SPECTROPHOTOMETRIC DETERMINATION OF TOTAL PHENOLIC CONTENT OF SOME COMMONLY CONSUMED TEAS IN INDIA 1 1 2 (original) (raw)
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Journal of food and nutrition research
The aim of this study was evaluation of individual phenolic compounds and antioxidant activity of commercially consumed black, green, fruit and herbal tea infusions in Serbia in order to characterize the quantity and quality of teas. The most abundant compound was gallic acid, followed by caffeic acid, rutin, (+)-catechin and (-)-epicatechin. The main procyanidin was procyanidin B1. The antioxidant activity was measured using five in vitro methods: determination of 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity (DPPH), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) radical cation-scavenging activity (ABTS), ferric reducing antioxidant power (FRAP), reduction power (RP) Fe(III) to Fe(II) and cyclic voltammetry (CV). Obtained results of FRAP and of the Fe(III)/Fe(III) method correlated strongly with the total phenolics content (R 2 = 0.92246, R 2 = 0.88084, p < 0.0001). Antioxidant power of green tea and bearberry tea was considerably higher than that of black tea. Raspberry and cherry showed the highest antioxidant power among fruit tea infusions. Contribution of phenolic compounds to tea antioxidant activity was also quantified in this study. Stepwise linear regression demonstrated that quantification of different phenolic compounds responsible for tea antioxidant activity was dependent on the method used. Gallic acid, caffeic acid (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, procyanidin B1, procyanidin B2 together made up 43.6-99.9% of the antioxidant activity of tea.
Beverages, 2022
Tea contains about 230 chemical bioactive compounds, of which polyphenols represent the most considerable fraction (30% of total dry weight). These compounds have relevant nutritional and pharmacological effects on human health, exerting antioxidant activities against oxidative stress-induced damage. The industrial processes applied in tea production can lead to qualitative and quantitative changes in the phenolic content and composition and in antioxidant properties, thus influencing their potential biological activities. Meanwhile, the procedure for tea preparation may influence the quantity of the extracted phenolic compounds. In this study, the effects of different infusion parameters, such as the water type used for infusion (tap water, distilled water, and natural mineral water), time (3, 5, and 10 min), temperature (T = 80 °C and 100 °C), and pH (ranged between 3 and 9) were considered. The optimal infusion variables resulting from the study were obtained by extracting phenol...
Asian Journal of Dairy and Food Research, Volume 42 Issue 2: 204-209 (June 2023)
Background: Worldwide tea consumption as beverage ranks next to water. The high consumption of tea is attributed to richness in flavor, aroma, antioxidant properties and health benefits. Tea has complex chemical composition having catechins, flavonoids, alkaloids, carotenoids, chlorophyll, amino acids, polysaccharides, lipids, vitamins, minerals and more than 600 different volatile compounds. Methods: The present study focuses on determining the physicochemical parameters, phyto-chemical assay and microbiological qualities of commercially packaged green and black tea samples within West Bengal following standard methods. Result: The values of proximate parameters like moisture, ash, acid insoluble ash and water extractive have complied with standard specifications. High pressure liquid chromatography (HPLC) analysis quantified significantly higher polyphenol content of green tea in compare to black tea samples respectively with 65.12 ppm and 18.58 ppm with gallic acid equivalence and green tea epigallocatechin gallate (EGCG) content was found 449.28 ppm with respect to pure EGCG standard. In vitro antioxidant activity of green tea and black tea extracts as reported by IC 50 value were found to be 192.97-301.08 μg/ml and 342.54-481.91 μg/ml respectively.
American Journal of Plant Sciences, 2015
Tea (Cammelia sinensis) is the most widely consumed beverage in the world and has been reported to have unlimited health benefits due to its antioxidant properties. There is a high correlation between polyphenol compounds with antioxidant properties. Tea leaves are a major source of polyphenols. The aim of the present investigation was to determine the approximate level of polyphenols in different other parts of the tea plant to give comparative data on obtaining extracts that can be used to design products through value addition to assist in the prevention of diseases associated with oxidative stress. Twenty-one selected region specific tea varieties were used to obtain roots, flowers, leaves and barks. Leaves were prepared by microwaving and the remaining portions processed as green non-aerated teas and black aerated tea. Roots, barks, flowers were sun-dried and milled. Total polyphenol content was determined by calorimetric method using Folin-Ciocalteu reagent. The obtained results suggest that different parts of tea plant have varying numbers of total polyphenols with microwaved leaves having mean levels at 23.1%, steamed leaves (non-aerated green tea) at 22.37%, aerated leaves at 15.51%, barks at 14.92%, flowers at 10.62% and roots at 1.48%.
Determination of Phenolic Components and Antioxidant Activity of Some Egyptian Tea Samples
Objective: Tea is the most widely consumed beverage in the world. Green tea (Camellia sinensis) is a good source of bioactive compounds and it is gaining interest due to its health benefits. The present study was conducted to determine the total polyphenols and total flavonoid content as well as the antioxidant activity of ethanolic extracts from different Egyptian tea samples. Methods: The determination process carried out using standard spectrophotometric methods and quantified various phenolic and flavonoid compounds by using high performance liquid chromatography (HPLC) method. The comparison was also made between Egyptian tea samples and commonly tea samples in the markets. Results: Results from this study showed that Egyptian green tea showed a significant higher values of total phenol and flavonoid, contents. The same trend was also observed in antioxidant activity as assessed using DPPH (2, 2-diphenyl-1-picrylhydrazyl) free radical scavenging assay. It revealed that the total antioxidant activity could be due to its total phenol content. Conclusion: The study concludes that Egyptian green tea offers higher amount of antioxidant properties.
The analysis of quality and antioxidant activity of green tea extracts
The aim of the research was to analyze the composition of biologically active compounds, to determine the correlation between the concentration of biologically active compounds and antioxidant activity, the dependence of extractive compounds on the extraction time, the quality of different tea preparation forms (daily tea, infusions, decoctions) of those teas found in Lithuanian market. Four specimens of green tea from different regions of the world have been chosen as the object of analysis. Quality criteria's have been analyzed by using gravimetric and spectrophotometric methods. Detailed analysis has been performed using high performance liquid chromatography (HPLC) technique. With reference to analysis results it can be stated that in the aspect of relation to antioxidant activity/phenolic compounds, the teas with highest numbers in these dimensions were those from China region. The least numbers in antioxidant activity, dry residue and phenolic compounds were of teas from S...
Phenolic compounds like catechin undergo spontaneous natural oxidation producing poly-phenols or tannins by aerial O 2 , heat or exposure to UV radiation. Using synthetic catechin as standard, its levels in dry leaves is assessed spectrophotometrically at 260 nm (57 mg / g) and also by the F-C reagent (76 mg / g) for both green and black teas which are found to be the same. Extraction of dry commercial leaves by EtOH in the dark at RT shows two distinct identical peaks (λ max) at 260 and 400 nm for both green and black whereas synthetic catechin under similar condition shows only one (λ max = 260 nm), confirming the presence of pre-oxidized phenolics in extracts. The EtOH extracts if diluted and incubated at different pH, shows identical spectral pattern having λ max at 260 and 360-380 nm except at pH 4.7. Noticeably, λ max is shifted backward from 400 nm (in EtOH) to 360 or 380 nm in the aqueous buffer at normal or higher pH. At pH 4.7 the native catechin shows a single peak at 260 nm but the EtOH extracts of both leaves display λ max at 260 nm with distinctive additional shoulder at 360 nm. The shoulder is turned to whole peak if the acidity is lowered to pH 7.5 or further. The analysis by HPLC with detection at 440 nm of green and black tea extracts shows major peak comprising of ~57 and 73% area out of the total accompanied by other components having the same retention time (~9.2 min) which is an indication of the presence of pre-oxidized poly-phenolics in both. As per conclusion, the study insists to believe that in addition to total content, the level of oxidation are about the same for both teas and the event of oxidation takes place during commercial processing of the leaves but not in course of experimentation.
Antioxidant Character and Levels of Polyphenols in Several Tea Samples
ACS Omega
The present study measured the antioxidant properties of 15 commercial tea samples as expressed by the oxygen radical absorbance capacity (ORAC) hydro, ORAC lipo, and ferric reducing antioxidant power (FRAP) indexes. The main antioxidant compounds known to be present in tea are several catechins and catechin gallates, gallic acid, theaflavin and some theaflavin gallates, and theogallin. In this study, only gallic acid and the four most common catechins (epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate) were analyzed in the tea samples. In addition, caffeine levels were measured. The ORAC and FRAP values for these compounds were also determined. The levels of theaflavin, theaflavin gallates, and theogallin were not measured since these compounds are present at relatively low levels in tea. The ORAC (and FRAP) indexes for each tea sample were also calculated based on the content of individual antioxidant compounds and their ORAC and FRAP indexes. Correlations between the experimental ORAC (and FRAP) and the calculated values were further obtained. The correlations were poor, with R 2 = 0.3657 for ORAC hydro, R 2 = 0.2794 for ORAC lipo, and R 2 = 0.6929 for FRAP. The poor correlation between the overall catechin content and the experimental ORAC values in tea infusions was previously reported in the literature. The present study directly calculated the expected ORAC index from individual antioxidant components and reached the same result of poor correlation. For FRAP values, no comparison was previously reported in the literature. The poor correlations were not well explained, indicating that the cause of the antioxidant character of tea is more complex than simply produced by the main catechins.
Proceedings of the Society for Experimental Biology and Medicine, 1999
Tea is the most highly consumed beverage in the world, other than water. However, unlike water, tea contains substantial amounts of polyphenols that have unique biological activities and may be responsible for many of the health benefits of tea. As a result, it is essential to be able to measure the various tea‐associated polyphenols. Total polyphenol content is currently measured by using methodology based on reducing activity. Several HPLC systems with detectors that, collectively, have wide ranges in sensitivity have been developed for analysis of individual flavonoids in tea and biological samples, and for theaflavins in tea. Catechins also have been measured in plasma by solid phase extraction, addition of a chromophore, and colorimetric quantification. Except for theaflavins in tea, routine and robust methods for the measurement of polyphenol condensation products (dimers and thearubigens) in tea and biological samples have not been developed. Although in vitro and animal stud...
Modeling of Total Phenolic contents in Various Tea samples by Experimental Design Methods
Open Chemistry, 2018
Tea, from the old ages to the day, is widely consumed both for enjoyment and health care due to its positive effects. The consumption of these products is increasing day by day as a result of the clear presentation of the fact that tea contains high amount of antioxidant substances (such as phenolic compounds), which is important in prevention and treatment of diseases. Tea beverage is a very important source of polyphenols. In this study, phenolic content and antioxidant capacity of different tea species were calculated by modeling with experimental design method. In the experimental part, polyphenol content was determined using the Folin-Ciocalteu method. The total amount of phenolic substance content was examined by Box-Behnken design and response surface method on black tea, green tea and white tea on different extraction temperature, extraction time and solid / liquid ratio. Solid / liquid ratio was found to be the most important parameter in terms of polyphenol content extract...