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 Constituents.

 The phenolics are particularly abundant (up to

20% and more of the dry weight) but their

concentration varies depending on the variety,

the age of the leaf (the youngest leaves are the

richest), and the season (the level is higher in the

summer than in the spring).

 Polyphenols in green tea leaves reach 15-30%

and are examplified by cathechin, its derivatives

(vitamin P), flavonoids and tannins.

 Catechins: in unfermented (green) tea 10-25%,

with fermentation partially changing over into

oligomeric quinones with tannin character, into

theaflavine, theaflavin acid, thearubigene, or into

non-water soluble polymeric- flavonoids:

including, among others, quercetin, kaempferol,

myrecetin.