Black Tea Extract Research Articles

Unveiling chemical responses in the kombucha-based fermentation of black tea, banana flower, and grape juice: LC-ESIMS, GNPS, MS-DIAL, and MS-FINDER-assisted chemical characterization.

The lack of studies evaluating the chemical responses of kombucha microorganisms when exposed to plants is notable in the literature. Therefore, this work investigates the chemical behaviour of 7-, 14- and 21 day-fermentation of kombucha derived from three extracts obtained from banana inflorescence, black tea, and grape juice. After the acquisition of UPLC-ESI-MS data, GNPS molecular networking, MS-Dial, and MS-Finder were used to chemically characterize the samples. The microbial chemical responses were enzymatic hydrolysis, oxidation, and biosynthesis. The biosynthesis was different among the kombucha samples. In fermented black tea, gallic and dihydrosinapic acids were found as hydrolysis products alongside a sugar-derived product namely 7-(α-D-glucopyranosyloxy)-2,3,4,5,6-pentahydroxyheptanoic acid. The sphingolipids, safingol and cedefingol alongside capryloyl glycine and palmitoyl proline were identified. In fermented grapes, sugar degradation and chemical transformation products were detected together with three cell membrane hopanoids characterized as hydroxybacteriohopanetetrol cyclitol ether, (Δ6 orΔ11)-hydroxybacteriohopanetetrol cyclitol ether, and methyl (Δ6 or Δ11)-hydroxybacteriohopanetetrol cyclitol. The fermented banana blossom showed the presence of methyl (Δ6 or Δ11)-hydroxybacteriohopanetetrol cyclitol together with sphingofungin B, sphinganine and other fatty acid derivatives. Parts of these samples were tested for their inhibition against α-glucosidase and their antioxidant effects. Except for the 14-day fermented extracts, other black tea extracts showed significant inhibition of α-glucosidase ranging from 42.5 to 42.8%. A 14-day fermented extract of the banana blossom infusion showed an inhibition of 29.1%, while grape samples were less active than acarbose. The 21-day fermented black tea extract showed moderate antioxidant properties on a DPPH-based model with an EC50 of 5.29 ± 0.10 μg mL-1, while the other extracts were weakly active (EC50 between 80.76 and 168.12 μg mL-1).

Phenolic Compounds, Free Radical Scavenging Activity and α-Glucosidase Inhibition Properties of Green, Oolong and Black Sacha Inchi Tea Extract

Sacha Inchi leaves may possess antioxidant function which is naturally rich in bioactive ingredients and has been widely processed into herbal teas that has many benefits to human health. According to the global data from the World Health Organization (WHO), there has been a rise in the frequency of diabetes mellitus (DM) among adults. Sacha Inchi tea was prepared using several methods, with green tea not fermented, oolong partially fermented, and black tea completely fermented. The phenolic compounds (total phenolic content (TPC), total flavonoid content (TFC), tannin), free radical scavenging activity (DPPH) and inhibition properties of α-Glucosidase on green, oolong and black Sacha Inchi tea extract were determined. The green Sacha Inchi tea extract displayed the highest TPC and TFC values among the oolong and black Sacha Inchi tea extracts at a concentration of 500µg/mL, with values of 2.10±0.01 µg GAE/mL and 3.23±0.20 µg QE/mL, respectively. Meanwhile, at a concentration of 500µg/mL, Sacha Inchi black tea extract demonstrated strong antioxidant activity by DPPH with radical scavenging activity (%) (89.4±0.45). Furthermore, at a concentration of 15.625 µg/mL, black, oolong, and green tea extracts exhibited stronger inhibitory effects on α-Glucosidase (95%, 95%, 92%, respectively) than acarbose (90%). Therefore, the processing steps involved in tea production impact the phenolic compounds, free radical scavenging activity, and the ability to inhibit α-Glucosidase in green, oolong, and black tea extracts.

Contents of ɑ-dicarbonyl compounds in commercial black tea and affected by the processing

The species and contents of ɑ-dicarbonyls in commercial black tea were examined, along with the effects of the manufacturing process and drying temperature on the formation of ɑ-dicarbonyls. Ten ɑ-dicarbonyls were quantified in commercial and in-process black tea samples by using UPLC-MS/MS and their derived quinoxalines. The ɑ-dicarbonyls content in commercial black tea decreased significantly (p < 0.05) in the following order: 3-deoxyglucosone > glucosone > 3-deoxypentosone = threosone > galactosone ≥ methylglyoxal = glyoxal ≥ 3-deoxygalactosone = 3-deoxythreosone = diacetyl. Except for 3-deoxyglucosone and 3-deoxygalactosone, a further eight ɑ-dicarbonyls were identified in all manufacturing steps of black tea. Except for the drying step, the rolling and fermenting played important roles in the formation of ɑ-dicarbonyls. The total contents of ɑ-dicarbonyls in black tea infusion ranged from 16.48 to 75.32 μg/g based on our detected ten ɑ-dicarbonyls.

The Impact of PSR™ (Plant Small RNA Technology), Tea Extract, and Its Principal Components on Mitochondrial Function and Antioxidant Properties in Skin Cells

Objective: This study explored the impact of a black tea extract obtained through (plant small RNA) PSRTM technology, characterized by its abundance of small molecules, particularly citric acid—an antioxidant and tricarboxylic acid (TCA) cycle contributor—on mitochondrial health. The primary focus was to assess whether this extract could counteract reactive oxygen species (ROS)-induced mitochondrial alterations associated with aging, which lead to impaired mitochondrial function, reduced ATP production, and increased ROS generation. Methods: The PSRTM extraction method was employed to obtain a high content of polyphenols and small molecules, particularly citric acid. Results: In comparison with a conventional extract, the PSRTM extract demonstrated significant enhancements in aconitase activity, an ROS-sensitive enzyme in the TCA cycle, as well as basal respiration and ATP synthesis in fibroblast cells and skin biopsies. Moreover, the PSRTM extract effectively reduced ROS production by safeguarding this critical enzyme within the Krebs cycle and displayed superior capabilities in scavenging free radicals when exposed to UV-induced stress. When administered post-UV exposure, the PSRTM extract protected nuclear DNA by reducing the formation of cyclobutane pyrimidine dimers (CPDs) and promoting DNA repair mechanisms. Furthermore, the extract exhibited beneficial effects on the extracellular matrix, characterized by a reduction in matrix metalloprotease 1 (MMP1) and an increase in fibrillin 1 expression. Conclusions: These findings collectively suggest that the PSRTM extract holds promising antiaging potential, potentially functioning as a mitochondrial nutrient/protector due to its multifaceted benefits on mitochondrial function, nuclear DNA integrity, and the extracellular matrix.

Stability of Flavan-3-ols, Theaflavins, and Methylxanthines in 30 Industrial Green, Black, and White Tea (Camellia sinensis L.) Extracts Characterized via Liquid Chromatography Techniques.

Commercially available tea extracts for dietary supplements and nutraceuticals are standardized to characteristic components of Camellia sinensis L., such as epigallocatechin gallate (EGCG) and total catechins or polyphenols. However, since most commercial tea extracts are highly concentrated into only one molecule such as EGCG, the comparatively less stable catechin, the oxidative stability of the extract during the 24-month shelf life was questioned. It was hypothesized that the overall oxidative stability is reduced for highly purified/concentrated tea extracts due to the absence of other natural antioxidants stabilizing the complex mixture. Via liquid chromatographic analysis, the individual chromatographic profiles of 30 commercial white, green, and black tea extracts were evaluated and compared regarding oxidative stability and functional properties. The contents of bioactive flavan-3-ols, theaflavins, and methylxanthines differed much from what was claimed by the suppliers. At the end of the product shelf life, most of the commercial green and black tea extracts showed a decrease in the flavan-3-ol content, the main bioactive components of tea. A high EGCG content to the detriment of other possibly stabilizing flavan-3-ols or antioxidants in tea was found to explain the lower oxidative stability of such tea extract products. A natural overall composition of molecular structures was found to be superior to a strong enrichment in just one molecule.

The Antiobesity Effects and Potential Mechanisms of Theaflavins.

Theaflavins are the characteristic polyphenols in black tea which can be enzymatically synthesized. In this review, the effects and molecular mechanisms of theaflavins on obesity and its comorbidities, including dyslipidemia, insulin resistance, hepatic steatosis, and atherosclerosis, were summarized. Theaflavins ameliorate obesity potentially via reducing food intake, inhibiting pancreatic lipase to reduce lipid absorption, activating the adenosine monophosphate-activated protein kinase (AMPK), and regulating the gut microbiota. As to the comorbidities, theaflavins ameliorate hypercholesterolemia by inhibiting micelle formation to reduce cholesterol absorption. Theaflavins improve insulin sensitivity by increasing the signaling of protein kinase B, eliminating glucose toxicity, and inhibiting inflammation. Theaflavins ameliorate hepatic steatosis via activating AMPK. Theaflavins reduce atherosclerosis by upregulating nuclear factor erythropoietin-2-related factor 2 signaling and inhibiting plasminogen activator inhibitor 1. In randomized controlled trails, black tea extracts containing theaflavins reduced body weight in overweight people and improved glucose tolerance in healthy adults. The amelioration on the hyperlipidemia and the prevention of coronary artery disease by black tea extracts were supported by meta-analysis.

Black Tea Waste as Corrosion Inhibitor for Carbon Steel in 0.5 M HCl Medium

Indonesian black tea (BT) waste was utilized as a green corrosion inhibitor for carbon steel (CS) corrosion in a 0.5 M HCl medium. The BT extract was characterized using Fourier transform infra-red. The corrosion inhibition evaluation was studied using conventional weight loss methods, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). Further, scanning electron microscopy-energy dispersive X-ray was applied to analyze the surface morphology of pure CS before and after contact with the inhibitor extract. After the addition of inhibitors, CS surface showed a better morphological transformation. The effect of oxygen contamination has also been studied in this research. The corrosion measurements of weight loss, potentiodynamic polarization, and EIS showed that the %IE BT extract was 84.70; 70.00; 72.80% at 0.20 g/L of inhibitor concentration. Adsorption isotherm studies have determined the reaction mechanism between the CS and inhibitor; in which the adsorption follows Langmuir. Gibbs free energy for the three methods is −16.62; −25.34; −24.35 kJ/mol, indicating electrostatic interaction (physisorption) between the metal surface and inhibitor. SEM and focus ion beam show that oxygen contamination can increase the corrosion rate resulting in CS damage. It shows that tea waste products can be used as an alternative corrosion inhibitor.

Effect of extraction conditions and tannase enzyme application on catechin content and cream formation in Turkish black tea extracts

Effect of extraction conditions and tannase enzyme application on catechin content and cream formation in Turkish black tea extracts

Effects of brewing water on the volatile composition of tea infusions.

There is a huge demand for brewing water in tea consumption, and the sensory flavor of tea infusion is significantly affected by the water used for brewing. To investigate the impact of brewing water on the aroma of tea infusions made from Camelia senensis, the three tea infusions of green, oolong and black tea brewed by six different drinking waters were analyzed by sensory evaluation, solid-phase microextraction, gas chromatography-mass spectrometry, and chemometrics. Brewing water with high pH values (>8.10) and high TDS content (>140ppm) resulted in a lower overall aroma acceptability for tea infusion, where HCO3-, Ca2+ and Mg2+ were key influencing ions. A total of 86, 106, and 131 volatiles were identified in green, oolong and black tea infusions, respectively, which were strongly influenced by six different brands of waters. Decanal, dimethyl sulfide, β-ionone and linalool were potent volatiles in tea aroma changes caused by brewing water.

Azorean Black Tea (Camellia sinensis) Antidermatophytic and Fungicidal Properties

The treatment of dermatophytoses, the most common human fungal infections, requires new alternatives. The aim of this study was to determine the antidermatophytic activity of the aqueous Azorean Black Tea extract (ABT), together with an approach to the mechanisms of action. The phytochemical analysis of ABT extract was performed by HPLC. The dermatophytes susceptibility was assessed using a broth microdilution assay; potential synergies with terbinafine and griseofulvin were evaluated by the checkerboard assay. The mechanism of action was appraised by the quantification of the fungal cell wall chitin and β-1,3-glucan, and by membrane ergosterol. The presence of ultrastructural modifications was studied by Transmission Electron Microscopy (TEM). The ABT extract contained organic and phenolic acids, flavonoids, theaflavins and alkaloids. It showed an antidermatophytic effect, with MIC values of 250 µg/mL for Trichophyton mentagrophytes, 125 µg/mL for Trichophyton rubrum and 500 µg/mL for Microsporum canis; at these concentrations, the extract was fungicidal. An additive effect of ABT in association to terbinafine on these three dermatophytes was observed. The ABT extract caused a significant reduction in β-1,3-glucan content, indicating the synthesis of this cell wall component as a possible target. The present study identifies the antidermatophytic activity of the ABT and highlights its potential to improve the effectiveness of conventional topical treatment currently used for the management of skin or mucosal fungal infections.

Aflatoxin detoxification by biosynthesized iron oxide nanoparticles using green and black tea extracts

Researchers have recently been interested in employing nanoparticles (NPs) obtained from herbal extracts through green synthesis for various applications. This study investigated the detoxification of aflatoxins, which are toxic substances produced by molds Aspergillus flavus and Aspergillus parasiticus. The present work examined the levels of aflatoxins in hazelnut and peanut puree. Turkish black tea extract (BTE), Turkish green tea extract (GTE), green synthesized black tea-based iron oxide nanoparticles (BTFeONPs), and green tea-based iron oxide nanoparticles (GTFeONPs) were produced for aflatoxin removal. Characterizations and various antioxidant and antimicrobial activities of the tea extracts and iron oxide nanoparticles (FeONPs) were investigated. The aflatoxin levels of hazelnut puree used for this study were 6.57 ± 0.06 µg/kg for aflatoxin B1 and 13.03 ± 0.16 µg/kg for total aflatoxin, whereas the aflatoxin levels of (AFLB1) peanut puree were 7.79 ± 0.15 µg/kg for AFLB1 and 15.21 ± 0.12 µg/kg for total aflatoxin. Using soluble BTE resulted in a 40 to 50% decrease in aflatoxin levels in hazelnut and peanut purees, while soluble GTE led to a 30 to 45% decrease. Meanwhile, using BTFeONPs and GTFeONPs resulted in a 33 to 48% and 40 to 50% decrease, respectively, in aflatoxin levels in hazelnut and peanut purees.

A method for obtaining aqueous and dry ethanol extracts of grass (a mixture of flowers with leaves) and a stalk of St. John's wort (Hypericum perforatum L.) with inhibitory activity on the replication of the SARS‐CoV‐2 coronavirus in vitro

Aim. In vitro evaluation of the inhibitory activity of aqueous extracts and dry ethanol extracts of St John's wort (Hypericum perforatum L.) on the replication of SARS-CoV-2 according to three experimental schemes – direct inactivation (neutralisation) of the virus as well as "prevention" and "treatment" of cells.Materials and Methods. The laboratory strain SARS-CoV-2/human/RUS/Nsk-FRCFTM-1/2020 was passed on Vero cell culture. Water extracts and dry ethanol extracts of parts of H. perforatum L. collected during the flowering period in the Novosibirsk region were prepared. Dry extracts were dissolved in DMSO. Comparison samples are dry ethanol extracts of chaga, cloves and black tea.Results. It is shown that the aqueous extract of grass (a mixture of flowers with leaves) of H. perforatum L. with direct inactivation of the virus it is active in dilution of 1/4096. For the dry ethanol extract of the herb H. perforatum L., 50 % effective concentrations (EC50) were found equal to 2.44±0.87; 8.79±1.91 and 14.65±1.91 μg/ml respectively with direct inactivation as well as according to the "preventive" scheme and with the "treatment" of cells. Taking into account cytotoxicity, as well as in comparison with control samples, the values of selective indices (SI50) of the studied herbal preparations during direct inactivation were higher than with other experimental schemes and were distributed as follows (in descending order): 204.92; 153.68; 115.27; 32.01 and 21.33 for dry ethanol extracts of black tea from India, cloves, herbs, a mixture of flowers with leaves, of H. perforatum, chaga and the stems of H. perforatum respectively. The HPLC method has shown that the ethanol extract of the herb H. perforatum L. contains a greater amount of flavonoids than the extract of stems. Nevertheless, antiviral activity was also detected for the extract of stems of this plant with EC50 equal to 14.65±1.91; 78.13±20.05 and 117.19±15.31 μg/ml (according to three experimental schemes), respectively.Conclusion. For the preparation of antiviral drugs the whole plant of H. perforatum L., including stems, can be used as raw materials.

Responses of Saccharomyces cerevisiae Cells Grown in Cultures Prepared from Different Tea Infusions to Oxidative Stress

Tea is one of the most consumed beverages. Saccharomyces cerevisiae, a model organism in studies on oxidative stress and toxicology, was used to investigate the effects of tea on oxidative stress induced by H2O2. S. cerevisiae cultures were prepared from black, green and white tea infusions and incubated at 30°C for 72 hours. Glutathione-S-transferase enzyme activity and total protein spectrophotometric, malondialdehyde, glutathione and alpha-tocopherol and ergosterol analyses from cell pellets obtained from cultures were performed by HPLC, and fatty acids were performed by GC device. Although protein level in tea infusion groups was higher (p

Aged black tea alleviates constipation in mice by modulating intestinal neurotransmitters and decreasing AQP3 and AQP9 expression

Background: Black tea is fully fermented tea with abundant functional components that benefit the gastrointestinal tract. But whether black tea extract relieves constipation is unknown. Therefore, we used loperamide to induce constipation in mice to assess the therapeutical effect of extracts from aged black tea with different storage times.&#x0D; Design: Sixty-three C57BL/6J male mice were randomly divided into Control group (Con), Model group (Mod), Positive group (Pos), aged 6 years group (15Y), aged 4 years group (17Y), aged 2 years group (19Y), and unaged group (21Y). Mice were given loperamide (20 mg/kg, twice a day) to induce constipation for 10 days, and black tea extracts (500 mg/kg) were intragastrically given for 7 days while continuing modeling.&#x0D; Results: The results showed that black tea extracts relieved constipation symptoms by improving defecation weight, fecal water content, and gastrointestinal transit rate. Black tea extracts can also protect colon tissue, regulate serum neurotransmitters, increase the levels of excitatory neurotransmitters motilin (MTL) and substance P (SP), and decrease the levels of inhibitory neurotransmitters vasoactive intestinal peptide (VIP) and nitric oxide (NO). Immunohistochemistry (IHC) showed that black tea extracts were able to reduce AQP3 and AQP9 expression in the colon of constipated mice. In addition, Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) showed that black tea extracts could decrease AQP3 and AQP9 mRNA expression. The relief effect of aged black tea (15Y) with the longest storage was better than that of other years, which may be due to the role of active ingredients such as thearubigins (TRs), soluble sugar, tea polysaccharide (TPS), gallic acid (GA), and catechin gallate (CG) in aged black tea.&#x0D; Conclusions: Based on these results, we believe that regular consumption of black tea is effective in relieving constipation, and that black tea is more effective in relieving constipation as the storage time increases.

The UV protectant properties of tea extracts on entomopathogenic fungus spores and their lethal effect on Galleria mellonella (L., 1758) (Lepidoptera: Pyralidae)

The present study aims to investigate the effectiveness of various tea extracts in providing ultraviolet (UV) protection for entomopathogenic fungi. UV radiation could have detrimental effects on viability of these fungi, which are important biocontrol agents against insect pests. This study was carried out in the Microbiology Laboratory of the Department of Biology Karadeniz Technical University in 2023. We evaluated the UV protective properties of various tea extracts in entomopathogenic fungi [Beauveria bassiana (Bals.) Vuil. (Hypocreales: Cordycipitaceae) and Metharizium flavoviride (Gams and Rozsypal 1956) (Hypocreales: Clavicipitaceae)] and tea extracts effectiveness against Galleria mellonella (L.,1758) (Lepidoptera: Pyralidae) larvae. Our findings demonstrate that certain tea extracts exhibit significant UV protection for entomopathogenic fungi, suggesting their potential application in improving the performance of biocontrol agents in outdoor environments. The highest UV-B protection was observed by adding black and green tea extracts to fungal spores, resulting in a radial growth measurement of 14.6 mm and 14.3 mm, respectively, at the end of 10 days of exposure for 120 minutes. These results contribute to the development of eco-friendly strategies for pest management in agriculture.

In vitro compositional and phytochemical analysis of green and black tea

The traditional beverage that people consume more after water is a tea. The ethanolic extract of green and black tea have antioxidant and antimicrobial activity and these activities may differ in their processing methods. In this study, physiochemical analysis of green and black tea was carried out. The physiochemical analysis showed that green tea has higher moisture content, crude fat and crude fiber except for crude protein and ash content which is found higher in black tea. The maceration process was used for extraction purposes. This extract was used to analyze the total phenolic and flavonoid content, antioxidant potential, and antimicrobial activity. A significant difference was found in the total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity of green and black tea. The flavonoids and phenolic content in T1 (ethanol 100%) acquired average and significant in the extract of green and black tea. The maximum value of TPC was observed in green tea extract 152.17a ± 0.28 mg GAE/g in treatment T1, and the value of TFC in green tea was found 40.26±11.387mg QE/g and the minimum value was found in black tea at 36.85±13.68 mg QE/g of extract. Antioxidant activity of green tea extract ranged from 90.64% to 69.07%, and black tea extract ranged from 89.05% to 50.93% in each extract. The parallel determination of the inhibitory effect of gram-negative and positive bacterial strains (Streptococcus pyogenes, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa) was found sensitivity and resistivity towards extract of tea. The positive and negative effect was found in antimicrobial activity by using antibiotics against these bacterial strains.

Influence of citric acid on the extraction level of manganese in green and black tea infusions

Manganese concentration in green and black tea (10 samples of each type) was determined by means of graphite-furnace atomic absorption spectrometry. Both the dry leaves and the infusions were analysed. The concentration of manganese in dry leaves was in the range of 502–1277 mg · kg−1 for black tea and 798–1906 mg · kg−1 for green one. Since lemon juice is commonly added for tea to enrich its taste, citric acid was used to simulate lemon juice influence on manganese concentration in the infusions. The infusions prepared with and without citric acid addition were analysed and the results showed significant influence of citric acid on manganese leaching. The average extraction levels of manganese from black tea equal 16% (for non-acidified infusions) and 34% (for acidified ones) while these values for green tea equal 13% and 38%, respectively. Statistical evaluation of the results showed that the differences between acidified and non-acidified infusions were statistically significant. High manganese content makes the tea an important source of manganese in human diet.

The protective effects of black tea as nitrite replacer on the oxidation, physicochemical and sensory properties of steamed beef

Having in mind the potential hazard of nitrite as carcinogens and its extensive use in realistic meat preservation, a natural substitute of nitrite was expected to be explored from the massive antioxidants contained in black tea. This study investigated the effect of black tea infusion (BTI) on proximate composition, texture, surface color, sensory, antioxidant activity, lipid oxidation, protein oxidation and microbial quality of steamed beef. Steamed beef was prepared with the treatment of BTI (1%, 2%, 3%, 4% and 5%), and nitrite (0.01%), respectively. Compared to the control group, beef treated with both BTI and nitrite showed significantly improved texture characteristics, decreased L* values, higher a* values, increased antioxidant activities as well as enhanced resistance to lipid and protein oxidation. In addition, the optimal value of acceptability for BTI-treated beef was 4%. Beef with BTI was more stable in color than beef with nitrite. Based on the above results, BTI possessed as positive function as nitrite on the texture and flavor enhancement, oxidation prevention of steamed beef. Hence, our finding provides theoretical support for the application of BTI as natural replacer for nitrite in maintaining beef quality and freshness.

New Approaches to Using Plant Flavor-Forming Enzymes

Background. Proteases, as well as enzyme complexes with various combinations of lipase, amylase, and cellulase, are used as flavor enzymes to impart aroma to processed raw materials. Plant-derived enzymes have significant potential for influencing aroma-forming reactions. Objective. The aim of this study is to investigate the intentional alteration of the aroma of onions, linden leaves, and cherry leaves by either activating (in the case of linden and cherry leaves) or inhibiting (in the case of onions) specific plant enzyme complexes. Methods. Linden and cherry leaves, as well as onion bulbs, were selected as the subjects that change their aroma by a complex of enzymes. To activate the enzymes present in the tree leaves, fermentation conditions similar to those used in tea leaf processing were applied. Mustard seeds and horseradish roots were employed as supplementary sources of enzymes. Ginger, extracts of bleck tea, grean tea, and oark bark were used to influence the reactions of onion aroma formation. Results. It was determined that flavor enzymes of tree leaves are active in different periods of leaf formation: enzyme complex in cherry leaves becomes active after flowering, while linden leaves exhibit enzymatic activity before flowering. Plant enzymes, such as mustard myrosinases and horseradish polyphenol oxidases, were found to be effective in modifying the onion's flavor. The substances contained in extracts of black tea, green tea, and ginger were observed to effectively inhibit the development of onion aroma. Conclusions. The compounds of ginger, black tea, and green tea extracts were found to slow down or inhibit the development of the onion aroma. The aroma of cherry and linden tree leaves undergoes transformation due to the natural leaf enzymes, resulting in aromas reminiscent of cherry berries and linden blossoms, respectively. Plant aroma-forming enzymes in linden leaves have a a more significant impact on the aroma before flowering, whereas aroma-forming enzymes in cherry leaves exert a stronger influence after fruiting.

Ameliorative effect of black tea extract on the skin of D-galactose-induced aging mice.

Aging is a universal and irreversible process, and the skin is an important feature that reflects the aging of the organism. Skin aging has been a focus of attention in recent years because it leads to changes in an individual's external features and the loss of many important biological functions. This experiment investigated the improvement effect of black tea extract (BTE) on the skin of aging mice under D-galactose induction. After 6 weeks of administration, the changes in skin bio-chemical indices and tissue structure were compared with the blank and positive control groups. It was observed that BTE increased water and hyaluronic acid (HA) content, decreased malondialdehyde (MDA) content, enhanced superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activities in the skin of aging mice, and improved the structure of aging damaged skin tissues and increased the content of total collagen. The experimental results showed that BTE can play a significant anti-aging effect on the skin, which can be used as a functional food for aging inhibition.