Distinct Changes of Metabolic Profile and Sensory Quality during Qingzhuan Tea Processing Revealed by LC-MS-Based Metabolomics

Abstract

Qingzhuan tea (QZT) is a unique type of dark tea exclusively produced in Hubei Province of China. In the current study, liquid chromatography–mass spectrometry (LC-MS) coupled with multivariate analysis was applied to characterize the chemical composition of QZT and investigate the effect of QZT processing on its metabolic profile and sensory quality. The contents of polyphenols and flavonoids decreased significantly while the polysaccharides content remained stable, while the theabrownin content inversely increased during QZT processing. LC-MS-based metabolomics analyses revealed that the tea sample after microbial fermentation (MFT) was dramatically different from the sample before microbial fermentation (UFT), while MFT was very similar to QZT. A total of 102 compounds were identified as critical metabolites responsible for metabolic changes caused by QZT processing, with the contents of catechins and flavonoids significantly decreased, and some novel phenolic acids and catechin derivatives were formed. The sensory quality of QZT was mainly formed during microbial fermentation, which greatly reduced the astringency and bitterness of raw tea leaves and produced its characteristic woody and stale aroma as well as mellow taste. These results suggested that microbial fermentation is the critical process in changing the metabolic profile of raw tea leaves and forming the sensory quality of QZT.

Dynamic Evolution and Correlation between Metabolites and Microorganisms during Manufacturing Process and Storage of Fu Brick Tea

“…The separation was carried out using a BEH C18 column (1.7 μm, 2.1 mm × 100 mm, Waters, USA) and the column was maintained at 45 °C and eluted with a gradient of 1–100% methanol containing 0.1% ( v / v ) formic acid over 15 min at a flow rate of 0.4 mL/min. A 1 μL sample was injected into the column, and the gradient elution condition followed a previous publication [ 18 ].…”

“…This approach mainly focuses on the identification of small molecular endogenous metabolites in organisms [ 17 ]. However, the nutritional and healthy ingredients in Fu brick tea are mostly macromolecules, such as polysaccharides, tea polyphenols, and catechin [ 18 ]. To make up for this defect, biochemical methods were used to assess these contents of macromolecules in Fu brick tea.…”

Comparative evaluation for phytochemical composition and regulation of blood glucose, hepatic oxidative stress and insulin resistance in mice and HepG2 models of four typical Chinese dark teas

“…The contents of gallic acid, caffeine, theobromine and seven critical catechins including catechin (C), epicatechin (EC), epicatechin gallate (ECG), gallocatechin (GC), epigallocatechin (EGC), gallocatechin gallate (GCG) and epigallocatechin gallate (EGCG), were determined using a LC-20A High performance liquid chromatography (HPLC) system (Shimadzu, Tokyo, Japan) according to a previously reported method. 21…”

Promoting Human Nutrition and Health through Plant Metabolomics: Current Status and Challenges

“…In addition to dietary foods, humans consume many other plant-derived products such as wine, coffee, and tea. Today, metabolomics has been used to evaluate the quality of those typical plant-derived products, to correlate metabolites with taste and health properties in humans, and to promote the production of high-quality health-benefit plantderived drinks [96][97][98][99][100]. Increasing studies begin to focus on metabolomics responses of humans to these plant-derived beverages as well.…”