Increasing the antioxidant power of tea extracts by biotransformation of polyphenols

Green tea (Camellia sinensis) and yerba mate (Ilex paraguariensis) are rich in polyphenolic compounds, which are thought to contribute to the health benefits of tea. The aim of this study was to evaluate the potential antioxidant properties of green tea and yerba mate extracts before and after the enzymatic biotransformation reaction catalysed by the Paecilomyces variotii tannase. The antiradical properties of the tea extracts, as well as the standards of chlorogenic acid and EGCG, were assessed using the ORAC and DPPH assays before and after the tannase biotransformation. The antioxidant power of enzyme-treated green tea and yerba mate increased by 55% and 43%, respectively, compared with that of untreated teas. The antioxidant power of the standards was also highly increased by enzyme treatment. These results provide relevant data about the potential of the tannase application on various polyphenol sources and to increase the antioxidant power of two widely consumed beverages.     

Effects of extraction solvents on concentration and antioxidant activity of black and black mate tea polyphenols determined by ferrous tartrate and Folin–Ciocalteu methods

Effect of the use of water and different organic solvents such as acetone, N,N-dimethylformamide (DMF), ethanol or methanol at various concentrations on the total polyphenol content and antioxidant activity was studied for the black tea and mate tea. Polyphenol contents of extracts were determined using ferrous tartrate (method # 1) and Folin–Ciocalteu (method # 2) assays. For black tea, 50% DMF extract showed the highest polyphenol content of 131.9 mg/g and 99.8 mg GAE/g by method # 1 and method # 2, respectively. For mate tea, 50% acetone showed the highest polyphenol content of 132.5 mg/g and 120.4 mg GAE/g by method # 1 and method # 2, respectively. Fifty percent ethanol extract from mate tea and 50% acetone from black tea had the greatest antioxidant activity. The results showed that solvent with different polarity had significant effect on polyphenol content and antioxidant activity. A high correlation between polyphenol content and antioxidant activity of tea extracts was observed.     

Comparison of the Antioxidant Properties of Commonly Consumed Commercial Teas

The antioxidant properties of various commonly consumed commercial teas were screened and compared to check what the consumers get in commercial tea bags in the range of consume preparation conditions. It includes flavored black teas and green teas, as well as some fruit teas. Electron transfer-based assays, such as phenolic content by Folin-Ciocalteu method and cupric ion reducing antioxidant capacity (CUPRAC), were applied. Higher antioxidant activity values were obtained for green and black tea infusions in comparison to fruit teas. The correlation between FC total phenolic and CUPRAC assay for all studied teas was significant (R² = 0.871). The antioxidant power of tea infusions were also measured using cyclic voltammetry. The observed anodic waves were broadened in comparison with voltammograms of single flavonoids due to the response of several antioxidants with different oxidation potentials. The values of Trolox equivalents obtained by electrochemical approach were lower than in the CUPRAC assay; however, the increased order of the antioxidant capacity of tea infusions was the same.     

Mechanism of the interaction between insoluble wheat bran and polyphenols leading to increased antioxidant capacity

This study aimed to provide an in-depth investigation of the interaction between insoluble wheat bran and polyphenols. Treatment with tannic acid, but not gallic acid, increased the bound antioxidant capacity of insoluble wheat bran depending on its aqueous concentration (p < 0.05). Among the beverages tested (white and red wines, black and green tea infusions), treatment with green tea infusion caused the highest increase in the total antioxidant capacity. Temperature, time, air and pH were found to significantly affect the reaction between insoluble wheat bran and polyphenols. The bound antioxidant capacity of insoluble bran increased to above 100 mmol TE.kg^− 1 after treatment with green tea infusion at optimum conditions (50 °C, pH 9.0, no airflow). Concentration of free amino groups available in wheat bran significantly decreased (59.5%) after the treatment. The results suggested that polyphenols are oxidized to quinones under alkaline conditions further bound to free amino groups available on the surface of wheat bran.     

Analysis of Antioxidant Activity,Chlorogenic Acid,and Rutin Content of Camellia sinensis Infusions Using Response Surface Methodology Optimization

Optimization of the extraction process of green tea using response surface methodology (RSM) was performed. The optimized conditions were 14.91 min and 94.15 °C (2,2-diphenyl-1-picrylhydrazyl (DPPH) assay). The experimental values were close with the predicted values. The procedure was used to measure antioxidant activity using DPPH free radical and phenolic compounds of all types of Camellia sinensis and Tabebuia impetiginosa infusions. The antioxidant activity of infusions was in the order (mean for analyzed types) of pure green tea > white tea > green tea with additives > black tea = Pu-erh tea > semifermented tea > Red Lapacho. After the fermentation process, the content of rutin is lowered and the amount of gallic acid in infusions is increased. A negative correlation between total phenolic acids and organic acids was also observed (R ²?=?0.6437). Red Lapacho infusion contains phenolic acids such as caffeic, protocatechuic, p-coumaric, ferulic, and syringic. No rutin and quercetin were found in this beverage.     

Comparison of the effects of black and green tea on in vitro lipoprotein oxidation in human serum

Lipoprotein oxidation is a process thought to be involved in atherogenesis. Dietary antioxidants that prevent or inhibit oxidative damage to lipoproteins may help to prevent atherosclerosis. Both black and green teas can be major dietary sources of flavonoids and other phenolics with antioxidant activity. Results of previous studies suggest that green tea may have a greater antioxidant potential than black tea. The aim of this study was to assess and compare the effects of black and green tea on in vitro lipoprotein oxidation. The tea extracts were prepared using a method similar to that used to prepare infusions of tea for drinking. Antioxidant activities of seven black teas and four green teas were assessed using an in vitro assay that measures Cu²⁺ ‐induced oxidation of lipoproteins in human serum. All tea extracts inhibited in vitro lipoprotein oxidation in human serum to a similar extent. No significant difference in antioxidant activity was found between black and green tea. Caffeine prepared to a comparable concentration to that found in tea had no effect on lipoprotein oxidation. Further studies are required to determine the importance of these findings in relation to possible protective effects of black and green tea consumption against atherogenesis and cardiovascular disease. © 1999 Society of Chemical Industry     

The effect of the duration of infusion,temperature, and water volume on the rutin content in the preparation of mate tea beverages: An optimization study

The consumption of tea beverages has increased 30% over the last decade, mainly due to the presence of bioactive compounds. Mate tea, produced by infusing the leaves and stems of Ilex paraguariensis, is the most widely consumed beverage in Brazil. The present study employed a central composite experimental design to optimize the transfer of rutin from the leaves and stems to the beverage during the infusion process. The optimum condition was applied to three batches of mate tea beverages from five commercial samples. Analysis of the rutin content was performed by high performance liquid chromatography coupled to a photo diodo array detector. The maximum rutin content in the beverage was obtained when the infusion was performed using 2 g of mate tea added to 100 mL of water at 72 °C and infused for 9 min. The commercial tea beverages prepared under these conditions contained from 0.16 to 1.1 mg of rutin in the ready-to-drink product.     

Screening of the most consumed beverages and spices for their bioactive non-nutrient contents

The present research emphasizes on the bioactive non-nutrient components of the frequently consumed food products daily. The most popular beverages (instant, filter and Turkish coffee, green, black, sage, apple, rosehip, linden and fennel tea infusions) and herbal spices (cinnamon thyme, cumin, mint, sweet pepper, chili pepper, sumac, black pepper and clove) were investigated to evaluate the antioxidant capacities of the samples. Amount of total biophenols (TB) and total flavonoids (TF) were measured by Folin–Ciocalteu and Aluminum chloride colorimetric methods, respectively. CUPRAC (The cupric ion reducing antioxidant capacity) assay and DPPH (α, α-diphenyl-β-picrylhydrazyl) free radical scavenging method were applied to determine the antioxidant activity (AA) of the products. Antimicrobial analyses of the samples were also conducted based on in vitro study. Furthermore, the main biophenol of each sample was identified through high performance liquid chromatography (HPLC). The outcome of the present study will be a useful guidance for the researchers looking for the health benefits of these daily consumed food products.     

Antimicrobial activity of olive oil, vinegar, and various beverages against foodborne pathogens

The survival of foodborne pathogens in aqueous extracts of olive oil, virgin olive oil, vinegar, and several beverages was evaluated. Vinegar and aqueous extracts of virgin olive oil showed the strongest bactericidal activity against all strains tested. Red and white wines also killed most strains after 5 min of contact, black and green tea extracts showed weak antimicrobial activity under these conditions, and no effect was observed for the remaining beverages (fruit juices, Coca-Cola, dairy products, coffee, and beer). The phenolic compound content of the aqueous olive oil and virgin olive oil extracts could explain their antibacterial activity, which was also confirmed in mayonnaises and salads used as food models. Virgin olive oil in mayonnaises and salads reduced the counts of inoculated Salmonella Enteritidis and Listeria monocytogenes by approximately 3 log CFU/g. Therefore, olive oil could be a hurdle component in certain processed foods and exert a protective effect against foodborne pathogens when contaminated foods are ingested.     

Temperature and Time of Steeping Affect the Antioxidant Properties of White,Green, and Black Tea Infusions

Tea (Camellia sinensis) is the most highly consumed beverage in the world next to water. The common way of preparation is steeping in hot water which is varying for different type of tea. We investigated the antioxidant properties of 6 type of tea leaves under different time and temperatures of extraction method used. In general, all samples tested in this study demonstrated high levels of antioxidant capacity and antioxidant activity. The results indicate that the antioxidants activity is significantly affected by time and temperature of steeping and the highest was depending on the variety. White state values, green and black teas showed different levels of antioxidants under different extraction conditions. Overall, the highest activity for white tea was in prolonged hot and in some assays prolonged hot and cold extracts, whereas for green tea the highest activity observed in prolonged cold steeping while, for black tea was in short hot water infusion. The results of this study showed the antioxidant capacity of white and green tea was greater than black tea.     

Use of the Attenuation of Luminol-Perborate Chemiluminescence with Flow Injection Analysis for the Total Antioxidant Activity in Tea Infusions,Wines, and Grape Seeds

This study establishes a simple and fast flow injection analysis methodology for the determination of the antioxidant activity in wines, tea infusions, and grape seeds, based on the inhibition effect of their natural antioxidants on the Co(II)/EDTA-induced luminol-perborate chemiluminescence. At the optimum operational conditions, the antioxidant activity was measured by plotting the inhibition percentage vs logarithm of sample mass to calculate the IC₅₀ (mass of sample needed to reduce in 50% the chemiluminescence in absence of the antioxidant). The method was examined with pure phenolic compounds for the purpose of relating the molecular structure with the response of the method, and then with the composition of tea infusions, wines, and grape seeds on the antioxidant activity. The results revealed that the white and green tea samples and the red wine had a stronger antioxidant activity because these showed smaller IC₅₀. Results showed good agreement with the total biophenolic content determined by the Folin-Ciocalteu method.     

凤凰单枞乌龙茶抗氧化特性研究

本文研究了凤凰单枞乌龙茶、绿茶(龙井和碧螺春)以及红茶(滇红和英德红茶)水浸出物的抗氧化特性。结果表明凤凰单枞乌龙茶具有较多的水浸出物,并富含茶多酚、氨基酸、可溶性糖;同时表现出较高的DPPH、超氧阴离子和羟自由基清除能力和抑制油脂过氧化特性,与绿茶水浸出物的抗氧化能力相似,显著高于红茶。这与凤凰单枞乌龙茶的水浸出物中存在较高含量的茶多酚、茶黄素和茶红素,特别是与其中的儿茶素类密切相关。     

Toxicological and biochemical effects of different beverages on human intestinal cells

The objective of the present study was to examine and compare the effects of frequently consumed beverages on the human intestinal cell line, Caco-2, in terms of toxicity, growth, and differentiation. For this purpose, Caco-2 cells were incubated for 24 h in the presence of: a mineral water, fresh orange juice, packaged orange juice, a cola drink, an energy drink, black, camomille, and green teas, and drip coffee. Toxicity was evaluated firstly by measuring the lactate dehydrogenase leakage from the cells and secondly by performing the MTT assay. Cell differentiation was determined by measuring two brush border membrane enzyme activities. Growth rates of Caco-2 cells were evaluated by cell counting. The results indicated that there were no significant differences between the beverages in toxicity and cell proliferation. Cells exposed to fresh orange juice exhibited higher tetrazolium reduction rates in the MTT assay (121.3% of control). These cells also showed higher succinate cytochrome c reductase activities than the other samples, implying that the contents of fresh orange juice, such as ascorbic acid, stimulated mitochondrial metabolism. The alkaline phosphatase and aminopeptidase N activities of the Caco-2 cells lay between 61.50 and 110.00%, indicating a partial influence of some beverages on Caco-2 differentiation.     

Total content and speciation of aluminium in tea leaves and tea infusions

A total of 29 tea samples of different origin, 13 green tea samples, 13 black tea samples, two semi-fermented and one white tea, imported to the Czech Republic, were collected and analysed for total content of aluminium (Al) in tea leaves and tea infusions, as well as for Al compounds in these infusions. The total content of metals in tea leaves differs according to the type of tea (green or black) and is probably influenced by many factors, e.g., soil properties. The HPLC/IC speciation of Al in tea infusions was performed for all samples. The addition of Al³⁺ to the tea infusion proved that Al³⁺, Al(Y)²⁺ and Al(X)¹⁺ species can be determined in tea infusions. Increased extraction time did not show any affect on Al speciation, neither did the addition of sugar. After the addition of lemon juice, the speciation changed in one sample of black tea and five samples of green tea. These findings suggest that lemon juice as an additive can significantly influence Al speciation in tea infusions.     

Aqueous extracts of yerba mate (Ilex paraguariensis) as a natural antimicrobial against Escherichia coli O157:H7 in a microbiological medium and pH 6.0 apple juice

Ilex paraguariensis is popularly used in the preparation of a tea infusion (yerba mate), most commonly produced and consumed in the South American countries of Uruguay, Paraguay, Argentina, and Brazil. In this study, aqueous extracts of commercial tea, derived from the holly plant species I. paraguariensis were evaluated for their ability to inhibit or inactivate Escherichia coli O157:H7 in a microbiological medium and modified apple juice. Dialyzed, lyophilized aqueous extracts were screened for antimicrobial activity against E. coli O157:H7 strains ATCC 43894 and 'Cider' in tryptic soy broth (TSB) and apple juice (adjusted to pH 6.0 to allow for growth of the bacterium). A mixture of the two strains was used as the inoculum when apple juice was used as the medium. MBCs were determined to be ca. 5 and 10 mg/ml for ATCC 43894 and 'Cider', respectively, in TSB. Higher concentrations of the extract were required to inactivate E. coli O157:H7 in pH-adjusted apple juice. An approximate 4.5-log reduction was observed for E. coli O157:H7 treated with 40 mg/ml extract. It was concluded that aqueous extracts from commercial yerba mate have potential to be used as antimicrobials in foods and beverages against pathogenic E. coli O157:H7.     

Retardation of lipid oxidation in blue sprat by hot water tea extracts

The blue sprat is a small fish belonging to the family Clupeidae. Deterioration of its freshness after catching is so rapid that the fish is cooked in simple ways and consumed locally. The prooxidant activity of the skin, dark meat and ordinary meat was much higher than that of other fishes such jack mackerel. Suppression of lipid peroxidation in blue sprat was attempted using hot‐water extracts of five types of Taiwanese tea with different degrees of fermentation, ie Longjing‐type green tea, Shy Jih Chuen oolong tea, Tungting oolong tea, Pouchong tea and black tea. All the tea extracts showed antioxidant activity on oxidation of linoleic acid induced by the extracts of blue sprat's tissues. The antioxidant activity of each tea extract showed a positive correlation with the contents of total catechins, especially with that of epigallocatechin gallate, but a poor correlation with the contents of total polyphenols. The Tungting oolong tea together with Chinese green tea effectively suppressed the prooxidant activities of the dark meat and skin of blue sprat. Impregnation of blue sprat in the extract of the Tungting oolong tea retarded the lipid oxidation in fish meat assessed by peroxide value and carbonyl value during refrigeration. Copyright © 2005 Society of Chemical Industry     

Tea flavonoids: their functions,utilisation and analysis

The three main categories of tea: green, black and oolong, result from different processing procedures. In recent years tea has attracted more and more attention because of reported health benefits, in particularly as an antioxidant, but also as an anticarcinogenic and antiarteriosclerotic agent. It is generally believed that flavonoids are mainly responsible for these actions. Tea is now consumed throughout the world not just as a popular beverage, but, because its extracts have been prepared in a variety of physical forms, for example, strong infusions, soft extracts and powders, it is now widely available in a range of food, beverage, and toiletry and cosmetic products.     

Influence of starter cultures on the antioxidant activity of kombucha beverage

This paper investigates the influence of starter cultures, obtained from kombucha isolates, on the antioxidant activity of kombucha beverages. Three starter cultures were used as follows: (1) mixed culture of acetic bacteria and Zygosaccharomyces sp. (SC1); (2) mixed culture of acetic bacteria and Saccharomyces cerevisiae (SC2); as well as (3) native local kombucha. The starter cultures were added to black and green tea sweetened with 7% of sucrose. Fermentation was carried out at 28 °C for 10 days. Antioxidant activity to hydroxyl and DPPH radicals was monitored. Kombucha beverage on black tea has shown the highest antioxidant activity to both types of radicals with starter SC1, while the green tea beverage has shown the highest activity with native kombucha. The main reason for the different antioxidant activities, beside tea composition, was ascribed to differing production of both vitamin C and total organic acids in the investigated systems.     

Caffeoylquinic acid derived free radicals identified during antioxidant reactions of bitter tea (Ilex latifolia and Ilex kudincha)

In order to provide some insight into the chemical basis for the antioxidant behaviour of bitter tea, the Chinese medicinal beverage derived from leaves of Ilex kudincha or Ilex latifolia, free radicals generated during the oxidation of aqueous extracts of dried leaves have been investigated by electron paramagnetic resonance (EPR) spectroscopy. With both beverages, the major components in the EPR spectra after accelerated autoxidation under alkaline conditions or oxidation with the superoxide anion radical were comparable to those derived from reactions of caffeoylquinic acids. Thus these reaction products have sufficient stability for biological activity, and the present results suggest that such molecules contribute appreciably to the antioxidant chemistry of these beverages.     

The composition of polyphenols and methylxanthines in teas and herbal infusions

The popularity of tea is increasing on the global aspect because of its role as a significant source of phenolic compounds in human diet. The purpose of this study was to determine and compare the phenolic and methylxanthine composition as well as the antioxidant capacity of white, green, Oolong and black teas, and chamomile and linden infusions depending on the extraction conditions (water temperature and multiple extractions). The content of total phenols and total flavonoids in teas and herbal infusions was determined by using UV/vis spectrophotometric methods, whilst individual polyphenols (phenolic acids and flavan-3-ols) and methylxanthines were identified and quantified by using high performance liquid chromatography coupled with photodiode array detection. In order to determine the antioxidant capacity of teas the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging assays were applied. The highest content of phenolic compounds was determined in green tea, which also demonstrated the highest antioxidant capacity, whilst herbal infusions were characterised with the lowest content of phenolic compounds, as well as the lowest antioxidant capacity. The highest content of caffeine, as the most abundant methylxanthine, was determined in black tea. Extraction at 100 °C is the most effective to extract the highest content of polyphenols and methylxanthines in all studied teas.