Metabolomics Analysis Reveals Four Novel N‑Ethyl-2-pyrrolidinone-Substituted Theaflavins as Storage-Related Marker Compounds in Black Tea

Tea market is currently oversupplied, and unsold tea often needs to be properly stored for a period of time. However, the chemical changes occurring in black tea during storage are limitedly understood. In this study, a comprehensive nontargeted and targeted metabolomics approach was used to investi...

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Veröffentlicht in:Journal of agricultural and food chemistry 2021-11, Vol.69 (46), p.14037-14047
Hauptverfasser: Chen, Dan, Zhao, Yanni, Peng, Jiakun, Zhang, Yue, Gao, Jianjian, Wu, Wenliang, Xie, Dongchao, Hu, Zhengyan, Lin, Zhi, Dai, Weidong
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Sprache:eng
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Zusammenfassung:Tea market is currently oversupplied, and unsold tea often needs to be properly stored for a period of time. However, the chemical changes occurring in black tea during storage are limitedly understood. In this study, a comprehensive nontargeted and targeted metabolomics approach was used to investigate the dynamic changes in compounds in time-series (0–19 months)-stored black teas. The contents of flavanols, theaflavins (TFs), theasinensins, procyanidins, most phenolic acids, amino acids, quercetin-O-glycosides, and myricetin-O-glycosides decreased during storage, while the contents of N-ethyl-2-pyrrolidinone-substituted flavanols, flavone-C-glycosides, and most kaempferol-O-glycosides increased. More importantly, four novel compounds strongly positively correlated with storage duration (r = 0.922–0.969) were structurally assigned as N-ethyl-2-pyrrolidinone-substituted TFs and validated with synthetic reactions of TFs and theanine standards. The content of N-ethyl-2-pyrrolidinone-substituted TFs was 51.54 μg/g in black tea stored for 19 months. To the best of our knowledge, N-ethyl-2-pyrrolidinone-substituted TFs were discovered in tea for the first time.
ISSN:0021-8561
1520-5118
DOI:10.1021/acs.jafc.1c05850