Quantitative Measurement Reveals Dynamic Volatile Changes and Potential Biochemical Mechanisms during Green Tea Spreading Treatment

Abstract

Quantitative data provide clues for biochemical reactions or regulations. The absolute quantification of volatile compounds in tea is complicated by their low abundance, volatility, thermal liability, matrix complexity, and instrumental sensitivity. Here, by integrating solvent-assisted flavor evaporation extraction with a gas chromatography-triple quadrupole mass spectrometry platform, we successfully established a method based on multiple reaction monitoring (MRM). The method was validated by multiple parameters, including the linear range, limit of detection, limit of quantification, precision, repeatability, stability, and accuracy. This method was then applied to measure temporal changes of endogenous volatiles during green tea spreading treatment. In total, 38 endogenous volatiles were quantitatively measured, which are derived from the shikimic acid pathway, mevalonate pathway, 2-C-methylerythritol-4-phosphate pathway, and fatty acid derivative pathway. Hierarchical clustering and heat-map analysis demonstrated four different changing patterns during green tea spreading treatment. Pathway analysis was then conducted to explore the potential biochemistry underpinning these dynamic change patterns. Our data demonstrated that the established MRM method showed high selectivity and sensitivity for quantitative tea volatile measurement and offered novel insights about volatile formation during green tea spreading.