Study of the dynamic changes in the non-volatile chemical constituents of black tea during fermentation processing by a non-targeted metabolomics approach. (January 2016) - Tan, Junfeng
Abstract: Fermentation is a critical manufacturing process to produce black tea, in which the chemical compositions are greatly changed. However, the dynamic changes of this sophisticated process are far from clear, and were often characterized by determining a small number of compounds. In this study, we applied a non-targeted metabolomics approach based on ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry to comprehensively profile the variations of metabolites in tea samples with various fermentation durations of 0, 1, 2, 4, 6, 8, 10, 12 and 14 h. Principal component analysis indicated obvious stepwise alterations of tea metabolome during the fermentation. Relative quantitation of 61 identified metabolites including catechins, dimeric catechins, flavonol glycosides, amino acids, phenolic acids, alkaloids, and nucleosides revealed distinct changes of phenol pathway. Dynamic changes of a part of these compounds were mapped for the first time. To the best of our knowledge, this study offered the most comprehensive profiles of metabolite changes during the tea fermentation process. Highlights: A LC–MS based metabolomics approach was used to study the tea fermentation process. Obvious stepwise alterations of the tea metabolome were observed. Dynamic changes of 61 identified metabolites were profiled. Changes of metabolites along the phenylpropanoid/flavonoid pathway were mapped. A novel derivative of theanine was discovered and identified as theanine glucoside.