Sensory and chemical characteristics of Tieguanyin oolong tea after roasting

Qing-Qing Cao; Yan-Qing Fu; Jie-Qiong Wang; Liang Zhang; Fang Wang; Jun-Feng Yin; Yong-Quan Xu

doi:10.1016/j.fochx.2021.100178

Sensory and chemical characteristics of Tieguanyin oolong tea after roasting

Food Chem X. 2021 Dec 2:12:100178. doi: 10.1016/j.fochx.2021.100178. eCollection 2021 Dec 30.

Authors

Qing-Qing Cao^{1

2}, Yan-Qing Fu¹, Jie-Qiong Wang¹, Liang Zhang³, Fang Wang¹, Jun-Feng Yin¹, Yong-Quan Xu¹

Affiliations

¹ Tea Research Institute Chinese Academy of Agricultural Sciences, Key Laboratory of Tea Biology and Resources Utilization, Ministry of Agriculture, 9 South Meiling Road, Hangzhou 310008, China.
² Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China.
³ State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, China.

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.

Keywords: (+)-catechin (PubChem CID: 1203); (−)-Epigallocatechin gallate (PubChem CID: 65064); (−)-catechin gallate (PubChem CID: 6419835); (−)-epicatechin (PubChem CID: 72276); (−)-epicatechin gallate (PubChem CID: 367141); (−)-epigallocatechin (PubChem CID: 72277); (−)-gallocatechin (PubChem CID: 9882981); (−)-gallocatechin gallate (PubChem CID: 199,472; Caffeine (PubChem CID:2519); Gallic acid (PubChem CID: 370); L-theanine (PubChem CID: 439378); Non-targeted analysis; Roasting; Sensory evaluation; Targeted analysis; Theobromine (PubChem CID: 5429); Tieguanyin oolong tea.