EGCG (epigallocatechin gallate)
The most abundant catechin in green tea, and the clearest single demonstration that astringency and bitterness are different things.
What a drinker notices
- Astringency — a tactile sensation
Astringency, and it is a texture rather than a taste — the mouth dries, the tongue feels rough against the palate, the sensation builds over a few seconds and lingers after swallowing. It is not bitterness. A cup can be strongly drying and hardly bitter at all, which is exactly what a well-brewed sencha is.
How much of it there is matters: The sensation accumulates across sips in a way a taste does not. Three cups in, the mouth is drier than the third cup alone would explain, and no amount of the fourth cup will read as soft.
What this gets credited for, wrongly
Blamed for bitterness constantly, in vendor copy and in tasting notes. Bitterness in a green tea comes mostly from caffeine and from the non-galloylated catechins; this compound supplies the drying.
What it is
EGCG is the largest single catechin in a green tea leaf and the compound most responsible for the sensation people misname when they call a strong cup tannic. It carries a gallate group, and that group is what makes it dry the mouth so effectively: the gallate end is what lets it associate with salivary proteins and pull them out of solution. It is slow to extract and steeply temperature-dependent, so the drinker has an unusual amount of control over how much of it reaches the cup — more control than over almost anything else in tea.
Chemically: Galloylated flavan-3-ol — the most abundant catechin in green tea.
Where it occurs in the plant
The dominant catechin of sun-grown young leaf, suppressed by shading and lower in mature leaf. Assam-type plants generally carry more of it than China-type plants, which is one compositional reason Assam material makes better black tea than green.
What processing does to it
In tea, processing is not a modifier applied to a fixed composition — it is what decides the composition. These are the steps that move this compound, and each links to the step itself.
- Shading — Lowers it
- Falls sharply under cover. The swing from a brisk sencha to a sweet gyokuro is largely this one compound retreating while the amino acids advance.
- Oxidation — Turns it into something else
- The principal starting material for theaflavin formation. EGCG oxidised alongside EGC produces theaflavins; oxidised with itself it produces theasinensins, which is the oolong route rather than the black one.
- Steaming (Japanese fixation) — Locks it in place
- Japanese steaming arrests the enzymes within seconds, so a steamed green tea keeps close to the leaf's full complement of it. That is why sencha is more drying than a pan-fired Chinese green from comparable leaf.
How brewing brings it out
Extraction rate: Slow — needs heat and time
Strongly temperature-dependent — one of the steepest curves in the leaf. Water near boiling pulls it out readily and water at 60 °C pulls out much less, which is the whole basis of low-temperature green tea brewing and of cold brew tasting sweet.
Across infusions: Rises through the early infusions rather than falling. A second cup at the same parameters is drier than the first because this compound is still arriving after the fast ones have gone.
Water: Hard water mutes it, and the visible sign is a dull liquor rather than a bright one. Very soft water gives the sharpest expression of astringency and the clearest colour.
Leaf, ratio and agitation: Agitation raises it disproportionately. Stirring a mug or squeezing a bag pushes far more of it into solution than the same time undisturbed.
What you can change
- Drop to 70 °C or below for green tea
- Pour off completely rather than leaving the leaf standing
- Do not squeeze the bag or press the leaf
- Cold-brew, where it barely extracts at all
Where this gets misdescribed
That EGCG is the bitter compound in green tea. It is the drying one. The mistake matters at the kettle, because the fix for a drying cup is shorter contact and less agitation while the fix for a bitter one is lower heat, and a drinker who has merged the two will reach for the wrong one about half the time.
Teas this compound defines
Read next
- Catechins — The largest soluble fraction of a green tea leaf, the source of astringency, and the compounds oxidation turns into everything a black tea is.
- ECG (epicatechin gallate) — The other galloylated catechin, and weight for weight the most drying thing in the leaf.
- Theaflavins — The bright orange-red pigments oxidation builds from catechins, and the compounds the tea trade means by briskness.
- Theasinensins — The dimers formed when two catechins of the same type couple — the oxidation route oolong takes and black tea largely does not.
What this page does not say
EGCG is the compound almost every health claim about green tea is built on. This record does not make, repeat, hedge or contradict any of them. It describes what EGCG does to a mouthful of liquor and nothing about what it does in a body — that question sits on TeaHQ's held surface and is not answered here.
Sources
- TeaHQ editorial synthesis — TeaHQ
This page is TeaHQ’s own synthesis of well-established tea chemistry. No external technical document stands behind it, and that constraint is why there are almost no numbers here: directions, rankings and mechanisms are stated plainly, quantities are not, because a figure nobody can check would look more authoritative than it deserves.