The phenolic content in tea refers to the

phenols In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of one or more hydroxyl groups (− O H) bonded directly to an aromatic hydrocarbon group. The simplest is phenol, . Phenolic compounds ar ...

and

polyphenol Polyphenols () are a large family of naturally occurring phenols. They are abundant in plants and structurally diverse. Polyphenols include phenolic acids, flavonoids, tannic acid, and ellagitannin, some of which have been used historically as ...

s, natural plant compounds which are found in tea. These

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

s affect the flavor and mouthfeel of tea. Polyphenols in tea include catechins,

theaflavin Theaflavin (TF) and its derivatives, known collectively as ''theaflavins'', are antioxidant polyphenols in tea, polyphenols that are formed from the condensation of flavan-3-ols in tea leaves during the enzymatic oxidation (sometimes erroneously re ...

s, tannins, and flavonoids. Polyphenols found in

green tea Green tea is a type of tea made from the leaves and buds of the '' Camellia sinensis'' that have not undergone the withering and oxidation process that creates oolong teas and black teas. Green tea originated in China in the late 1st millenn ...

include, but are not limited to, epigallocatechin gallate (EGCG), epigallocatechin, epicatechin gallate, and epicatechin; flavanols such as kaempferol, quercetin, and myricitin are also found in green tea.

Catechins

Catechins include epigallocatechin-3-gallate (EGCG), epicatechin (EC), epicatechin-3-gallate (ECg), epigallocatechin (EGC), catechin, and gallocatechin (GC). The content of EGCG is higher in

. Catechins constitute about 25% of the dry mass of a fresh tea leaf, although total catechin content varies widely depending on species, clonal variation, growing location, season, light variation, and altitude. They are present in nearly all teas made from '' Camellia sinensis'', including white tea, green tea,

black tea Black tea (also literally translated as red tea from various East Asian languages) is a type of tea that is more tea processing, oxidized than oolong, yellow tea, yellow, white tea, white, and green tea, green teas. Black tea is generally st ...

and oolong tea. A 2011 analysis by the European Food Safety Authority found that a cause and effect relationship could not be shown for a link between tea catechins and the maintenance of normal blood LDL-cholesterol concentration. 4-Hydroxybenzoic acid, 3,4-dihydroxybenzoic acid (protocatechuic acid), 3-methoxy-4-hydroxy-hippuric acid and 3-methoxy-4-hydroxybenzoic acid (vanillic acid) are the main catechins

metabolite In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...

s found in humans after consumption of

infusions.

Theaflavins

Catechin monomer structures are metabolized into dimers

s and oligomers thearubigins with increasing degrees of oxidation of tea leaves. Theaflavins contribute to the bitterness and astringency of black tea. The mean amount of theaflavins in a cup of black tea (200 ml) is 12.18 mg. Three main types of theaflavins are found in black tea, namely theaflavin (TF-1), theaflavin-3-gallate (TF-2), and theaflavin-3,3-digallate (TF-3).

Tannins

Tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and Precipitation (chemistry), precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' is widel ...

s are astringent, bitter polyphenolic compounds that bind to and precipitate organic compounds. Gallic acid conjugates all of the catechins, such as EGCG ( Epigallocatechin gallate), which are

tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and Precipitation (chemistry), precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' is widel ...

s with astringent qualities.

Flavonoids

Phenols called

flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

s are under preliminary research, as of 2020, but there is no evidence that flavonoids have antioxidant activity in vivo, or affect physical health or diseases. Tea has one of the highest contents of flavonoids among common food and beverage products.U.S. Department of Agriculture, USDA Database for the Flavonoid Content of Selected Foods, Release 2.1, January 2007 Catechins are the largest type of flavonoids in growing tea leaves. 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

, and 233.12 mg for

Research

A 2020 review found low- to moderate-quality evidence that daily tea consumption might lower the risk for

cardiovascular disease Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina, heart attack), heart failure, hypertensive heart disease, rheumati ...

and death.

References