Analyzing the influence of withering degree on the dynamic changes in non-volatile metabolites and sensory quality of Longjing green tea by non-targeted metabolomics

Abstract

Withering is an important processing stage in green tea, which contributes to the tea flavor quality. The aim of this work was to comprehensively investigate the changes of chemical features and flavor attributes in Longjing green teas produced with five different withering degrees (moisture content of 75.05, 72.53, 70.07, 68.00, and 64.78%, w.b.). Combined with human sensory evaluation, electronic tongue and chromatic differences analysis, an assessment of the relationship between the withering degree and the sensory quality of Longjing tea was obtained. By using a non-targeted metabolomics approach, 69 significantly differential metabolites were screened. As the withering degree increased, most free amino acids and catechin dimers were increased, largely attributed to the hydrolysis of proteins and catechin oxidative polymerization, respectively. The contents of organic acids as well as phenolic acids and derivatives were reduced. Interestingly, flavone C-glycosides decreased overall while flavonol O-glycosides increased. The correlation analysis revealed that metabolites such as theasinensin F, theasinensin B, theaflavin, theaflavin-3,3′-gallate, theaflavin-3′-gallate, malic acid, succinic acid, quinic acid, theanine glucoside and galloylglucose had a greater influence on the taste and color of tea infusion (|r| > 0.6, p < 0.05). Overall, an appropriate withering degree at a moisture content of around 70% is more favorable to enhance the Longjing tea quality. These results may enhance the understanding of green tea flavor chemistry associated with withering and provide a theoretical basis for green tea processing.

Study on the correlation between color and taste of beauty tea infusion and the pivotal contributing compounds based on UV–visible spectroscopy, taste equivalent quantification and metabolite analysis

“…Theaflavins were believed to play an important role in the astringency of tea infusion, which was confirmed by our study with the highest correlation coefficient (correlation coefficient > 0.83). From our results, we found that theaflavins contributed synergistically to the strong, bitter, and astringent taste in BT infusion, in line with previous research ( Shan et al, 2023 ). The presence of thearubigins also significantly contributed to the astringency of BT infusion ( Francis et al, 2008 , Liang et al, 2019 ), corroborating the findings of our study.…”

“…In this study, theaflavins exhibited a significant correlation (P < 0.01) with color (yellow-green, yellow, orange and red). It is worth noting that the highest correlation coefficient was observed with the color yellow (465nm) ( Table 2 ), which aligns with previous studies ( Cui et al, 2022 , Shan et al, 2023 ). Additionally, the study showed ( Wang, Hua, Jiang, Wang & Yuan, 2020 ) that theaflavin, theaflavin 3,3′-digallate and theaflavin-3gallate were essential for color difference in black tea infusion, which was consistent with the results of this study.…”

The Integration of Metabolomics, Electronic Tongue, and Chromatic Difference Reveals the Correlations between the Critical Compounds and Flavor Characteristics of Two Grades of High-Quality Dianhong Congou Black Tea

“…The representative different key compounds of phenolic acids, flavonols, and flavone/flavonol glycosides are exhibited in the metabolic pathway ( Figure 4 ). Quinic acid and p -coumaric acid have been reported to be mainly responsible for the bitterness and astringency taste in tea liquid [ 32 ]. Theogallin, as a derivative of quinic acid, can enhance the umami taste in tea infusions [ 32 ].…”

Roles of CcDFR and CcOMT9 in the cyanidin biosynthesis and development of Cordyceps cicadae

“…In this study, the non-targeted metabolomics analysis of secondary metabolites was conducted on WT and mutants ΔCcDFR and ΔCcOMT9 using liquid chromatography-mass spectrometry (LC–MS) technology (Bioincloud, Shenzhen), and the specific analytical method was done according to the methodology described by Shan et al (2023) .…”