Brick Tea Research Articles

Eurotium cristatum, a potential probiotic fungus from Fuzhuan brick tea, alleviated obesity in mice by modulating gut microbiota.

Obesity is one of the major public health problems worldwide, mainly resulting from unhealthy lifestyles and diet. Gut microbiota dysbiosis may lead to obese humans and animals. Modulating gut bacteria through probiotics or certain dietary supplements could normalize gut microbiota and subsequently alleviate obesity. The daily consumption of Fuzhuan brick tea (FBT) or its extracts has been observed to alleviate obesity in humans and experimental animals. In this study, high-fat diet (HFD)-induced obesity in mice, such as body weight gain and fat accumulation, was prevented by the consumption of Eurotium cristatum, the dominant fungus during the manufacturing and storage of FBT. The dysbiosis of gut microbiota in C57BL/6J mice was also partially normalized. E. cristatum was able to modulate both gut fungal and bacterial compositions, based on the analysis of the microbiota composition of mice fecal samples (n = 5). E. cristatum increased acetate and butyrate-producing bacteria in mouse gut. There was five times more butyrate in the fecal samples from mice fed with E. cristatum than that from untreated HFD mice. Our results suggest that E. cristatum may be used as a probiotic fungus to alleviate obesity and to modulate gut microbiota in humans beneficially.

Simultaneous degradation of β-cypermethrin and 3-phenoxybenzoic acid by Eurotium cristatum ET1, a novel "golden flower fungus" strain isolated from Fu Brick Tea.

Beta‐cypermethrin (β‐CY) and its major metabolite 3‐phenoxybenzoic acid (3‐PBA) spread extensively in the environment because of utilization in agricultural and home formulations, exerting negative impact on environment as well as human health. Several golden flower fungi were isolated from fu brick tea, by which the biodegradation of β‐CY and 3‐PBA was evaluated, turning out strain Eurotium cristatum ET1 had the highest capacity. Furthermore, β‐CY and 3‐PBA degradation rates were positively correlated with biomass of E. cristatum ET1, and the processes of degradation fitted well with a first‐order kinetic equation. The half‐lives of β‐CY and 3‐PBA ranged from 3.382 to 11.517 days and 1.749 to 3.194 days, respectively, under different substrate concentrations, incubation temperatures, and pH values. The degraded products were analyzed using gas chromatography‐mass spectrometry and liquid chromatography‐mass spectrometry, and results showed that E. cristatum ET1 degrades β‐CY by transforming it into 3‐PBA, which is then gradually metabolized into phenol and catechol. Moreover, E. cristatum ET1 showed efficiency in degrading these metabolites. Our results suggest that this strain is a potential microorganism for bioremediation of pesticide‐contaminated environments and fermented foods.

Brick tea consumption is a risk factor for dental caries and dental fluorosis among 12-year-old Tibetan children in Ganzi.

Brick tea contains high concentration of fluoride. The aim of the present work was to explore whether and how the brick tea is a risk factor for dental caries and dental fluorosis among Tibetan children in Ganzi. A cross-sectional study was conducted with 368 12-year-old Tibetan children in Ganzi. Dental caries was measured by DMFT index, and dental fluorosis severity was measured by Dean's Index. Community Fluorosis Index was used to estimate public health significance of dental fluorosis. Oral health-related behaviors and awareness, dietary habits and socioeconomic status were determined by a questionnaire. Bivariate and multivariate analyses were used to determine risk factors associated with dental caries and dental fluorosis. Dental caries prevalence was 37.50%, mean DMFT was 0.84 ± 1.53, while dental fluorosis prevalence was 62.23%. Community Fluorosis Index was 1.35, indicating a medium prevalent strength of dental fluorosis. Dental fluorosis was associated with mother's regular consumption of brick tea and residence altitude, and dental caries was associated with mother's regular consumption of brick tea. Mother's regular consumption of brick tea was a risk factor for both dental fluorosis and dental caries among children. Reducing mother's brick tea consumption during pregnancy and lactation may improve oral health status of their children.

Comparative proteomic analysis reveals the regulatory network of the veA gene during asexual and sexual spore development of Aspergillus cristatus.

Aspergillus cristatus is the predominant fungal population during fermentation of Chinese Fuzhuan brick tea, and belongs to the homothallic fungal group that undergoes a sexual stage without asexual conidiation under hypotonic conditions, while hypertonic medium induces initiation of the asexual stage and completely blocks sexual development. However, the veA deletion mutant only produces conidia in hypotonic medium after a 24-h culture, but both asexual and sexual spores are observed after 72 h. The veA gene is one of the key genes that positively regulates sexual and negatively regulates asexual development in A. cristatus. To elucidate the molecular mechanism of how VeA regulates asexual and sexual spore development in A. cristatus, 2D electrophoresis (2-DE) combined with MALDI-tandem ToF MS analysis were applied to identify 173 differentially expressed proteins (DEPs) by comparing the agamotype (24 h) and teleomorph (72 h) with wild-type (WT) A. cristatus strains. Further analysis revealed that the changed expression pattern of Pmk1-MAPK and Ser/Thr phosphatase signaling, heat shock protein (Hsp) 90 (HSP90), protein degradation associated, sulphur-containing amino acid biosynthesis associated, valine, leucine, isoleucine, and arginine biosynthesis involved, CYP450 and cytoskeletal formation associated proteins were involved in the production of conidia in agamotype of A. cristatus. Furthermore, the deletion of veA in A. cristatus resulted in disturbed process of transcription, translation, protein folding, amino acid metabolism, and secondary metabolism. The carbohydrate and energy metabolism were also greatly changed, which lied in the suppression of anabolism through pentose phosphate pathway (PPP) but promotion of catabolism through glycolysis and tricarboxylic acid (TCA) cycle. The energy compounds produced in the agamotype were mainly ATP and NADH, whereas they were NADPH and FAD in the teleomorph. These results will contribute to the existing knowledge on the complex role of VeA in the regulation of spore development in Aspergillus and provide a framework for functional investigations on the identified proteins.

Characterization and molecular basis for the block of Kv1.3 channels induced by carvedilol in HEK293 cells

Carvedilol is a non-selective β-adrenoreceptor antagonist and exhibits a wide range of biological activities. The voltage-gated K+ (Kv) channel is one of the target ion channels of this compound. The rapidly activating Kv1.3 channel is expressed in several different tissues and plays an important role in the regulation of physiological functions, including cell proliferation and apoptosis. However, little is known about the possible action of carvedilol on Kv1.3 currents. Using the whole-cell configuration of the patch-clamp technique, we have revealed that exposure to carvedilol produced a concentration-dependent blocking of Kv1.3 channels heterologously expressed in HEK293 cells, with an IC50 value of 9.7 μM. This chemical decelerated the deactivation tail current of Kv1.3 currents, resulting in a tail crossover phenomenon. In addition, carvedilol generated a markedly hyperpolarizing shift (20 mV) of the inactivation curve, but failed to affect the activation curve. Mutagenesis experiments of Kv1.3 channels identified G427 and H451, two related sites of TEA block, as important residues for carvedilol-mediated blocking. The present results suggest that carvedilol acts directly on Kv1.3 currents by inducing closed- and open-channel block and helps to elucidate the mechanisms of action of this compound on Kv channels.

Biochemical Components Associated With Microbial Community Shift During the Pile-Fermentation of Primary Dark Tea.

Primary dark tea is used as raw material for compressed dark tea, such as Fu brick tea, Hei brick tea, Hua brick tea, and Qianliang tea. Pile-fermentation is the key process for the formation of the characteristic properties of primary dark tea, during which the microorganism plays an important role. In this study, the changes of major chemical compounds, enzyme activities, microbial diversity, and their correlations were explored during the pile-fermentation process. Our chemical and enzymatic analysis showed that the contents of the major compounds were decreased, while the activities of polyphenol oxidase, cellulase, and pectinase were increased during this process, except peroxidase activity that could not be generated from microbial communities in primary dark tea. The genera Cyberlindnera, Aspergillus, Uwebraunia, and Unclassified Pleosporales of fungus and Klebsiella, Lactobacillus of bacteria were predominant in the early stage of the process, but only Cyberlindnera and Klebsiella were still dominated in the late stage and maintained a relatively constant until the end of the process. The amino acid was identified as the important abiotic factor in shaping the microbial community structure of primary dark tea ecosystem. Network analysis revealed that the microbial taxa were grouped into five modules and seven keystone taxa were identified. Most of the dominant genera were mainly distributed into module III, which indicated that this module was important for the pile-fermentation process of primary dark tea. In addition, bidirectional orthogonal partial least squares (O2PLS) analysis revealed that the fungi made more contributions to the formation of the characteristic properties of primary dark tea than bacteria during the pile-fermentation process. Furthermore, 10 microbial genera including Cyberlindnera, Aspergillus, Eurotium, Uwebraunia, Debaryomyces, Lophiostoma, Peltaster, Klebsiella, Aurantimonas, and Methylobacterium were identified as core functional genera for the pile-fermentation of primary dark tea. This study provides useful information for improving our understanding on the formation mechanism of the characteristic properties of primary dark tea during the pile-fermentation process.

Realization of Automatic Processing of Buttered Tea Based on Expert Control Algorithm

Traditional craft and parameters of butter tea manufacturing have been optimized and intelligent manufacturing could work well. In order to reduce fluoride content in the brick tea, pretreatment process is added. One-step process of extraction of tea is adopted and of parameters is optimized. The total numbers of colony and bacterium of the extraction of tea are tested at temperature 25. The local optimums found by hill climbing algorithm could be fit for a special group. Control rules worked out on the basis of good practice and user characteristics. Intelligent manufacturing of buttered tea is achieved. Soluble fluorine is decreased effectively. The scientific craft ensures quality of the extraction of tea in the storing process. It saves time of making buttered tea. Improving quality of butter tea and intelligent processing be realized.

Magnetic Porous Molecularly Imprinted Polymers Based on Surface Precipitation Polymerization and Mesoporous SiO₂ Layer as Sacrificial Support for Efficient and Selective Extraction and Determination of Chlorogenic Acid in Duzhong Brick Tea.

Magnetic porous molecularly imprinted polymers (MPMIPs) for rapid and efficient selective recognition of chlorogenic acid (CGA) were effectively prepared based on surface precipitation polymerization using CGA as template, 4-vinylpyridine (4-VP) as functional monomer, and mesoporous SiO2 (mSiO2) layer as sacrificial support. A computational simulation by evaluation of electronic binding energy is used to optimize the stoichiometric ratio between CGA and 4-VP (1:5), which reduced the duration of laboratory trials. The porous MIP shell and the rid of solid MIPs by magnet gave MPMIPs high binding capacity (42.22 mg/g) and fast kinetic binding (35 min). Adsorption behavior between CGA and MPMIPs followed Langmuir equation and pseudo-first-order reaction kinetics. Furthermore, the obtained MPMIPs as solid phase adsorbents coupled with high performance liquid chromatography (HPLC) were employed for selective extraction and determination of CGA (2.93 ± 0.11 mg/g) in Duzhong brick tea. The recoveries from 91.8% to 104.2%, and the limit of detection (LOD) at 0.8 μg/mL were obtained. The linear range (2.0–150.0 μg/mL) was wide with R2 > 0.999. Overall, this study provided an efficient approach for fabrication of well-constructed MPMIPs for fast and selective recognition and determination of CGA from complex samples.

FRZB1 rs2242070 polymorphisms is associated with brick tea type skeletal fluorosis in Kazakhs, but not in Tibetans, China.

Skeletal fluorosis is a metabolic bone and joint disease caused by excessive accumulation of fluoride in the bones. Compared with Kazakhs, Tibetans are more likely to develop moderate and severe brick tea type skeletal fluorosis, although they have similar fluoride exposure. Single nucleotide polymorphisms (SNPs) in frizzled-related protein (FRZB) have been associated with osteoarthritis, but their association with the risk of skeletal fluorosis has not been reported. In this paper, we investigated the association of three SNPs (rs7775, rs2242070 and rs9288087) in FRZB1with brick tea type skeletal fluorosis risk in a cross-sectional case-control study conducted in Sinkiang and Qinghai, China. A total of 598 individuals, including 308 Tibetans and 290 Kazakhs, were enrolled in this study, in which cases and controls were 221 and 377, respectively. The skeletal fluorosis was diagnosed according to the Chinese diagnostic criteria of endemic skeletal fluorosis (WS192-2008). The fluoride content in tea water or urine was detected using the fluoride ion electrode. SNPs were assessed using the Sequenom MassARRAY system. Binary logistic regressions found evidence of association with rs2242070 AA genotype in only Kazakh participants [odds ratio (OR) 0.417, 95% CI 0.216-0.807, p = 0.009], but not in Tibetans. When stratified by age, this protective effect of AA genotype in rs2242070 was pronounced in Kazakh participants aged 46-65 (OR 0.321, 95% CI 0.135-0.764, p = 0.010). This protective association with AA genotype in rs2242070 in Kazakhs also appeared to be stronger with tea fluoride intake > 3.5mg/day (OR 0.396, 95% CI 0.182-0.864, p = 0.020). Our data suggest there might be differential genetic influence on skeletal fluorosis risk in Kazakh and Tibetan participants and that this difference might be modified by tea fluoride intake.

Evaluation of chemical property, cytotoxicity and antioxidant activity in vitro and in vivo of polysaccharides from Fuzhuan brick teas

Fuzhuan brick tea (FBT) possesses various health-promoting functions. However, the available information regarding biological activity of polysaccharides from FBT (FBTPS) is still limited. In this work, the chemical property, cytotoxicity and antioxidant activity in vitro and in vivo of FBTPS were evaluated. It was found that FBTPSs were typical acidic heteropolysaccharides mainly composed of Man, Rha, GalA, Glc, Gal and Ara with little molar content of Rib and GlcA. FBTPS showed little toxicity to human hepatic epithelial (L-02) cell. FBTPS exhibited antioxidant activities, including limited scavenging activity on DPPH free radicals (ranged from 54.3 ± 1.9 to 67.8 ± 2.5%), noticeable scavenging activity on superoxide radicals (over 85%), superior scavenging activity on ABTS radicals (near 100%), and protective effect on H2O2-induced oxidative injury in rat pheochromocytoma line 12 (PC12) cell. Moreover, FBTPS showed significant amelioration of high-fat diet-induced oxidative injury in mice. The results suggest that FBTPS, as natural safe antioxidants, may have potential application in functional foods.

Qing brick tea (QBT) aqueous extract protects monosodium glutamate-induced obese mice against metabolic syndrome and involves up-regulation Transcription Factor Nuclear Factor-Erythroid 2-Related Factor 2 (Nrf2) antioxidant pathway

BackgroundQing brick tea (QBT), traditional and popular beverage for Chinese people, is an important post-fermentation dark tea. Our present study was performed to investigate the ameliorative effects of QBT aqueous extract on metabolic syndrome (Mets) in monosodium glutamate-induced obese mice and the potential mechanisms. MethodMonosodium glutamate-induced obese mice were used to evaluate the anti-Mets effects of QBT. Content levels of malonaldehyde (MDA), reactive oxygen species (ROS) and protein carbonylation, antioxidant enzyme activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), glutathione reductase (GR) in the skeletal muscle were assessed by commercial kits, respectively. Western blot and Q-PCR were used to detect the expressions of Transcription Factor Nuclear Factor-Erythroid 2-Related Factor 2 (Nrf2) signaling pathway and downstream antioxidant factors. In addition, activity of AKT signaling and expression of glucose transporter type 4 (GLUT4) in the skeletal muscle were investigated by western blot. ResultQBT treatment limited gain of body weight, waistline and LEE index, improved insulin resistance and glucose intolerance, reduced lipid level in MSG mice. Content levels of MDA, ROS and protein carbonylation in skeletal muscle of QBT group were significantly improved compared to those of MSG mice. The antioxidant enzyme activities of SOD, GPx, CAT, and GR were increased in skeletal muscle of MSG mice intervened with QBT. After 20-week QBT treatment, Nrf2 signaling pathway and downstream antioxidant factors were both increased in the skeletal muscle. In addition, QBT treatment improved insulin signaling by preferentially augmenting AKT signaling, as well as increased the protein expression of GLUT4 in the skeletal muscle. ConclusionOur results showed that QBT intake was effective in protecting monosodium glutamate-induced obese mice against metabolic syndrome and involved in the Nrf2 signaling pathway in the skeletal muscle.

Study on the Intellectual Property Protection and Cultural Heritage Inheritance of the Borderland-selling Tea Jingyang Fu Brick Tea

The borderland-selling tea, mainly dark tea and brick tea, is a kind of special commodity of the ethnic minority in China. The famous historical tea, Jingyang Fu brick tea, is a kind of competitive borderland-selling tea on the Ancient Tea Route, the main cargo for export on the Ancient Silk Road. This paper introduces the general situation of the borderland-selling tea, and analyzes the agricultural intellectual property rights of the tea, based on geographical indications, agricultural biological genetic resources, traditional knowledge, trademark rights, patent rights and new varieties of plant. This paper discusses the countermeasures of traditional tea culture inheritance and innovation development from the aspects of intellectual property protection, transmission of traditional knowledge, innovation of agricultural science and technology, cultural inheritance of the Ancient Tea Route, “Along the way” strategy. The corresponding recommendations are put.

Fuzhuan Brick Tea Polysaccharides Attenuate Metabolic Syndrome in High-Fat Diet Induced Mice in Association with Modulation in the Gut Microbiota.

An increasing amount of evidence suggests that the gut microbiota composition and structure contribute to the pathophysiology of metabolic syndrome (MS), which has been put forward as a new target in the treatment of diet-induced MS. In this work, we aimed to investigate effects of Fuzhuan brick tea polysaccharides (FBTPS) on MS and gut microbiota dysbiosis in high-fat diet (HFD) fed mice and to further investigate whether its attenuation of MS is related to the modulation of gut microbiota. The results showed that FBTPS intervention could significantly attenuate metabolic syndrome in HFD-induced mice. Based on results of sequencing, FBTPS treatment could increase the phylogenetic diversity of HFD-induced microbiota. FBTPS intervention could significantly restore the HFD-induced increases in relative abundances of Erysipelotrichaceae, Coriobacteriaceae, and Streptococcaceae. Spearman's correlation analysis showed that 44 key OTUs were negatively or positively associated with MS. Our results suggested that FBTPS could serve as a novel candidate for prevention of MS in association with the modulation of gut microbiota.

Kudingcha and Fuzhuan Brick Tea Prevent Obesity and Modulate Gut Microbiota in High‐Fat Diet Fed Mice

Kudingcha (KDC) from Ilex kudingcha and Fuzhuan brick tea (FBT) are popular beverages in China, and their preventive and therapeutic roles in metabolic disorders have been reported. However, the relationship between the gut microbiota modulatory effects of KDC and FBT and prevention of obesity is still not clearly understood. KDC and FBT are tested individually for their capacities to prevent obesity and modulate the gut microbiota in high-fat diet (HFD) fed C57BL/6J mice. The results show that both KDC and FBT supplementation could modulate oxidative injury, inflammation, lipid metabolism, and reduce HFD induced obesity significantly. Both KDC and FBT could enhance the diversity of gut microbiota. KDC could reduce the relative abundance of Erysipelotrichaceae, while FBT could reduce the ratio of Firmicutes to Bacteroidetes and enhance the relative abundance of Bifidobacteriaceae. These findings suggest that KDC and FBT could attenuate features of the metabolic syndrome in HFD-fed mice, which might be due to the modulation of gut microbiota by KDC and FBT.

Semi-continuous pressurized hot water extraction of black tea

The pressurized hot water extraction (PHWE) of six representative compounds from black tea brick was investigated in a semi-continuous extractor under the conditions of various temperatures (120–180 °C) and water flow rates (6–18mLmin-1). The extracted solutions were dark brown liquid suspensions, and a significant proportion of the six compounds (70.7–92.0%) was found in the supernatant phase after centrifugation. Theophylline is the most stable compound with respect to increasing temperature and extraction time. Epicatechin gallate (ECG) and epigallocatechin gallate (EGCG) were sensitive to temperature, while the other compounds (caffeine, catechin, and gallocatechin gallate (GCG)) were affected by both temperature and water flow rate. The optimum conditions were found to be 160 °C and 12 mL min−1. Compared to the traditional tea brewing (TTB) method, PHWE can achieve significantly higher extraction yields of theophylline, caffeine, catechin, and GCG.

Converting the Depolarization-Activated Shaker KV Channel into a Hyperpolarization-Conducting Cation-Selective Channel by Two Pore Mutations

Substituting the pore residue W434 in the Shaker Kv channel by a phenylalanine (W434F) accelerates its C-type inactivation, which involves the collapse of the selectivity filter (SF). In Shaker-W434F this collapse precedes S6-gate opening upon activation and no ionic currents are recorded. However, a valine mutation for the residue T449 (T449V) slows inactivation and introducing this T449V substitution in the Shaker-W434F rescues ionic conduction. The human Shaker-type Kv1.2 channel has a valine at the homologous T449 position (V381). Interestingly, the Kv1.2-W366F mutant yielded ionic current (similar to the Shaker -W434F-T449V combination). Accordingly, substituting V381 in Kv1.2-W366F by a threonine resulted in a similar (non-conducting) phenotype as Shaker-W434F. Thus the rate of SF collapse can be controlled by specific combinations of pore residue mutations. Patch-clamp analysis of the ionic currents of Kv1.2-W366F and Shaker-W434F-T449V showed that the channels remained K+ selective. Thus, the SF of Shaker-W434F-T449V adopts a K+-selective conformation when the S6-gate opens. To study the SF conformation of Shaker-W434F when the S6-gate closes, we combined Shaker-W434F with the mutation P475D, that by itself prevents complete closing of the S6-gate. We expected to record ionic currents of the double Shaker-W434F-P475D mutant at hyperpolarized potentials when the S6-gate closes and the SF recovers from its collapsed inactivated state. Indeed, Shaker-W434F-P475D resulted in functional voltage-dependent channels that were conducting at hyperpolarized potentials and ceased conducting at depolarized potentials. Interestingly, this conductive state of Shaker-W434F-P475D was both Na+ and K+ permeable, i.e. the high K+ selectivity was lost. The mutant remained, however, sensitive to external TEA block. Thus, preventing full closure of the S6-gate appears to affect the recovery process of the SF such that it is trapped in a conformation conducting both Na+ and K+.

Fumarate-based metal-organic frameworks as a new platform for highly selective removal of fluoride from brick tea

Adsorption and removal of fluoride from brick tea is very important but challenging. In this work, two fumarate-based metal-organic frameworks (MOFs) were synthesized for the selective removal of fluoride from brick tea infusion. MOFs were examined for adsorption time, effect of dose, and uptake capacity at different initial concentrations and temperatures. Remarkably, over 80% fluoride removal was achieved by MOF-801 within 5 min at room temperature, while no significant adsorption occurred for the catechins and caffeine in the brick tea infusion. Further, with the use of the Langmuir equation, the maximum fluoride uptake capacity for the nontoxic calcium fumarate (CaFu) MOF was calculated to be as high as 166.11 mg g−1 at 373 K. As observed from FTIR, EDX and XPS results, hydroxyl group in MOFs were substituted by fluoride. This work demonstrates that the novel fumarate-based MOFs are promising materials for the selective removal of fluoride from brick tea infusion.

Digestion under saliva, simulated gastric and small intestinal conditions and fermentation in vitro by human intestinal microbiota of polysaccharides from Fuzhuan brick tea

The aim of present study was to examine whether the digestivesystem (saliva, simulated gastric and small intestinal conditions) could break down and large intestinal microbiota could utilize the polysaccharides from Fuzhuan brick tea (FBTPS). The results showed that there was no change in molecular weight, monosaccharide content and content of reducing sugars before and after saliva, simulated gastric and small intestinal digestion, indicating that FBTPS could pass through the digestive system without being broken down and reach the large intestine safely. The content of carbohydrate was significantly decreased by fermentation in vitro of gut microbiota, suggesting that FBTPS could be broken down and utilized by gut microbiota. FBTPS could significantly modulate the composition and abundance of gut microbiota. Furthermore, the contents of short-chain fatty acids were significantly increased. Therefore, FBTPS is expected to be a functional food to improve human health and prevent disease through promoting the gut health.

Fungal community succession and major components change during manufacturing process of Fu brick tea

Fu brick tea is a unique post-fermented tea product which is fermented with microorganism during the manufacturing process. Metabolic analysis showed that most metabolites content were decreased during the manufacturing process of Fu brick tea, except GA (gallic acid). Illumina MiSeq sequencing of ITS gene amplicons was applied to analyze the fungal community succession. The genera Aspergillus, Cyberlindnera and Candida were predominant at the early stage of manufacturing process (from “primary dark tea” to “fermentation for 3 days”), but after the stage of “fermentation for 3 days” only Aspergillus was still dominated, and maintain a relatively constant until to the end of manufacturing process. The effects of metabolites on the structure of the fungal community were analyzed by redundancy analysis (RDA) and variation partitioning analysis (VPA). The results indicated that GCG (gallocatechin gallate), EGCG (epigallocatechin gallate) and GA as well as the interactions among them were the most probably ones to influence, or be influenced by the fungal communities during the fermentation process of Fu brick tea. This study revealed fungal succession, metabolite changes and their relationships, provided new insights into the mechanisms for manufacturing process of Fu brick tea.

Structural characterization and evaluation of the antioxidant activities of polysaccharides extracted from Qingzhuan brick tea

The crude tea polysaccharides (CTPS) from Qingzhuan brick tea(QZBT) were extracted and fractionated to afford two fractions, namely TPS-1 and TPS-2. Analyses were conducted concerning the structural characterization and antioxidant activities of these samples. Component analysis revealed that the carbohydrate, uronic acid, protein and polyphenol contents of these samples differed significantly. Fourier transform infrared analysis showed that these samples showed similar characteristic absorption peaks for polysaccharides. Ultraviolet-visible spectroscopy, circular dichroism, scanning electron microscopy and thermogravimetric analyses indicated that there were considerable differences in the presence of protein, surface features, conformational characteristics and thermodynamic behaviors. For antioxidant activities in vitro, CTPS, TPS-1 and TPS-2 exhibited concentration-dependent antioxidant activities, with TPS-2 showing significantly higher antioxidant activity than CTPS and TPS-1. These results provide a scientific and strong foundation for the use of tea polysaccharides(TPS) from QZBT and further research towards the relationships between the characteristics and antioxidant activities of TPS.