The phenolic profiles and antioxidant activity in different types of tea

Microencapsulation Efficiency of Carboxymethylcellulose, Gelatin, Maltodextrin, and Acacia for Aroma Preservation in Jasmine Instant Tea

Enhancing the sensory appeal of jasmine instant tea, particularly its aroma, poses a significant challenge due to the loss of volatile organic compounds during conventional processing. This study introduces a novel approach to address this issue through the application of microencapsulation techniques, aimed at preserving these key aromatic elements. Our investigation focused on the encapsulating agents gelatin, acacia gum, carboxymethylcellulose (CMC), and maltodextrin, chosen for their compatibility with the volatile organic compounds of tea. A statistical analysis was conducted on the analytical results through comprehensive analytical techniques like Principal Component Analysis (PCA), Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA), and Variable Importance in Projection (VIP) analysis for microcapsule characterization. The statistical analysis revealed gelatin to be a particularly effective encapsulating medium, preserving an aroma profile more akin to fresh tea. The statistical analysis confirmed the reliability of these findings, highlighting the potential of microencapsulation in refining the quality of jasmine instant tea products. The results of this research suggest that microencapsulation could be instrumental in improving the sensory quality and shelf life of instant tea products, offering new opportunities for product enhancement in the beverage industry.

Characteristics and Relationships between Total Polyphenol and Flavonoid Contents, Antioxidant Capacities, and the Content of Caffeine, Gallic Acid, and Major Catechins in Wild/Ancient and Cultivated Teas in Vietnam

Vietnam has diverse and long-established tea plantations but scientific data on the characteristics of Vietnamese teas are still limited. Chemical and biological properties including total polyphenol and flavonoid contents (TPCs and TFCs), antioxidant activities (DPPH, ABTS, FRAP, and CUPRAC), as well as the contents of caffeine, gallic acid, and major catechins, were evaluated for 28 Vietnamese teas from North and South Vietnam. Higher values of TPCs and TFCs were found for green (non-oxidised) and raw Pu'erh (low-oxidised) teas from wild/ancient tea trees in North Vietnam and green teas from cultivated trees in South Vietnam, as compared to oolong teas (partly oxidised) from South Vietnam and black teas (fully oxidised) from North Vietnam. The caffeine, gallic acid, and major catechin contents depended on the processing, geographical origin, and the tea variety. Several good Pearson's correlations were found (r² > 0.9) between TPCs, TFCs, the four antioxidant capacities, and the content of major catechins such as (-)-epicatechin-3-gallate and (-)-epigallocatechin-3-gallate. Results from principal component analysis showed good discriminations with cumulative variances of the first two principal components varying from 85.3% to 93.7% among non-/low-oxidised and partly/fully oxidised teas, and with respect to the tea origin.

Herbal tea with bacoside loaded saponins: formulation and characterization for food fortification from Bacopa monnieri L

In recent times, there is a renewed interest of herbal tea because of growing consumer awareness for the health benefits of herbal tea consumption in the covid era. Bacopa monnieri is a natural medicine mainly used to enhance nerve impulse transmission, improves memory and mental function as well as the enhancement of other cognitive function because of the presence of triterpenoid saponins and bacoside A. The present experiment was conducted for the development of herbal tea with known health benefits from Bacopa monnieri using different spices or herbal ingredients combinations, i.e., Pepper, cardamom, and ginger to increase its aesthetic properties. A higher sensory score for pepper-brahmi was found superior with 8.71 (colour), 8.43 (aroma), 8.43 (taste), 8.29 (after taste), and 8.46 (overall acceptability) over three combinations and control. Jal brahmi tisane revealed, 0.036 ± 0.0004 mg/100 ml Bacoside A, 87.72 mg TE/100 ml TAC, 106.02 mg GAE/100 ml TPC, 21,100 µg/100 ml calcium, and 87 µg/100 ml iron, which is essentially good for human health.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05532-y.

Relationship between the Grade and the Characteristic Flavor of PCT (Panyong Congou Black Tea)

Panyong Congou black tea (PCT) is one of the most representative and historically famous Congou black teas in China and has been gaining more and more attention for its beneficial health properties. Currently, four grades of PCT are available, based on the raw leaf materials and consumer palatability. The chemical profiles distinguishing different grades of PCT are yet to be defined, nor has the relationship with grade been evaluated. In the present study, chemometric analysis showed that epigallocatechin (EGC), catechin (C), polyphenols, gallic acid (GA), and free amino acids are grade related bio-markers of PCT. These compounds are associated with the sweet and mellow aftertaste of PCT. A total of 34 volatile components were identified, of which the three component types with the highest relative percentages were alcohols (51.34–52.51%), ketones (27.31–30.28%), and aldehydes (12.70–13.18%). Additionally, our results revealed that sweet floral and fruity aromas were positively correlated with six volatile organic compounds (VOCs), 1-pentanol, propyl hexanoate, linalool, cyclohexanone, hexanal, and 2,5-dimethylpyrazine. Clear discrimination was achieved using orthogonal projections to latent structures discriminant analysis (OPLS-DA). The findings provide vital information on the characteristic flavor of each grade of PCT.

Effect of fixation methods and various clones of Camellia sinensis var. sinensis (L) properties and antioxidant activity of Indonesian green tea

Fixation is essential in green tea processing to inactivate the polyphenol oxidase enzyme. In Indonesia, green tea is made from the Assam variety and produced using the panning method. Few studies are reported on green tea made from Indonesian clones of the Sinensis variety. This study aims to identify chemical characteristics, antioxidant activity, and sensory evaluation of green tea from local clones of the Sinensis variety (GMBS 2, GMBS 4, and GMBS 5) with different fixation methods (panning and steaming). The results show that the caffeine content of green tea products ranged from 2.51-2.59% and 2.67-2.74% for panning and steaming methods. The panning method produced green tea with higher total polyphenol and flavonoid content than the steaming method. Green tea with the panning method has an IC50 value of 14.45; 14.41; and 17.41 mg/L for GMBS 2, GMBS 4, and GMBS 5, respectively. The panning method resulted in a smaller IC50 value than the steaming method for GMBS 2 and GMBS 4 clones. The steaming method produced green tea with a higher taste, aroma, and total score than those the panning method. However, different fixation methods did not significantly affect the appearance, liquor color, and leaf infusion. In conclusion, different fixation methods on GMBS 2, GMB 4, and GMB 5 produced green tea products that met the Indonesian National Standard 3945:2016. Further research is needed to determine the role of the plucking period/season and the characteristics of volatile compounds of green tea from GMBS clones with different fixation methods.

Green Tea (Camellia sinensis): A Review of Its Phytochemistry, Pharmacology, and Toxicology

Objectives Green tea (Camellia sinensis) is a kind of unfermented tea that retains the natural substance in fresh leaves to a great extent. It is regarded as the second most popular drink in the world besides water. In this paper, the phytochemistry, pharmacology, and toxicology of green tea are reviewed systematically and comprehensively. Key findings Green tea has been demonstrated to be good for human health. Nowadays, multiple pharmacologically active components have been isolated and identified from green tea, including tea polyphenols, alkaloids, amino acids, polysaccharides, and volatile components. Recent studies have demonstrated that green tea shows versatile pharmacological activities, such as antioxidant, anticancer, hypoglycemic, antibacterial, antiviral, and neuroprotective. Studies on the toxic effects of green tea extract and its main ingredients have also raised concerns including hepatotoxicity and DNA damage. Summary Green tea can be used to assist the treatment of diabetes, Alzheimer’s disease, oral cancer, and dermatitis. Consequently, green tea has shown promising practical prospects in health care and disease prevention.

Phenolic, Carotenoid and Saccharide Compositions of Vietnamese Camellia sinensis Teas and Herbal Teas

Tea (Camellia sinensis) and herbal tea have been recognized as rich sources of bioactive constituents with the ability to exert antioxidant actions. The aims of this study were to analyze phenolic, carotenoid and saccharide contents in a set of Vietnamese tea and herbal tea and compare the results with those of green and black teas marketed in the U.S. In total, 27 phenolics, six carotenoids and chlorophylls, and three saccharides were quantitatively identified. Catechins, quercetin glycosides and chlorogenic acid were the predominating phenolics in the teas, with the concentrations following the order: jasmine/green teas > oolong tea > black tea. Lutein was the dominant carotenoid in the teas and its concentrations were generally found to be higher in the jasmine and green teas than in the oolong and black teas. The study showed that the green teas originating in Vietnam had much higher levels of phenolics and carotenoids than their counterparts stemming from another country. The application of partial least squares discriminant analysis (PLS-DA) as a chemometric tool was able to differentiate phenolic profiles between methanolic extracts and tea infusions. Through principal component analysis (PCA), the similarities and dissimilarities among the jasmine, green, oolong, black teas and herbal teas were depicted.

Green-tea-synthesized silver nanoparticles as a sensing platform for determination of tetracycline in honey samples

BACKGROUND

Silver nanoparticles (AgNPs) can be easily obtained in aqueous solution by chemical reduction using appropriate reducing agents and stabilizers. The development of environmentally friendly methods using non-toxic solvents and reagents has become an alternative for the synthesis of these particles and their future application as sensor probes for agricultural products. In this work, a straightforward method based on green tea extracts as reducing and capping agent is proposed for the synthesis of AgNPs, followed by their evaluation as a sensing platform for determination of tetracycline in honey samples.

RESULTS

Highly stable nanoparticles were easily obtained by combining green tea aqueous extracts and ultrasound irradiation for 2 min. The as-synthesized AgNPs, spherical in shape and with average size of 8.5 nm, were evaluated for determination of tetracycline by following the changes on the localized surface plasmon resonance band at 450 nm induced by the presence of this antibiotic at pH 5.8. The method was successfully applied in the concentration range between 200 and 800 μg L^-1 with R²  > 0.996 and limit of detection of 52.7 μg L^-1 . Multiple honey samples were analyzed, and the recovery values obtained ranged between 82.8% and 116%, with relative standard deviation values lower than 6.69%.

CONCLUSION

The results obtained demonstrate that the AgNPs synthesized using just green tea extracts represent a promising and sustainable alternative tool for the cost-effective determination of tetracycline antibiotics in honey. © 2021 Society of Chemical Industry.

Characteristics and upregulation of antioxidant enzymes of kitchen mint and oolong tea kombucha beverages

Kombucha is a healthy traditional beverage which is made by fermenting products with a symbiotic culture of acetic acid bacteria and yeasts. In present study, leaves of kitchen mint (Mentha cordifolia Opiz. Ex Fresen) and leaves of oolong tea (Camellia sinensis) were fermented in kombucha formula. After fermentation, titratable acidity contents and ethanol of kitchen mint, oolong tea, and mixtures of oolong tea and kitchen mint kombucha samples gradually increased with a period of fermentation time. At day 14 of fermentation, phenolic compounds and flavonoids were increased in all kombucha samples. The numbers of acetic acid bacteria and yeast in kombucha had gradually raised during 7-14 days of fermentation. DPPH and ABTS scavenging activities of these kombucha increased over a period of fermentation time and shown the highest antioxidant capacity on day 14 of fermentation. In addition, all kombucha samples exhibited the antioxidant effects by attenuating H₂ O₂ -induced ROS production, increasing mRNA expression of catalase, glutathione reductase (GRe), and Mn-SOD, and inducing GRe enzymatic activity in HEK-293 cells. Kombucha beverage can be used as the healthy beverages for attenuation of oxidative stress in many diseases.

Effect of freezing treatment in tea preparation using Camellia sinensis leaves

This study was conducted to examine the effect of freezing in the tea preparation using Camellia sinensis leaves in order to develop new technology for improving tea quality. Effects of single and combined treatments of freezing (F: - 20 °C, 15 days), steaming (S: 100 °C, 3 min), and hot-air drying (HD: 50 °C, 12 h) on the physicochemical characteristics of tea (powder and hot-water leachate) prepared from treated Camellia sinensis leaves were investigated. The L ^* , b ^* , and C ^* values of the powder were the highest in SHD-treated leaves, followed by HD-, SFHD-, and FHD-treated leaves. Redness (+a ^* value) was only seen in FHD-treated leaves and greenness (- a ^* value) was the highest in SHD-treated leaves. Browning index of the leachate was significantly lower in SHD- and SFHD-treated leaves than in FHD-treated leaves (p < 0.05). Soluble solids, acidity, and phenolic compounds of FHD-treated leaves were significantly lower than in SHD- and SFHD-treated leaves (p < 0.05). Sucrose was highest in SHD-treated leaves and glucose was highest in FHD-treated leaves. Sensory preference was better evaluated in FHD-treated leaves than in SHD- and SFHD-treated leaves. These results suggest that freezing treatment in tea processing promotes browning and component decomposition and enhances sensual preference. Therefore, freezing has a potential application in the tea manufacturing.

Residue reduction and risk evaluation of chlorfenapyr residue in tea planting, tea processing, and tea brewing

The chlorfenapyr residues in the entire tea chain, i.e., in tea planting, tea processing, and tea brewing, were systematically investigated. The degradation rate constants of chlorfenapyr in the tea plants ranged from 0.2460 to 0.2870 with the half-life of 2.4-3.0 days, and 87.5-89.9% of the chlorfenapyr in tea shoots dissipated in the interval of 7 days. In the processing process of both black tea and green tea, the chlorfenapyr residue decreased by 59.1-67.6% compared with the residue in tea shoots due to high vapor pressure (1.2 × 10^-2 mPa 25 °C), and drying was the key step that dissipated the chlorfenapyr. A low leaching efficiency of 2.2-3.4% from tea leaves to tea infusion, resulted in low water solubility (0.14 mg L^-1 25 °C), indicated that >90% of the residual chlorfenapyr was eliminated before the intake of tea infusion. On the basis of these results, an extremely large proportion of the chlorfenapyr deposited on tea shoots was degraded during tea planting, tea processing, and tea brewing, and the health risk was reduced primarily in the first and the last step rather than during tea processing. The remaining 0.2% chlorfenapyr sprayed on the tea shoots represents a negligible health risk based on the RQ assessment. The pesticides with high vapor pressure and low water solubility were more recommended in tea garden for pest control.

Effect of brewing conditions using a single-serve coffee maker on black tea (Lapsang Souchong) quality

Black tea powder was used to make tea infusion using a Keuring coffee maker. Effect of tea particle size (0.30 or 0.60 mm), water volume for brewing (118, 177, or 236 ml), and the amount of tea powder (1.0, 1.5, or 2.0 g) on tea infusion quality were evaluated. The concentration of four chemical compounds (soluble sugars, total amino acids, polyphenols, and caffeine) in tea infusion was measured. In general, the concentration of the four compounds in tea infusion increased with the amount of tea powder used and decreased with increasing water volume and tea particle size. Using 2.0 g of 0.30 mm tea powder and 118 ml of water per brew, the concentration of the above four components was 412.3, 251.6, 208.9, and 205.3 μg/ml, respectively, and higher than tea infusion prepared by traditional method (312.4, 204.1, 211.6, and 175.9 μg/ml). The highest extraction efficiency (mg/cup.g) for the four chemical components per unit weight of tea powder was at using 1.0 g of 0.30 mm tea powder with 236 ml water for soluble sugars (32.3 μg/ml) and caffeine (16.3 μg/ml), at using 1.5 g tea powders for polyphenols (22.3 μg/ml) and at using 2.0 g tea powders for amino acid (13.6 μg/ml). This study suggested using a single-serve coffee maker can be a convenient and effective way to prepare the tea infusion with high quality.

Antiproliferative activity of green, black tea and olive leaves polyphenols subjected to biosorption and in vitro gastrointestinal digestion in Caco-2 cells

Olive (Olea europaea L.) leaves and tea (Camellia sinensis) are rich sources of bioactive compounds, especially polyphenols. Our previous studies have evidenced the potential use of Saccharomyces cerevisiae as a natural delivery system for these antioxidants and a means to improve their bioaccessibility in the human gut. In the present work, the antiproliferative effect of green tea (GT), black tea (BT) and olive leaves (OL) infusions and suspensions of S. cerevisiae were evaluated, for the first time, in human colon cancer cells (Caco-2) after biosorption and in vitro gastrointestinal digestion. The bioaccessible fractions (BF) were not overtly cytotoxic, not affecting cell viability. ROS and mitochondrial membrane potential changes (Δψm) values were reduced compared with control cells. Moreover, all the BF after biosorption induced a significant (p < 0.05) increase in cell proportions in S-phase. The arrest of the cell cycle was reversible without induction of apoptosis, suggesting that the biosorbed phenolics in both infusions and suspensions act as cytostatic agents.

Phenolic Profiles and Antioxidant Activities of 30 Tea Infusions from Green, Black, Oolong, White, Yellow and Dark Teas

Tea is among the most consumed drink worldwide, and its strong antioxidant activity is considered as the main contributor to several health benefits, such as cardiovascular protection and anticancer effect. In this study, the antioxidant activities of 30 tea infusions, which were obtained by the mimic of drinking tea of the public, from green, black, oolong, white, yellow and dark teas, were evaluated using ferric-reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC) assays, ranging from 504.80 ± 17.44 to 4647.47 ± 57.87 µmol Fe²⁺/g dry weight (DW) and 166.29 ± 24.48 to 2532.41 ± 50.18 µmol Trolox/g DW, respectively. Moreover, their total phenolic contents (TPC) were detected by Folin-Ciocalteu assay and were in the range of 24.77 ± 2.02 to 252.65 ± 4.74 mg gallic acid equivalent (GAE)/g DW. Generally, Dianqing Tea, Lushan Yunwu Tea, and Xihu Longjing Tea showed the strongest antioxidant activities among 30 teas. Furthermore, the phenolic compounds in tea infusions were identified and quantified, with catechins most commonly detected, especially in green tea infusions, which were main contributors to their antioxidant activities. Besides tea polyphenols, considerable content of caffeine also presented in 30 tea infusions.

A Comparative Study of Antioxidant Potential and Phenolic Content in White (Silver Needle), Green and Black Tea

Background:

White, green and black are the major tea types obtained from the same tea plant (Camellia sinensis). The differences in processing result in different types of tea, of which green tea (20%) and black tea (78%) are the most consumed worldwide and also white tea is gaining popularity due to its subtle taste and recent evidences about its health benefits. Silver needle is a sub type of white tea, made purely from buds whereas green tea is procured from leaves that are steamed or panfried, and to produce black tea, the tea leaves are withered, fully oxidized and then dried.

Objective:

The present study was undertaken to analyze and compare the antioxidant activity and phenolic composition of white (silver needle), green and black teas of same brand.

Method:

The radical scavenging ability of different tea types was measured using various antioxidant assays. The total phenolic content was also estimated using Folin-Ciocalteu’s method.

Results:

The white tea (silver needle) demonstrated highest radical scavenging activity followed by green and then black tea in various antioxidant assays performed. The total phenolic content of different types of tea exhibited the following order: white tea (133.30mg/g) > green tea (118.37mg/g) > black tea (101.8mg/g). A strong correlation was observed between the total phenolic content and antioxidant activity of different tea types, the correlation coefficient ranged from 0.87-0.97.

Conclusion:

White tea (silver needle) manifested highest antioxidant activity followed by green and least in black tea. The pronounced antioxidant ability of WT (silver needle) may be ascribed to the different parts of the plant (unopened buds) and the least processing it undergoes, followed by obtaining green tea and black tea from different parts of the plant (leaves), and variation in degree of processing.

Green tea powder supplementation enhances fermentation and antioxidant activity of set-type yogurt

Yogurt is a fermented dairy food produced by growth of lactic acid bacteria (LAB). Green tea is associated with beneficial health effects. Thus, the aim of this study was to evaluate the effects of green tea powder (GTP) on the fermentation and bioactive properties of yogurt. Yogurt was supplemented with 0-3% GTP (w/v), and effects on fermentation were determined. In addition, antioxidant and anti-inflammatory effects of GTP supplemented yogurts were determined in HT-29 colon cells. GTP (1-3%) supplementation significantly increased the acidification rate and growth of LAB during yogurt fermentation. Removal of free radicals and cellular H₂O₂, and an increase of antioxidant Nrf2 and HO-1 proteins were observed in the 1-3% GTP groups. Yogurt extracts with 0-3% GTP showed decreased expression of TNF-α and IL-1β in cells. In summary, addition of GTP can enhance the beneficial health effects of yogurt by increasing its antioxidant activity, LAB growth and anti-inflammatory effects.

Effect of brewing time and temperature on antioxidant capacity and phenols of white tea: Relationship with sensory properties

White tea is highly consumed due to its sensory properties and health benefits, although most scientific reports don't include the analysis of both properties. Therefore, the objective of the present study was to unravel the best brewing conditions for optimal extraction of the bioactive compounds and antioxidant capacity, while realising the best sensory properties. Infusions of eighty commercial teas (sold in bags or leaves) were obtained at different time-temperature ratios, studying bioactive compounds (caffeine and individual catechins), antioxidant capacity and sensory analysis. Brewing at 98 °C for 7 min was the best condition to obtain a high content of antioxidant polyphenols and pleasant sensory properties. Those teas sold in bags give rise to tea brews with almost double antioxidant capacity. In conclusion, it is very important to link sensory and chemical data to obtain optimal sensorial quality and the highest healthy properties in white tea infusions.

Phytochemical profiles and antioxidant activity of 27 cultivars of tea

Tea, rich in phytochemicals, has been suggested to have human health benefits. The phenolic profiles, antioxidant and antiproliferative activities of 27 tea cultivars were determined. Wide ranges of variation were found in analyzed cultivars for the contents of water-soluble phenolics (121.6-223.7 mg/g dry weight (DW)), total catechins (TC) (90.5-177.2 mg/g DW), antioxidant activities (PSC values 627.3-2332.3 μmol of vitamin C equiv/g DW, ORAC values (1865.1-3489.3 μmol of vitamin C equiv/g DW), CAA values (37.7-134.3 μmol of QE/g DW without PBS wash and 25.3-75.4 μmol of QE/g DW with PBS wash) and antiproliferative activity (53.0-90.8% at the concentration of 400 μg/mL extracts). The PSC, ORAC and CAA values were significantly correlated with phenolics, epicatechin gallate (ECG), CC and TC. Knowledge of specific differences among tea cultivars is important for breeding tea cultivars and gives sights to its potential application to promote health.

Comparison of phytochemical profiles and health benefits in fiber and oil flaxseeds (Linum usitatissimum L.)

Flaxseed (Linum usitatissimum L.) is a rich source of nutritive and bioactive compounds. The research evaluated the disparity in phytochemical profiles along with total and cellular antioxidant activities between oil and fiber flaxseeds. There were significant differences in total phenolics, total flavonoids and antioxidant activities among the six cultivars of fiber and oil flaxseed, respectively. Four phytochemical compounds including caffeic acid, p-coumaric acid and ferulic acid, and secoisolariciresinol diglucoside (SDG) were identified and quantified in the cultivars of oil and fiber flaxseed by HPLC analysis. Notably, the average of total phenolic and flavonoid contents, along with total antioxidant activities between fiber and oil flaxseeds were not different significantly; even the cellular antioxidant activity of fiber flaxseed was superior to oil flaxseed. These results suggest that fiber flaxseeds would be valuable candidates as functional products and dietary supplements production owing to the higher bioactive values as well as oil flaxseeds.

Combination of Antioxidants from Different Sources Could offer Synergistic Benefits: A Case Study of Tea and Ginger Blend

Tea and ginger are plants with high antioxidant potential. Combinations of antioxidants from different sources could also produce synergistic antioxidant effects. This study investigated the influence of solvent on antioxidant content of tea, ginger, and tea + ginger blends. Under the investigated extraction conditions, water was the most effective extraction solvent to maximise peroxide scavenging and iron chelating activity of tea, ginger, and their blends. Aqueous ethanol was the most effective solvent to maximise ABTS radical scavenging activity and ethanol was the best solvent to maximise DPPH radical scavenging activity. A good multivariate regression model that explains the relationship between the total flavonoid content of the extracts and their antioxidant activities was obtained (R2 and Q2 of 0.93 and 0.83, respectively). Extracts of tea-ginger blends exhibited synergistic effects in their ABTS and DPPH radical scavenging activity.

Effects of alternative steeping methods on composition, antioxidant property and colour of green, black and oolong tea infusions

Cold water steeping is reported to maximise tea health benefits, but requires long infusion time. In this work, the employment of a brief hot infusion step followed by ice addition was evaluated. The comparison of this innovative method with hot and cold steeping was investigated on green, black and oolong teas. Catechins, xanthines and gallic acid content, antioxidant power, total phenolics and colour analysis were evaluated. Hot infusion shown rapid extractive power, but relevant compound degradation. On the contrary, cold infusion extracted higher level of healthy molecules with slow kinetic. The innovative method achieved in short time similar properties of cold infusion in terms of antioxidant power. As for bioactive compounds, such as gallic acid and epigallocatechin gallate, highest values, about double than in hot infusion, were recorded for green and black teas. This steeping method may represent an alternative approach for industrial beverage preparation.

Spatial variability of theaflavins and thearubigins fractions and their impact on black tea quality

The spatial distribution of theaflavin and thearubigin fractions and their impact on black tea quality were investigated using multivariate and geostatistics techniques. Black tea samples were collected from tea gardens of six geographical regions of Assam and West Bengal, India. Total theaflavin (TF) and its four fractions of upper Assam, south bank and North Bank teas were higher than the other regions. Simple theaflavin showed highest significant correlation with tasters' quality. Low molecular weight thearubigins of south bank and North Bank were significantly higher than other regions. Total thearubigin (TR) and its fractions revealed significant positive correlation with tasters' organoleptic valuations. Tea tasters' parameters were significantly and positively correlated with each other. The semivariogram for quality parameters were best represented by gaussian models. The nugget/sill ratio indicated a strong/moderate spatial dependence of the studied parameters. Spatial variation of tea quality parameters may be used for quality assessment in the tea growing areas of India.

Concentrated green tea supplement: biological activity and molecular mechanisms

AIM

This study was undertaken to determine the biological activity of a green tea supplement with respect to cells and erythrocyte membranes and the molecular mechanism of that activity.

MAIN METHODS

The extract's activity was evaluated on the basis of its hemolytic, antioxidant and antiinflammatory actions. In addition, the extract's effect on the physical properties of the erythrocyte membrane was examined. We also conducted a detailed analysis of supplement ingredients using high-yield liquid chromatography, supplemented with standard tests of total content of polyphenols and flavonoids in the supplement.

KEY FINDINGS

The study showed that green tea extract has a high antioxidant and anti-inflammatory capacity with no deleterious effect on red blood cells. The extract modifies the physical properties of the erythrocyte membrane, apparently by binding to its hydrophilic region, with consequent rigidity of the hydrophobic region, increased hydration and a moderate increase in its resistance to changes in tonicity of the medium. Because the extract's components anchor in the polar region of membrane lipids, they are able to effectively scavenge free radicals in the immediate vicinity of the membrane and hinder their diffusion into its interior.

SIGNIFICANCE

Green tea supplement at concentrations markedly exceeding the blood plasma physiological polyphenol concentrations has no destructive effect on the erythrocyte membrane. Due to the high content of flavan-3-ols, the supplement exhibits high biological activity, which makes it an alternative source of those substances to the commonly used infusion of green tea leaves.

Black tea increased survival of Caenorhabditis elegans under stress

The present study examined the effects of black tea (Camellia sinensis) extracts (BTE) in Caenorhabditis elegans under various abiotic stressors. Results showed BTE increased nematode resistance to osmosis, heat, and UV irradiation treatments. However, BTE could not increase nematodes' lifespan under normal culture conditions and MnCl2-induced toxicity at concentrations we used. Further studies showed that BTE decreased reactive oxygen species and up-regulated some antioxidant enzymes, including GSH-PX, and genes, such as gsh-px and sod-3. However, only a slight extension in mev-1 mutants mean lifespan was observed without significance. These results indicated that the antioxidant activity of BTE might be necessary but not sufficient to protect against aging to C. elegans. Moreover, BTE increased the mRNA level of stress-response genes such as sir-2.1 and sek-1. Our finding demonstrated BTE might increase heat and UV stress resistance in a sir.2.1-dependent manner. Taken together, BTE enhanced stress resistance with multiple mechanisms in C. elegans.

Phytochemical profiles and antioxidant activities in six species of ramie leaves

Increased consumption of vegetables or plant food has been associated with decreased risk of developing major chronic diseases, such as cancers, diabetes, cardiovascular diseases, and age-related functional decline. Ramie leaves are rich in phenolics and flavonoids, which have been suggested for human health benefits. Phenolic contents, flavonoid contents, phenolic compounds, and anti-cancer properties in six species of ramie leaves were analyzed by Folin-reagent method, sodium borohydride/chloranil-based assay (SBC), HPLC method and antiproliferation, cytoxicity, respectively. Antioxidant activities were measured through peroxyl radical scavenging capacity (PSC) method, oxygen radical absorbance capacity (ORAC) method, and cellular antioxidant activity (CAA). Research indicated that Boehmeria penduliflora contained the highest total phenolic content (2313.7±27.28 mg GAE/100 g FW), and flavonoid content (1682.4±27.70 mg CAE/100 g FW). Boehmeria tricuspis showed the highest PSC value (9574.8±117.63 µM vit. C equiv./100 g FW), while Boehmeria penduliflora indicated the highest ORAC value (330.44±16.88 µmol Trolox equiv./g FW). The antioxidant activities were correlated with phenolic contents and flavonoid contents. Boehmeria tricuspis had the highest antiproliferative capacity with the lowest EC₅₀ (4.11±0.19 mg/mL). The results for the analyzed ramie for CAA were significantly different from each other (p<0.05), Boehmeria tricuspis had the highest CAA value (133.63±7.10 µmol QE/100 g). Benzoic acid, 4-coumaric acid, caffeic acid, and ferulic acid were the dominant phenolic ingredients in the ramie leaves according to HPLC analysis. Our research is the first report to study the phytochemical profiles and antioxidant activities in different species of ramie leaves for their health benefit.

Effects of season and plantation on phenolic content of unfermented and fermented Sri Lankan tea

The effects of season and plantation on the polyphenol content of Camellia sinensis (tea) leaves were determined. Aqueous and organic extracts of freeze-dried fresh (unfermented) and black (fully-fermented) tea leaves were prepared for a structured set of samples (fermented and unfermented teas from six high-, mid- and low-grown plantations; fermented and unfermented teas from two harvesting seasons from four highland plantations), collected from the main tea-growing regions in Sri Lanka. Total catechin content and amounts of individual catechins, flavonols and theaflavins were determined by HPLC. Mean values for the phenolic constituents were generally significantly higher (p<0.05) with solvent extraction. The mean values for total catechins, total flavonols and caffeine in the aqueous extracts from unfermented teas were 10.6%, 1.5% and 2.9%, respectively. For both unfermented and fermented tea leaves, a significant (p<0.05) interaction between plantation and season was observed for phenolic constituents. Ferric reducing antioxidant power was positively (p<0.05) correlated with (-)-epicatechin gallate and total phenolic contents.

Modeling the antioxidant capacity of red wine from different production years and sources under censoring

The health benefit of drinking wine, expressed as capacity to defend the human organism from the free radicals action and thus reducing the oxidative stress, has already been demonstrated, and the results had been published in scientific literature. The aim of our study was to develop and assess a model able to estimate the antioxidant capacity (AC) of several samples of Romanian wines and to evaluate the AC dependency on the vintage (defined as the year in which wine was produced) and grape variety under presence of censored data. A contingency of two grape varieties from two different vineyards in Romania and five production years, with some missing experimental data, was used to conduct the analysis. The analysis showed that the antioxidant capacity of the investigated wines is linearly dependent on the vintage. Furthermore, an iterative algorithm was developed and applied to obtain the coefficients of the model and to estimate the missing experimental value. The contribution of wine source to the antioxidant capacity proved equal to 11%.