| [chemical and sensory characterization of tea (thea sinensis) consumed in chile]. | by means of descriptive analysis four varieties of tea (thea sinensis) were assesed: argentinean op (orange pekoe) tea (black), brazilian op tea (black), ceylan op tea (black) and darjeeling op tea (green). the appearance of dry tea leaves were qualitatively characterized comparing with dry leaves standard. the attributes: colour, form, regularity of the leaves, fibre and stem cutting were evaluated the differences obtained were related to the differences produced by the effect of the fermentati ... | 2005 | 16187684 |
| about the cover illustration: thea sinensis - the common tea plant. | | 2005 | 15976762 |
| oxidation of tea extracts and tea catechins by molecular oxygen. | tea polyphenols (pp) are known as potent antioxidants. at the same time, pp have been repeatedly reported to oxidize by molecular oxygen with the formation of active forms of oxygen. in this work, the clark electrode technique was applied to study the kinetics of the autoxidation of tea extracts and individual tea pp as well as model pp, catechol, gallic acid, and pyrogallol. aqueous extracts of both green and black teas were found to undergo extensive autoxidation under physiological conditions ... | 2005 | 15913321 |
| novel chemiluminescence-inducing cocktails, part ii: measurement of the anti-oxidant capacity of vitamins, thiols, body fluids, alcoholic beverages and edible oils. | using two luminescence-inducing cocktails, two distinct patterns of inhibition of light by different anti-oxidants have been identified, comprising group a, in which a complete inhibition of light emission which is then followed by re-emergence of light, forming apparent s-shaped curves or similar shapes. this light pattern is induced by the "classical" anti-oxidants, ascorbate, vitamin e, uric acid, thiols, deferoxamine, as well as by anti-oxidant agents present in plasma, saliva, urine and in ... | 2004 | 15901412 |
| phenolic constituents and antioxidant activity of wendita calysina leaves (burrito), a folk paraguayan tea. | burrito tea originates from the leaves of wendita calysina, an indigenous paraguayan plant, which is commonly consumed in south america and in western countries. phytochemical investigation of this species has led to the isolation of 14 constituents, among them 2 new flavanonols, dihydroquercetagetin (1) and 3,5,6,7,4'-pentahydroxyflavanonol (2), in addition to several known methoxyflavones, methoxyflavonols, phenylethanoid glycosides, and benzoic acid derivatives (4-14). all structures were elu ... | 2004 | 15366833 |
| influence of milk on the antimutagenic potential of green and black teas. | the objective of this study was to evaluate whether addition of milk to green, black and decaffeinated black teas alters their antimutagenic activity. | 2016 | 14666689 |
| chain-breaking antioxidant activity and cyclic voltammetry characterization of polyphenols in a range of green, oolong, and black teas. | a series of eight green, eight oolong, and 17 black teas have been analyzed for polyphenol content by absorbance at 272 nm and cyclic voltammetry response at an inert carbon electrode, a new method developed to provide a rapid measure of easily oxidizable polyphenols in beverages. the chain-breaking antioxidant activity of the teas has also been determined during the chain oxidation of methyl linoleate in a ph 7.4 micellar solution, for which realistic kinetic parameters have been derived. while ... | 2003 | 12952436 |
| thoughts on thearubigins. | the chemistry underlying the changes which occur during tea leaf fermentation is reviewed and used as a basis for proposals for the structure of thearubigins, the major pigments of black teas. | 2003 | 12946406 |
| determination of tea components with antioxidant activity. | levels of essential elements with antioxidant activity, as well as catechins, gallic acid, and caffeine levels, in a total of 45 samples of different teas commercialized in spain have been evaluated. chromium, manganese, selenium, and zinc were determined in the samples mineralized with hno(3) and v(2)o(5), using etaas as the analytical technique. the reliability of the procedure was checked by analysis of a certified reference material. large variations in the trace element composition of teas ... | 2003 | 12848521 |
| chain-breaking antioxidant capability of some beverages as determined by the clark electrode technique. | the protective effects of red wine, tea, and coffee on cancer, atheroclerosis, and other diseases are attributed to the antioxidant activity (aoa) of polyphenols, which are abundant in those beverages. we present a rational procedure for determining the total chain-breaking aoa of beverages with the use of the clark electrode technique. the procedure is based on the steady monitoring of oxygen consumption accompanying the chain peroxidation of methyl linoleate in triton x-100 aqueous micelles in ... | 2001 | 12639404 |
| total phenol, catechin, and caffeine contents of teas commonly consumed in the united kingdom. | levels of total phenol, catechins, and caffeine in teas commonly consumed in the united kingdom have been determined using reversed phase high-performance liquid chromatography. tea bags or tea leaves were purchased from local supermarkets and extracted in boiling water for 5 min. the resulting data showed considerable variability in both total phenols [80.5-134.9 mg/g of dry matter (dm) in black teas and 87-106.2 mg/g of dm in green teas] and catechins (5.6-47.5, 51.5-84.3, and 8.5-13.9 mg/g of ... | 2002 | 11804530 |
| [amounts of selected minerals in green and black teas]. | the paper contains the results of 19 minerals (ca, k, p, na, mg, zn, fe, mn, cu, f, ni, co, cr, li, sr, al, cd, hg, pb) determined in green and black species of market teas. the examined minerals (except phosphorus, fluoride and mercury) were determined by asa-method using air-acetylene flame (aluminium was determined in the nitrous oxide-acetylene flame). mercury was determined by cold vapour method. the phosphorus and fluoride was determined by spectrophotometry methods (phosphorus in the form ... | 2000 | 11138481 |
| eat to live, not live to eat. | most of the prevailing chronic diseases in the world have an important nutritional component by directly causing a specific disease, enhancing the risk through phenomena of promotion, exerting a beneficial effect in decreasing risk, or preventing the disease. international studies in geographic pathology have shown that a given disease may have vastly different incidence and mortality as a function of residence. laboratory research in animal models can reproduce fairly accurately what is learned ... | 2000 | 11032452 |
| comparative analysis of tea catechins and theaflavins by high-performance liquid chromatography and capillary electrophoresis. | this paper describes the simultaneous determination of catechins and theaflavins in green and black teas, using reversed-phase high-performance liquid chromatography (hplc) and capillary electrophoresis (ce). the tea polyphenols analyzed included (+)-catechin, catechin gallate, (-)-epicatechin, epicatechin-3-gallate, epigallocatechin, epigallocatechin-3-gallate, theaflavin, theaflavin-3-monogallate, theaflavin-3'-monogallate and theaflavin-3,3'-gallate. these polyphenols together with six other ... | 2000 | 10905726 |
| antioxidant capacity and polyphenolic components of teas: implications for altering in vivo antioxidant status. | the oxygen radical absorbance capacity (orac) assay was used to determine the total antioxidant capacity of tea. green and black teas (n = 18) had a mean antioxidant capacity of 761.1 +/- 85.3 micromol trolox equivalents (te) per g dry matter. however, their antioxidant capacity varied from 235 micromol to over 1526 micromol trolox equivalents (te)/g dry matter, and total phenolics ranged from 32 to 147 mg/g in different commercial teas. one tea phenolics extract had an antioxidant capacity of 4 ... | 1999 | 10202399 |
| aluminium and fluoride in hospital daily diets and in teas. | the levels of aluminium and fluoride have been determined in hospital daily diets including breakfast, dinner and supper, as well as in black teas and herbal teas purchased from the local market. in tea, aluminium was determined directly in a sample solution by atomic absorption spectroscopy using nitrous oxide and an acetylene flame. for analysis of the hospital diet, samples containing lower levels of aluminium were analysed using a spectrophotometric method which measured aluminium in the for ... | 1995 | 8525696 |
| [ dietary intake of fluorine through of tea prepared by the traditional method in senegal]. | the consumption of tea in senegal is known and called "trois normaux". the use of thea sinensis as drink many times per day with a lot of sugar, may cause some public health problems. in the aim to face that situation, we have analysed the fluor level in the available tea samples in the senegalese market in respect of the ways of the preparation. the fluor level has been analysed by ionometric specific electrode. the concentrations were from 3.8 to 6.1 mg/l in the infusion and from 11.1 mg/l in ... | 1994 | 8654184 |
| natural antioxidants. i. antioxidative components of tea leaf (thea sinensis l.). | | 1984 | 6467480 |
| metabolism of xanthine and hypoxanthine in the tea plant (thea sinensis l.). | 1. the metabolism of xanthine and hypoxanthine in excised shoot tips of tea was studied with micromolar amounts of [2(-14)c]xanthine or [8(-14)c]hypoxanthine. almost all of the radioactive compounds supplied were utilized by tea shoot tips by 30 h after their uptake. 2. the main products of [2(-14)c]xanthine and [8(-14)c]hypoxanthine metabolism in tea shoots were urea, allantoin and allantoic acid. there was also incorporation of the label into theobromine, caffeine and rna purine nucleotides. 3 ... | 1975 | 1147906 |
| metabolism of methylamine in the tea plant (thea sinensis l.). | 1. the metabolism of methylamine in excised shoot tips of tea was studied with micromolar amounts of [(14)c]methylamine. of the [(14)c]methylamine supplied 57% was utilized by tea shoots during the 10h experimental period. 2. the main products of [(14)c]methylamine metabolism in tea shoots were serine, gamma-glutamylmethylamide, theobromine, caffeine and co(2). there was also incorporation of the label into glutamate, aspartate, rna purine nucleotides and s-adenosylmethionine. 3. the formation o ... | 1973 | 4721610 |
| [triterpenes. xxv. on the structure of "theasaponin", a mixture of saponins from thea sinensis l. exhibiting strong antiexudative properties]. | | 1969 | 5800718 |
| [saponins from the seeds of thea sinensis l. iii. the constitution of thea-sapogenol. (1)]. | | 1954 | 13215030 |