Chromosome-scale Genome Assembly and Characterization of Top-quality Japanese Green Tea Cultivar 'Seimei'.

Japanese green tea, an essential beverage in Japanese culture, is characterized by the initial steaming of freshly harvested leaves during production. This process efficiently inactivates endogenous enzymes such as polyphenol oxidases, resulting in the production of sencha, gyokuro, and matcha that preserves the vibrant green color of young leaves. Although genome sequences of several tea cultivars and germplasms have been published, no reference genome sequences are available for Japanese green tea cultivars. Here, we constructed a reference genome sequence of the cultivar 'Seimei', which is used to produce high-quality Japanese green tea. Using the PacBio HiFi and Hi-C technologies for chromosome-scale genome assembly, we obtained 15 chromosome sequences with a total genome size of 3.1 Gb and an N50 of 214.9 Mb. By analyzing the genomic diversity of 23 Japanese tea cultivars and lines, including the leading green tea cultivars 'Yabukita' and 'Saemidori', revealed several candidate genes that could be related to the characteristics of Japanese green tea. The reference genome of 'Seimei' and information on genomic diversity of Japanese green tea cultivars should provide crucial information for effective breeding of such cultivars in the future.

Combined treatment of human mesenchymal stem cells and green tea extract on retinal ganglion cell regeneration in rats after optic nerve injury.

Retinal ganglion cell (RGC) death and axonal loss cause irreversible vision loss upon optic nerve (ON) injury. We have independently demonstrated that mesenchymal stem cells (MSCs) and green tea extract (GTE) promote RGC survival and axonal regeneration in rats with ON injury. Here we aimed to evaluate the combined treatment effect of human bone marrow-derived MSCs (hBM-MSCs) and GTE on RGC survival and axonal regeneration after ON injury. Combined treatment of hBM-MSCs and GTE promoted RGC survival and neurite outgrowth/axonal regeneration in ex vivo retinal explant culture and in rats after ON injury. GTE increased Stat3 activation in the retina after combined treatment, and enhanced brain-derived neurotrophic factor secretion from hBM-MSCs. Treatment of 10 µg/mL GTE would not induce hBM-MSC apoptosis, but inhibited their proliferation, migration, and adipogenic and osteogenic differentiation in vitro with reducing matrix metalloproteinase secretions. In summary, this study revealed that GTE can enhance RGC protective effect of hBM-MSCs, suggesting that stem cell priming could be a prospective strategy enhancing the properties of stem cells for ON injury treatment.

Green Tea Polyphenols Alleviate Kidney Injury Induced by Di(2-Ethylhexyl) Phthalate in Mice.

INTRODUCTION: Di(2-ethylhexyl) phthalate (DEHP) is a common plasticizer. Studies have revealed that DEHP exposure can cause kidney damage. Green tea is among the most popular beverages in China. Green tea polyphenols (GTPs) have been proven to have therapeutic effects on organ damage induced by heavy metal exposure. However, few studies have reported on GTP-relieving DEHP-induced kidney damage. METHODS: C57BL/6J male mice aged 6-8 weeks were treated with distilled water (control group), 1,500 mg/kg/d DEHP + corn oil (model group), 1,500 mg/kg/d DEHP + corn oil + 70 mg/kg GTP (treatment group), corn oil (oil group), and 70 mg/kg GTP (GTP group) by gavage for 8 weeks, respectively. The renal function of mice and renal tissue histopathology of each group were evaluated. The renal tissues of mice in the model, treatment, and control groups were analyzed using high-throughput sequencing. We calculated the differentially expressed microRNAs (miRNAs) and messenger RNAs (mRNAs) using the limma R package, the CIBERSORT algorithm was used to predict immune infiltration, the starBase database was used to screen the miRNA-mRNA regulatory axis, and immunohistochemical analyses were performed to verify protein expression. RESULTS: GTP alleviated the deterioration of renal function, renal inflammation and fibrosis, and mitochondrial and endoplasmic reticulum lesions induced by DEHP in mice. Differential immune infiltrations of plasma, dendritic, T, and B cells were noted between the model and treatment groups. We found that three differentially expressed miRNAs (mmu-miR-383-5p, mmu-miR-152-3p, and mmu-miR-144-3p), three differentially expressed mRNAs (Ddit4, Dusp1, and Snx18), and three differentially expressed proteins (Ddit4, Dusp1, and Snx18) played crucial roles in the miRNA-mRNA-protein regulatory axes when GTPs mitigate DEHP-induced kidney damage in mice. CONCLUSION: GTP can alleviate DEHP-induced kidney damage and regulate immune cell infiltration. We screened four important miRNA-mRNA-protein regulatory axes of GTP, mitigating DEHP-induced kidney damage in mice.

Gut microbiota-mediated metabolism of green tea catechins and the biological consequences: An updated review.

Multiple beneficial effects have been attributed to green tea catechins (GTCs). However, the bioavailability of GTCs is generally low, with only a small portion directly absorbed in the small intestine. The majority of ingested GTCs reaches the large intestinal lumen, and are extensively degraded via biotransformation by gut microbiota, forming many low-molecular-weight metabolites such as phenyl-γ-valerolactones, phenolic acids, butyrate, and acetate. This process not only improves the overall bioavailability of GTC-derived metabolites but also enriches the biological activities of GTCs. Therefore, the intra- and inter-individual differences in human gut microbiota as well as the resulting biological contribution of microbial metabolites are crucial for the ultimate health benefits. In this review, the microbial degradation of major GTCs was characterized and an overview of the in vitro models used for GTC metabolism was summarized. The intra- and inter-individual differences of human gut microbiota composition and the resulting divergence in the metabolic patterns of GTCs were highlighted. Moreover, the potential beneficial effects of GTCs and their gut microbial metabolites were also discussed. Overall, the microbial metabolites of GTCs with higher bioavailability and bioactive potency are key factors for the observed beneficial effects of GTCs and green tea consumption.

Green Tea Catechins Decrease Solubility of Raloxifene In Vitro and Its Systemic Exposure in Mice.

PURPOSE: Green tea is a widely consumed beverage. A recent clinical study reported green tea decreased systemic exposure of raloxifene and its glucuronide metabolites by 34-43%. However, the underlying mechanism(s) remains unknown. This study investigated a change in raloxifene's solubility as the responsible mechanism. METHODS: The effects of green tea extract, (-)-epigallocatechin gallate (EGCG), and (-)-epigallocatechin (EGC) on raloxifene's solubility were assessed in fasted state simulated intestinal fluids (FaSSIF) and fed state simulated intestinal fluids (FeSSIF). EGCG and EGC represent green tea's main bioactive constituents, flavan-3-gallate and flavan-3-ol catechins respectively, and the tested concentrations (mM) match the µg/mg of each compound in the extract. Our mouse study (n = 5/time point) evaluated the effect of green tea extract and EGCG on the systemic exposure of raloxifene. RESULTS: EGCG (1 mM) and EGC (1.27 mM) decreased raloxifene's solubility in FaSSIF by 78% and 13%, respectively. Micelle size in FaSSIF increased with increasing EGCG concentrations (> 1000% at 1 mM), whereas EGC (1.27 mM) did not change micelle size. We observed 3.4-fold higher raloxifene solubility in FeSSIF compared to FaSSIF, and neither green tea extract nor EGCG significantly affected raloxifene solubility or micelle size in FeSSIF. The mice study showed that green tea extract significantly decreased raloxifene Cmax by 44%, whereas EGCG had no effect. Green tea extract and EGCG did not affect the AUC0-24 h of raloxifene or the metabolite-to-parent AUC ratio. CONCLUSIONS: This study demonstrated flavan-3-gallate catechins may decrease solubility of poorly water-soluble drugs such as raloxifene, particularly in the fasted state.

Association of green tea consumption with prediabetes, diabetes and markers of glucose metabolism in rural Vietnam: a cross-sectional study.

The literature on green tea consumption and glucose metabolism has reported conflicting findings. This cross-sectional study examined the association of green tea consumption with abnormal glucose metabolism among 3000 rural residents aged 40-60 years in Khánh Hòa province in Vietnam. Multinomial logistic regression analysis was conducted to examine the association of green tea consumption (0, < 200, 200-< 400, 400-< 600 or ≥ 600 ml/d) with prediabetes and diabetes (based on the American Diabetes Association criteria). Linear regression analysis was performed to examine the association between green tea consumption and the log-transformed homeostatic model assessment of insulin resistance (HOMA-IR) (a marker of insulin resistance) and the log-transformed homeostatic model assessment of ß-cell function (HOMA-ß) (a marker of insulin secretion). The OR for prediabetes and diabetes among participants who consumed ≥ 600 ml/d v. those who did not consume green tea were 1·61 (95 % CI = 1·07, 2·42) and 2·04 (95 % CI = 1·07, 3·89), respectively. Higher green tea consumption was associated with a higher level of log-transformed HOMA-IR (Pfor trend = 0·04) but not with a lower level of log-transformed HOMA-ß (Pfor trend = 0·75). Higher green tea consumption was positively associated with the prevalence of prediabetes, diabetes and insulin resistance in rural Vietnam. The findings of this study indicated prompting the need for further research considering context in understanding the link between green tea consumption and glucose metabolism, especially in rural settings in low- and middle-income countries.

The effects of green tea extract supplementation on body composition, obesity-related hormones and oxidative stress markers: a grade-assessed systematic review and dose-response meta-analysis of randomised controlled trials.

Research indicates that green tea extract (GTE) supplementation is beneficial for a range of conditions, including several forms of cancer, CVD and liver diseases; nevertheless, the existing evidence addressing its effects on body composition, oxidative stress and obesity-related hormones is inconclusive. This systematic review and meta-analysis aimed to investigate the effects of GTE supplementation on body composition (body mass (BM), body fat percentage (BFP), fat mass (FM), BMI, waist circumference (WC)), obesity-related hormones (leptin, adiponectin and ghrelin) and oxidative stress (malondialdehyde (MDA) and total antioxidant capacity (TAC)) markers. We searched proper databases, including PubMed/Medline, Scopus and Web of Science, up to July 2022 to recognise published randomised controlled trials (RCT) that investigated the effects of GTE supplementation on the markers mentioned above. A random effects model was used to carry out a meta-analysis. The heterogeneity among the studies was assessed using the I2 index. Among the initial 11 286 studies identified from an electronic database search, fifty-nine studies involving 3802 participants were eligible to be included in this meta-analysis. Pooled effect sizes indicated that BM, BFP, BMI and MDA significantly reduced following GTE supplementation. In addition, GTE supplementation increased adiponectin and TAC, with no effects on FM, leptin and ghrelin. Certainty of evidence across outcomes ranged from low to high. Our results suggest that GTE supplementation can attenuate oxidative stress, BM, BMI and BFP, which are thought to negatively affect human health. Moreover, GTE as a nutraceutical dietary supplement can increase TAC and adiponectin.

Association between green tea intake and digestive system cancer risk in European and East Asian populations: a Mendelian randomization study.

PURPOSE: Previous observational studies have shown that green tea consumption is associated with a reduced incidence of digestive system cancers (DSCs). However, the observed association could be due to confounding factors. Therefore, we used a two-sample Mendelian randomization (MR) approach to assess the causal effect of green tea intake on the risk of five common DSCs. METHODS: Independent genetic variants strongly associated with green tea consumption in European and East Asian populations were selected as instrumental variables in genome-wide association studies involving up to 64,949 European individuals and 152,653 East Asian individuals, respectively. The associations between genetic variants and DSCs were extracted from the FinnGen study and the Japan Biobank. The primary analysis was performed using random-effects inverse variance weighting (IVW). Other MR analyses, including weighted mode-based estimate, weighted-median, MR-Egger regression, Mendelian Randomization-Pleiotropy Residual Sum and Outlier (MR-PRESSO) analysis, were used for sensitivity analyses. In addition, a multivariate MR design was performed to adjust for smoking and alcohol consumption. RESULTS: The IVW results showed no causal relationship between tea intake and DSCs risk in European population (esophagus cancer: odds ratio (OR) = 1.044, 95% confidence interval (CI) 0.992-1.099, p = 0.096; stomach cancer: OR = 0.988, 95% CI 0.963-1.014, p = 0.368; colorectal cancer: OR = 1.003, 95% CI 0.992-1.015, p = 0.588; liver cancer: OR = 0.996, 95% CI 0.960-1.032, p = 0.808; pancreatic cancer: OR = 0.990, 95% CI 0.965-1.015, p = 0.432). The MR-Egger regression, MR-PRESSO analysis and other methods also confirmed the reliability of the conclusion. Similarly, no significant association was found between green tea consumption and the incidence of DSCs among East Asians. This relationship is not significant even after adjusting for smoking and alcohol consumption (P > 0.05). CONCLUSION: Our study provides evidence that genetically predicted green tea intake is not causally associated with the development of DSCs in the European and East Asian population.

Coffee and green tea consumption with the risk of COVID-19 among the vaccine recipients in Japan: a prospective study.

BACKGROUND: While coffee and green tea have been suggested to have immunoprotective effects, it remains elusive whether they can decrease the risk of COVID-19. OBJECTIVE: We prospectively examined the association between coffee and green tea consumption and the risk of COVID-19 among mRNA vaccine recipients during the epidemic of the Omicron variant. METHOD: Participants were 2,110 staff (aged 18 to 76 years) of a large medical facility in Tokyo, who attended a serosurvey in June 2022, predominatly received ≥3 doses of vaccine, and were followed for COVID-19 until December 2022. Coffee and green tea consumption was ascertained via a questionnaire. COVID-19 was identified through the in-house registry. Cox proportional hazards model was used to estimate the hazard ratios (HRs) of COVID-19 across the categories of beverage consumption. RESULT: During 6 months of follow-up, 225 (10.6%) cases of COVID-19 were identified. Contrary to the expectation, higher consumption of coffee was associated with a significant increase in the risk of COVID-19; multivariable-adjusted HRs (95% CI) was 1.00, 0.92 (0.62-1.35), 1.48 (0.99-2.22), and 1.82 (1.20-2.76) for <1 cup/day, 1 cup/day, 2 cups/day, and ≥3 cups/day, respectively (p trend=0.003). Green tea consumption was not significantly associated with the risk of COVID-19. The association with coffee was attenuated if serologically detected infection was added to the cases. CONCLUSION: In a cohort of Japanese hospital staff who received COVID-19 vaccine, higher consumption of coffee was associated with an increased risk of COVID-19 during the epidemic of the Omicron variant. There was no evidence of a significant association between green tea consumption and COVID-19 risk.

Comparison of colorimetric methods for the analysis of total polyphenols in green tea extracts.

Two colorimetric methods are used to determine the total polyphenol contents of tea, namely, "the Folin-Ciocalteu method," defined by the International Organization for Standardization, and the "iron tartrate method," specified in the Standard Tables of Food Composition in Japan. In this study, we compared the Folin-Ciocalteu and iron tartrate methods using green tea extracts. When comparing the 2 methods, the sum of the 4 major catechins measured using high-performance liquid chromatography (HPLC) was regarded as the standard value. The total polyphenol contents obtained using the Folin-Ciocalteu method were closer to the HPLC value than those obtained using the iron tartrate method. However, the iron tartrate method is adequate if the current official method is improved, that is, our results suggest that the coefficients appropriate for common green tea varieties, as well as the degree and duration of cover cultivation, in the official iron tartrate method must be considered.

A two-sample Mendelian randomization study of mutual relations of six types of diets in atopic dermatitis.

BACKGROUND: In the continuous endeavor to find safe and efficient treatments for Atopic Dermatitis (AD), there remains a considerable focus on dietary adjustments. Nevertheless, the limited availability of research and conflicting findings in the academic literature pose a hurdle in establishing conclusive recommendations. METHOD: Mendelian randomization (MR) was applied to the most comprehensive genome-wide association studies (GWAS) data on tea intake (447 485), green tea intake (n = 64 949), flavored milk intake (n = 64 941), never eat eggs, dairy, wheat, sugar: Wheat products(n = 461 046), never eat eggs, dairy, wheat, sugar: Sugar or foods/drinks containing sugar (n = 461 046), never eat eggs, dairy, wheat, sugar: I eat all of the above (n = 461 046) and atopic dermatitis (n = 218 467). We used the inverse-variance weighted method (IVW) as the primary method. RESULTS: The IVW analyses have demonstrated an increased tea intake was genetically associated with a reduced risk of AD (odds ratio [OR]: 0.646, 95% confidence interval [CI]: 0.430-0.968, p = 0.034). Furthermore, green tea intake was significantly negatively associated with AD (IVW OR: 0.986, 95% CI: 0.975-0.998; p = 0.024) in the IVW model. AD risk could be reduced by never eating wheat products (IVW OR: 8.243E-04, 95% CI: 7.223E-06-9.408E-02, p = 0.003). There was no association between never eating eggs, dairy, wheat, sugar: Sugar, or foods/drinks containing sugar, I eat all of the above and AD. CONCLUSIONS: Our MR study suggests a causal relationship between tea intake, green tea intake, and the avoidance of eating wheat products with atopic dermatitis. Our findings recommend that preventing and managing atopic dermatitis may be achieved by never eating wheat products while increasing tea and green tea intake.

A novel optimized eco-friendly simple spectrofluorimetric method for the determination of total catechins in green tea extract: Application to commercial tablet.

Green tea extract (GTE) contains antioxidants that are present in green tea. The active constituents of green tea extract are catechins. This study demonstrates a spectrofluorimetric method for measuring GTE's catechin concentration based on its native fluorescence. To design a quick, sensitive, and ecological spectrofluorimetric approach, all features were investigated and adjusted. This method relies on determining the GTE ethanolic solution's native fluorescence at 312 nm after excitation at 227 nm. The calibration graph displayed a linear regression for values between 0.05 and 1.0 µg mL-1. The detection and quantification limits of the proposed technique were 0.008 and 0.026 µg mL-1, respectively. Two pure catechins present in GTE, (-)-epicatechin and (-)-epigallocatechin gallate, were examined by the proposed method. The analytical estimation of GTE in the pharmaceutical tablet was achieved effectively using this approach. An adequate degree of agreement was found when the findings were compared to those obtained by the comparative technique. Therefore, the novel strategy may be used in the GTE quality control study with minimal risks to people or the environment. The quantum yields of catechins were estimated. The validated technique was accepted by the International Council of Harmonization criteria.

Decaffeinated green tea polyphenols supplementation had no adverse health effects in girls with obesity: a randomized controlled trial.

BACKGROUND AND OBJECTIVES: While the health promoting effects of green tea polyphenols have been identi-fied among adult, research on children is scarce probably due to safety concerns about caffeine. This study aims to evaluate the safety of decaffeinated green tea polyphenols (DGTP) supplementation in girls with obesity and lay the foundation for its application in children population. METHODS AND STUDY DESIGN: This 12-week randomized, double-blinded, parallel-controlled trial was performed among 62 girls with obesity aged 6 to 10 years old. Participants were allocated to take 400 mg/d DGTP (DGTP group, n = 31) or isodose placebo (Control group, n = 31) at random. Anthropometric measurements and biochemical parameters including hepatic and renal function indicators, serum minerals concentrations, and routine blood parameters, were measured at baseline and the end of this trial. DGTP intake diary was required for each participant to record any abnormal reactions. RESULTS: After the 12-week supplementation, compared to Control group, the uric acid concentration in DGTP group showed a significant decrease (-48.0 ± 83.2 vs -0.01 ± 69.1, µmol/L), within the normal range. Regarding other biochemical indicators, there were no significant differences in changed values between the two groups. Throughout the trial, no adverse effects were reported in either group. CONCLUSIONS: This study indicated that the supplementation of 400 mg/d DGTP for 12 weeks had no adverse health effects in girls with obesity, providing evidence for the DGTP adoption in children research.

Kombucha as a Potential Active Ingredient in Cosmetics-An Ex Vivo Skin Permeation Study.

Kombucha is a non-alcoholic beverage, that is increasingly used in the cosmetic industry. The available literature reports the positive effects of kombucha on the skin, in particular its antioxidant action. However, there is a lack of information on skin permeation and the accumulation of active ingredients showing such effects. Skin aging is largely dependent on oxidative stress, therefore in our study we assessed the ex vivo permeation of two types of kombucha (green and black tea) through porcine skin. The antioxidant activity (DPPH, ABTS, FRAP methods) and total polyphenol content of these extracts were determined before and after permeation testing. Moreover, the content of selected phenolic acids as well as caffeine was assessed. Skin permeation was determined using a Franz diffusion cell. The antioxidant activity of both Kombuchas was found to be high. In addition, gallic acid, chlorogenic acid, protocatechuic acid, coumaric acid, m-hydroxybenzoic acid, and caffeine were identified. A 24-h ex vivo study showed the permeation of some phenolic acids and caffeine and their accumulation in the skin. Our results confirm the importance of studying the skin permeation of what are still little known ingredients in cosmetic preparations. Evaluation of the accumulation of these ingredients can guarantee the efficacy of such preparations.

Progress of research on aroma absorption mechanism and aroma fixation pathway of jasmine green tea.

This overview summarizes the latest research progress on the aroma absorption mechanism and aroma fixation pathway of jasmine green tea, and discusses in depth the aroma absorption mechanism of green tea, the aroma release mechanism of jasmine flowers, as well as the absorption and fixation mechanism of the aroma components of jasmine green tea in the process of scenting, to provide a theoretical basis for the improvement of the quality of jasmine green tea and the innovation of processing technology. It was found that the aroma absorption mechanism of jasmine green tea is mainly associated with both physical and chemical adsorption, aroma release in jasmine involves the phenylpropanoid/benzoin biosynthetic pathway, ß-glycosidase enzymes interpreting putative glycosidic groups, and heat shock proteins (HSPs) as molecular chaperones to prevent stress damage in postharvest flowers due to high temperatures and to promote the release of aroma components, and so forth. The preparation of aroma-protein nano-complexes, heat stress microcapsules, and the spraying of polymeric substances - ß-cyclodextrin are three examples of aroma-fixing pathways. This overview also summarizes the problems and future development trends of the current research and proposes the method of loading benzyl acetate, the main aroma component of jasmine, through konjac glucomannan (KGM)-based gel to solve the problem of volatile aroma and difficult-to-fix aroma, which provides a reference for the sustainable development of the jasmine green tea industry. © 2024 Society of Chemical Industry.

Non-targeted metabolomic analysis reveals the mechanism of quality formation of citrus flower-green tea.

BACKGROUND: Citrus flower-green tea (CT) is a scented tea processed from green tea (GT) and fresh citrus flower, which is favored by consumers due to its potential health benefits and unique citrus flavor. This study evaluated the quality of CT and revealed the mechanism of its quality formation. RESULTS: The CT had a significant citrus flavor and a good antioxidant activity, and its sensory quality was superior to that of GT. Headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) analysis revealed that the scenting process resulted in a significant increase of alkenes such as ß-pinene, trans-ß-ocimene, α-farnesene, isoterpinolene, and γ-terpinene, as well as a significant decrease of alcohols such as α-terpineol, l-menthol, and linalool in CT in comparison with GT. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis revealed that the levels of flavonoids (such as neohesperidin, hesperidin, tangeritin, hesperetin 5-O-glucoside, and nobiletin) and alkaloids (such as trigonelline and theobromine) in CT increased significantly after scenting process, while the levels of amino acids (such as valine and l-phenylalanine) and organic acids (such as ascorbic acid) decreased significantly. CONCLUSION: These observations showed that the scenting process promoted the absorption of aroma from citrus flowers by GT and the changes in its non-volatile metabolites, leading to the formation of citrus flavor quality in CT. © 2024 Society of Chemical Industry.

Yellow leaf green tea modulates the AMPK/ACC/SREBP1c signaling pathway and gut microbiota in high-fat diet-induced mice to alleviate obesity.

BACKGROUND: Yellow leaf green tea (YLGT) is a new variety of Camellia sinensis (L.) O. Ktze, which has yellow leaves and the unique qualities of 'three green through three yellow'. The present study aimed to investigate the anti-obesity effect of YLGT in mice fed a high-fat diet (HFD) and to explore the potential mechanisms by regulating the AMPK/ACC/SREBP1c signaling pathways and gut microbiota. RESULTS: The results showed that YLGT aqueous extract reduced body weight, hepatic inflammation, fat accumulation and hyperlipidemia in HFD-induced C57BL/6J mice, and also accelerated energy metabolism, reduced fat synthesis and suppressed obesity by activating the AMPK/CPT-1α signaling pathway and inhibiting the FAS/ACC/SREBP-1c signaling pathway. Fecal microbiota transplantation experiment further confirmed that the alteration of gut microbiota (e.g. increasing unclassified_Muribaculaceae and decreasing Colidextribacter) might be an important cause of YLGT water extract inhibiting obesity. CONCLUSION: In conclusion, YLGT has a broad application prospect in the treatment of obesity and the development of anti-obesity function beverages. © 2024 Society of Chemical Industry.

Effects of instant controlled pressure drop treatment combined with refractance window drying on infusion quality of made green tea.

BACKGROUND: The study aimed to determine the effects of instant controlled decompression of steam pressure, termed as ICPD (instant controlled pressure drop) on fresh tea leaves, when combined with refractance window drying (RWD) of rolled green teas during green tea manufacturing. The ICPD steam treatment pressure (TP; 0.1-0.3 MPa), treatment time (TT; 10-20 s) and refractance window drying temperature (RWDT; 70-90 °C) were used as the processing parameters for manufacturing of green tea. RESULT: Response surface methodology was employed to enumerate the effects of ICPD process conditions and temperature of RWD on total phenolic content (TPC), total flavonoid content (TFC) and DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity of the green tea infusion. An optimum condition for green tea processing was found at TP 0.2 MPa, TT 20 s with RWDT at 70 °C. In comparison to made green tea manufactured without ICPD treatment, the ICPD treated green tea showed enhanced TPC, TFC and DPPH radical scavenging activity along with better colour and sensory attributes. The microstructural study of ICPD treated green tea samples showed more deformed cell surface integrity, larger stomatal pore size and cracks at the leaf surface in comparison with non-treated green tea sample. CONCLUSION: Present study reveals that an ICPD treatment at 0.2 MPa for 20 s can be used as an alternative to the traditional enzyme inactivation step of hot water treatment, for green tea leaves to improve the infusion quality in terms of increased levels of TPC and TFC and DPPH radical scavenging activity. © 2024 Society of Chemical Industry.

Pesticide application behavior in green tea cultivation and risk assessment of tea products: a case study of Rizhao green tea.

Previous research on pesticides in green tea mainly focused on detection technology but lacked insights into pesticide use during cultivation. To address this gap, a survey was conducted among Rizhao green tea farmers. The survey results showed that most tea farmers were approximately 60 years old and managed small, scattered tea gardens (< 0.067 ha). Notably, tea farmers who had received agricultural training executed more standardized pesticide application practices. Matrine and thiazinone are the most used pesticides. A total of 16 types of pesticides were detected in the tested green tea samples, with 65% of the samples containing residues of at least one pesticide. Notably, higher levels of residues were observed for bifenthrin, cyfluthrin, and acetamiprid. The presence of pesticide residues varied significantly between seasons and regions. The risk assessment results indicated that the hazard quotient (HQ) values for all 16 pesticides detected in green tea were < 1, suggesting that these residue levels do not pose a significant public health concern.

Analysis of the Antimicrobial Activity of Epigallocatechin-3-Gallate (EGCG).

We studied antimicrobial activity of epigallocatechin-3-gallate (EGCG), a green tea polyphenolic catechin, and its combined use with ceftazidime (CAZ) against bacterial strains of Klebsiella pneumoniae. EGCG exhibited no activity against strains of K. pneumoniae with a different sensitivity to CAZ. However, for a "sensitive" strain, a decrease in minimum inhibitory concentration (MIC) of CAZ (from 0.064 to 0.023 mg/liter) was revealed when CAZ was co-administered with EGCG. For a "resistant" stain, MIC of CAZ remained high, but activation of EGCG at its high concentrations was observed. Indirect evidence of antimicrobial effect of EGCG co-administered with CAZ on Klebsiella was obtained.