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

This study investigated the impact of "flowering" process (<i>Aspergillus cristatus</i>-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, <i>in vitro</i> assessments of their antioxidant and hypolipidaemic activities were also evaluated. Results indicated a significant decrease (<i>p</i> < 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 (<i>e.g.</i> diallyl sulfide) and 47 non-volatile compounds (<i>e.g.</i> 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 (<i>p</i> < 0.05). These findings underscore the pivotal role of flowering process in shaping the functional metabolite profile and bioactivity of Fu brick tea.