Yan Liang

Fu tea is a unique microbially fermented tea from China, and has two types. The primary distinction between these two types—Fu brick tea (FBT) and Fu loose tea (FLT)—is that FBT is compressed into bricks, whereas FLT is maintained as loose leaves. To investigate the differences in the chemical composition and sensory characteristics between the two types of Fu tea, this study utilized samples produced from the same batch of raw dark tea material to ensure comparability. Multiple analytical approaches were applied, including main active component analysis, sensory flavor evaluation, metabolomics, and differential characteristic component analysis. These methods were employed to comprehensively compare and characterize the two tea types. The results showed that compared to FBT, FLT exhibited a longer-lasting fungal flower aroma and a mellower taste. Furthermore, the quantity of Eurotium cristatum in FLT was 56.7% higher than that in FBT, indicating a significant difference. Untargeted ultrahigh-performance liquid chromatography–mass spectrometry was used to screen metabolites in Fu tea samples, and after multivariate statistical analysis, 12 differential metabolites were finally identified, including phenolic acids and their derivatives, coumarins and their derivatives, phenylpropanoids, and flavonoids and their glycosides. Subsequently, a targeted UHPLC-QQQ-MS/MS-based method was established and validated for the main differential metabolites, phenolic acids and catechins. The results indicated that gallic acid, catechin, and epicatechin can serve as characteristic markers for distinguishing between FBT and FLT. Notably, the content of gallic acid in FLT was 168.6% higher than that in FBT. These findings elucidate the impact of the pressing process on Fu tea, provide guidance for discriminating between FBT and FLT, and are significant for quality control in the industrial production of Fu tea.

Fu tea is receiving increasing attention for its specific aroma, flavor, and dramatic functional benefits. Herein, we explored the effects and underlying mechanisms of Fu loose tea (FLT), Fu brick tea (FBT), and diet pills (orlistat) on a high-fat diet (HFD)-induced obesity. The results indicated that FLT and FBT administration effectively inhibited weight gain, glucose metabolic dysregulation, fat accumulation in organs, hepatic and kidney injury, and oxidative stress induced by HFD. Additionally, FLT and FBT treatments improved the lipid profiles and reduced the production of proinflammatory cytokines by regulating the expression levels of lipid metabolism- and inflammation-related genes. Furthermore, FLT and FBT ameliorated the gut microbiota dysbiosis in HFD-mice in a dose-dependent relationship by increasing the abundance of family Verrucomicrobiaceae and genus Akkermansia and Turicibacter and simultaneously reducing the abundance of family Erysipelotrichaceae and genus Bifidobacterium; in contrast, orlistat did not exert a regulatory effect on gut microbiota similar to FLT and FBT to improve HFD-induced obesity. KEGG analysis of gut microbiota annotation revealed that “metabolism” was the most enriched category. This study further provides a theoretical basis for FLT and FBT to be potential supplements to alleviate diet-induced obesity.

Fu brick tea (FBT), a product of microbial fermentation from primary dark tea, also known as raw material tea (RMT), has been extensively studied for its functional properties. However, its potential as a staple food supplement for weight loss remains poorly understood. This study compared the weight loss effects of orlistat, traditional plain noodles (NN), and noodles supplemented with varying amounts of RMT (RMTN) and FBT (FBTN), with the aim to elucidate their lipid-reducing effects and underlying mechanisms. Experimental trials on high fat diet fed mice revealed significant weight loss, lipid-lowering, and hypoglycemic effects upon supplementation with orlistat, RMTN, and FBTN. Moreover, supplementation with orlistat, RMTN, and FBTN effectively restored serum and liver-related index levels, mitigating high-fat diet-induced dyslipidemia. Additionally, these supplements ameliorated liver and kidney damage by inhibiting oxidative stress and inflammatory responses. Furthermore, orlistat, RMTN, and FBTN exert their anti-obesity effects primarily by modulating genes associated with lipid metabolism and inflammatory responses and through regulation of the composition and structure of the gut microbiota. Importantly, FBTN demonstrated a significantly stronger lipid-lowering effect compared to RMTN, particularly at higher tea addition ratios. In contrast, NN supplementation exhibited minimal to no weight loss effects. Based on these findings, it could be inferred that FBT holds promise as a staple food supplement to ameliorate high-fat diet-induced obesity and its associated health conditions.

In this study, Fu-brick tea (FBT) was used for kombucha preparation. The succession of microbial community structures, changes in physicochemical properties, and the volatiles were investigated during the kombucha fermentation. The sequencing analysis showed that Komagataeibacter was the most predominant bacterium. Aspergillus and Zygosaccharomyces were the dominant fungi before fermentation whereas Zygosaccharomyces and Derkella were the dominant fungi after 3 days of fermentation. The physicochemical analysis revealed that acetic acid, glucuronic acid, and polyphenols increased by 10.22 g/L, 0.08 g/L, and 177.40 mg/L, respectively, by the end of fermentation. The GC-MS analysis showed that a total of 49 volatile compounds were detected during the fermentation. Moreover, there were great differences in volatile components among the kombucha samples with different fermentation times. Furthermore, the relevance among microbial community and volatile compounds was evaluated through correlation network analysis. The results suggested that Komagataeibacter, Aspergillus, Zygosaccharomyces, and Dekkera were closely related to the main volatile compounds of FBT kombucha. The results in this study may provide deep understanding for constructing the microbiota and improving the quality of FBT kombucha.