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Juvenile hormone III (JH III) maintains larval characteristics in insects and promotes ovary development in adults. Hydroprene, kinoprene, and methoprene are synthesized analogs based on natural JH III. A novel and precise method was established to mitigate the matrix effects and concurrently determine these juvenile hormone analogs in tea employing gas chromatography-tandem mass spectrometry (GC-MS/MS). Water addition as a sample extraction approach was utilized and contrasted with protocols excluding water. Concurrently, the sought compounds underwent extraction with 1% (v/v) acetic acid-acetonitrile, followed by purification utilizing 0.1 g graphitized carbon black (GCB), 0.4 g primary secondary amine (PSA), and 0.4 g C18. Following separation via a DB-17MS column, detection of the analytes was conducted through GC-MS/MS in dynamic multiple reaction monitoring (DMRM) mode with quantification by a matrix-matching standard curve. Satisfactory linear relationships were established for the trio of juvenile hormone analogs within a 0.01–0.32 mg/L range, exhibiting correlation coefficients (R2) exceeding 0.999 and quantitation limits (LOQs) approximately spanning 0.005–0.01 mg/kg. Mean recoveries, spanning three concentrations (0.02, 0.1, 0.2 mg/kg), varied between 77.6% and 115.9%. The relative standard deviations (RSDs, n = 6) were from 0.5% to 5.8%. Detection of the juvenile hormone analogs was accomplished in tea samples. In summary, this investigation demonstrated a proficient approach in addressing complications by diminishing the matrix effects in a complex sample. [ABSTRACT FROM AUTHOR]

A simple, quick and environmentally friendly microwave-assisted synthesis method was developed to produce MoS2 nanoparticles (MoS2NP) for the preconcentration of thallium. The characteristics of the synthesized MoS2NP were validated by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The determination of thallium was achieved with MoS2NP based preconcentration and a flame atomic absorption spectrophotometer (MoS2NP-PM-FAAS). A detection limit of 14.6 µg/kg was achieved for thallium using the optimum conditions by the MoS2-PM-FAAS method. The developed method provided an improvement in the detection power of the FAAS system by approximately 20-fold. The applicability of the method was validated with tea samples through spike recovery experiments. [ABSTRACT FROM AUTHOR]

Background: Herbal tea drinks, different from classical Camellia beverages, are a wide variety of herbal drinks consumed for therapeutic purposes or health promotion. Herbal tea is widely consumed in Guangxi. However, the documentation on the plants for herbal tea and their related health benefits is still limited. Methods: An ethnobotanical survey was conducted in 52 villages and 21 traditional markets in Guangxi from 2016 to 2021. Semi-structured interviews, key informant interviews, and structured questionnaires were applied to obtain ethnobotanical information of herbal tea, in which 463 informants had participated. Relative frequency of citation (RFC) and cultural food significance index (CFSI) were used to evaluate the most culturally significant herbal tea plants, and informant consensus factor (ICF) was applied to assess the agreement among informants. Results: This study recorded 155 herbal tea species belonging to 49 families. The most commonly used parts included leaf (27.61%), whole plant (22.09%), branch and leaf (19.02%), and flower (13.50%). The most frequent preparation method of herbal tea was decoction. Herbal tea was very popular in Guangxi, attributing to its therapeutic value, special odor, and good taste. There are 41 health benefits classified into eight categories. Among them, clearing heat was the most medicinal effects. Local people had high consistency in tonic, removing cold and cough, improving blood circulation, and clearing heat away. Based on CFSI values of each species, the most culturally significant herbal tea species were Siraitia grosvenorii (Swingle) C. Jeffrey ex A. M. Lu & Zhi Y. Zhang, Plantago asiatica L., Gynostemma pentaphyllum (Thunb.) Makino, Zingiber officinale Roscoe, Pholidota chinensis Lindl., and Morus alba L. Conclusion: Herbal tea is a valuable heritage that carries the local people's traditional knowledge, like health care and religious belief. The recorded herbal tea species in this study possess tremendous potential for local economic development in the future. Further research on efficacy evaluation and product development of herbal tea species is necessary. [ABSTRACT FROM AUTHOR]

The study examines the seasonal variation in phytometabolite content in Camellia sinensis var. assamica , a prevalent tea variety in Northeast India. Focusing on both bud and dormant leaf (banjhi) samples harvested during the monsoon, autumn, and winter seasons, the research aims to assist cultivators in selecting optimal harvesting times for tea production. An LC-MS/MS method was developed and validated for phytometabolite quantification. Epigallocatechin gallate (EGCG) emerged as the most abundant catechin, with concentrations ranging from 78.01±13.31–125.21±5.65 µg/mg in buds during the monsoon and decreasing to 17.86±1.22–51.11±1.21 µg/mg in winter. Banjhi leaves exhibited even higher EGCG levels, from 203.86±21.06–312.58±28.23 µg/mg in the monsoon, dropping to 74.43±15.22–97.52±8.47 µg/mg in autumn. Similarly, epicatechin gallate concentrations in buds ranged from 17.04±2.57–24.78±1.15 µg/mg in the monsoon and decreased to 5.36±0.39–11.16±1.74 µg/mg in winter, while banjhi leaves showed a decline from 63.61±1.60–72.72±1.23 µg/mg in the monsoon, dropping to 12.73±2.07–15.35±1.33 µg/mg in autumn. The study also noted seasonal variations in catechin hydrate, caffeine, gallic acid, theanine, and theaflavin. These findings underscore the importance of harvest timing for maintaining tea quality and optimizing cultivation and processing practices for sustainability amid environmental changes. [Display omitted] • Study analyses seasonal variation in flavonoids, caffeine, gallic acid, theanine, and theaflavin. • Focus on bud and dormant leaf samples harvested during monsoon, autumn, and winter. • LC-MS/MS method developed for precise phytometabolite quantification in Assam tea. • Epigallocatechin gallate (EGCG) is most abundant in monsoon, decreasing significantly in winter. • Findings highlight the importance of harvest timing for optimal tea quality and sustainability. [ABSTRACT FROM AUTHOR]

Pesticides are used in agricultural production for prevent and control crop diseases and pests, but it is easy to cause excessive pesticides residues in agricultural products, polluting the environment and endangering human health. Due to their unmatched and sustainable capabilities, nanoextraction procedures are becoming every day more important in Analytical Chemistry. In particular, nanoconfined liquid phase extraction has shown extraction capabilities toward polar, medium polar, and/or nonpolar substances, which can be easily modulated depending on the nanoconfined solvent used. Furthermore, this "green" technique showed excellent characteristics in terms of recoveries, extraction time (≤1 min), reliability, and versatility. (97) In this work, the advantages of this technique have been coupled with those of filtration membrane extraction, making use of carbon nanofibers (C n Fs) growth on carbon microspheres (C μ S). This substrate has been deposited on a filter, which combined with gas chromatographic mass spectrometry (GC-MS) analysis successfully employed for the nanoextraction of 30 pesticides (18 organochlorine and 12 pyrethroids) in tea samples. Under the optimized extraction conditions, the linear range with standard solutions was from 1 to 1000 ng mL−1 (R2 ≥ 0.99), the limit of detections in tea samples were in the range 0.56–17.98 μg kg−1. The accuracy of the developed method was evaluated by measuring the extraction recovery of the spiked tea samples, and recoveries between 74.41 % and 115.46 %. (119) Considering the versatility of nanoconfined liquid phase extraction and the functionality of the filtration membrane extraction procedure, this new extraction method can be considered a powerful candidate for automatized high-throughput analyses of real samples. (34) [Display omitted] • Synthesis of carbon nanofibers onto carbon microspheres (C n Fs/C μ S) has been proposed. • Nanoconfined solvent on C n Fs/C μ S was used to extract 30 pesticides from real samples. • Nanoconfined liquid phase nanoextraction was applied as a membrane extraction method. [ABSTRACT FROM AUTHOR]

Crush–tear–curl (CTC) black tea is a popular beverage, owing to its unique taste characteristics and health benefits. However, differences in the taste quality and chemical profiles of CTC black tea from different geographical regions remain unclear. In this study, 28 CTC black tea samples were collected from six geographical regions and analyzed using electronic tongue and ultrahigh performance liquid chromatography‐Orbitrap‐mass spectroscopy. The e‐tongue analysis indicated that each region's CTC black tea has its own relatively prominent taste characteristics: Sri Lanka (more umami and astringent), North India (more umami), China (more sweetness and astringent), South India (moderate umami and sweetness), and Kenya (moderate umami and astringent). Based on multivariate statistical analysis, 78 metabolites were tentatively identified and used as potential markers for CTC black tea of different origins, mainly including amino acids, flavone/flavonol glycosides, and pigments. Different metabolites, which contributed to the taste characteristics of CTC black tea, were clarified by partial least squares regression correlation analysis. Our findings may serve as useful references for future studies on origin traceability and quality characteristic determination of CTC black teas. Practical Application: This study provides useful references for future studies on the origin traceability and taste characteristic determination of CTC black teas from different geographical regions. [ABSTRACT FROM AUTHOR]

Recently, a bowl containing charred suspected tea remains unearthed from the early stage of Warring States period tomb in Zoucheng City, Shandong Province, China. To identify the remains is significant for understanding the origin of tea and tea drinking culture. Scientific investigations of the remains were carried out by using calcium phytoliths analysis, Fourier transform infrared spectroscopy (FTIR), Gas Chromatograph Mass Spectrometer (GC/MS) and Thermally assisted hydrolysis—methylation Pyrolysis Gas Chromatography Mass Spectrometry (THM-Py-GC/MS) techniques. Modern tea and modern tea residue were used as reference samples. Through phytoliths analyses, calcium phytoliths identifiable from tea were determined in the archeological remains. The infrared spectra of the archaeological remains was found similar as modern tea residue reference sample. In addition, the biomarker compound of tea—caffeine was determined in the archaeological remains by THM-Py-GC/MS analysis. Furthermore, through GC/MS analysis, some compounds were found both in the archeological remains and the modern tea residue reference samples. Putting the information together, it can be concluded that the archaeological remains in the bowl are tea residue after boiling or brewing by the ancient. [ABSTRACT FROM AUTHOR]

Spectroscopic sensing provides physical and chemical information in a non-destructive and rapid manner. To develop non-destructive estimation methods of tea quality-related metabolites in fresh leaves, we estimated the contents of free amino acids, catechins, and caffeine in fresh tea leaves using visible to short-wave infrared hyperspectral reflectance data and machine learning algorithms. We acquired these data from approximately 200 new leaves with various status and then constructed the regression model in the combination of six spectral patterns with pre-processing and five algorithms. In most phenotypes, the combination of de-trending pre-processing and Cubist algorithms was robustly selected as the best combination in each round over 100 repetitions that were evaluated based on the ratio of performance to deviation (RPD) values. The mean RPD values were ranged from 1.1 to 2.7 and most of them were above the acceptable or accurate threshold (RPD = 1.4 or 2.0, respectively). Data-based sensitivity analysis identified the important hyperspectral regions around 1500 and 2000 nm. Present spectroscopic approaches indicate that most tea quality-related metabolites can be estimated non-destructively, and pre-processing techniques help to improve its accuracy. [ABSTRACT FROM AUTHOR]

Tea, a widely consumed beverage, has long been utilized for promoting human health with a close correlation to hyperglycemia. The Tea Metabolome Database (TMDB), the most complete and comprehensive curated collection of tea compounds data containing 1271 identified small molecule compounds from the tea plant (Camellia sinensis), was established previously by our research team. More recently, our studies have found that various tea types possess an antihyperglycemic effect in mice. However, the bioactive ingredients from tea have potential antihyperglycemic activity and their underlying molecular mechanisms remain unclear. In this study, we used a molecular docking approach to investigate the potential interactions between a selected 747 constituents contained in tea and 11 key protein targets of clinical antihyperglycemic drugs. According to our results, the main antihyperglycemic targets of tea composition were consistent with those of the drug rosiglitazone. The screening results showed that GCG, ECG3'Me, TMDB-01443, and CG had great target binding capacity. The results indicated that these chemicals of tea might affect hyperglycemia by acting on protein targets of rosiglitazone. [ABSTRACT FROM AUTHOR]

Kombucha is a valuable traditional natural tea that contains beneficial compounds like organic acids, minerals, different vitamins, proteins, polyphenols, and several anions. Kombucha possesses anticancer, antioxidant, antimicrobial, and antifungal activity as well as hepatoprotective effects. Considering the unique properties of Kombucha, several investigations have already been conducted on its nutritional properties. In this review, an effort has been devoted to pool recent literature on the biomedical application of Kombucha under the objectives, including the chemical composition of Kombucha and industrial production, and highlight different properties of Kombucha. Finally, we explain its adverse effects and prospect. This review is an active, in-depth, and inclusive report about Kombucha and its health benefits. [ABSTRACT FROM AUTHOR]

Bi, Fe, and Ti ternary co-doped ZrO2 (BFT-ZrO2) nanocomposites have been prepared by a sol-gel process and used as both adsorbent and matrix for the enrichment and determination of small molecules by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS). The BFT-ZrO2 nanocomposites not only can selectively enrich a wide variety of low-mass toxic pollutants but can also be used as an excellent matrix to enhance the laser desorption/ionization efficiency with low background noise and uniform co-crystalline film. Low limits of detection (LODs) (0.1 pg mL−1 for bisphenol A (BPA), 2 pg mL−1 for tetrabromobisphenol A (TBBPA), 0.1 pg mL−1 for alizarin (AZ), 0.001 pg mL−1for bisphenol S (BPS), 0.01 pg mL−1 for indigo blue (ID), 0.01 pg mL−1 for pentachlorophenol (PCP), 100 pg mL−1 for estradiol (E2), 0.001 pg mL−1 for cetyltrimethylammonium bromide (CTAB), 0.1 pg mL−1 for crystal violet (CV), 1 pg mL−1 for malachite green (MG), 0.01 pg mL−1 for rhodamine B (RhB), and 0.01 pg mL−1 for perfluorooctane sulfonate (PFOS) were achieved. The relative standard deviations (RSDs) of shot-to-shot are 9.4–24% and of sample-to-sample 5.2–17%. The BFT-ZrO2 matrix was successfully applied to the determination of TBBPA and BPA in tea samples. This method shows a new strategy for determination of toxic compounds in tea. [ABSTRACT FROM AUTHOR]

Doxorubicin is an anthracycline antibiotic that is used for the treatment of various types of cancer. However, its clinical usage is limited due to its potential life-threatening adverse effects, such as cardio- and nephrotoxicities. Nonetheless, simultaneous administration of doxorubicin and antioxidants, such as those found in green tea leaves, could reduce cardiac and renal tissue damage caused by oxidative stress. The methylxanthine fraction isolated from Bancha tea leaves were tested in vitro for its antioxidant activity and in vivo for its organoprotective properties against doxorubicin-induced cardio- and nephrotoxicities in a rat model. The in vivo study was conducted on male Wistar rats divided into 6 groups. Methylxanthines were administered at high (5 mg/kg body weight) and low (1 mg/kg body weight) doses, while doxorubicin was administered at a cumulative dose of 20 mg/kg body weight. Serum creatinine, uric acid, and urea concentrations, as well as serum enzyme levels (creatinine kinase (CK), creatinine kinase MB fraction (CK-MB), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH)) and electrolytes (Na+, K+, and Cl-), were analysed. In addition, histological analysis was performed to assess cardiac and renal tissue damage. The concomitant administration of Bancha methylxanthines and doxorubicin showed a dose-dependent reduction in the serum biochemical parameters, indicating a decrease in the cardiac and renal tissue damage caused by the antibiotic. Histological analysis showed that pretreatment with methylxanthines at the dose of 5 mg/kg resulted in an almost normal myocardial structure and a significant decrease in the morphological kidney changes caused by doxorubicin exposure compared with the group that received doxorubicin alone. The putative mechanism is most likely related to a reduction in the oxidative stress caused by doxorubicin. [ABSTRACT FROM AUTHOR]

Background. Thunbergia laurifolia (TL) is a commonly used herbal medicine in Thailand and in other Asian countries. TL has been approved as a Thai traditional medicine for detoxifying poisons, and the list of possible adverse effects includes hypoglycemia. TL showed hypoglycemic effect in animals possibly due to antioxidant effect and beta-cell preservation. However, the safety of TL herbal tea and its effects on glucose homeostasis have never been investigated in humans. Methods. Twenty healthy volunteers (10 men and 10 women) drank TL herbal tea 3 times/day for 2 weeks. Ten subjects took TL herbal tea 9 grams daily. After the safety of TL herbal tea was established, 10 more subjects took TL 12 grams daily. Clinical and biochemical tests were assessed at baseline and at 2 weeks. Results. Mean age was 34.9 ± 10.2 years, and mean body mass index was 27.5 ± 5.8 kg/m2. Baseline and posttreatment plasma concentrations were as follows: fasting plasma glucose (89 ± 6 vs. 89 ± 7 mg/dL), fructosamine (213 ± 32 vs. 212 ± 33 μmol/L), fasting insulin (8.8 [IQR: 5.9–18.4] vs. 10.4 [IQR: 7.4–15.2] μU/mL), HOMA-B (101.6 [IQR: 82.3–189.8] vs. 120.4 [IQR: 93.2–153.2]), and HOMA-IR (1.1 [IQR: 0.8–2.3] vs. 1.4 [IQR: 0.9–2.0]), all respectively. There were no significant changes in these parameters, including body weight, blood pressure, lipid profile, and C-reactive protein. No serious adverse events were observed during the study period. Conclusions. TL herbal tea at doses of 9 and 12 grams daily had good tolerability without any significant adverse effects on fasting plasma glucose level or other glucose homeostasis parameters measured. [ABSTRACT FROM AUTHOR]

Purpose: In this study, we aimed to study the correlation between acute and habitual intakes of flavonols, their main food sources and their 24-h urinary concentrations in an European population. Methods: A 24-h dietary recall (24-HDR) and 24-h urine samples were collected on the same day from a convenience subsample of 475 men and women from four countries (France, Italy, Greece and Germany) of the European Prospective Investigation into Cancer and Nutrition (EPIC) study. A standardized 24-HDR software and a country/centre-specific validated dietary questionnaire (DQ) were used to collect acute and habitual dietary data, respectively. The intake of dietary flavonols was estimated using the Phenol-Explorer database. Urinary flavonols (quercetin, isorhamnetin, and kaempferol) were analysed using tandem mass spectrometry with a previous enzymatic hydrolysis. Results: Weak partial Spearman correlations between both dietary acute and habitual intake and urinary concentrations of quercetin (both Rpartial ~ 0.3) and total flavonols (both Rpartial ~ 0.2) were observed. No significant correlations were found for kaempferol and isorhamentin. Regarding flavonol-rich foods, weak correlations were found between urinary concentrations of quercetin and total flavonols and the acute intake of onions and garlics, fruits, tea, and herbal tea (all Rpartial ~ 0.2). For habitual intake, statistically significant correlations were only found between urinary quercetin concentration and herbal tea (Rpartial = 0.345) and between urinary total flavonol concentration and tea, and herbal tea consumption (Rpartial ~ 0.2). Conclusions: Our results suggest that urinary quercetin level can be used as potential concentration biomarkers of both acute and habitual quercetin intake, while urinary concentrations of flavonols are unlikely to be useful biomarkers of individual flavonol-rich foods. [ABSTRACT FROM AUTHOR]

In this work, the stable isotope ratios of carbon, nitrogen, hydrogen, oxygen, and mineral elements and their stoichiometric methods were examined as possible factors that could certify Chinese tea based on its production years. A total of 43 multi-element stable isotope ratios of Xiangzhujing Pu'er tea in five production years were determined through inductively coupled plasma mass spectrometry (ICP-MS) and elemental analyzer-isotope ratio mass spectrometry (EA-IRMS) methods. Two unsupervised learning techniques (principal component analysis and hierarchical clustering analysis) and three supervised learning techniques (partial least squares discriminant analysis [PLS-DA], back-propagation artificial neural network [BP-ANN], and linear discriminant analysis [LDA]) were used on the basis of 18 statistically significant multi-elemental stable isotope ratios to build authentication models for Pu'er tea. The clustering abilities of the two unsupervised learning methods were worse than those of the three supervised learning methods. The three supervised models correctly separated the corresponding production years of the samples. The authentication performance was obtained through BP-ANN and LDA, with 100% recognition and prediction abilities, which were better than those of PLS-DA. δD, δ13C, and 154Sm/152Sm were determined as the markers for the accurate authentication of Pu'er tea in different production years. The profiles of multi-element stable isotope ratios obtained via ICP-MS and EA-IRMS with chemometric methods could serve as potential and powerful factors for authenticating Chinese tea in different production years. This study contributed to the generalization of the use of multi-elemental stable isotope ratio fingerprinting as a promising tool for testing the authenticity of tea worldwide. [ABSTRACT FROM AUTHOR]

Objective: To investigate the color stability of hybrid ceramics and to compare it to composite and lithium disilicate ceramics. Materials and Methods: One hundred eighty samples were fabricated and processed with a semiautomatic grinding and polishing device (final step: 1200 grit). After thermocycling, samples were immersed in a staining solution (five subgroups: water, red wine, curry, black tea, cola) for 4 weeks. A spectroradiometer was used to determine the color of the samples in CIE L*a*b*. Color measurements were performed before staining (baseline, initial color), after thermocycling, after 2 and 4 week storage in staining solution and each after a two stage repolishing approach. Discoloration of specimens was calculated by means of ΔE00 compared to baseline values. Results: All factors (material, staining solution, aging stage) were significantly associated with the extent of discolorations (P <.001). Maximum color changes occurred after 28 days staining (EN: ΔE00 = 4.5 ± 4.0; GB: ΔE00 = 5.0 ± 4.5; LS: ΔE00 = 3.0 ± 2.3) clearly exceeding the 50:50 threshold for acceptable color deviations. Due to repolishing, discoloration of LS samples was almost completely eliminated (ΔE00 = 0.4 ± 0.3) and significantly reduced for the other two materials (EN: ΔE00 = 1.0 ± 0.9; GB: ΔE00 = 0.9 ± 0.4; P =.428). Conclusion: Discoloration of hybrid ceramics ranged in‐between lithium disilicate and composites, however more comparable to composites. Repolishing could reduce discolorations substantially. Clinical Relevance: This study should help dental practitioners to estimate the color stability of common dental materials and the effect of polishing in removal of discolorations. [ABSTRACT FROM AUTHOR]

Iced teas (ITs), also known as ready-to-drink teas, have gained much popularity among many nations. The modulatory effect of tea beverages on CYP3A4 increases the possibility of their potential interactions with many coadministered medications. Being a substrate of CYP3A4, sorafenib (SOR), the first-line therapy for the treatment of hepatocellular carcinoma, shows a great probability to exhibit pharmacokinetic (PK) interaction with ITs. For this purpose, different groups of Wistar rats were given oral doses of SOR (40 mg/kg), along with different types of ITs. The concentration of SOR in rat plasma was determined using UPLC-MS/MS. Chromatographic analysis was performed on a C18 analytical column, Acquity UPLC BEH™ (100 × 1.0 mm, i.d., 1.7 μm particle size), using erlotinib (ERL) as an internal standard. Isocratic elution was performed with a mobile phase consisting of two solvents: solvent A (water with 0.1% formic acid) and solvent B (acetonitrile with 0.1% formic acid), in a ratio of 30 : 70, v/v, respectively. Quantitation was performed using MRM of the transitions from protonated precursor ions [M+H]+ to product ions at m/z 465.12 > 252.02 (SOR) and m/z 394.29 > 278.19 (ERL). The method was fully validated as per the FDA guidance for bioanalytical method validation in the concentration range of 2.5–500 ng/mL. Different PK parameters were calculated for SOR in all rat groups and groups administered with ITs and SOR, compared with groups with simply water and SOR. Experimental data revealed that ITs caused a general reduction in SOR bioavailability; an approximate reduction of 30% was recorded for all types of tested ITs. These data indicate that ITs could affect the PK profile of SOR in rats. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to evaluate the effect of the addition of antibacterial agents to composites on color changes after immersion of these composites in different beverages. Materials and Methods: Composite resins containing antibacterial agents (bioactive glass [BAG] and nano‐zinc silicium [NZS]) and a control group (no agent) were produced. The treatment groups were as follows: control, BAG, NZS, and BAG + NZS. Forty‐eight disc‐shaped specimens (8 mm in diameter and 2‐mm thick) were prepared, with 12 specimens in each group. Color measurements were measured before and after immersion of the specimens in staining solutions (tea, coffee, and water) for 1, 7, and 30 days. The color measurements were repeated, and changes were calculated using the CIEDE2000 (ΔE00) formula. Results: Color differences were analyzed using a two‐way analysis of variance and Tukey's tests. Significant differences were observed among the composite groups and solutions after all days in all the groups (P < .05). Conclusions: The addition of the antibacterial agents did not reduce color changes. Color changes of the specimens immersed in coffee were greater than those of the specimens immersed in the other beverages, with the highest color change observed in the BAG groups. Clinical Significance: The results provide information on the color stability of composite resins containing BAG and NZS and the staining potential of drinks commonly consumed in daily life. In terms of esthetic dentistry, BAG and NZS containing composites should be used in the posterior region, where there is a high risk of caries due to coloration. [ABSTRACT FROM AUTHOR]

The aim of this study was to isolate a-glucosidase inhibitory constituents from Malus halliana Koehne tea. The ethyl acetate and n-butanol extract of M. halliana tea showed α-glycosidase inhibitory activity (IC50 332.24 and 168.92 μg/mL, respectively) and eleven compounds (1-11) were isolated and identified by extensive NMR data (¹H and 13C NMR) and mass spectrum. Eleven compounds were isolated from this plant for the first time, and compounds 2, 4, 5, 7 and 8 were isolated from the genus for the first time. The α-glucosidase inhibitory activity of compounds 6, 8, 9 and 10 (IC50 6.32, 15.53, 37.68 and 7.87 μM) were better than that of other compounds (IC50 > 200 μM). Compounds 1~5 and 11 displayed moderate inhibitory effects on α-glucosidase, with IC50 values of 226.76~435.56 μM, whereas compound 7 (IC50 3246.17 μM) was inactive, and lower than that of acarbose as positive control (IC50 1819.72 μM). [ABSTRACT FROM AUTHOR]

Highlights • Untargeted metabolic analysis of Tieguanyin tea was developed. • Metabolites of teas with different seasons/years were analyzed by UPLC–Q-TOF/MS. • The differences of chemical components were revealed by heat map analysis. Abstract The taste and aroma quality of Tieguanyin tea fluctuate seasonally and yearly. However, the compounds responsible for the seasonal and year variations of metabolic pattern and its sensory quality are far from clear. 60 Tieguanyin tea samples harvested in different years and seasons were analyzed by ultraperformance liquid chromatography–quadrupole time-of-flight mass spectrometry (UPLC–Q-TOF/MS) and chemometrics. Principal component analysis (PCA) explained 33.2% of the total variance, while orthogonal projection to latent structures discriminate analysis (OPLS-DA) can obtain potential metabolites with better discrimination, and with R2X and Q2 of cross-validation as 0.974 and 0.937, respectively. Subsequently, heat map analysis (HCA) visualized relationships between Tieguanyin teas with these significantly different potential metabolites by Mann-Whitney U test (p < 0.05). Furthermore, the best discriminate metabolites contributing to different sensory qualities were revealed by stepwise liner discrimination analysis (SLDA) with 100% accuracy rate. The present strategy also exhibited great potential for untargeted metabolomics of other foods. [ABSTRACT FROM AUTHOR]

Highlights • NMR is used to characterize the compositional changes of two different dark teas. • Catechin metabolisms are different between aerobic and anaerobic fermentations. • Anaerobic fermentation using LAB retains anti-glycation activity of dark tea. • Pyrogallol is a potent anti-glycation metabolite produced in the LAB fermentation. Abstract Post-fermented tea (dark tea) is produced from enzyme-inactivated fresh tea leaves by microbial fermentation. Batabata tea and Awaban tea are two major dark teas fermented under aerobic and anaerobic conditions, respectively. However, how their chemical compositions and functionalities change during different post-fermentation processes remains unclear. Nuclear magnetic resonance (NMR)-based analyses showed that (−)-epigallocatechin gallate (EGCG), (−)-epigallocatechin (EGC) and (−)-epicatechin (EC) decreased in Batabata tea during post-fermentation with aerobic molds. In contrast, EGC and EC increased, and pyrogallol was produced in Awaban tea during post-fermentation with lactic acid bacteria (LAB). The anti-glycation activities of two dark teas were investigated using an in vitro assay system with human serum albumin (HSA). The anti-glycation activity decreased in Batabata tea, but it was retained in Awaban tea during post-fermentation. Our results showed that post-fermentation with LAB was an efficient way to enhance phenol content and that pyrogallol contributed to anti-glycation activity of Awaban tea. [ABSTRACT FROM AUTHOR]

Highlights • Different grades of Bai Mudan white tea showed differential metabolite composition. • The grade variation of Bai Mudan white tea was revealed by multivariate analysis. • 21 Structurally-identified metabolites correlated with tea grade variation. • Non-targeted metabolomics could be used for Bai Mudan white tea grade evaluation. Abstract So far, the chemical quality of different grades of white tea has largely remained unexplored. The objective of this study was to establish a model for quality evaluation of different grades of Bai Mudan white tea. We applied non-targeted ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry in combination with multivariate analysis and analyzed four different grades of Bai Mudan white tea. We found that the metabolite composition from the super-grade and the first-grade shared higher similarity compared to the second-grade or the third-grade white tea, and the Partial Least Square-Discriminant Analysis model showed high capability to explain the sample variation (R2Y = 0.998, Q2 = 0.95 in negative ionization modes). In total, 93 metabolites were structurally identified, wherein 21 low abundant metabolites showed distinct changes in abundance that were closely correlated with tea grade variation. These findings suggested their potential as markers to discriminate different grades of Bai Mudan white tea. [ABSTRACT FROM AUTHOR]

Abstract Kawakawa (Piper excelsum) has food, medicinal and cultural importance to the indigenous Māori people of New Zealand, and is being incorporated into a range of commercial food and therapeutic products, including tea. In this study, the chemical compositions of kawakawa fresh leaves, dried leaves for tea, and hot brewed tea, were analysed and compared. The key metabolites were diayangambin, elemicin, myristicin, unidentified lignans and amides. The safety of brewed tea and tea leaves were evaluated in 8 week old Sprague Dawley rats in a 14 day acute study followed by a 28 day subacute study. In the 14 day study, the rats received the equivalent of 1, 2, 3 or 4 cups of kawakawa tea, and the rats in the 28 day study received daily doses that were equivalent to 4 cups per day. There were no adverse effects observed in the rats, and body weights and food intakes were not significantly different between the control and the kawakawa treated animals. There were small differences in organ weights, biochemical and haematology parameters observed in the rats given the kawakawa tea. In conclusion, the consumption of kawakawa tea could be considered safe within the conditions used in this study. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

Abstract The potential of selected spectroscopic methods - UV–Vis, synchronous fluorescence and NIR as well a data fusion of the measurements by these methods - for the classification of tea samples with respect to the production process was examined. Four classification methods - Linear Discriminant Analysis (LDA), Quadratic Discriminant Analysis (QDA), Regularized Discriminant Analysis (RDA) and Support Vector Machine (SVM) - were used to analyze spectroscopic data. PCA analysis was applied prior to classification methods to reduce multidimensionality of the data. Classification error rates were used to evaluate the performance of these methods in the classification of tea samples. The results indicate that black, green, white, yellow, dark, and oolong teas, which are produced by different methods, are characterized by different UV–Vis, fluorescence, and NIR spectra. The lowest error rates in the calibration and validation data sets for individual spectroscopies and data fusion models were obtained with the use of the QDA and SVM methods, and did not exceed 3.3% and 0.0%, respectively. The lowest classification error rates in the validation data sets for individual spectroscopies were obtained with the use of RDA (12,8%), SVM (6,7%), and QDA (2,7%), for the UV–Vis, SF, and NIR spectroscopies, respectively. NIR spectroscopy combined with QDA outperformed other individual spectroscopic methods. Very low classification errors in the validation data sets - below 3% - were obtained for all the data fusion data sets (SF + UV–Vis, SF + NIR, NIR + UV–Vis combined with the SVM method). The results show that UV–Vis, fluorescence and near infrared spectroscopies may complement each other, giving lower errors for the classification of tea types. Graphical Abstract Unlabelled Image Highlights • The potential of UV-Vis, SF and NIR spectroscopies for classification of tea samples was investigated. • The lowest classification error for the UV-Vis, SF, and NIR spectroscopies were obtained with the use of RDA, SVM, and QDA. • UV-Vis, SF, and NIR spectroscopies complement each other, giving lower errors for the classification of tea types. • The lowest classification error (<1.4%) of tea samples was obtained for data fusion of the NIR and UV-Vis spectroscopies. • SVM outperforms the LDA, QDA, and RDA classification methods in distinguishing tea types for data fusion models. [ABSTRACT FROM AUTHOR]

Abstract Tea plant is an important economic crop and is vulnerable to drought. A good understanding of tea drought tolerance mechanisms is required for breeding robust drought tolerant tea varieties. Previous studies showed mesophyll cells' ability to maintain K+ is associated with its stress tolerance. Here, in this study, 12 tea varieties were used to investigate the role of mesophyll K+ retention ability towards tea drought stress tolerance. A strong and negative correlation (R2 = 0.8239, P < 0.001) was found between PEG (mimic drought stress)-induced K+ efflux from tea mesophyll cells and overall drought tolerance in 12 tea varieties. In agreement with this, a significantly higher retained leaf K+ content was found in drought tolerant than the sensitive tea varieties. Furthermore, exogenous applied K+ (5 mM) significantly alleviated drought-induced symptom in tea plants, further supporting our finding that mesophyll K+ retention is an important component for drought tolerance mechanisms in tea plants. Moreover, pharmacological experiments showed that the contribution of K+ outward rectifying channels and non-selective cation channels in controlling PEG-induced K+ efflux from mesophylls cells are varied between drought tolerant and sensitive tea varieties. Highlights • Mesophyll K+ retention is an important component for drought tolerance mechanisms in tea plants. • Non-selective cation channels (NSCC) play a major role in controlling K+ efflux from tea leaf mesophyll cells under drought. • The contribution of the K+ selective channels and NSCC channels is varied in tea varieties contrasting in drought tolerancee. [ABSTRACT FROM AUTHOR]

Free amino acids are an important indicator of the freshness of yellow tea. This study investigated a novel procedure for predicting the free amino acid (FAA) concentration of yellow tea. It was developed based on the combined spectral and textural features from hyperspectral images. For the purposes of exploration and comparison, hyperspectral images of yellow tea (150 samples) were captured and analyzed. The raw spectra were preprocessed with Savitzky-Golay (SG) smoothing. To reduce the dimension of spectral data, five feature wavelengths were extracted using the successive projections algorithm (SPA). Five textural features (angular second moment, entropy, contrast, correlation, and homogeneity) were extracted as textural variables from the characteristic grayscale images of the five characteristic wavelengths using the gray-level co-occurrence matrix (GLCM). The FAA content prediction model with different variables was established by a genetic algorithm-support vector regression (GA-SVR) algorithm. The results showed that better prediction results were obtained by combining the feature wavelengths and textural variables. Compared with other data, this prediction result was still very satisfactory in the GA-SVR model, indicating that data fusion was an effective way to enhance hyperspectral imaging ability for the determination of free amino acid values in yellow tea. [ABSTRACT FROM AUTHOR]

Highlights • New hydrophobic liquid deep eutectic solvents with high density were prepared. • The new deep eutectic solvents (DESs) were used as extraction agents in DLLME. • The microvolume DES-rich phase is in the bottom, easy to be collected. • DES aggregates (800 nm–5.6 μm in diameter) were found in the DES-rich phase. • The new DLLME is simple, rapid, efficient and eco-friendly for extraction of pyrethroids. Abstract A series of new hydrophobic deep eutectic solvents (DESs), which are liquid at room temperature and have high density (>1.4 g mL−1), were synthesized using hexafluoroisopropanol (HFIP) as hydrogen-bond donor and l -carnitine/betaine as hydrogen-bond acceptor. Then these hydrophobic DESs were used as extraction solvents to establish dispersive liquid-liquid microextraction (DLLME) method for extraction of pyrethroids. The DES extraction phase was in the bottom after DLLME, being easy to be collected for analysis. After optimization by one-variable-at-a-time and response surface methodology, the enrichment factors of 265–360 were achieved for five pyrethroids. The proposed DLLME method coupled with HPLC has good performance: linear ranges of 0.25/0.5/1–100/200/400 ng/mL (r ≥ 0.9990), limits of detection of 0.06–0.17 ng mL−1, relative recoveries of 85.1–109.4%, intra-day and inter-day RSDs below 7.5%. The novel DLLME method is simple, rapid, highly efficient and eco-friendly for extraction of pyrethroids in real tea beverages and fruit juices. [ABSTRACT FROM AUTHOR]

Cross-linked polymeric colloids are coated over porous polysulfone support by a simple method to prepare high-flux membrane for separation of tea polyphenols. The colloidal particles were prepared by electrostatic interaction and cross-linking between poly(vinyl alcohol) and maleic acid. The membrane exhibited >90% rejection of polyethylene glycol of 6000 Da molecular weight. The membranes exhibited flux of about 15-20 LMH with 70-90% polyphenol retention depending upon the coating and support types at 500 psi and had shown stability under continuous running of the separation experiments in water or methanol at pressurized condition. [ABSTRACT FROM AUTHOR]

Highlights • Presents the development of a method for analysis of bioactive compounds. • The method is based on the principles of green chemistry with high recovery. • Multivariate analysis in the classification of brands and the processing levels of the teas. Abstract This study deals with the development of a separation and quantification method by high performance liquid chromatography with a diode array detector (HPLC- DAD), for the determination of phenolic acids and methylxanthines in tea (Camellia Sinensis) samples. Six phenolic acids (Gallic, trans -cinnamic, caffeic, ferulic and p-coumaric acids) and two methylxanthines (caffeine, theobromine) were studied, according to the principles of green chemistry, with the goal of comparing teas with different processing level. After development and validation of separation and extraction methods was applied to 11 extracts obtained by infusions of green and black tea samples in commercial areas of the city of Salvador-BA, showing feasible and efficient. Was employed multivariate data analysis and the Tukey test to correlate the chromatographic profile with the different samples. Principal component and analysis and hierarchical cluster analysis were used for the chromatographic analysis, allowing the visualization of two groups, formed by green and black tea samples. [ABSTRACT FROM AUTHOR]

Abstract In this work, the aqueous extract obtained from Brazilian ginseng (Pfaffia glomerata) roots (BGR), rich in beta-ecdysone and fructooligosaccharides (FOS), was powdered by spray drying and freeze drying techniques aiming to obtain a novel functional food product. The effects of these drying techniques on the chemical and nutritional quality, morphological and redispersion properties of the BGR powders were evaluated. The BGR powders obtained by both spray drying and freeze drying techniques maintained their beta-ecdysone and FOS contents after drying, demonstrating the stability of these functional compounds. It was found that the wettability of the powders obtained by different treatments was affected by the drying technique because freeze-dried particles reached the lower values (66 ± 5 s) while spray-dried particles showed a greater time for dispersion into water (150 ± 25 s). This behavior was mainly associated with differences between powder morphological properties since the freeze-dried particles presented a more porous structure, resulting in a greater water diffusivity into microstructure during the redispersion process. Drying process did not affect the storage stability of powders because the glass transition temperature (Tg) for both samples was approximately 160 °C at a relative humidity of 56%. Thus, both BGR powders presented adequate redispersion properties to constitute a new functional tea or even to be used as a functional ingredient in food products. Graphical abstract Unlabelled Image Highlights • An instant powder rich in bioactive compounds was obtained in this work. • Brazilian ginseng extract was dried by spray drying and freeze drying. • The dried powders maintained their fructooligosaccharides and beta-ecdysone contents. • The powders presented satisfactory redispersion properties. [ABSTRACT FROM AUTHOR]

Summary: The objective of this study was to investigate the feasibility of discriminating harvest seasons of tea by the multi‐elemental fingerprinting technique. A total of 162 tea leaf samples were collected in spring, summer and autumn of 2015 and 2016 respectively. The concentrations of 25 elements were determined by inductively coupled plasma mass spectrometry. Analysis of variance and linear discriminant analysis were performed to analyse the differences of tea leaves of different harvest seasons and years and identify the seasons and years of tea leaves. The results showed that tea leaves of different harvest seasons and years had their own elemental profiles. For tea leaves of 2015 and 2016, using the established discriminant models, the total accuracy of season‐based identification reached 95.1% and 87.7% respectively. The classifications of tea leaves of different years were 100% accurate. Therefore, the multi‐elemental fingerprinting technique can be used to identify harvest seasons of tea. Multi‐elemental fingerprints could be used to classify harvest seasons of tea leaves. [ABSTRACT FROM AUTHOR]

Highlights • We simulated herbivory on moderately and severely drought stressed tea plants. • Non-volatile metabolites were unaffected by drought stress nor simulated herbivory. • Most volatiles were not induced by simulated herbivory under severe drought. • Methyl salicylate had greater induction by simulated herbivory under severe drought. • Drought affects plant responses to biotic stress with consequences for tea quality. Abstract Plants often experience multiple sources of stress simultaneously, yet little is known about interactive effects of multiple stressors on plant metabolic responses. Plants are well known to respond to both drought and insect herbivory through the induced production of secondary metabolites. However, severe drought stress limits photosynthesis and may therefore inhibit the production of induced secondary metabolites in response to herbivory due to carbon limitation. On the other hand, drought-stressed plants may be primed to respond more strongly to herbivory due to hormonal crosstalk or redundancy of metabolites that are produced in response to drought and herbivory. We tested the interactive effects of drought and simulated herbivory in tea plants (Camellia sinensis (L.) Kuntze var. sinensis) grown in the field under varying rainfall interception treatments and then exposed to an exogenous methyl jasmonate (MeJA) treatment. We show that severe drought generally inhibits the induction of secondary metabolites by exogenous MeJA (simulated herbivory). However, a few volatile metabolites, including methyl salicylate, are more strongly induced by MeJA in severely drought-stressed plants compared to moderately stressed plants, possibly due to priming by drought stress. Our approach of using multiple levels of drought stress and a targeted/untargeted approach to measuring volatile metabolites was essential to discovering these patterns of induction. In addition to having implications for plant-herbivore interactions in the presence of abiotic stress, these results have important implications for tea quality. [ABSTRACT FROM AUTHOR]

This work presents a reliable approach to trace teas' geographical origins despite changes in teas caused by different harvest years. A total of 1447 tea samples collected from various areas in 2014 (660 samples) and 2015 (787 samples) were detected by FT-NIR. Seven classifiers trained on the 2014 dataset all succeeded to trace origins of samples collected in 2014; however, they all failed to predict origins for the 2015 samples due to different data distributions and imbalanced dataset. Three outlier detection based undersampling approaches—one-class SVM (OC-SVM), isolation forest and elliptic envelope—were then proposed; as a result, the highest macro average recall (MAR) for the 2015 dataset was improved from 56.86% to 73.95% (by SVM). A model updating approach was also applied, and the prediction MAR was significantly improved with increase in the updating rate. The best MAR (90.31%) was first achieved by the OC-SVM combined SVM classifier at a 50% rate. [ABSTRACT FROM AUTHOR]

Abstract Background Catechins, polyphenols derived from tea leaves, have been shown to have antibacterial properties, through direct killing of bacteria as well as through inhibition of bacterial toxin activity. In particular, certain catechins have been shown to have bactericidal effects on the oral bacterium, Aggregatibacter actinomycetemcomitans , as well as the ability to inhibit a key virulence factor of this organism, leukotoxin (LtxA). The mechanism of catechin-mediated inhibition of LtxA has not been shown. Methods In this work, we studied the ability of six catechins to inhibit LtxA-mediated cytotoxicity in human white blood cells, using Trypan blue staining, and investigated the mechanism of action using a combination of techniques, including fluorescence and circular dichroism spectroscopy, confocal microscopy, and surface plasmon resonance. Results We found that all the catechins except (−)-catechin inhibited the activity of this protein, with the galloylated catechins having the strongest effect. Pre-incubation of the toxin with the catechins increased the inhibitory action, indicating that the catechins act on the protein, rather than the cell. The secondary structure of LtxA was dramatically altered in the presence of catechin, which resulted in an inhibition of toxin binding to cholesterol, an important initial step in the cytotoxic mechanism of the toxin. Conclusions These results demonstrate that the catechins inhibit LtxA activity by altering its structure to prevent interaction with specific molecules present on the host cell surface. General significance Galloylated catechins modify protein toxin structure, inhibiting the toxin from binding to the requisite molecules on the host cell surface. Graphical abstract Unlabelled Image Highlights • Galloylated catechins alter the structure of A. actinomycetemcomitans leukotoxin. • Galloylated catechins prevent leukotoxin from binding to cholesterol. • Leukotoxin activity is thus greatly inhibited by galloylated catechins. [ABSTRACT FROM AUTHOR]

Highlights • A new florecence reagent was synthesized/used for the determination of As(III)/As(V). • The system was firstly used. • The fluorimetric system minimizes the analysis time and manpower needed in laboratories. • The method was applied for the determination of arsenic species in some tea samples. Abstract A sensitive and selective fluorimetric method for the rapid determination of trace amounts of As(III)/As(V) species in certain tea samples forms the basis of the study. 3′,6′-bis(diethylamino)-2-{[(1 E )-(4,5-dimethyl-2-furyl)methylene]amino}spiro[isoindole-1,9′-xanthen]-3(2 H )-one (DMBD), was synthesized and characterized as a new fluorescence reagent for the speciation of As(III)/As(V) species. As(III) was quantitatively recovered with fluorescence reagent at concentrations between 0.5 and 1.5 mol L−1 of HNO 3 , while As(V) was not quantitatively recovered at any pH. The optimum conditions for the speciation of As(III)/As(V) species were investigated on certain commonly tested experimental parameters such as acidity and pH of the sample, amount of reagent, effects of temperature, and interfering ions etc. In order to determine trace amounts of total arsenic, KI and l (+) ascorbic acid were used to reduce As(V) to the trivalent state in the sample solution prior to determination. The concentration of As(V) in the sample solution were calculated by the difference in concentration between As(III) and the total arsenic in the sample solution. The study yielded a linear function of the concentration of As(III) in the 0–5 mg L−1 range with a detection limit of 0.22 µg L−1. The relative standard deviation was found to be 0.3% for the 0.5 mg L−1 As(III) level. The proposed method was successfully applied for the determination of trace amounts of As(III) and As(V) in certain tea samples. The results of analysis of the certified reference material (INCT-TL-1 tea sample) was found to be in good agreement with the certified value. [ABSTRACT FROM AUTHOR]

Highlights • Phenylpyruvic acid was the precursor of benzaldehyde in tea. • Phenylpyruvic acid was derived from l -phenylalanine in tea. • CsAAAT1 showed high l -phenylalanine transamination activity. • CsAAAT1 was localized in the cytoplasm of leaf cells. Abstract Aromatic aroma compounds contribute to flavor of tea ( Camellia sinensis (L.) O. Kuntze) and they are mostly derived from l -phenylalanine via trans -cinnamic acid or directly from l -phenylalanine. The objective of this study was to investigate whether an alternative pathway derived from l -phenylalanine via phenylpyruvic acid is involved in formation of aroma compounds in tea. Enzyme reaction with phenylpyruvic acid showed that benzaldehyde, benzyl alcohol, and methyl benzoate were derived from phenylpyruvic acid in tea leaves. Feeding experiments using [2H 8 ] l -phenylalanine indicated that phenylpyruvic acid was derived from l -phenylalanine in a reaction catalyzed by aromatic amino acid aminotransferases (AAATs). CsAAAT1 showed higher catalytic efficiency towards l -phenylalanine ( p ≤ 0.001) while CsAAAT2 showed higher catalytic efficiency towards l -tyrosine ( p ≤ 0.001). Both CsAAATs were localized in the cytoplasm of leaf cells. In conclusion, an alternative pathway for the formation of aromatic aroma compounds derived from l -phenylalanine via phenylpyruvic acid occurred in tea leaves. [ABSTRACT FROM AUTHOR]

Abstract This paper investigates the adsorption performance of spent tea leaves (STL) modified with polyethylenimine (PEI) on two anionic dyes, namely Reactive Black 5 (RB5) and Methyl Orange (MO), from simulated wastewater. Modification of STL surface with PEI reduced the STL surface area. Abundant basic groups and high point of zero charge were found for PEI-STL. Adsorption capacities of 71.9 mg/g (RB5) and 62.11 mg/g (MO) on PEI-STL were recorded. The adsorption performance of PEI-STL increased with contact time until 100 min, when it became nearly constant. Increasing pH resulted in lower adsorption performance of PEI-STL on RB5 and MO. A positive correlation between adsorbent dosage and adsorption performance of PEI-STL was also observed. Higher temperature promoted the adsorption performance of RB5 dyes, but reduced the adsorption performance of MO. It is proposed that the dyes adsorption proceeds via electrostatic attraction and hydrogen bonding between dyes molecules and adsorbent, while the role of pore filling is minimal. This study demonstrates the superior property of PEI-STL in adsorption of RB5 and MO dyes without carbonization and activation. Graphical abstract Image Highlights • Spent tea leaves (STL) was modified with polyethyleneimine (PEI). • Adsorption of methyl orange (MO) and reactive black 5 (RB5) using PEI-STL was studied. • Adsorption capacities of 71.9 mg/g (RB5) and 62.1 mg/g (MO) were recorded. • The adsorption obeys pseudo-second order kinetic model. • The adsorption data were well fitted to Temkin isotherm model. [ABSTRACT FROM AUTHOR]

Highlights • The tar concentration in the gasification of Camellia sinensis branches increases with the temperature rising. • At 900 °C, most tar compounds come from lignin decomposition in the gasification of Camellia sinensis branches. • Most of heterocycles and ketones come from cellulose decomposition and phenolics derives from lignin decomposition mainly. • The formation mechanism for main compounds of heterocycles, ketones and phenolics are determined. • Phenol and cresol are derived from both of lignin and cellulose decomposition, but the formation is different. Abstract The present research employed experimental and numerical methods to develop a tar formation model for the gasification of Camellia sinensis branches. Gasification experiments using lignin and cellulose extracted from Camellia sinensis branches were conducted to provide insights on the reaction mechanisms of Camellia sinensis branches because of the its complex components and structure. The extracted biomass was characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy, while the gasification products were analyzed by gas chromatography and mass spectrometry to figure out the tar compounds relationship between Camellia sinensis branches and its extracted biomass. For surveying tar formation pathways in the gasification of Camellia sinensis branches, the reaction energetics, structure of precursors, intermediates, transition states, products were examined by density functional theory. Theoretical results were in good agreement with experimental observations and showed that the tar compounds concentration increased with temperature, while the tar composition partially shifted from single ring hydrocarbons to polyaromatic compounds. The major compounds in tar were lignin-derived phenolics, while ketones, aldehydes and alcohols mainly originated from the decomposition of cellulose. The presence of phenol and cresol was attributed to both lignin and cellulose, but had different formation pathways. [ABSTRACT FROM AUTHOR]

Abstract The theaflavin-to-thearubigin ratio (TF/TR) is an important parameter for evaluating the degree of fermentation and quality characteristics of Congou black tea. Near infrared (NIR) spectroscopy, one of the most promising techniques for evaluating large-scale tea processing quality, in association with chemometrics, can be used as a selection tool when a fast determination of the requested parameters is required. The aim of this work is to develop a unique model for the determination of TF/TR. First, 11 key wavelength variables were screened by synergy interval partial least-squares regression (SI-PLS) and competitive adaptive reweighted sampling (CARS). Based on these characteristic variables, a new extreme learning machine (ELM) combined with an adaptive boosting (ADABOOST) algorithm (ELM-ADABOOST) was applied to construct the nonlinear prediction model for TF/TR, and an independent external set was used for the validation. A determinate coefficient (R p 2) of 0.893, root mean square error of prediction (RMSEP) of 0.0044, RSD below 10%, and RPD above 3 were acquired in the prediction model. These results demonstrate that NIR can be used to rapidly determine the TF/TR value during fermentation, and it effectively simplify the model and improve the prediction accuracy when combined with the SI-CARS variable. Graphical Abstract This paper conducted the modeling prediction on theaflavins-to-thearubigins ratio for determination of Congou black tea fermentation quality by using novel hybrid methods (ELM-ADABOOST) and NIR spectral technology with variable selection. It can be applied to black tea automatic fermentation systems to predict and monitor quality parameters. Unlabelled Image Highlights • Key spectrum variables were screened by SI-PLS combined with CARS. • A novel algorithm (ELM-AdaBoost) was used to construct model of TF/TR. • NIRS combined to nonlinear is effective for estimating quality of Congou black tea. • This study potentially allows the on-line monitor in standardization processing. [ABSTRACT FROM AUTHOR]

Due to the effect of interfering ion, the content of fluoride ion in tea brew, detected by ion-exchange chromatography, was markedly higher than ion-selective electrode. Ion-exclusion chromatography, a new method for the determination of fluoride ion in tea brew, was proposed and evaluated in this study. Two Metrosep organic acid columns in series resulted in better separation of fluoride ion than single column. The most suitable organic modifier for eluent and its percentage were checked, the optimal conditions of the mobile phase was 0.33 mM sulfuric acid solution containing 10.5% (v/v) acetone, at a flow rate of 0.5 mL/min. Satisfactory sensitivity and wide linearity range were obtained. The applicability of the method was demonstrated by the analysis of various tea samples in China, the accuracy of the results was proved by recovery tests, and the concordance with the values was obtained by ion-selective electrode. [ABSTRACT FROM AUTHOR]

Tea is the most consumed manufactured drink in the world. In recent years, various high end analytical techniques such as high-performance liquid chromatography have been used to analyse tea products. However, these techniques require complex sample preparation, are time consuming, expensive and require a skilled analyst to carry out the experiments. Therefore, to support rapid and non-destructive assessment of tea products, the use of near infrared (NIR) (950–1760 nm) hyperspectral imaging (HSI) for classification of six different commercial tea products (oolong, green, yellow, white, black and Pu-erh) is presented. To visualise the HSI data, linear (principal component analysis (PCA) and multidimensional scaling (MDS)) and non-linear (t-distributed stochastic neighbour embedding (t-SNE) and isometric mapping (ISOMAP)) data visualisation methods were compared. t-SNE provided separation of the six commercial tea products into three groups based on the extent of processing: minimally processed, oxidised and fermented. To perform the classification of different tea products, a multi-class error-correcting output code (ECOC) model containing support vector machine (SVM) binary learners was developed. The classification model was further used to predict classes for pixels in the HSI hypercube to obtain the classification maps. The SVM-ECOC model provided a classification accuracy of 97.41 ± 0.16% for the six commercial tea products. The methodology developed provides a means for rapid, non-destructive, in situ testing of tea products, which would be of considerable benefit for process monitoring, quality control, authenticity and adulteration detection. [ABSTRACT FROM AUTHOR]

The treatment of hepatitis C virus (HCV) infection by combination of direct acting antivirals (DAA), with different mode of action, has made substantial progress in the past few years. However, appearance of resistance and high cost of the therapy is still an obstacle in the achievement of the therapy, more specifically in developing countries. In this context, search for affordable antivirals with new mechanisms of action is still needed. Tea, after water, is the most popular drink worldwide. Polyphenols extracted from green tea have already shown anti-HCV activity as entry inhibitors. Here, three different theaflavins, theaflavin (TF1), theaflavin-3’-monogallate (TF2), and theaflavin-3-3’-digallate (TF3), which are major polyphenols from black tea, were tested against HCV in cell culture. The results showed that all theaflavins inhibit HCV infection in a dose-dependent manner in an early step of infection. Results obtained with HCV pseudotyped virions confirmed their activity on HCV entry and demonstrated their pan-genotypic action. No effect on HCV replication was observed by using HCV replicon. Investigation on the mechanism of action of black tea theaflavins showed that they act directly on the virus particle and are able to inhibit cell-to-cell spread. Combination study with inhibitors most widely used in anti-HCV treatment regimen demonstrated that TF3 exerts additive effect. In conclusion, theaflavins, that are present in high quantity in black tea, are new inhibitors of HCV entry and hold promise for developing in therapeutic arsenal for HCV infection. [ABSTRACT FROM AUTHOR]

Abstract Tea possesses a distinctive flavor profile and can have health benefits owing to the high levels of flavonoids in its leaves. However, the mechanism of the flavonoid glycosylation hasn't been well studied in tea plants, especially glycosylation at the 7-OH site has rarely been reported. In this study, four UGT genes CsUGT73A20 , CsUGT75L12 , CsUGT78A14 and CsUGT78A15 were isolated from tea leaves and overexpressed in the model plants Arabidopsis thaliana and Nicotiana tabacum for the functional identification of genes in vivo. In order to characterize the CsUGT functions in model plants, flavonoids in seeds of Arabidopsis and the flowers of tobacco were identified first. In CsUGT73A20 -overexpressing Arabidopsis and tobacco, the level of certain flavonol glycosides involved in glycosylation reactions at the 3-OH and 7-OH sites increased considerably, but the level of flavan-3-ols decreased. In CsUGT75L12 transgenic Arabidopsis, the level of flavonol glycosides exhibiting glucosyltransferase activity at the 7-OH position increased markedly, but the concentrations of quercetin and kaempferol and flavan-3-ols decreased. In both transgenic Arabidopsis and tobacco, CsUGT78A14 promoted the synthesis of more flavonol glucosides with UDP-glucose as a sugar donor at the 3-OH glycosylation site. In CsUGT78A15 transgenic plants, flavonol galactosides at the 3-OH glycosylation site with UDP-galactose as a sugar donor were increased. In the tea plant, the corresponding flavonoid glycosides such as kaempferol‑3‑ O ‑β‑ d ‑glucosides, kaempferol‑3‑ O ‑β‑ d ‑galactosides, kaempferol‑7‑ O ‑β‑ d ‑glucoside, and luteolin‑7‑ O ‑β‑ d ‑glucoside were identified. And it could be possible that they were products of CsUGT78A14, CsUGT78A15, CsUGT73A20 and CsUGT75L12, respectively. [ABSTRACT FROM AUTHOR]

Nucleotides, nucleosides, and nucleobases are important bioactive compounds. Recent studies suggested that they possess taste activity. However, it remains unknown about their presence in white tea and how they change during white tea manufacture. Here, we first established method based on hydrophilic interaction liquid chromatography coupled with quadrupole-orbitrap ultra high resolution mass spectrometry (HILIC-Quadrupole-Orbitrap-UHRMS) platform, then applied it to study the dynamic changes of nucleotides, nucleosides, and nucleobases during white tea withering process. Five compounds, including adenosine 5′-monophosphate monohydrate (AMP), guanosine 5′-monophosphate disodium salt hydrate (GMP), adenosine, cytidine, thymine and uracil, were detected from withering samples. They showed a general decline trend during white tea withering process, however, considerable amount of them was retained after withering for 48 h except adenosine which was below detection limit after withering for 21 h. This study provided a complete picture about nucleotides, nucleosides and nucleobases changes during white tea withering process. [ABSTRACT FROM AUTHOR]

Summary: The aim of this study was to develop a novel ethanol‐water based enzymatic synthesis coupled with column chromatography purification technique to synthesise theaflavin‐3,3′‐digallate (TFDG) using underutilised summer and autumn fresh tea leaves. Enzymatic synthesised TFDG was incorporated into nanoliposome using ethanol injection combined with dynamic high‐pressure microfluidisation technique at pH 5.5. TFDG with a purity of 90.5% at the gram level was achieved by applying ethanol with different concentrations as eluent, and the yield of TFDG was 36.00%. TFDG nanoliposome showed the great in vitro digestion stability, with the particle size, polydispersity, zeta potential being 59.43 ± 5.67 nm, 0.31 ± 0.025 and ‐8.28 ± 0.24 mV, respectively. Nanoliposome encapsulation can significantly improve the stability of TFDG as indicated by the greater resistance upon in vitro digestion studies under both the mild alkaline pH and simulated intestinal fluid. The current research laid a foundation for the further application of TFDG as functional ingredients in food industry. High purity of theaflavin‐3,3′‐digallate (TFDG) was enzymatically synthesized using underutilized summer and fall green tea leaves and its inherent polyphenol oxidase. The in vitro digestive stability of TFDG was improved by nanoliposome encapsulation. [ABSTRACT FROM AUTHOR]

Tea (Camellia sinensis) is the second most commonly consumed beverage in the world, and its consumption has been associated with several important health benefits due in part to its high concentration of polyphenolic compounds. Tea varieties, including white, green, oolong, pu-erh, and black tea, are all produced from the same plant but differ in postharvest processing. The level of oxidative processing from white to black tea (low to high) drives changes in polyphenol profiles from monomeric polyphenols (catechins) to oxidative products (theaflavins and thearubigins) that convert the subtle yellow color of green tea to the distinctive red/copper color of oolong and black tea. Polyphenol compounds from green teas have been well studied; however, oxidative products are more difficult to characterize and may require a combination of analytical techniques for identification and quantification. This technical summary introduces the major polyphenols in tea and discusses the main steps of tea processing and instrumentation used for polyphenol analysis. [ABSTRACT FROM AUTHOR]

Active edible films were prepared by incorporating tea polyphenols (TP) into gelatin and sodium alginate. The effects of 0.4%–2.0% TP (w/w, TP/gelatin) on physical, antioxidant, and morphological properties of gelatin-sodium alginate films were evaluated. Tensile strength (Ts), contact angle (CA), and cross-linking degree showed an enhanced trend as TP concentration in the film increased, whereas elongation at break (EAB) and water vapor permeability (WVP) possessed a decline trend. The light transmittance of the film was decreased by the incorporation of TP. Antioxidant capacity was improved by increasing TP content in the films. For DPPH and ABTS radical, the films with 2.0% TP possessed the highest values of 90.62 ± 2.48% and 53.36 ± 1.06 Trolox (mg Trolox equivalent/g film), respectively. Fourier transform infrared spectroscopy analyses (FTIR) indicated the interactions existed between gelatin‑sodium alginate and TP. Smooth and continuous surface and dense internal structure of the films with TP were observed by scanning electron microscopy (SEM). Thus, incorporating TP into gelatin and sodium alginate film solution was an effective method in order to improve physical properties and antioxidant activity of the films. Gelatin-sodium alginate films with TP could be used as an edible film for food packaging applications. [ABSTRACT FROM AUTHOR]

In this research, Pickering emulsion stabilized by taro starch nanoparticles was successfully prepared, and the potential application of encapsulating tea polyphenols was investigated. The nanoparticle size (about 460 nm) and contact angle (81.5°) of taro starch indicate that it is suitable for adsorbing on the oil-water interface and forming a dense interfacial layer. Emulsion stability at different particle concentrations, oil-water ratios, and sodium chloride concentrations has been systematically studied. By considering the particle size, zeta potential, and stability index of Pickering emulsion, it is considered that the emulsion has the best stability when the particle concentration is 7% and the oil fraction is 0.5. Low concentration of salt ions (0.04 mM NaCl) will cause a slight flocculation to improve the stability, but adding high concentration of salt will make emulsion break. In addition, we found that this Pickering emulsion could encapsulate the tea polyphenols greatly with a retention rate of up to 67%. The findings may have great significance for the design and fabrication of native starch particle stabilized emulsion. [ABSTRACT FROM AUTHOR]