Sensory and chemical characteristics of Tieguanyin oolong tea after roasting
Qing-Qing Cao, Yanqing Fu, Jieqiong Wang, Liang Zhang, Fang Wang, Jun‐Feng Yin, Yong‐Quan Xu
Abstract
Roasting, a critical process for oolong tea, has been applied to Tieguanyin tea to improve flavor attributes. To investigate the effects of the roasting on the flavor of Tieguanyin , the global metabolomics analysis on the non-volatile and volatile components were proceeded. The weakening of bitterness and astringency , caused by roasting, may be attributed to the decreasing of flavonoids glycosides and procyanidins , whereas the enhancing of sweet aftertaste to the increasing of gallic acid. Besides, l -theanine flavan-3-ols adducts ( N -ehtyl-2-pyrrolidinone substituted flavan-3-ols) increased dramatically at 130 °C compared with 105 °C, with the reduction of l -theanine and flavan-3-ols. Meanwhile, high temperature hampered the volatiles’ diversity and intensity, resulting from the lowering of floral volatiles, i.e., β-ionone, jasmine, and nerolidol, yet the nitrogen-containing heterocyclic compounds increased, e.g., pyrroles and pyrazines. The results can help to comprehensively understand the influences of roasting technology on the flavor and chemistry of oolong tea.