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Annually, lots of useless black tea [Camellia sinensis (L.) Kuntze] residue is produced in Iranian factories; nonetheless, their bioactive compounds can be extracted and used in the pharmaceutical and food industries. The investigation, which looked at the extraction of all compounds from tea residue, was conducted from 2006 to 2008 to solve environmental problems related to the disposal of tea residues. Extracting one compound to build a lateral products factory is unprofitable, but extracting all bioactive compounds can increase productivity. Four bioactive substances (caffeine, polyphenol, protein, and fiber) were extraction from four tea residues types (dust, fluff, footstalk, and stalk) that nine tea companies generated in the spring, summer, and autumn, assessed in this study. Caffeine was measured by spectrophotometer, followed by cellulose and polyphenol by weight technique, and protein by micro-Kjeldal. Statistical analysis was done on a split plot in randomized complete blocks with three replications (sampling places were randomly selected, and treatments were fixed). The triple effect of residue types, harvest seasons, and factories were significant at a 0.01 level on the levels of caffeine, protein, and fiber, according to the variance analysis findings. The highest amount of caffeine in the dustx summer x Moein factory, followed by protein in the dust x spring x Poltan factory, and fiber in the stalk x autumn x Tohied and Setareh Shomal factories, was observed. Finally, the result demonstrated that consideration must be given to the types of residue, harvest seasons, and factories when using tea factory residues for industrial purposes. [ABSTRACT FROM AUTHOR]

Black tea is known to contain condensed tannins including catechin (C), epicatechin (EC), and epigallocatechin gallate (EGCG), as well as caffeine (CAF). Some consumers of specific diets avoid consuming tannins or CAF. Therefore, this study aimed to explore the fast and simple development of a method for separating and quantifying tannins and CAF in black tea using microwave-assisted extraction (MAE) followed by high-performance liquid chromatography (HPLC) analysis. MAE, a type of solid-phase extraction recently developed, was used with a modified microwave that simultaneously accommodates up to 24 samples. The effects of various MAE parameters, including microwave irradiation power, temperature, and solvent, were studied, with concentrations measured in mg/kg. The results showed that optimal extraction conditions were achieved at a microwave irradiation power of 1500 W, a temperature of 80°C, and methanol as the extraction solvent. The extracted samples were analyzed using a C18-M-SE reverse phase column (150 × 4.6 mm) with a mobile phase consisting of acetonitrile, methanol, and H3PO4 (1:49:50), and NaH2PO4 (20 mM) at pH 2.5. The three tannin compounds and CAF were separated in less than 10 min. The method demonstrated excellent repeatability (RSD = 2%, n = 3), accuracy (96.7-102.5%), and was successfully applied to determine tannin content in commercial black tea samples. [ABSTRACT FROM AUTHOR]

Withering is one of the major processing steps critical for the quality of black tea. In this study, we investigated the mechanisms underlying the physicochemical changes in metabolites and gene expression during the withering process of black tea using metabolomic and transcriptomic approaches, respectively. Based on gas chromatography/mass spectrometry non-targeted metabolomic approaches (GC-MS) and ultra-high performance liquid chromatograph–tandem mass spectrometry (UHPLC-MS/MS), a total of 76 volatile compounds and 160 non-volatile compounds were identified from tea leaves, respectively. RNA-seq analysis revealed that the number of differentially expressed genes (DEGs) for the comparative combination of withering time (i.e., W4h, W6h, W8h, W10h, and W12h) compared with CK (i.e., fresh leaves) were 3634, 2906, 4127, 5736, and 7650, respectively. The core genes in starch metabolism, namely alpha-amylase (AMY) and beta-amylase (BAM), were upregulated as withering time increased. AMY and BAM contributed to the decomposition of starch to increase the soluble sugars. The content of tea leaf alcohols and aldehydes, which are the vital contributors for greenish aroma, gradually decreased as withering time increased due to the downregulation of associated genes while the compounds related to sweet and fruity characteristics increased due to the upregulated expression of related genes. Most DEGs involved in amino acids were significantly upregulated, leading to the increase in free amino acids content. However, DEGs involved in catechins metabolism were generally downregulated during withering, and resulted in a reduction in catechins content and the accumulation of theaflavins. The same trend was observed in alpha-linolenic acid metabolism-related genes that were downregulated and enhanced the reduction in grassy aroma in black tea. The weighted gene co-expression network analysis (WGCNA) of DEGs showed that one module can be associated with more components and one component can be regulated by various modules. Our findings provide new insights into the quality formation of black tea during the withering process. [ABSTRACT FROM AUTHOR]

In this study, the taste quality difference between high (Ninghong-Jinhao tea, JH, unfolded fresh leaves) and low (Ninghong-Congou tea, CG, unfurled fresh leaves) grades of Ninghong tea (unique black tea) was analyzed from the perspective of sensory omics, non-targeted metabolomics, and chemical dose. JH was characterized by sweetness and mellowness with umami, while CG was characterized by sweetness and thickness. A total of 94 differential metabolites contribute to the quality difference between two grades. Further quantitative analysis revealed that JH exhibited a high accumulation of amino acids, catechins, and theaflavins, while CG demonstrated a high accumulation of water extract, tea polyphenols, flavonol glycosides, and saccharides. Taste activity values (TAVs) analysis revealed that the key taste components of JH and CG were catechin, epigallocatechin gallate, three theaflavins, caffeine, myrictin-3-O-glucoside, quercetin-3-O-rutinoside, quercetin-3-O-glucoside, quercetin-3-O-galactoside, kaempferol-3-O-rutinoside, kaempferol-3-O-glucoside, and gallic acid. Among the identified compounds, the TAVs of five flavonol glycosides in Ninghong tea were found to be greater than 10 for the first time. This study is helpful to understand the taste quality difference between different grades of Ninghong tea from the molecular sensory level, providing a scientific foundation for quality improvement and targeted regulation. [ABSTRACT FROM AUTHOR]

Black tea is known to contain condensed tannins including catechin (C), epicatechin (EC), and epigallocatechin gallate (EGCG), as well as caffeine (CAF). Some consumers of specific diets avoid consuming tannins or CAF. Therefore, this study aimed to explore the fast and simple development of a method for separating and quantifying tannins and CAF in black tea using microwave-assisted extraction (MAE) followed by high-performance liquid chromatography (HPLC) analysis. MAE, a type of solid-phase extraction recently developed, was used with a modified microwave that simultaneously accommodates up to 24 samples. The effects of various MAE parameters, including microwave irradiation power, temperature, and solvent, were studied, with concentrations measured in mg/kg. The results showed that optimal extraction conditions were achieved at a microwave irradiation power of 1500 W, a temperature of 80°C, and methanol as the extraction solvent. The extracted samples were analyzed using a C18-M-SE reverse phase column (150 × 4.6 mm) with a mobile phase consisting of acetonitrile, methanol, and H3PO4 (1:49:50), and NaH2PO4 (20 mM) at pH 2.5. The three tannin compounds and CAF were separated in less than 10 min. The method demonstrated excellent repeatability (RSD ? 2%, n = 3), accuracy (96.7-102.5%), and was successfully applied to determine tannin content in commercial black tea samples.

To reveal the chemical composition profile of Camellia ptilophylla, a rare natural low-caffeine tea variety, non-targeted metabolomics based on high-resolution mass spectrometry (HR-MS) was employed to identify the metabolite composition of green tea and black tea from C. ptilophylla and C. sinensis var. assamica. Additionally, the metabolomic differences between the two types of tea and between the two tea varieties were analyzed using principal component analysis (PCA), cluster analysis (CA), and orthogonal partial least squares-discriminant analysis (OPLS-DA). Differential metabolites were identified using standards and database. A total of 152 metabolites were identified in the four tea samples, the major ones being flavonoids (42%). These metabolites were categorized into four clusters. The metabolomic difference between C. ptilophylla and C. sinensis var. assamica was more pronounced than that between green and black teas. Notably, 24 metabolites including theasinensin B isomers, theobromine and 14 flavonoids such as tetrahydroxyxanthone and epitheaflagallin 3-O-gallate, which were more abundant in C. ptilophylla green tea than in C. sinensis green tea, were considered as the characteristic metabolites of C. ptilophylla green tea. In black tea from C. ptilophylla, 40 characteristic metabolites were identified including 25 flavonoids such as gallocatechin-3,5-digallate, tetrahydroxyxanthone and dihydromyricetin; 4 tannins such as theaflavin 3-gallate, theasinensin A isomers and theaflavin 3,3’-digallate; and theobromine. This study provides a reference for further exploration of bioactive compounds in C. ptilophylla.

This study used widely targeted and targeted metabolomics based on headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS) to analyze the non-volatile metabolites, volatile metabolites, and major quality components in congou black teas produced from the high-aroma black tea cultivars ‘Jinmudan’ and ‘Jinguanyin’, and it explored the differences in chemical characteristics between the two teas. The results showed that a total of 1 318 non-volatile metabolites were identified in the two teas, and the differential metabolites between them were most enriched in flavonoid-related synthesis pathways. Among them, catechins and quercetin-3-O-glucoside were significantly upregulated in ‘Jinmudan’ black tea, while chrysin and apigenin-7-O-neohesperidoside were significantly upregulated in ‘Jinguanyin’ black tea. A total of 759 volatile compounds were identified, among which 12 compounds, including β-ionone, geraniol, decanal and methyl benzoate, were the key aroma components of both teas. The results of relative odor activity value (ROAV) analysis indicated that aroma components such as indole, δ-decanolactone, trans-nerolidol, phenylacetaldehyde and jasmonone responsible for floral, fruity and milky aroma characteristics were more abundant in ‘Jinmudan’ black tea, which may be the key compounds contributing to the floral, fruity and peach-like aromas of ‘Jinmudan’ black tea. Aroma components such as methyl salicylate, (Z)-3-hexenol, and hexanol responsible for fresh and floral aromas were more abundant in ‘Jinguanyin’ black tea, which may be the key compounds contributing to its long-lasting aroma. The results of this study are helpful to elucidate the flavor and quality characteristics of ‘Jinmudan’ and ‘Jinguanyin’ black tea, providing a scientific basis for the development of black tea products from the excellent high-aroma tea cultivars ‘Jinmudan’ and ‘Jinguanyin’.

Obesity is a metabolic disorder due to over-accumulation of adipose tissue and ultimately becomes a “disease”. Brown adipose tissue (BAT) thermogenesis and white adipose tissue (WAT) browning emerge as a potential strategy of anti-obesity by dissipating energy as heat. However, drugs based on adipose tissue thermogenesis have not been successfully approved yet. In current study, we found that black tea extract (BTE) obtained by patent-authorized manufacturing process prevented body weight gain as novel thermogenic activator with reduction of adiposity, improvement of adipose distribution, and glucose metabolism improvement in diet-induced obesity mice. Mechanismly, anti-obesity effect of BTE depends on promoting BAT thermogenesis and WAT browning with upregulation of uncoupling protein 1 (UCP1), especially visceral adipose tissue (VAT) with browning resistance. Specifically, utilizing in silico approach of network pharmacology and molecular docking, we identified carbonic anhydrase 2 (CA2) in nitrogen metabolism as anti-obesity target of BTE and further elucidated that protein kinase B (AKT) signaling pathway linked CA2 and UCP1. Meanwhile gut microbiota regulation may prompt the CA2-dependent thermogenesis activation. Our findings demonstrated anti-obesity effect of BTE as thermogenic activator through CA2-mediated BAT thermogenesis and WAT browning via CA2-AKT-UCP1 signaling pathway, which could be developed as promising anti-obesity agent with good safety and efficacy.

Abstract An innovative Chardonnay wine flavored with black tea was prepared under optimal ultrasound conditions at 450.0 W for 22.6 min, and its physicochemical features, antioxidant power, total phenolic content, and volatile composition were systematically examined. A total of 165 phenolic and non-phenolic substances were characterized, including 27 newly formed phenolic substances and 10 non-phenolic substances that were not found in both black tea and Chardonnay wine. Catechin was found to be the phenolic compound with the largest amount detected, which was responsible for the potentiated antioxidant activities. The wine exhibited a profile of 44 volatile compounds, with 13 volatiles as odor-active compounds. Black tea infusion resulted in a decline in fruity, fermented and spicy aromas, but an increase in green and citrus odors, while ultrasound processing further intensified these odors. This study anticipated that ultrasound technology could hold promise for crafting flavored wines with heightened functionalities and appealing flavor profiles. Graphical Abstract Ultrasound-assisted infusion of black tea potentiated the antioxidant activity and enriched the volatile and phenolic profiles of Chardonnay wine.

Flat black tea (FBT) has been innovatively developed to alleviate homogenisation competition, but the dynamic changes in aroma components during the process remain unclear. This study employed HS-SPME-GC-MS to analyse the aroma components of tea samples from various processing stages of FBT, and to make a comparative assessment with conventional strip-like Congou black tea (SBT). Additionally, a proteomic analysis was conducted on fresh leaves, withered leaves, and frozen–thawed leaves. Significant changes were observed in the aroma components and proteins during the processing. The results of the multivariate and odour activity value analysis demonstrated that the principal aroma components present during the processing of FBT were linalool, (E)-2-hexen-1-al, methyl salicylate, geraniol, hexanal, benzeneacetaldehyde, (Z)-3-hexenyl butyrate, dimethyl sulphide, 2-methylbutanal, 2-ethylfuran, nonanal, nonanol, 3-methylbutanal, (Z)-3-hexen-1-ol, 2-pentylfuran, linalool oxide I, and β-myrcene. Freezing–thawing and final roasting are the key processing steps for forming the aroma quality of FBT. The final roasting yielded a considerable quantity of pyrazines and pyrroles, resulting in a high-fried aroma, but caused a significant reduction in linalool, geraniol, β-myrcene, and esters, which led to a loss of floral and fruity aromas. The freezing–thawing treatment resulted in an accelerated loss of aroma substances, accompanied by a decrease in the expression level of lipoxygenase and 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase. The formation of aroma substances in the linoleic acid metabolic pathway and terpenoid metabolic process was hindered, which had a negative impact on tea aroma. This study elucidates the causes of unsatisfactory aroma quality in tea products made from frozen tea leaves, providing theoretical support for the utilisation of frostbitten tea leaves, and helps us to understand the mechanism of aroma formation in black tea. [ABSTRACT FROM AUTHOR]

Citri Exocarpium Rubrum black tea (CER tea) is a novel blend tea infusion combining tea and CER. Due to its potential health benefits and unique flavor, it has gained popularity among consumers. Nevertheless, the aroma characteristics and key odorants of it remain to be distinguished and cognized. The HS‐SPME and GC/MS techniques were employed to analyze the alterations in volatile constituents throughout the critical stages of CER tea production. A total of 200 chemical compounds exhibited notable disparities during the processing procedures. Among them, terpenes and esters were the most abundant compounds in CER tea, which might be the key material basis for the aroma quality of CER tea. It is worth noting that 124 metabolites were significantly increased in the kneading stage and drying stage, including benzeneacet aldehyde, trans‐nerolidol, and D‐limonene, with contained floral and fruity odors, which might be closely related to the aroma of CER tea. Monoterpenes might be important contributors to the aroma of CER tea. This study provided a theoretical basis for the quality improvement of CER tea. [ABSTRACT FROM AUTHOR]

This study analyzed the possibility of using plant-originated waste materials (black and green tea dust) as functional polyethylene fillers. The dependence between the size of the filler particles and their antioxidant potential is discussed. Six fractions were selected: below 50 µm, 50–100 µm, 100–200 µm, 200–400 µm, 400–630 µm and 630–800 µm. Significant differences between the effect of particle size and the antioxidant properties of black and green tea were found using the extraction method to analyze antioxidant activity (DPPH method) and total phenolic content (Folin-Ciocalteu method), suggesting a higher potential for using green tea as a filler with antioxidant properties, as well as the benefits of finer active filler distribution. Biomass waste fillers were mixed with low-density polyethylene LDPE SEB 853 I'm Green®, Braskem. Those samples were oxidized at 100 °C for 5 and 15 days to investigate the radical scavenging properties of fillers in composites. Fourier transform infrared spectroscopic studies show that the addition of both types of filler prevents the thermo-oxidation of polyethylene for 5 days. After 15 days, all samples except the BTW 400–630 and 630–800 µm exhibited oxidation. The mechanical properties of the LDPE and its' composites were tested, and we noted an increased brittleness of neat LDPE after thermal oxidation. The addition of black tea particles above 100 µm in size prevents this behavior. [ABSTRACT FROM AUTHOR]

Tea is a highly consumed beverage around the world, and many studies have indicated its health benefits. However, tea products may contain heavy metals that may cause negative health effects due to their toxicity. This study aimed to quantify the levels of copper (Cu), zinc (Zn), lead (Pb) and cadmium (Cd) in six different imported black tea brands marketed in Mashhad city, Iran. Twenty samples from each six black tea brands were obtained from the markets of Mashhad city, Iran, in 2012. Overall, the content of Cu, Zn, Pb and Cd ranged 6.81–35.21 mg/kg (mean = 15.87 mg/kg), 14.61–164.84 mg/kg (mean = 47.68 mg/kg), 0.038–1.62 mg/kg (mean = 0.72 mg/kg) and 0.006–0.19 (mean = 0.05 mg/kg), respectively. The mean concentration of Zn in brands C, E and F, the mean concentration of Pb in brand B and the mean concentration of Cd in brand E exceeded the Iranian and WHO standard levels. Additionally, the estimation of hazard index (HI) showed that there is no potential adverse health effect due to the consumption of the studied tea samples (HI < 1). In terms of HI, the brands were ordered as B > D > F > E > A > C. However, estimation of excess lifetime cancer risk (ELCR) for Pb showed that there is a significant lifetime cancer risk as a result of consuming the black tea products. but the estimation of ELCR for Cd showed no potential health risks. [ABSTRACT FROM AUTHOR]

Huangjinya has recently seen widespread adoption in key tea-producing areas of China, celebrated for its unique varietal traits. Its leaves are also used to produce black tea with distinctive sensory characteristics. The fragrance-enhancing (EF) process is essential in crafting Huangjinya black tea (HJYBT) and is significant in flavor development. However, the impact of EF on non-volatile metabolites (NVMs), volatile metabolites (VMs), and their interactions remains poorly understood. This study aims to investigate how EF temperatures (60 °C, 70 °C, 80 °C, 90 °C, and 110 °C) influence HJYBT flavor transformation. Quantitative descriptive analysis revealed that EF improved the color, aroma, and appearance of tea leaves. Moreover, after an EF temperature of 80 °C, the HJYBT exhibited lower bitterness and astringency, whereas floral, sweet, and fruity aromas became stronger. However, when EF temperatures exceeded 90 °C, a pronounced burnt aroma developed, with HJYBT at 100 °C exhibiting caramel and roasted notes. Partial least squares discriminant analysis indicated that geraniol and linalool contribute to floral and fruity aromas, while 2-ethyl-6-methyl-pyrazine, furfural, and myrcene are key volatiles for caramel and roast aromas. Heptanal, methyl salicylate, α-citral, 1-hexanol, and (E)-3-hexen-1-ol were found to modify the green and grassy odor. Overall, HJYBT treated at 80 °C EF exhibited the highest umami, sweetness, floral and fruity aromas, and overall taste, exhibiting the least astringency, bitterness, and green and grassy notes. These results provide a significant theoretical basis for enhancing HJYBT quality and selecting the optimal EF method. [ABSTRACT FROM AUTHOR]

Volatile fatty acid derivatives (VFADs) play a significant role in contributing to flowery–fruity flavor black tea. Innovative black tea is typically crafted from aroma-intensive tea cultivars, such as Jinmudan, using defined production methodologies. In this study, the during-processing tea leaves of innovative black tea were applied as materials, and we selected a total of 45 VFADs, comprising 11 derived aldehydes, nine derived alcohols, and 25 derived esters. Furthermore, the dynamic variations of these VFADs were uncovered. Transcriptome analysis was performed to identify genes involved in the LOX (lipoxygenase) pathway, resulting in the identification of 17 CsLOX genes, one hydrogen peroxide lyase (CsHPL) gene, 11 alcohol dehydrogenases (CsADH) genes, 11 genes as acyl CoA oxidase (CsACOX) genes, and three allene oxide synthase (CsAOS) genes. Additionally, the expression levels of these genes were measured, indicating that the processing treatments of innovative black tea, particularly turn-over and fermentation, had a stimulation effect on most genes. Finally, qRT-PCR verification and correlation analysis were conducted to explain the relationship between VFADs and candidate genes. This study aims to provide a reference for illuminating the formation mechanisms of aroma compounds in innovative black tea, thereby inspiring the optimization of innovative processing techniques and enhancing the overall quality of black tea. [ABSTRACT FROM AUTHOR]

Rolling plays an important role in shaping the characteristic quality of black tea. However, the dynamic alterations in volatile compounds during the rolling process remain unclear, which hampers the quality control of black tea. In this study, the dynamic changes of volatile compounds in Congou black tea throughout the rolling process were explored by a combination of GC-E-Nose and GC-MS analysis. The results of PCA and PLS-DA by GC-E-Nose revealed significant alterations in the volatile profiles, particularly at the 15-min rolling stage. A total of 82 volatile compounds including eight categories were identified in Congou black tea during the rolling process. The most abundant volatiles were aldehydes, alcohols, and esters. Through the integration of variable importance in the projection >1 and p < 0.05, 21 volatile compounds were pinpointed as pivotal volatiles responsible for distinguishing diverse rolling processes. According to their pathways, glycoside-derived volatiles (GDVs) (such as linalool and geraniol) and fatty acid-derived volatiles (FADVs) (such as (Z)-2-hexen-1-ol and hexanal) highlighted the pivotal role in the formation of the aroma of black tea during rolling process. GDVs, characterized by floral, honeyed, and fruity aromas, reached the lowest point at 35-min rolling and subsequently rebounded. FADVs exhibited an ascending trajectory during the initial 15-min rolling, followed by a downward trend. These findings provide invaluable insights into the aroma evolution during the rolling stage, offering strategies for enhancing the aroma quality of Congou black tea. [ABSTRACT FROM AUTHOR]

An innovative Chardonnay wine flavored with black tea was prepared under optimal ultrasound conditions at 450.0 W for 22.6 min, and its physicochemical features, antioxidant power, total phenolic content, and volatile composition were systematically examined. A total of 165 phenolic and non-phenolic substances were characterized, including 27 newly formed phenolic substances and 10 non-phenolic substances that were not found in both black tea and Chardonnay wine. Catechin was found to be the phenolic compound with the largest amount detected, which was responsible for the potentiated antioxidant activities. The wine exhibited a profile of 44 volatile compounds, with 13 volatiles as odor-active compounds. Black tea infusion resulted in a decline in fruity, fermented and spicy aromas, but an increase in green and citrus odors, while ultrasound processing further intensified these odors. This study anticipated that ultrasound technology could hold promise for crafting flavored wines with heightened functionalities and appealing flavor profiles. Ultrasound-assisted infusion of black tea potentiated the antioxidant activity and enriched the volatile and phenolic profiles of Chardonnay wine. [ABSTRACT FROM AUTHOR]

Black tea is one of the commonly consumed beverages obtained from the oxidized leaves of Camellia sinensis assamica. It is commonly infused in India with basil leaves (Ocimum spp.) to enhance its flavor and medicinal properties. Leaves from different species of Ocimum are used for supplementing black tea but the antioxidant interaction between them is under-investigated. This study was designed to evaluate the antioxidant interaction and radical scavenging potential of the binary combination of black tea (BT) with three different Ocimum spp. employing chemical methods and ex-vivo assays. Black tea and O. gratissimum (BTOG) pair displayed the strongest antioxidant activity and additive interaction, whereas black tea and O. sanctum (BTOS) pair, and black tea and O. canum (BTOC) pair demonstrated substantially lower radical quenching ability and antagonistic interaction. BTOG contained the highest total phenolic and flavonoid content in comparison to BTOS and BTOC. [ABSTRACT FROM AUTHOR]

Theaflavins (TFs) are a kind of bioactive compound that formed during the fermentation stage of black tea. TFs play a vital role both in the sensory quality and the biological activity of black tea. However, the complex composition of black tea and the low content of TFs in black tea (0.3%–0.7%) make the technology for the preparation of high‐purity TFs a great challenge. This review provides an updated overview for extracting, synthesizing and purifying of TFs. Molecular imprinting technology, an efficient method for extracting bioactive compounds, will be a promising method for the preparation of TFs with high purity. Overall, this review can provide a scientific basis and technical support for the preparation of TFs with high purity and will be helpful for the in‐depth development and further research of TFs. [ABSTRACT FROM AUTHOR]

In recent decades, the consumption of tea has increased due to its various associated health benefits, prompting growing concerns regarding the safety and quality of tea products. Nevertheless, there has been a significant dearth of scientific information regarding the microbiological status of black tea leaves. This study sought to bridge this knowledge gap by investigating the microflora present in tea leaves at various processing stages of black tea production. Samples were meticulously collected during distinct processing steps, and their culturable microorganisms were identified through sequence‐based methods. The results revealed that the predominant bacterial genus throughout the tea manufacturing process was Bacillus, constituting a substantial 77% of the identified bacterial population. Other leading genera included Klebsiella (8%), Lysinibacillus (4%), Escherichia (2%) with the remaining 9% comprising various other genera. Among the fungal community, Aspergillus and Penicillium species exhibited a significantly higher relative abundance, each comprising 24%. Furthermore, yeast communities included Debaryomyces, Candida, Hyphopichia, Rhodosporidiobolus, and Wickerhamomyces species. Lactobacillus fermentum was identified in the fermented tea leaves, highlighting its role in the fermentation process. Yeasts and molds were also present in the final tea product, indicating potential post‐processing contamination. The study did not detect any mycotoxins in any of the samples. These findings had indicated that presence of some microorganisms is extremely common in different processing stages while alien microorganisms are being introduced during manufacturing. Thus, emphasizing the need for stringent regulations and quality assurance practices within the tea industry to ensure the safety and quality. [ABSTRACT FROM AUTHOR]

Tea is a widely consumed non-alcoholic beverage that can be contaminated with mycotoxins, including aflatoxins (AFs), which pose a significant health risk. In this study, a fast and accurate extraction method for the detection of AFs in black tea was developed and optimized. The method utilized Fe3O4 magnetic nanoparticles (MNPs) to enhance the extraction efficiency. Various parameters, such as the type and amount of extraction solvents, dilution by water, MNP amount, and extraction model, were investigated to optimize the method. The proposed method demonstrated satisfactory analytical performance, with acceptable recoveries more than 70% and low LODs for all AFs were achieved. The developed nano extraction method was compared to immunoaffinity column chromatography (IAC) cleanup and showed comparable results. The advantages of the proposed method include high speed, low cost, and ease of use. Overall, the method offers a reliable and efficient option for the repetitive analysis of AFs in tea samples. [ABSTRACT FROM AUTHOR]

The use of alternative ingredients as supplements to or blends with kombucha tea to improve organoleptic properties and health effects has recently increased. Indian gooseberry fruit is among the most promising alternative raw materials for producing functional kombucha since the berries contain several beneficial substances. In this study, the production of functional kombucha beverages from fusions of black tea and Indian gooseberry fruit homogenate (IGH) was investigated, and the chemical and biological properties of kombucha products were evaluated and compared with those of traditional black tea kombucha products. Chemical composition analysis revealed that IGH contains high amounts of polyphenols (627.4 mg GAE/L or 129.51 mg GAE/g dry weight), flavonoids (98.0 mg QE/L or 9.11 mg QE/g dry weight), and vitamins, specifically ascorbic acid (465.72 mg/100 g fresh weight). It also contains several amino acids, fatty acids, and trace elements. Supplementing or blending black tea kombucha with IGH in the range of 10 %–50 % (v/v) increased the total phenolic content (TPC), total flavonoid content (TFC), and total acidity of the fermented beverages. Several volatile organic compounds associated with the flavor, aroma, and health benefits of kombucha were also detected in black tea and IGH fusion kombucha products. Moreover, the black tea and IGH fusion kombucha products also displayed greater antioxidant and antimicrobial activities than the traditional black tea kombucha. Among the different combinations of black tea and IGH, supplementing black tea kombucha with 20 % IGH was the best combination for producing alternative and unique functional kombucha products with notable nutritional and health benefits.

Fermentation significantly influences the chemical composition of black tea, yet the effects of different fermentation temperatures on non-volatile components and their in vitro hypoglycemic activity are insufficiently studied. This research investigates how varying temperatures (20, 25, and 30°C) affect the bioactive profile and the inhibitory activity of Jinxuan black tea against α-glucosidase and α-amylase. Our results show that lower fermentation temperatures (20°C) lead to elevated levels of key bioactive compounds, including tea polyphenols (9.24%), soluble sugars (8.24%), thearubigins (7.17%), and theasinesin A (0.15%). These compounds correlate strongly with enhanced α-glucosidase inhibition (R = 0.76–0.97). Non-targeted metabolomic analysis revealed that 36 differential metabolites, including catechins, exhibited altered levels with increasing fermentation temperature. Notably, tea fermented at 20°C exhibited superior hypoglycemic activity, with α-glucosidase inhibition (IC50 = 14.00 ± 1.00 μg/ml) significantly outperforming α-amylase inhibition (IC50 = 2.48 ± 0.28 mg/ml). The findings of this research underscore the importance of fermentation temperature in optimizing the bioactive profile of black tea. It is proposed that recommendations for future processing or formulation should emphasize the use of lower fermentation temperatures, aimed at augmenting the health benefits linked to higher polyphenol content and stronger hypoglycemic activity.

Tea is central to the culture and economy of the Middle East countries, especially in Iran. At some levels of society, it has become one of the main food items consumed by households. Bioactive compounds in tea, known for their antioxidant and anti-inflammatory properties, have proven to confer neuroprotective effects, potentially mitigating diseases such as Parkinson's, Alzheimer's, and depression. However, the popularity of black tea has also made it a target for fraud, including the mixing of genuine tea with foreign substitutes, expired batches, or lower quality leaves to boost profits. This paper presents a novel approach to identifying counterfeit Iranian black tea and quantifying adulteration with tea waste. We employed five deep learning classifiers—RegNetY, MobileNet V3, EfficientNet V2, ShuffleNet V2, and Swin V2T—to analyze tea samples categorized into four classes, ranging from pure tea to 100% waste. The classifiers, tested in both patched and non-patched formats, achieved high accuracy, with the patched MobileNet V3 model reaching an accuracy of 95% and the non-patched EfficientNet V2 model achieving 90.6%. These results demonstrate the potential of image processing and deep learning techniques in combating tea fraud and ensuring product integrity in the tea industry. [ABSTRACT FROM AUTHOR]

In this study, the influence of different tea extract substrates on the biological activities of kombucha beverages was investigated. The variations in bioactive compounds such as polyphenols and flavonoids and their potential health-promoting properties represented by antioxidant activity were analyzed. Our findings shed light on the diverse effects of tea substrates on the production of bioactive compounds and their subsequent impact on the biological activities of kombucha, providing valuable insights for optimizing kombucha production and its potential health benefits. The new tea substrate for kombucha, called horchata, an Ecuadorian tea, shows a similar trend but with a low content of phenolics (4.511 ± 0.111 mg gallic acid equivalent (GAE)/g dry weight (DW)) and flavonoids (1.902 ± 0.0455 mg quercetin equivalent (QE)/g DW), and antioxidant activity (DPPH—33.569 ± 1.377 µmol TROLOX/g DW, ABTS—20.898 ± 2.709 µmol TROLOX/g DW, FRAP—34.456 ± 2.0618 Fe2+ mM/100 g DW compared to black and green tea as substrates for kombucha. Through HPLC-DAD, several polyphenols were registered, and homovanillic acid showed the highest concentration (74.45 mg/100 g). Horchata kombucha scored the highest in sweetness and smell, reflecting its popularity among the tasters, making it a valuable candidate as a kombucha substrate. [ABSTRACT FROM AUTHOR]

A Study of Black Tea's Anticancer Properties Using an In Vivo Model. Black tea contains compounds such as polyphenols, theaflavins, caffeine, L-theanine, and EGCG, which have been linked to potential anticancer properties. These compounds have been shown to prevent the growing of cancer cell and encourage involuntary cell death in laboratory studies. However, more study is required to conclude the exact anticancer properties of black tea in humans. Black tea's anti-carcinogenic qualities stem from its ability to regulate oxidative damage to endogenous antioxidants, mutagens, and biomolecules' antioxidant gene transcription pathways, among other things. Nonetheless, adding black tea to a healthy diet may have overall health benefits. Regular use of black tea, which is high in phytochemicals and may help prevent and treat cancer, has been connected regulation of several molecular targets, including 5-Lipoxygenase, Cyclooxygenase-2, c-Jun N-terminal Kinase, Signal Transducer and Activator of Transcription, Activator Protein 1, and MAPK. Black tea's anti-cancer action is supported in vivo; nevertheless, its impact on human trials is unknown, even if further clinical investigations at the molecular level are required to comprehend this feature. [ABSTRACT FROM AUTHOR]

Gas chromatography–ion mobility spectrometry (GC-IMS) is a smart method that has been applied to determine the volatile compounds in Chinese teas, but its use in comparing the volatile compounds of different types of tea has not been mentioned. In this study, the volatile compounds found in four types of samples (green, yellow, white, and black teas) made with fresh leaves of Camellia sinensis (L.) Kuntze 'Zhongcha 111' were analyzed using GC-IMS. The results showed that 93 volatile compounds were identified from our tea samples and that the average volume of aldehydes was higher than that for other compounds, especially in white tea. The different samples were successfully categorized using multivariate statistical analysis. Using partial least squares discriminant analysis (PLS-DA), we found 15 key compounds, including four differential components: (E)-2-hexenal, 2-furanmethanethio, 2-hexanol, and 1-octene. There were 29 common components, and their total content reached 386.0 μg/g. Moreover, the 3-methyl-2-butenal and dimethyl disulfide detected in the four samples were also differential compounds, varying according to the manufacturing technology. Thus, this study demonstrates that different types of teas can be discriminated easily using GC-IMS and that this is helpful to shorten the time for improving tea quality and developing new products. [ABSTRACT FROM AUTHOR]

The bioactivity of tea polysaccharides (TPs) has been widely reported, but studies to date have focused on green tea. Some human health investigations have implied that black tea may possess potential antidiabetic effects, but less is known about their potential role and related antidiabetic mechanism. The present study was, therefore, conducted to investigate the chemical properties and antidiabetic activity of TPs from black tea. Monosaccharide composition revealed that Alduronic acid (77.8 mol%) considerably predominated in the fraction. TP conformation analysis indicated that three components in TPs were all typical of high-branching structures. Oral administration of TPs could effectively alleviate fasting blood glucose in type 2 diabetes mellitus (T2D) mice, with the values 23.6 ± 1.42, 19.6 ± 2.25, and 16.4 ± 2.07 mmol/L in the 200, 400, and 800 mg/kg·BW groups, respectively. Among these TPs groups, the 800 mg/kg·BW groups significantly decreased by 37.88% when compared with the T2D+water group (p < 0.05). Further studies demonstrated that TP treatment upregulated the expression of p-Akt/p-PI3K (p < 0.001). Additionally, TP treatment significantly promoted glucose transporter protein 2 (GLUT2) translocation in the liver (p < 0.001). These findings suggest that TPs from black tea protect against T2D by activating PI3K/Akt/GLUT2 signaling and might serve as a novel therapeutic candidate for T2D. [ABSTRACT FROM AUTHOR]

Introduction: Saliva plays a critical role in preventing dental caries through regulation of pH, flow rate and proteins of saliva. Tea leaves from black tea (Camellia sinensis) is one of the plants containing catechins that has shown to influence secretion of saliva, thus it can inhibit the development of caries. This study aimed to investigate the effect of consuming black tea (Camellia sinensis) on level of salivary pH, flow rate and secreted lysozyme in caries and caries-free subjects. Materials and methods: Saliva was obtained from twenty four participants divided into two categories, caries and caries free group. Subjects were asked to collect saliva before and 30 minutes after drinking a cup of tea. Salivary pH was measured using a digital pH meter, while the flow rate was measured by weighing the collected saliva divided by time. The concentration of lysozyme was assessed by using ELISA kit. The data were analyzed using paired t-test and Mann Whitney test. Results: The results showed that black tea significantly increased pH and salivary flow rate, but had no significant effect on salivary lysozyme. It also demonstrated that there was no significant difference on salivary pH, flow rate, lysozyme after drinking black tea in the caries subjects compared to the caries free. Conclusion: Although drinking black tea could raise salivary pH and flow rate, but it did not promote the increase of lysozyme. This finding suggests that black tea had no unfavourable impact on saliva in oral environment. [ABSTRACT FROM AUTHOR]

Bovine and camel milk have several health benefits, including high antioxidant and radical scavenging activities. The thermal stability of camel and bovine milk could enhance the antioxidant potential of several natural sources, such as honey, black tea, and Matcha. The current study assessed the antioxidant capacity and radical scavenging potential of different natural sources in camel and bovine milk by using the 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) method and Ferric-Reducing Antioxidant Power (FRAP) assay. To examine the antioxidant capacity and the thermal stability of honey, black tea, and Matcha, each natural source was added to bovine and cow milk and later heated until it reached boiling point temperature for 30 minutes. Subsequently, the antioxidant capacity of these samples was evaluated. The results indicated that Matcha maintained its antioxidant activity with a significant induction of the radical scavenging potential in both camel (p ≤ 0.0001) and bovine milk (p ≤ 0.05) after heating. However, Black tea showed a significantly higher radical scavenging potential in camel milk only (p ≤ 0.001) but not in bovine milk. The results suggest that camel milk has better heat stability in conserving the antioxidant activity of black tea and Matcha sources than bovine milk. In contrast, the radical scavenging activity of honey remained consistent and unchanged in both types of milk, with no significant difference compared to the control. [ABSTRACT FROM AUTHOR]

As a non-destructive, fast, and cost-effective technique, near-infrared (NIR) spectroscopy has been widely used to determine the content of bioactive components in tea. However, due to the similar chemical structures of various catechins in black tea, the NIR spectra of black tea severely overlap in certain bands, causing nonlinear relationships and reducing analytical accuracy. In addition, the number of NIR spectral wavelengths is much larger than that of the modeled samples, and the small-sample learning problem is rather typical. These issues make the use of NIRS to simultaneously determine black tea catechins challenging. To address the above problems, this study innovatively proposed a wavelength selection algorithm based on feature interval combination sensitivity segmentation (FIC-SS). This algorithm extracts wavelengths at both coarse-grained and fine-grained levels, achieving higher accuracy and stability in feature wavelength extraction. On this basis, the study built four simultaneous prediction models for catechins based on extreme learning machines (ELMs), utilizing their powerful nonlinear learning ability and simple model structure to achieve simultaneous and accurate prediction of catechins. The experimental results showed that for the full spectrum, the ELM model has better prediction performance than the partial least squares model for epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), and epigallocatechin gallate (EGCG). For the feature wavelengths, our proposed FIC-SS-ELM model enjoys higher prediction performance than ELM models based on other wavelength selection algorithms; it can simultaneously and accurately predict the content of EC ( R p 2 = 0.91, RMSEP = 0.019), ECG ( R p 2 = 0.96, RMSEP = 0.11), EGC ( R p 2 = 0.97, RMSEP = 0.15), and EGCG ( R p 2 = 0.97, RMSEP = 0.35) in black tea. The results of this study provide a new method for the quantitative determination of the bioactive components of black tea. [ABSTRACT FROM AUTHOR]