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[10] [11] Tea has one of the highest contents of flavonoids among common food and beverage products. [7] Catechins are the largest type of flavonoids in growing tea leaves. [6] According to a report released by USDA, in a 200-ml cup of tea, the mean total content of flavonoids is 266.68 mg for green tea, and 233.12 mg for black tea. [7]
Epigallocatechin gallate (EGCG), also known as epigallocatechin-3-gallate, is the ester of epigallocatechin and gallic acid, and is a type of catechin.. EGCG – the most abundant catechin in tea – is a polyphenol under basic research for its potential to affect human health and disease.
The method consists in extracting of soluble substances in dried tea leaf, contained in a porcelain or earthenware pot, by means of freshly boiling water, pouring of the liquor into a white porcelain or earthenware bowl, examination of the organoleptic properties of the infused leaf, and of the liquor with or without milk, or both.
Other more detailed chemical research has elucidated the difficulty of isolating individual phenolics. Because significant variation in phenolic content occurs among various brands of tea, there are possible [9] inconsistencies among epidemiological studies implying beneficial health effects of phenolic antioxidants of green tea blends.
Chlorogenic acid (CGA) is the ester of caffeic acid and (−)-quinic acid, functioning as an intermediate in lignin biosynthesis. [1] The term chlorogenic acids refers to a related polyphenol family of esters, including hydroxycinnamic acids (caffeic acid, ferulic acid and p-coumaric acid) with quinic acid.
The Folin–Ciocâlteu reagent (FCR) or Folin's phenol reagent or Folin–Denis reagent, is a mixture of phosphomolybdate and phosphotungstate used for the colorimetric in vitro assay of phenolic and polyphenolic antioxidants, also called the gallic acid equivalence method (GAE). [1] It is named after Otto Folin, Vintilă Ciocâlteu, and Willey ...
The main dietary sources of catechins in Europe and the United States are tea and pome fruits. [12] [13] Catechins and epicatechins are found in cocoa, [14] which, according to one database, has the highest content (108 mg/100 g) of catechins among foods analyzed, followed by prune juice (25 mg/100 ml) and broad bean pod (16 mg/100 g). [15]
Black tea is first withered to induce protein breakdown and reduce water content (68–77% of original). The leaves then undergo a process known in the industry as disruption or leaf maceration , which through bruising or cutting disrupts leaf cell structures, releasing the leaf juices and enzymes that activate oxidation.