimethylpyrazine, 2-ethyl-5-methylpyrazine and 2,6-diethylpyrazine were the key aroma-active components of both large-leaf yellow tea and rice crust. 3,5-Diethyl-2-methylpyrazine was key to the formation of the rice crust-like aroma of large-leaf yellow tea, but contributed little to the characteristic aroma of rice crust. 3-Ethyl-2,5-dimethylpyrazine was key to the formation of the characteristic aroma of rice crust, butt contributed little to the characteristic aroma of large-leaf yellow tea.