Post-fermented Tea Research Articles

Analysis of lactic acid bacteria species in Miang, a post-fermented tea in Thailand, and their potential use as probiotics

IntroductionMiang is one of the post-fermented teas made in Northern Thailand. Although lactic acid bacteria are involved in fermentation of Miang, details are still not clear. This study investigated the diversity of Lactobacillaceae bacteria, related to fermentation of Miang. Probiotic potential of isolated Lactobacillaceae bacteria was examined.MethodsLactobacillaceae bacteria were isolated from 52 Miang samples collected from three provinces in northern Thailand and identified by MALDI-TOF MS. Hemolytic activity, antibiotic susceptibility, antimicrobial activity and tolerance to gastrointestinal juice were examined for probiotic potential of isolates.ResultsA total of 1,181 Lactobacillaceae bacteria strains were isolated from Miang. The most abundant isolates were Lactiplantibacillus pentosus. Besides Lactiplantibacillus plantarum, Levilactobacillus brevis, Paucilactobacillus suebicus, Lacticaseibacillus pantheris, and Secundilactobacillus collinoides were also found with frequency. Of these isolates, 450 with a high score for MALDI-TOF identification were then screened for probiotic ability. Most isolates were resistant to aminoglycosides and clindamycin. Then, 35 isolates were tested for their antimicrobial activity against pathogens using the well diffusion method, and 31 isolates exhibited inhibition zones against Staphylococcus aureus, Staphylococcus epidermidis, Salmonella enterica serovar Typhimurium, S. enterica serovar Enteritidis, Listeria monocytogenes, Propionibacterium acnes, and Streptococcus mutans. All 31 isolates were non-hemolytic and readily tolerated simulated gastric juice at pH 3 and simulated intestinal juice at pH 8.DiscussionMiang contains lactic acid bacteria that could potentially be used as probiotics.

Effects of different fermentation modes on tea leaves: Revealing the metabolites modification by quasi-targeted metabolomics

To investigate the effects of aerobic and anaerobic fermentation on tea leaves and to compare the differences between different fermentation modes, the metabolite profiles of pre-fermented tea, anaerobic-fermented tea, and aerobic-fermented tea from the same batch were comprehensively analyzed by quasi-targeted metabolomics. The results showed that the two fermentation modes altered tea metabolites significantly differently based on 1162 identified metabolites. A total of 611 differential metabolites were screened in different fermented teas, of which phenolics were the most critical compounds. Both fermentation modes reduced the levels of phenolic esters/glucosides in tea, accompanied by the accumulation of free phenolic. Notably, aerobic fermentation was more conducive for flavonoid glycosides and phenolic acid esters/glycosides reduction, while anaerobic fermentation better for free phenolic acids enhancement, especially gallic acid and its derivatives. Additionally, potential metabolic pathways of tea phenolics during fermentation were depicted, primarily involving the hydrolysis, methylation, and glycosylation of flavonoids, as well as the hydrolysis, esterification, degradation, and amination of phenolic acids. Furthermore, there were also some differences in the metabolism of amino acids, sugars, organic acids and lipids between the two fermentation modes. This study will advance our insights into the fermentation metabolism of post-fermented tea.

Tibetan tea extract exerts anti-tumor effects and potentiate paclitaxel-induced cytotoxicity and apoptosis in human hepatocellular carcinoma cells HepG2

Tibetan Tea (TT), traditionally esteemed by indigenous communities on the Qinghai-Tibet Plateau for over thirteen centuries, is a post-fermented tea recognized for its wide spectrum of biological functions. These include antioxidant capabilities, hypocholesterolemic effects, anti-hyperglycemic properties, and immune system enhancement. Nevertheless, additional medicinal potentials of TT, including its anticancer effects, remain to be unveiled in empirical studies. We aimed to evaluate the antiproliferative and chemotherapy-enhancing effects of TT extract on human hepatocellular carcinoma (HCC) cells, thereby initiating an inquiry into the potential molecular mechanisms involved. In this study, it was observed that TT extract suppressed the proliferation of HCC cells and triggered significant apoptosis. This apoptotic induction was facilitated through the activation of caspase-3, caspase-8, and caspase-9, along with decreased expression ratio of Bcl-2/Bax protein in HCC cells. Moreover, the combinational treatment of TT extract and Paclitaxel (Taxol) was found to enhance the anticancer effect. The expression level of P-glycoprotein (P-gp) encoded by the MDR1 (Multiple Drug Resistance) gene was remarkably decreased, revealing that TT extract might have the potential to be utilized as an adjuvant to promote HCC treatment. In conclusion, the Tibetan Tea extract exhibits cytotoxic, anticancer, and chemosensitization properties.

Aspergillus flavus and aflatoxins control in long-term storage of food ingredients of Puerh tea, peanut and polished rice

Aflatoxins are a group of high toxic mycotoxins in food chain. Recent studies showed that aflatoxins might contaminate post-fermented tea, but the result remains controversial. Here, Aspgergillus flavus growth and aflatoxin production were characterized in Puerh tea, peanut and polished rice at different initial water activity (aw) values for long-term storage. As a result, food initial aw value was the critical factor for A. flavus growth and aflatoxin production, and A. flavus almost not grew on foods at aw value lower than 0.8. A. flavus grew best in peanut, followed by rice, but growth on Puerh tea was limited. A. flavus growth was inhibited significantly by adding tea to Potato Dextrose Agar (PDA). Accordingly, aflatoxins produced dramatically in peanut, followed by rice at the first 90 days storage. However, aflatoxin neither produced in Puerh tea nor on tea modified PDA, indicating tea components inhibited A. flavus growth and aflatoxins synthesis.

Black Tea Manufacturing Process, Health Benefit, and Application in Food Industry: A Review

Tea (Camellia sinensis) is one of the most consumed beverages with its long history and was first consumed in China. People in ancient East Asia ate tea for centuries, perhaps even millennia, before ever consuming it as beverage. Based on the processing method, tea could be classified into six types, post-fermented (dark) tea, black tea, green tea, yellow tea, oolong tea, and white tea.

Occurrence, exposure estimation, and dietary risk assessment of biogenic amines in tea samples marketed in Malaysia

Biogenic amines (BAs) are one of the most studied food contaminants due to their widespread distribution in food matrices. However, the occurrence and dietary risks of BAs in tea, particularly in Malaysia, have not been comprehensively investigated. This study evaluates the occurrence of BAs in selected tea samples from Malaysia's market, and the estimation of the dietary exposure to assess the risk of their dietary intake. The targeted BAs (tyramine, histamine, tryptamine, spermine, spermidine, putrescine, and cadaverine) were extracted with 0.1 M HCl using ultrasound, followed by derivatization using dansyl chloride prior to high performance liquid chromatographic separation. The validated method was applied to analyzing BAs in various tea samples of different origins. Results showed that the occurrence of histamine (14.3–69.5 μg g−1) in fully fermented tea, semi-fermented tea, non-fermented tea, post-fermented tea, and tisanes was 8, 0, 63, 17, and 0%, respectively. Spermidine was found in all samples (except 2 tisanes) with concentrations ranging from 17.6 to 105.4 μg g−1. Tyramine was identified as the most prevalent BA (7.2–1271.7 μg g−1), with a detection frequency of 90.2%. Overall, the average total BAs content in fully fermented tea (284.2 μg g−1), semi-fermented tea (677.0 μg g−1), non-fermented tea (783.8 μg g−1), post-fermented tea (204.6 μg g−1), and tisanes (134.2 μg g−1) were below the recommended level of 1000 μg g−1. Dietary exposure was determined by estimated daily intake, whereas risk assessment was evaluated using the hazard quotient (HQ) and hazard index (HI) approaches. Based on the obtained HQ (≤0.017322) and HI (≤0.033437), the dietary exposure to BAs through the consumption of tea in Malaysia does not pose potential health risks to consumers.

Defense against oxidative stress in Caenorhabditis elegans by dark tea.

Dark tea, rich in nutricines including tea polyphenols and free amino acids, is a kind of post-fermented tea. The potential application of nutricines against oxidative damage and senescence, which drives animal health maintenance and disease prevention, has attracted considerable interest. In this study, the effect of dark tea and its effects on longevity and defense against oxidative stress was investigated in the Caenorhabditis elegans (C. elegans) model. Under normal conditions, dark tea extended the lifespan without significant impairment of propagation. It also improved the motility, alleviated the fat accumulation and apoptosis. Additionally, orally administered dark tea could significantly decrease the level of reactive oxygen species (ROS) and resulted in a superior lifespan in H2O2-induced oxidative stressed C. elegans. In antioxidant assays in vitro, dark tea was found to be rich in strong hydroxyl, DPPH and ABTS+ free radical scavenging capacity. Interestingly, mRNA sequence analyses further revealed that dark tea may catalyze intracellular relevant oxidative substrates and synthesize antioxidants through synthetic and metabolic pathways. These results suggest that dark tea is worth further exploration as a potential dietary supplement for the maintenance of animal health and the prevention of related diseases.

Preparation of Anti-Zearalenone IgY and Development of an Indirect Competitive ELISA Method for the Measurement of Zearalenone in Post-Fermented Tea.

Post-fermented tea (PFT) is one of the most commonly consumed beverages worldwide. Rapid microbial growth and significant changes in the microbial composition of PFT during processing and storage pose a potential risk of contamination with mycotoxins such as zearalenone (ZEN). Screening for ZEN contamination in a simple, rapid, and inexpensive manner is required to ensure that PFT is safe for consumption. To monitor ZEN in PFT, ZEN was conjugated with bovine serum albumin to prepare egg yolk immunoglobulins (IgY). A specific indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) based on IgY was developed and validated. ZEN was extracted with acetonitrile and water (50:50, v/v) containing 5% acetic acid and purified using a mixture of primary and secondary amines and graphitized carbon black to remove matrix interference from the PFT samples. Under optimal conditions, the linear range of this assay was 13.8-508.9 ng mL-1, the limit of detection was 9.3 ng mL-1, and the half-maximal inhibitory concentration was 83.8 ng mL-1. Cross-reactivity was negligible, and the assay was specific for ZEN-related molecules. The recovery rate of ZEN in the control blanks of PFT samples spiked with a defined concentration of ZEN of 89.5% to 98.0%. The recovery and accuracy of the method were qualified for PFT matrices. No significant differences were evident between the results of the actual PFT samples analyzed by high-performance liquid chromatography and ic-ELISA. The collective data indicate that the developed ic-ELISA can be used for the rapid and simple detection of ZEN in PFT products.

Postfermented Tea Extract Potently Alleviates Glucose Metabolism Disorders In Vitro and In Vivo

Postfermented Tea Extract Potently Alleviates Glucose Metabolism Disorders In Vitro and In Vivo

Fuzhuan brick tea extract ameliorates obesity-induced skeletal muscle atrophy by alleviating mitochondrial dysfunction in mice

Fuzhuan brick tea (FBT) is a post-fermented tea fermented by the fungus Eurotium cristatum and is mainly produced in Hunan Province, China. Our previous study revealed that FBT extract prevents obesity by increasing energy expenditure and mitochondrial content in mice. Therefore, in this study, we hypothesized that FBT extract could be effective in alleviating obesity-induced muscle atrophy by addressing mitochondrial dysfunction, and aimed to explore the underlying molecular mechanism of FBT extract in high-fat diet-induced obese mice. FBT extract increased skeletal muscle weight and size, myosin heavy chain isoforms, and muscle performance in obese mice. Additionally, FBT extract reduced obesity-induced intramuscular lipids, skeletal muscle inflammation, and the expression of skeletal muscle atrophy markers, and increased the expression of fibronectin type III domain-containing protein 5 in skeletal muscles. Obesity-induced skeletal muscle mitochondrial dysfunction was improved by FBT extract as analyzed through mitochondrial morphology, fatty acid oxidation, respiratory chain complexes, and mitochondrial dynamics and biogenesis. Epigallocatechin, a major bioactive compound in FBT extract, attenuated palmitic acid-induced muscle atrophy by regulating mitochondrial functions in C2C12 cells. In conclusion, FBT extract may prevent obesity-induced muscle atrophy by alleviating mitochondrial dysfunction in mice.

Relationship between the Physiological Activity of Japanese Post-Fermented Teas and Lactic Acid Bacteria

Post-fermented tea is a beverage or food made by fermenting tea leaves with microorganisms. Four types of post-fermented tea are traditionally produced in Japan. Three of these post-fermented teas are produced by lactic acid fermentation in the Shikoku region. Post-fermented tea has physiological activities such as antioxidant, antiallergic, and fat accumulation inhibitory effects. The composition of catechins in post-fermented tea differs from that in green tea. Compared to green tea, epigallocatechin, epigallocatechin gallate, epicatechin, and epicatechin gallate are reduced, and catechin polymers are formed in the post-fermented tea. In addition, post-fermented teas contain pyrogallol, γ-aminobutyric acid (GABA), and D-amino acids. The lactate fermentation of post-fermented teas on Shikoku Island involves Lactiplantibacillus plantarum and Lactiplantibacillus pentosus as the dominant species in the fermentation process. L. planratum and L. brevis isolated from Ishizuchi-kurocha, one of the post-fermented teas of Shikoku, contain amino acid racemases that produce D-amino acids. In addition, L. brevis has a high capacity for GABA production. Furthermore, L. plantarum is likely to produce bacteriocin. Lactic acid bacteria, represented by the L. plantarum group, play an essential role in the physiological activity of post-fermented tea, including lactic acid fermentation. An attempt has been made to create new post-fermented tea (brewed tea) based on traditional post-fermented tea production methods.

Possible Mechanisms of Dark Tea in Cancer Prevention and Management: A Comprehensive Review.

Tea is one of the most popular drinks in the world. Dark tea is a kind of post-fermented tea with unique sensory characteristics that is produced by the special fermentation of microorganisms. It contains many bioactive substances, such as tea polyphenols, theabrownin, tea polysaccharides, etc., which have been reported to be beneficial to human health. This paper reviewed the latest research on dark tea's potential in preventing and managing cancer, and the mechanisms mainly involved anti-oxidation, anti-inflammation, inhibiting cancer cell proliferation, inducing cancer cell apoptosis, inhibiting tumor metastasis, and regulating intestinal flora. The purpose of this review is to accumulate evidence on the anti-cancer effects of dark tea, the corresponding mechanisms and limitations of dark tea for cancer prevention and management, the future prospects, and demanding questions about dark tea's possible contributions as an anti-cancer adjuvant.

B-Type Fumonisins in Post-Fermented Tea: Occurrence and Consumer Dietary Exposure in Guangxi, China.

Post-fermented tea (PFT), a commonly consumed beverage worldwide, is characterized by the rapid growth of its microbial groups and the substantial changes they undergo. Consequently, PFT may contain mycotoxins such as B-type fumonisins (FBs). This study aimed to assess the intake of FBs through the consumption of PFT among consumers in Guangxi, China. A novel quantitative method using high-performance liquid chromatography-mass spectrometry was used to determine the FB concentration in PFT products. Additionally, a PFT consumption survey was conducted using a face-to-face questionnaire, recording their body weight and PFT consumption patterns based on a three-day dietary recall method. Finally, hazard index was calculated to estimate the health risk of FBs from the consumption of PFT products in Guangxi. The results revealed that the occurrence of FBs in PFT was 20% (24/120), with a concentration ranging from 2.14 to 18.28 μg/kg. The results of the survey showed that the average daily consumption of PFT by consumers was 9.19 ± 11.14 g. The deterministic risk assessment revealed that only 0.026% of the provisional maximum tolerable daily intake of FBs was consumed through PFT, indicating that FB contamination in PFT is not a public health risk.

Effects and Stress-Relieving Mechanisms of Dark Tea Polysaccharide in Human HaCaT Keratinocytes and SZ95 Sebocytes.

A new skincare application scenario for dark tea, a unique and post-fermented tea popular in the health food industry, was developed in this paper. The effects of dark tea polysaccharide (DTP) on stress-induced skin problems and its mechanism of action were investigated by modeling cortisone-induced stress injury in human HaCaT keratinocytes and SZ95 sebaceous gland cells. The results showed a reduced cortisol conversion induced by cortisone under the action of DTP with a concentration of 200 μg/mL, probably by inhibiting the expression of the HSD11B1 enzyme. DTP was also able to suppress the cortisone-induced elevation of lipid levels in SZ95 sebocytes at this concentration. In addition, the composition and structure of DTP were verified by ultrafiltration, ultraviolet-visible spectrophotometry (UV-VIS), high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and infrared spectroscopy. In brief, DTP has a unique and significant stress-relieving effect, which provides new ideas for the development of new ingredients for the skin care industry.

The key role of LeuRS in the development of the cleistothecium and the metabolization of the flavor during the fermentation of dark tea with Aspergillus montevidensis

Post-fermented tea has multiple health-promoting efficacy; however, the molecular mechanisms of quality formation remain largely unknown. Here, we found that leucyl-tRNA synthetase (LeuRS) is essential for the formation of ‘golden flowers' in dark teas fermented by A. montevidensis. Metabolomics based on UHPLC-Q-TOF/MS revealed 67, 130, and 98 differential metabolites in the compared groups of fermented teas by wide-type strains (WT)/by ΔleuRS mutants (MT) at 3, 9 and 15 days, respectively. These differential metabolites consisted mainly of flavonoids, sugars, organic acids, and fatty acids. Transcriptome analysis showed that hundreds of genes were significantly differentially expressed compared to WT with MT, which were mainly involved in KEGG pathways such as starch and sucrose metabolism, degradation of aromatic compounds, amino acid metabolism and lipid metabolism. These findings highlighted that LeuRS plays a crucial role in the development of the fungal cleistothecium and the flavor formation of the post-fermented teas with A. montevidensis.

Effects of water hardness on the flavor and antioxidant activity of Ishizuchi dark tea

Ishizuchi dark tea, a traditional Japanese post-fermented tea, has attracted considerable attention for its bioactivity. In this study, the effect of water hardness on Ishizuchi dark tea infusions was analyzed. Sensory testing revealed that the teas brewed in hard water were less sour in taste than those brewed in soft water. The most abundant organic acid found in the tea infusions was lactic acid, with a constant concentration of 4 mmol L−1, regardless of water hardness. The pH of the tea infusions increased from 4 to 5 with increasing water hardness, and a similar increase in pH was observed with increasing concentrations of Ca2+ (or Mg2+) and HCO32− in an aqueous solution of 4 mmol L−1 lactic acid. The antioxidative activity of the tea infusion was clearly independent of water hardness. Therefore, hard water is suitable for brewing Ishizuchi dark tea because tea brewed in hard water has a less sour taste, which is more favored, while maintaining the same degree of antioxidative ability.

Gut Bacterial Indole-3-acetic Acid Induced Immune Promotion Mediates Preventive Effects of Fu Brick Tea Polyphenols on Experimental Colitis

Ulcerative colitis has been consistently associated with gut microbiota imbalance and disturbed immune system. Emerging research suggests a protective function of polyphenols on prevention and treatment of ulcerative colitis, yet underlying mechanisms remain unclear. Fu brick tea, a postfermented tea, contains abundant polyphenols with anti-inflammatory and antioxidant properties. In the present study, we found that prophylactic supplementation of polyphenols extracted from Fu brick tea (FBTP) dose-dependently alleviated colitis symptoms, immune cells infiltration, and pro-inflammatory cytokines secretion in mice suffering dextran sulfate sodium induced murine colitis. FBTP substantially reshaped gut microbiota and promoted microbial transformation of tryptophan into indole-3-acetic acid (I3A), thereafter leading to aryl hydrocarbon receptor (AHR)-mediated protection from colitis through enhanced expressions of IL-22 and tight junction proteins (i.e., ZO-1, occluding and claudin-1) in colon. Multiomics integration analyses revealed strong connections between I3A, tryptophan-metabolizing bacteria, AHR activity, and pathological phenotypes of colitis. Notably, FBTP failed to significantly alleviate colitis symptoms in the absence of gut microbiota, while intragastric administration of I3A could imitate benefits of FBTP on colitis alleviation and intestinal epithelial homeostasis through a direct enhancement in AHR activity in microbiota-depleted mice. These findings further determine the key role of gut microbiota controlled I3A-AHR signaling in mediating the FBTP on colitis alleviation. This study provides the first data proposing the FBTP as a natural prebiotic for colitis alleviation through the gut microbiota-dependent modulation of the AHR pathway. Most importantly, we also identified I3A as a key microbial metabolite targeted by FBTP for exhibiting health-promoting effects.

Analysis of D-amino acid in Japanese post-fermented tea, Ishizuchi-kurocha.

The D-amino acid content of Ishizuchi-kurocha, a post-fermented tea produced in Ehime, Japan, was measured. Ishizuchi-kurocha mainly contains D-glutamic acid and D-alanine, but it also contains a small amount of D-aspartic acid. Two types of lactic acid bacteria, Lactiplantibacillus plantarum and Levilactobacillus brevis, are the main species involved in lactic acid fermentation during the tea fermentation process. Therefore, the D-amino acid-producing abilities of strains of these two species isolated from Ishizuchi-kurocha were examined. Specifically, the production of D-aspartic acid, D-alanine, and D-glutamic acid by L. brevis and L. plantarum strains was observed. The amount of D-aspartic acid produced by L. plantarum was low. D-glutamine was detected in culture supernatant but not in bacterial cells. D-arginine was detected in bacterial cells of the L. plantarum strains but not in the culture supernatant. Both the L. brevis and L. plantarum strains possessed at least three kinds of putative racemase genes: alanine racemase, glutamate racemase, and aspartate racemase. However, their expression and enzyme activity remain unknown. L. plantarum and L. brevis could play an important role in the production of D-amino acids in Ishizuchi-kurocha. In fact, Ishizuchi-kurocha is expected to possess the effective physiological activities of D-amino acids.

Goishi tea leaf powder affects lower body weight and visceral fat accumulation during energy restriction in obese rats.

Goishi tea is a unique Japanese post-fermented tea produced in Kochi prefecture. The aim of this study was to investigate whether the supplementation of energy-restricted diet with Goishi tea leaves affects body weight, visceral fat accumulation, and fecal lipids in diet-induced obese rats. 18 male Wistar rats were fed a high-fat diet for 12 weeks. Subsequently, the diet-induced obese rats were fed a low-energy diet containing 1% (G1 group) or 3% (G3 group) of Goishi tea leaf powder, or without any tea extracts (C group) for 4 weeks. After 4 weeks, body weight and body fat ratio were significantly lower in the G3 group than in the C group. Plasma insulin levels were significantly higher in the C group than in the G1 and G3 groups, whereas plasma leptin levels were significantly lower in the G3 group than in the C group. In addition, the lipid absorption rate was significantly lower in the G3 group than in the C and G1 groups. In conclusion, the administration of Goishi tea leaves under dietary restrictions might contribute to body weight reduction and inhibition of lipid absorption, as a diet therapy to help prevent obesity and metabolic syndrome. J. Med. Invest. 70 : 60-65, February, 2023.

Dynamic Analysis of Physicochemical Properties and Polysaccharide Composition during the Pile-Fermentation of Post-Fermented Tea.

Ultra-high performance liquid chromatography-quadrupole-time of flight tandem mass spectrometry (UHPLC-Q-TOF-MS/MS) was used to study the diversity of tea polysaccharides and the dynamic changes in the physicochemical indexes of tea samples. FT-IR spectra and the free radical scavenging ability of tea polysaccharides, during pile-fermentation of post-fermented tea, were analyzed. The results showed that 23 saccharide co mponents in tea polysaccharides were identified: these belonged to 11 monosaccharides, 5 oligosaccharides, and 6 derivatives of monosaccharides and oligosaccharides. The abundance of oligosaccharides decreased gradually, while monosaccharides, and derivatives of monosaccharides and oligosaccharides increased gradually with the development of pile-fermentation. According to the differences in polysaccharide composition and their abundance, the tea polysaccharide samples extracted from different pile-fermentation stages could be clearly classed into three groups, W-0, W-1~W-4 and W-5~C-1. The pile-fermentation process affected the yield, the content of each component, FT-IR spectra, and the DPPH free radical scavenging ability of tea polysaccharides. Correlation analysis showed that microorganisms were directly related to the changes in composition and the abundance of polysaccharides extracted from different pile-fermentation stages. The study will further help to reveal the function of tea polysaccharides and promote their practical application as a functional food.