ECG (epicatechin gallate)

What a drinker notices

• Astringency — a tactile sensation

Drying, and the fastest-acting of the catechins to declare itself. Where EGCG builds over seconds, this arrives promptly and gives the immediate grip of an over-steeped black tea.

What it is

ECG sits well behind EGCG in amount and ahead of it in intensity: gram for gram it is generally described as the most astringent of the tea catechins. It matters because it shows that astringency is about structure rather than about quantity — the gallate group is what dries the mouth, and a leaf with less total catechin but a higher gallate share can be harsher than one with more. It is also, with EGCG, one of the two catechins whose gallate group is stripped off during pile fermentation, which is a large part of why a shou pu-erh has almost no drying edge left.

Chemically: Galloylated flavan-3-ol — the second gallate-carrying catechin of tea.

Where it occurs in the plant

A minor share of the catechin pool in most cultivars, rising in mature sun-grown leaf. Assam-type material generally carries a higher gallate share than China-type material.

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.

Oxidation — Turns it into something else

Consumed alongside EGCG into the theaflavins. The gallated theaflavins that result are themselves briskly astringent, so oxidation moves the sensation rather than removing it.

Wet piling (wo dui) — Lowers it

The pile hydrolyses the gallate group away, and with it goes the drying edge. It is the clearest example in tea of a sensation being removed by chemistry rather than by dilution.

How brewing brings it out

Extraction rate: Slow — needs heat and time

Needs heat, like its relative, and rises steeply with it. It is one of the compounds a low-temperature brew leaves behind in the leaf.

Across infusions: Arrives across the early and middle infusions rather than the first, and contributes to a session getting grippier before it gets weaker.

Water: Galloylated, and therefore among the compounds hard water flattens most. Calcium and magnesium associate with the gallate group, which both dulls the astringency and contributes to the scum on the surface of a cup made in a limescale district.

Leaf, ratio and agitation: Coarser and more mature leaf carries proportionally more of it, so leaf grade moves this compound independently of steep time.

What you can change

• Lower the temperature
• Cut the steep time
• Choose a finer plucking standard

Teas this compound defines

• Assam
• Bancha
• Shou pu-erh (ripe)

Read next

• EGCG (epigallocatechin gallate) — The most abundant catechin in green tea, and the clearest single demonstration that astringency and bitterness are different things.
• 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.
• Gallic acid — The gallate group after it has been separated from its catechin — small, sour, drying, and a marker of how far a dark tea has fermented.
• Theaflavins — The bright orange-red pigments oxidation builds from catechins, and the compounds the tea trade means by briskness.