Search Results (122)

This study investigates the effect of precursor pH (1.3, 2, 4, 6, 8, and 10) on the synthesis of gold nanoparticles (AuNPs) via a green synthesis approach using an aqueous extract of green tea (Camellia sinensis) leaves. The formation of AuNPs was monitored using UV-vis spectrophotometry and confirmed using transmission electron microscopy (TEM). The results confirmed that the morphology and size of the AuNPs are strongly dependent on the pH of the reaction medium. Based on spectral features, the color of the colloids, and TEM analysis, the synthesized samples were classified into three groups. The first (pH 8 and 10) contained predominantly spherical nanoparticles with an average diameter of ~18 nm, the second (pH 1.3 and 2) contained different shaped nanoparticles (20–250 nm in diameter), and the third (pH 4 and 6) contained flower-like nanostructures with a mean diameter of ~60 nm. UV-vis analysis revealed good stability of all AuNP colloids, except at pH 1.3, where a significant decrease in absorbance intensity over time was observed. These findings confirm that tuning the precursor pH allows for controlled manipulation of nanoparticle morphology and stability in green synthesis systems. Full article

Organic amendments provide a sustainable strategy to enhance soil quality in degraded environments while also helping to reduce greenhouse gas emissions, for example, by improving soil structure, minimizing the use of synthetic fertilizers, and promoting a green economy. This study assessed the comparative effects of two organic amendments—vermicompost leachate and biochar—on the performance of popcorn maize (Zea mays L. var. everta) cultivated in saline soil conditions. Four treatments were evaluated: T0 (Control), T1 (Vermicompost leachate), T2 (Biochar), and T3 (Vermicompost leachate + Biochar), each with 10 replicates arranged in a Completely Randomized Design (CRD). Although various soil physicochemical, microbiological, and agronomic parameters displayed no significant differences compared to the control, the application of biochar resulted in considerable improvements in soil total organic carbon, the microbial community (mesophilic aerobic bacteria, molds, and yeasts), and increased seed length and diameter. In contrast, vermicompost leachate alone negatively impacted plant growth, leading to decreases in leaf area, stem thickness, and grain yield. Specifically, grain yield declined by 46% with leachate alone and by 31% when combined with biochar, compared to the control. These findings emphasize the superior effectiveness of biochar over vermicompost leachate as a soil amendment under saline conditions and highlight the potential risks of widely applying compost teas in stressed soils. It is recommended to conduct site-specific assessments and screenings for phytotoxins and phytopathogens prior to use. Additionally, the combined application of leachate and biochar may not be advisable given the tested soil characteristics. Full article

This study aimed to determine the caffeine and L-theanine contents in tea infusions prepared under varying fermentation degrees, brewing conditions (temperature and time), and serving methods (tea bag/loose-leaf). Infusions of six tea types (green, white, yellow, oolong, black, and Pu-erh) and various serving forms of green, white, and black tea were brewed at 80 °C and 100 °C for 2, 5, and 10 min. Contents were analyzed using reversed-phase high-performance liquid chromatography. Caffeine levels were highest in black and yellow tea (14 ± 1.0 mg/200 mL and 13.8 ± 0.2 mg/200 mL, respectively), both of which were significantly higher than the levels in green, white, and oolong tea (11 ± 2.1 mg/200 mL; 5.8 ± 0.7 mg/200 mL; and 4 ± 1.6 mg/200 mL, respectively; p < 0.001), whereas Pu-erh tea (13 ± 2.9 mg/200 mL) had caffeine levels comparable to that of black tea (p > 0.05). L-Theanine levels were highest in black and green tea (12.3 ± 2.8 mg/200 mL and 12.5 ± 2.5 mg/200 mL, respectively), and these levels were significantly higher than those in the other tea types (p < 0.001). Brewing temperature only affected caffeine levels n, whereas L-oolong tea (4.4 → 13.5 mg/200 mL, p < 0.05); theanine remained stable (p > 0.05). Longer brewing times significantly raised both components (e.g., yellow tea caffeine levels rose to 53 ± 16.9 mg/200 mL at 10 min; p < 0.05). In black tea, cup-sized bags yielded higher caffeine levels (39 ± 9.9 mg/200 mL) than loose-leaf (24 ± 7.2 mg/200 mL) and teapot bags (p < 0.001). Serving method had no effect on green and white teas (p > 0.05). In conclusion, fermentation rate, brewing conditions, and serving method were found to influence the caffeine and L-theanine levels of tea infusions. Full article

Tea plant [Camellia sinensis (L.) O. Kuntze] is an economically important evergreen crop cultivated worldwide. While most tea plants have green leaves, albino cultivars with yellow or white young leaves have attracted growing interest due to their elevated levels of L-theanine, a key compound that enhances the umami flavor and overall quality of green tea. In this study, we characterized the morphological and biochemical traits of a novel albino tea cultivar, ‘Geumda’, developed in Korea. ‘Geumda’ exhibited yellow young shoots during the first flush and smaller leaves compared to the green-leaf standard cultivar, ‘Sangmok’. Although the catechin content of ‘Geumda’ was lower than that of ‘Sangmok’, it exhibited significantly higher levels of total amino acids, L-theanine, and arginine by 2.1-, 2.0-, and 9.8-fold, respectively. Transmission electron microscopy and gene expression analysis revealed that the elevated amino acid content in ‘Geumda’ was associated with impaired chloroplast development, leading to reduced chlorophyll content and diminished photosynthetic capacity. These findings suggest that ‘Geumda’, with its high concentrations of theanine and arginine and its impaired chloroplast development, represents a valuable genetic resource for the production of functional green teas enriched in umami flavor and beneficial health properties. Full article

Sea buckthorn (Hippophae rhamnoides) is a valuable plant rich in biologically active compounds, mainly found in its berries and leaves. The harvesting process, which includes pruning, freezing, and shaking, leaves behind large amounts of biomass and juice-pressing residues, typically composted. The aim of this study is to expand knowledge of the valorization of sea buckthorn secondary raw materials by applying an innovative pressure cyclic solid–liquid (PCSL) extraction method and to develop value-added functional food products. Extraction was performed in 20 and 60 cycles, each lasting from 2 to 10 min. The highest concentrations of proanthocyanidins (5.51 g_CE/L) and total phenolics (12.42 g_GAE/L) were obtained under prolonged conditions, but the L-4 extract (20 cycles × 2 min) was selected for kombucha production due to its favorable balance between efficiency and sustainability. Microbial safety evaluation showed that kombucha with sea buckthorn leaf extract exhibited significantly stronger antimicrobial activity against tested pathogens compared to green tea kombucha. Additionally, sensory analysis revealed higher consumer acceptability of beverages enriched with sea buckthorn extracts. Shotgun metagenomic analysis identified high microbial diversity in the M. gisevii MI-2 starter culture and fermented kombucha products (227 bacteria and 44 eukaryotes), most of which (92.5% bacteria, 77.8% eukaryotes) remain viable and contribute to fermentation dynamics. New biotechnological strategies and genetic modifications raise concerns about the safe use of microorganisms in food production. To address these issues, these findings provide a foundation for future strategies aimed at the safe application of beneficial microorganisms in food biotechnology and support the long-term goals of the European Green Deal by promoting sustainable biomass valorization and circular economy advancement in the food sector. Full article

Matcha, a finely powdered green tea, has been cherished in Japan for centuries, used in the traditional tea ceremony and nowadays also valued for its health-promoting properties. Cultivated under shaded conditions to enhance chlorophyll production, which gives the typical vibrant green color, matcha is rich in important bioactive compounds, including caffeine, catechins, and theanine. This study analyzes three matcha grades—ceremonial grade 1 (G1), grade 4 (G4), and food grade (FG)—to assess variations in their metabolite profiles. The Bligh–Dyer method was employed to extract polar and non-polar metabolites from organic and hydroalcoholic phases. High-performance thin-layer chromatography (HPTLC) was used for qualitative metabolite analysis, while nuclear magnetic resonance (NMR) spectroscopy was employed for both qualitative and quantitative analyses. Results reveal a decreasing gradient of amino acids and caffeine from grade 1 to food grade, while other metabolites, such as polyphenols, display an increasing trend. These findings suggest that factors such as harvesting time and leaf maturity significantly influence matcha’s chemical composition, providing a scientific basis for its quality differentiation and potential nutraceutical uses. Full article

Tea is one of the most widely consumed beverages globally and a significant dietary source of fluoride. This systematic review aimed to identify and evaluate the factors influencing fluoride concentration in tea infusions. A comprehensive literature search was conducted in March 2025 across PubMed, Scopus, and Web of Science databases, following PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and the PICO framework. Eligible studies investigated fluoride release in tea infusions, published in English from the year 2000 onward. Thirty articles met the inclusion criteria, and the risk of bias in the articles was assessed using the Joanna Briggs Institute (JBI) quality checklist. Fluoride concentration in tea infusions varied widely across studies, ranging from 0.008 to over 8 mg/L. Key factors influencing fluoride release included tea type (with black and green teas showing the highest values), leaf form (powdered and bagged teas released more fluoride than loose leaves), brewing time and temperature, water composition, and the presence of additives such as spices. A longer brewing time and higher temperature consistently increased fluoride extraction. Lower pH or water hardness also significantly affected fluoride availability. Regional origin of tea and production methods were additional sources of variation. Fluoride release in tea is influenced by a complex interplay of botanical, environmental, and preparation-related factors. These findings are clinically relevant, particularly for populations at risk of fluoride overexposure. Further standardized research is needed to inform safe consumption guidelines and public health recommendations. Full article

Implant-associated infections, particularly those linked to Staphylococcus aureus (S. aureus), continue to compromise the clinical success of β-tricalcium phosphate (β-TCP) implants despite their excellent biocompatibility and osteoconductivity. This investigation aims to tackle these challenges by integrating femtosecond (fs)-laser surface processing with two complementary strategies: ion doping and functionalization with green-synthesized silver nanoparticles (AgNPs). AgNPs were produced via fs-laser photoreduction using green tea leaf extract (GTLE), noted for its anti-inflammatory and antioxidant properties. Fs-laser processing was applied to modify β-TCP scaffolds by systematically varying scanning velocities, fluences, and patterns. Lower scanning velocities generated organized nanostructures with enhanced roughness and wettability, as confirmed by scanning electron microscopy (SEM), optical profilometry, and contact angle measurements, whereas higher laser energies induced significant phase transitions between hydroxyapatite (HA) and α-tricalcium phosphate (α-TCP), as revealed by X-ray diffraction (XRD). AgNP-functionalized scaffolds demonstrated markedly superior antibacterial activity against S. aureus compared to the ion-doped variants, attributed to the synergistic interplay of nanostructure-mediated surface disruption and AgNP-induced bactericidal mechanisms. Although ion-doped scaffolds exhibited limited direct antibacterial effects, they showed concentration-dependent activity in indirect assays, likely due to controlled ion release. Both strategies promoted osteogenic differentiation of human bone marrow mesenchymal stem cells (hBM-MSCs) under defined conditions, albeit with transient cytotoxicity at higher fluences and excessive ion doping. Overall, this approach holds promise for markedly improving antibacterial efficacy and osteogenic compatibility, potentially transforming bone regeneration therapies. Full article

The content and health impact of harmful heavy metals in agricultural products from strong geological background concentration areas have received increasing attention. To investigate the impact of soil heavy metal contamination on the tea plantation gardens of Guizhou Province, a major tea-producing area with strong geological background concentrations in China, a total of 37 paired soil–tender tea leaf samples (containing one bud and two leaves) were collected and analyzed for eight harmful heavy metals. The results showed that the average contents of Hg, As, Pb, Cd, Cr, Ni, Sb, and Tl in the surface soil (0–20 cm) were 0.26, 23.9, 37.9, 0.29, 75.9, 37, 2.78, and 0.84 mg/kg, respectively. The majority of the soil Hg, As, Pb, Sb, and Tl levels exceeded their background values for cultivated land soil in Guizhou Province to some extent. The geo-accumulation index revealed that Sb and As are the main pollutants of tea garden soil. The average contents of Hg, As, Pb, Cd, Cr, Ni, Sb, and Tl in the tea leaves were 4, 49, 310, 55, 717, 12,100, 30, and 20 μg/kg (on a dry weight basis), respectively, all of which were significantly lower than their national recommended limits for tea. The bioconcentration factors of these eight heavy metals in tea leaves were relatively low when compared with those in soil, ranging between 0.003 (for As) and 0.603 (for Ni). The health risk assessment indicated that the total hazard quotient (THQ) due to drinking tea was in the order of Tl > Ni > As > Pb > Cd >Sb > Hg > Cr, with both the THQ for each heavy metal and the health risk index (HI) being less than 0.29, indicating that the risk of exposure to these heavy metals through drinking Guizhou green tea is low. Although some harmful heavy metals are present in the tea garden soil of Guizhou, their bioavailability for young tea leaves is extremely low. This may be related to the physical and chemical properties of the soil, such as the high proportion of organic matter (up to 9%) which strongly binds with these elements. Full article

Oxidative stress and inflammation are critical factors in hypertension and type 2 diabetes mellitus (T2DM). Kombucha, a fermented tea beverage, is enriched with bioactive compounds during fermentation. This study evaluated the antihypertensive, antihyperglycemic, antioxidant, and anti-inflammatory activities of kombucha made from mulberry leaf green tea (MLGT) and black tea (MLBT) during in vitro digestion. The bioaccessibility of 1-deoxynojirimycin (DNJ), γ-aminobutyric acid (GABA), phenolics, and flavonoids was assessed through simulated oral, gastric, and intestinal phases. MLGT kombucha exhibited higher initial antioxidant activity, while MLBT showed greater compound stability and ACE inhibitory activity during digestion. Notably, α-glucosidase inhibition declined significantly in the intestinal phase, in parallel with reduced DNJ and flavonoid content. Strong correlations were observed between specific phenolic acids and bioactivity profiles, highlighting ρ-coumaric and sinapic acids in ACE inhibition and DNJ in antiglycemic activity. These findings demonstrate the functional potential of mulberry leaf kombucha as a beverage to support metabolic health, pending confirmation through in vivo studies. Full article

The distribution of moisture content in stacked tea leaves during processing significantly influences tea quality. Visualizing this moisture distribution is crucial for optimizing processing parameters. In this study, we utilized hyperspectral imaging (HSI) technology combined with machine learning algorithms to evaluate the moisture content and its distribution in the stacked tea leaves in West Lake Longjing and Tencha green tea products during the processing flow line. A spectral quantitative determination model was developed, achieving high accuracy (${\mathrm{R}}_{\mathrm{p}}^2$ > 0.940) The model demonstrated strong generalization ability, allowing it to predict moisture content in both types of tea. Through hyperspectral imaging, we visualized moisture distribution in seven key processing steps and observed that moisture content was non-uniform, with the leaf tips and petioles having higher moisture levels than the leaf surface. This study offers a novel solution for real-time moisture monitoring of stacked tea leaves in tea production, ensuring consistent product quality. Future research could focus on refining model transfer techniques and exploring additional tea varieties to further enhance the generalization of the approach. Full article

Drying methods play a crucial role in the formation of green tea aromas. This study investigated the aroma characteristics and volatile component profiles of large-leaf green tea under hot-air drying, pan-fired drying, and sun drying. The results revealed significant differences in the sensory aroma characteristics and volatile components of the large-leaf green tea among the three drying methods. The pan-fire-dried green tea (PDGT) exhibited a distinct roasted aroma, while the hot-air-dried green tea (HDGT) and sun-dried green tea (SDGT) displayed a faint scent and lasting aroma characteristics, with the SDGT additionally featuring a noticeable sun-dried odor. A total of 48 differential volatile components were identified, among which β-Ionone, (E)-β-Ionone, 2,2,6-Trimethylcyclohexanone, Dihydroactinidiolide, BenzeneacetAldehyde, 2-Pentylfuran, 1,1,6-Trimethyl-1,2-dihydronaphthalene, δ-Cadinene, β-Myrcene, Geranylacetone, o-Cymene, 6-Methyl-5-hepten-2-one, (E)-β-Ocimene, and BenzAldehyde were identified as the primary contributors to the aroma differences among the three large-leaf green teas. Additionally, 43 differential volatile compounds were found to be significantly correlated with at least one of the aroma types (floral, sweet, green, faint scent, nutty, or roasted). The findings of this study provide a theoretical foundation for understanding the formation of aroma qualities in large-leaf green tea and offer valuable insights for improving its aromatic characteristics. Full article

Active packaging using an edible coating could be an essential and sustainable alternative solution to preserve the properties of fruits and to prevent food loss and food waste. Fruits generate significant food wastes and losses. Reducing food waste is a global priority. For this research, nature-based solutions (NBSs) were applied, using micro-sized chitosan (CsMPs) and selenium microparticles (SeMPs), which are green-synthesized from black tea leaf extracts, and thyme essential oil. In this study, the effects of the new generation active food preservative coating agents formed from combinations of micro-sized chitosan (CsMPs) and selenium (SeMPs), and thyme essential oil (Oil) on the quality of “0900 Ziraat” sweet cherry fruits after harvest were investigated. After the fruits were coated with edible colloid solution, they were stored at 4 °C and 21 °C for 20 days, and quality parameter analyses were performed on days 0, 5, 10, 15, and 20. As a result of this study, it was determined that the application of CsMPs + SeMPs and the subsequent application of CsMPs + SeMPs + Oil from colloid solution coatings reduced weight loss, respiration, and decay rates. Also, it was determined that these applications were the most effective in preserving color values (L*, chroma, and hue), fruit firmness, total soluble solid (TSS) amount, acidity content and total phenolics, anthocyanin, and antioxidant capacity. These results show that CsMPs + SeMPs and CsMPs + SeMPs + Oil applications can be used as edible coatings to preserve the quality of sweet cherry fruits and extend their shelf life after harvest. This study’s results will contribute to obtaining micro-sized composite coating agents/agents produced with new technology to extend the shelf life. Full article

The increasing presence of various organics poses significant threats to aquatic ecosystems and living organisms. Conventional water treatment methods are often insufficient, necessitating the development of powerful and sustainable alternatives. This study addresses this challenge by exploring the synthesis of ZnO nanoparticles using green tea leaves extract—an eco-friendly approach—for the sunlight-activated removal of organics in agri-food wastewater. The research examined different conditions for the removal of clomazone (CLO), tembotrione (TEM), ciprofloxacin (CIP), and zearalenone (ZEA). Nitrate-derived ZnO synthesized in a water medium (N-gZnO_w) exhibited the highest photocatalytic activity, removing 98.2, 95.8, 96.2, and 96.6% of CLO, TEM, CIP, and ZEA. Characterization techniques (XRD, Raman spectroscopy, SEM, zeta potential measurements, UV–visible spectroscopy) confirmed the synthesis of N-gZnO_w, with an average particle size of 14.9 nm, an isoelectric point of 9.9, and a band gap energy of 2.92 eV. Photocatalytic experiments identified 0.5 mg/cm³ as an optimal catalyst loading, while a higher initial pollutant concentration reduced degradation efficiency. LC-ESI-MS/MS measurements confirmed the efficient pollutant degradation and the formation of degradation intermediates. Hence, this study demonstrates that green tea extract-synthesized ZnO nanoparticles offer a promising, sustainable solution for removing herbicides, pharmaceuticals, and mycotoxins from wastewater, paving the way for eco-friendly water purification technologies. Full article

Objective: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a chronic condition affecting a broad population. This review aimed to identify and summarize the current evidence on bioactive-substance-based interventions for adults with MASLD, formerly known as nonalcoholic fatty liver disease (NAFLD), covering publications from 2000 to 2023. Methods: A search was conducted across six databases (MEDLINE, CINAHL, Cochrane CENTRAL, Cochrane Database of Systematic Reviews, Food Science Source, and SPORTDiscus) for randomized controlled trials and other study types (e.g., prospective cohort studies and systematic reviews), reflecting the scoping nature of this review. The search was limited to studies in adults (>18 years old), with an intervention of interest and at least one comparator group. Results: A total of 4572 articles were retrieved, with 201 full-text articles screened for eligibility. Of these, 131 primary studies and 49 systematic reviews were included in the scoping review. The most studied bioactive substances were Curcumin (Turmeric) (n = 25), Silymarin (Milk Thistle) (n = 17), Resveratrol (n = 10), Coffee (n = 7), Green Tea (n = 5), and Berberine (n = 5 each). Moreover, 46 studies reported on 36 other bioactive substances with 2 or fewer articles each. Among the included systematic reviews, 13 focused on Curcumin, 12 on Coffee or Tea, 10 on bioactive substance combinations, 6 on Resveratrol, and 2 each on Silymarin and Artichoke Leaf. The included studies showed substantial heterogeneity in reported outcomes, which primarily focused on hepatic health, body weight, adverse events, glycemic control, blood lipids, and body composition. Conclusions: This scoping review highlights a range of bioactive substances used in the treatment of MASLD. While evidence is abundant for bioactive substances like Curcumin and Silymarin, further research and synthesis of findings is necessary to establish the clinical efficacy of all bioactive substances. Full article