Tea Chemistry

Harbowy, Matthew E.; Balentine, Douglas A.; Davies, Alan P.; Cai, Yuzhi

doi:10.1080/07352689709701956

Cited by 454 publications

(178 citation statements)

References 222 publications

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“…54 Therefore, any health effects of tea may have important public health implications. Certainly, epidemiological data suggest that tea consumption is associated with decreased risk of cardiovascular disease.…”

Section: Duffy Et Al Tea Effects On Platelet Aggregationmentioning

confidence: 99%

Effect of Acute and Chronic Tea Consumption on Platelet Aggregation in Patients With Coronary Artery Disease

Duffy

Vita

Holbrook

et al. 2001

ATVB

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Abstract-Epidemiological studies suggest that tea consumption is associated with a decreased risk of cardiovascular events, but the mechanisms of benefit remain undefined. Platelet aggregation is a precipitating event in cardiovascular disease, and tea contains antioxidant flavonoids that are known to decrease platelet aggregation in vitro. To test the effect of tea consumption on platelet aggregation, we randomized 49 patients with coronary artery disease to either 450 mL of black tea or water consumed initially, followed by 900 mL of tea or water daily for 4 weeks in a crossover design. Ex vivo platelet aggregation in platelet-rich plasma was assessed in response to ADP and thrombin receptor-activating peptide at baseline and 2 hours and 4 weeks after beverage consumption. We observed dose-dependent platelet aggregation in response to each agonist, and neither relation was altered by acute or chronic tea consumption. Plasma flavonoids increased with acute and chronic tea consumption, indicating adequate absorption of tea flavonoids. In conclusion, these results demonstrate that acute and chronic black tea consumption does not affect ex vivo platelet aggregation in patients with coronary artery disease. These findings suggest that an effect of tea flavonoids on platelet aggregation is unlikely to be the explanation for the reduction in risk of cardiovascular events noted in epidemiological studies. Key Words: platelet aggregation Ⅲ tea Ⅲ flavonoids Ⅲ coronary artery disease R ecent epidemiological studies strongly suggest an inverse relationship between tea consumption and cardiovascular disease risk, 1-5 with 1 notable exception. 6 There is also convincing evidence that dietary intake of antioxidant flavonoids from tea and other sources (eg, red wine, onions, apples, and broccoli) is associated with reduced cardiovascular risk. [1][2][3][4][5][7][8][9] The benefit of high flavonoid intake may be greater for individuals with established coronary artery disease (CAD), 1,10 although favorable effects have also been demonstrated in people without evidence of atherosclerosis. 5,8,9 One proposed mechanism for the apparent benefit of tea and other sources of flavonoids is their favorable effect on platelet aggregation. [11][12][13][14][15][16] These polyphenols may inhibit platelet aggregation by a number of different mechanisms, including inhibition of lipoxygenase, cyclooxygenase, 13,17 cAMP phosphodiesterase, 12,18 and cGMP phosphodiesterase. 19 Other platelet-inhibitory effects of flavonoids include thromboxane receptor antagonism, 15 scavenging of reactive oxygen species such as superoxide anion, 20 decreasing phospholipase C activation by blunting hydrogen peroxide production, 21 and inhibition of lipid peroxidation. 14 Flavonoids also enhance nitric oxide (NO) production from the endothelium. 22 NO is a potent inhibitor of platelet adhesion, aggregation, [23][24][25] and thrombosis, 26 and impaired platelet production of NO has been associated with acute coronary syndromes. 27 A recent study demonstrated dose-...

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Section: Duffy Et Al Tea Effects On Platelet Aggregationmentioning

confidence: 99%

Effect of Acute and Chronic Tea Consumption on Platelet Aggregation in Patients With Coronary Artery Disease

Duffy

Vita

Holbrook

et al. 2001

ATVB

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“…Instrumental techniques can be used to analyze changes in physicochemical parameters including color, pH, and turbidity as well as microbial activity (Brown 2011). Consumer acceptance and preference sensory test have been used as essential tools to evaluate the sensory attributes of new products as well as to ensure that the optimal final product formula has been achieved (Lawless and Heymann 2010;Fuller 2011). …”

Section: Introductionmentioning

confidence: 99%

Protein-rich beverage developed using non-GM soybean (R08-4004) and evaluated for sensory acceptance and shelf-life

et al. 2016

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Protein beverages have been in demand due to an increasing consumers' interest in healthy eating habit. However, there is an increased concern on the use of genetic modified (GM) ingredient in the food product. This study aimed to develop protein hydrolysate beverages using a non-GM soybean (R08-4004/high protein line) grown in Arkansas. Protein isolate was prepared from the soybean using alkaline method (pH 9.5). Due to its poor solubility in acidic condition, alcalase 2.4 L (food grade protease) hydrolyzed soy protein was used to develop a beverage containing 20 g protein per serving (500 mL). Three flavored beverages: Chai tea (C), tangerine (T), and mixed berries (MB) were prepared using bitter blocker, masking agent, and citric acid to minimize an unpleasant bitter taste developed in the soy hydrolysates. Protein solubility, pH, microbial growth, instrumental color parameters, and turbidity were measured to evaluate the shelf-life stability of the beverages at refrigerated storage (5°C) for 42 days. Beverages T and MB received overall highest scores from the sensory panel. Citric acid alone or in combination with bitter blocker or masking agent lowered the bitterness. Pasteurization (90-95°C for 5 min) was effective in preventing microbial growth. Although pH remained constant, decrease in protein solubility and color changes were observed over the storage time in all the three flavored beverages. Cloudiness in beverage C increased over the storage period while beverages T and MB were very stable. Overall, T and MB flavored beverages have the potential for commercial application.

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“…Green tea, which is brewed from unfermented leaves, contains a rich source of monomer flavanols, while full fermentation to black tea produces a series of theaflavins and thearubigins (Harbowy et al 1997). These phenolic .…”

Section: Electrochemical Characterization Of Tea Samplesmentioning

confidence: 99%

Classification of Green and Black Teas by PCA and SVM Analysis of Cyclic Voltammetric Signals from Metallic Oxide-Modified Electrode

et al. 2013

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Forty-three samples of green and black teas were analyzed by an electronic tongue technique. A class of metallic oxide-modified nickel foam electrodes (SnO 2 , ZnO, TiO 2 , Bi 2 O 3 ) was compared in their sensitivity in this system. The signals obtained by cyclic voltammetry were submitted to multivariate data analysis. In the explorative analysis based on principal component analysis (PCA), the score plots showed that two of these sensors were able to distinguish varieties of teas. The resulting PCA scores were modeled with a support vector machine (SVM) that accomplished final prediction with the qualitative classification of teas. The optimal SVM model was achieved after grid search optimization of some parameters and the conduction of the three commonly used kernel functions. With a comparison of classification accuracies, Bi 2 O 3 -modified nickel foam electrode performed the best among the four electrodes and SVM model using the polynomial kernel attained the highest within the three used kernels. This work demonstrated that cyclic voltammetry combined with the SVM pattern recognition method could be successfully applied in the classification of green and black teas.

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Tea Chemistry

Cited by 454 publications

References 222 publications

Effect of Acute and Chronic Tea Consumption on Platelet Aggregation in Patients With Coronary Artery Disease

Effect of Acute and Chronic Tea Consumption on Platelet Aggregation in Patients With Coronary Artery Disease

Protein-rich beverage developed using non-GM soybean (R08-4004) and evaluated for sensory acceptance and shelf-life

Classification of Green and Black Teas by PCA and SVM Analysis of Cyclic Voltammetric Signals from Metallic Oxide-Modified Electrode

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