| Title: | Non-targeted metabolomics analysis reveals dynamic changes of volatile and non-volatile metabolites during oolong tea manufacture |
| Author(s): | Chen S; Liu H; Zhao X; Li X; Shan W; Wang X; Wang S; Yu W; Yang Z; Yu X; |
| Address: | "College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China; FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou 350002, China. College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China. FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou 350002, China. Fujian Academy of Agriculture Science, Fuzhou 350002, China. FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Center for Plant Cell Biology, Institute of Integrated Genome Biology, and Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA. Electronic address: yang@ucr.edu. FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou 350002, China. Electronic address: xmyu0616@fafu.edu.cn" |
| DOI: | 10.1016/j.foodres.2019.108778 |
| ISSN/ISBN: | 1873-7145 (Electronic) 0963-9969 (Linking) |
| Abstract: | "Oolong tea is a partially fermented tea with distinct tastes and aromas. However, the dynamic biochemical changes during oolong tea processing are not well understood. In this study, we performed metabolomics-based profiling of non-volatile and volatile constituents of oolong tea during its entire processing procedures by UPLC-QTOF MS and GC-TOF MS. A step-wise change of tea metabolome was observed, where catechins and oxidized products, flavonol glycosides and amino acids were identified as key discriminate metabolites. The ZuoQing process comprising alternating YaoQing and TanQing steps was deemed most critical for key metabolic transformation. Extensive YaoQing facilitated the oxidative polymerizations of catechins into theaflavins and proanthocyanidins, lowering the astringency in raw tea. Two direct terpene precursors farnesyl pyrophosphate and geranyl pyrophosphate accumulated to high levels during ZuoQing, which provided more substrates for the synthesis of downstream volatile terpenes. Moreover, both YaoQing and prolonged TanQing facilitated the formation of terpenes as well as fatty acid and benzenoid-derived volatiles, which contributed to the fruity and floral fragrances in oolong tea. The fixation step not only converted amino acids into aromatic compounds, but also lowered the amounts of flavonol glycosides, potentially improving the flavor quality of the final tea product. This study provides a comprehensive profile of flavor-related metabolic changes during oolong tea processing and will contribute to better quality control and flavor improvement of oolong tea" |
| Keywords: | "Camellia sinensis/*chemistry Chromatography, Gas Chromatography, Liquid Food Handling Mass Spectrometry/methods Metabolomics/*methods Odorants/*analysis Tea/*chemistry Volatile Organic Compounds/*analysis Aromas Gc-tof ms Metabolomics Oolong tea Tastes Te;" |
| Notes: | "MedlineChen, Si Liu, Huihui Zhao, Xiaoman Li, Xinlei Shan, Wenna Wang, Xiaxia Wang, Shanshan Yu, Wenquan Yang, Zhenbiao Yu, Xiaomin eng Research Support, Non-U.S. Gov't Canada 2020/01/21 Food Res Int. 2020 Feb; 128:108778. doi: 10.1016/j.foodres.2019.108778. Epub 2019 Nov 8" |
