Evolution in the chemical composition of Liubao tea during processing.

Area of Science:

• Food Chemistry
• Metabolomics
• Biochemistry

Background:

• Liubao tea (LBT), a dark tea, undergoes complex biochemical changes during processing.
• Fermentation and aging significantly influence LBT's chemical composition and quality.

Purpose of the Study:

• To comprehensively analyze the metabolomic profiles of LBT at different processing stages and aging durations.
• To identify key metabolites and metabolic pathways affected by fermentation and aging in LBT.

Main Methods:

• Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for comprehensive metabolomic analysis.
• Comparative analysis of metabolite profiles in Mao tea and fermented tea across different storage durations (2010 vs. 2015).

Main Results:

• Fermented tea exhibited superior sensory qualities compared to Mao tea.
• 189 differential metabolites were identified, with flavonoids and phenolics being predominant.
• Fermentation led to decreased catechin derivatives and phenolic esters, and increased alkaloids, terpenoids, amino acid derivatives, and phenolic acids.
• Aging modulated metabolite composition, with 12 shared differential metabolites identified between 2010 and 2015 samples.
• Flavonoid transformation and purine metabolism were identified as central pathways in LBT evolution.

Conclusions:

• Fermentation is the primary driver of chemical transformation in Liubao tea.
• Aging further modulates the metabolite composition of LBT, influencing its quality.
• The study provides a metabolomic foundation for LBT quality assessment and process optimization.