Investigation on green tea lipids and their metabolic variations during manufacturing by nontargeted lipidomics

Lipids are hydrophobic metabolites implicated in tea flavor quality. Understanding their transformations during tea manufacture is of particular interest. To date, the detailed lipid composition and variations during green tea manufacture are largely unknown. Herein, we performed a comprehensive characterization of the dynamic changes of lipids during green tea manufacture, by applying nontargeted lipidomics using ultrahigh performance liquid chromatography-quadrupole-Orbitrap mass spectrometry (UHPLC-Q-Exactive/MS) combined with chemometric tools. Totally, 283 lipid species were detected, covering 20 subclasses. Significant lipidomic variations were observed during green tea manufacture, especially in the fixation stage, mainly associated with chlorophyll decomposition, phosphatidic acids (PAs) reduction and glycolipids degradation, which potentially contribute to tea color and aroma quality. Specifically, the most prominent decrease of PAs content during green tea manufacture was identified for the first time. This study provides insights into the lipid metabolic fates upon green tea manufacture, and their roles in green tea sensory quality.