# Effects of the flowering process on the metabolite profiles and bioactivities of Shaanxi Fu brick tea

## TL;DR

This study shows how a fermentation process called 'flowering' changes the chemical makeup and health benefits of a type of tea.

## Contribution

The study reveals specific metabolites and their roles in antioxidant and lipid-lowering effects after the flowering process.

## Key findings

- Flowering reduces tea polyphenols by 13.09% and amino acids by 38.24%.
- Fuzhuanin A, teadenol A, and betaine are linked to lipid-lowering activity.
- Echinulin and 6-gingerol are associated with antioxidant capacity.

## Abstract

This study investigated the impact of “flowering” process (Aspergillus cristatus-mediated fermentation) on the quality of Shaanxi Fu brick tea. Metabolic profiles of twenty samples, collected before (BF) and after (AF) fermentation were analysed. Moreover, in vitro assessments of their antioxidant and hypolipidaemic activities were also evaluated. Results indicated a significant decrease (p < 0.05) in tea polyphenols (13.09%) and free amino acids (38.24%), while caffeine and flavonoids showed no significant changes after flowering process. Integrated gas chromatography–mass spectrometry (GC–MS) and liquid chromatography-mass spectrometry (LC-MS) found that 15 volatiles (e.g. diallyl sulfide) and 47 non-volatile compounds (e.g. fuzhuanin A) were significantly increased. Correlation analysis revealed that antioxidant capacity was closely associated with echinulin and 6-gingerol, whilst hypolipidaemic effect was correlated with fuzhuanin A, teadenol A, and betaine (p < 0.05). These findings underscore the pivotal role of flowering process in shaping the functional metabolite profile and bioactivity of Fu brick tea.

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•Flowering-induced chemical and bioactive changes in Fu-brick tea were investigated.•Flowering reduces tea polyphenols by 13.09% and amino acids by 38.24%.•Volatiles and non-volatiles were analysed by widely target metabolomics.•The antioxidant activity is closely related to echinulin and 6-gingerol.•Fuzhuan A, Teadenol A, and betaine contribute to lipid-lowering activity.

Flowering-induced chemical and bioactive changes in Fu-brick tea were investigated.

Flowering reduces tea polyphenols by 13.09% and amino acids by 38.24%.

Volatiles and non-volatiles were analysed by widely target metabolomics.

The antioxidant activity is closely related to echinulin and 6-gingerol.

Fuzhuan A, Teadenol A, and betaine contribute to lipid-lowering activity.