Detection and quantification of flavoalkaloids in different tea cultivars and during tea processing using UPLC-TOF-MS/MS

Abstract

Flavoalkaloids have been found from tea. However, there is limited information about their content in different teas. Herein, 51 tea samples were screened for flavoalkaloid content. Twelve teas with relatively higher contents of flavoalkaloids were further quantified by UPLC-TOF-MS/MS. The cultivars Yiwu and Bulangshan had the highest levels, with total flavoalkaloid contents of 3063 and 2727 µg g^-1, respectively. Each of the six flavoalkaloids were at levels > 198 µg g^-1 in these cultivars. Of the flavoalkaloids, etc-pyrrolidinone A had the highest content in the teas, reaching 835 µg g^-1 in Yiwu. The content of the flavoalkaloids varied among tea cultivars and with processing procedures, particularly heating. The potential of using flavoalkaloids to discriminate grades of Keemun black tea was studied and discussed. The teas identified in this work with high levels of flavoalkaloids can be used in the future to study the mechanisms by which flavoalkaloids are synthesized in tea.

Keywords: (+)-catechin (C, PubChem CID: 9064); (+)-gallocatechin (GC, PubChem CID: 65084); (–)-epicatechin (EC, PubChem CID: 72276); (–)-epicatechin gallate (ECG, PubChem CID: 107905); (–)-epigallocatechin (EGC, PubChem CID: 72277); (–)-epigallocatechin gallate (EGCG, PubChem CID: 65064); Camellia sinensis; Flavoalkaloids; Keemun black tea; Maillard reaction; Quantification; Thermochemical reaction; d, l-4-chlorophenylalnine (PubChem CID: 4652); l-Theanine (PubChem CID:439378).