Chlorophyll

The green of the leaf, and — because it barely dissolves — the reason a steeped green tea is yellow while a whisked one is green.

PigmentsA family, not a single compoundAlso called chlorophyll aAlso called chlorophyll bAlso called 葉緑素

What a drinker notices

Colour — appearance

Green, but only where the leaf itself is present. In a steeped tea it is almost entirely left behind in the leaf; in matcha, koicha and any whisked or ground preparation it is the dominant visual character.

What this gets credited for, wrongly

A yellow green-tea liquor is routinely read as a sign of poor quality or of the tea being old. It is neither: a clear yellow-green is what a properly steeped green tea looks like, because the green pigment does not dissolve. A steeped tea that IS strongly green usually has something added to it.

What it is

Chlorophyll is a ring with a magnesium atom at its centre, and both halves of that description matter in tea. The ring is not water-soluble, so almost none of it leaves the leaf during steeping: a sencha liquor is yellow-green because it contains flavonols and almost no chlorophyll, while matcha is vividly green because the leaf itself is in suspension and you are drinking it. And the magnesium is loosely held, so heat and acid can displace it — at which point the pigment turns olive-brown and cannot be turned back. Between them, those two facts explain most of what people find puzzling about the colour of green tea.

Chemically: Magnesium-centred porphyrin pigment.

Where it occurs in the plant

Throughout the leaf, and raised by shading: a plant under cover makes more chlorophyll to capture less light, which is why tencha and gyokuro leaf is a deeper green than sun-grown leaf and why good matcha is so vivid.

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 — Raises it: Shading raises chlorophyll directly. The colour of high-grade matcha is bought with weeks under cover, and it is one of the few quality markers a buyer can assess by eye.
Steaming (Japanese fixation) — Locks it in place: Fast steaming denatures the enzymes that would otherwise take chlorophyll apart, which is why Japanese green tea holds its colour so much better than a slowly fixed leaf.
Ageing and storage — Lowers it: Falls steadily in storage, especially in warmth and light. The fading of a green tea's colour over a year is this pigment going, and it goes alongside the aroma rather than instead of it.
Stone milling — Leaves it broadly alone: Milling does not change the pigment; it changes whether you drink it. Grinding tencha into matcha is what puts chlorophyll into the cup at all, and the low, slow grinding of a stone mill keeps the powder from heating and browning.
Sealed yellowing (men huang) — Lowers it: The step that makes yellow tea, and this pigment is what it is doing. Smothering warm damp leaf under cloth for hours takes the chlorophyll apart steadily, and the colour a reader sees in the name is the direct visible record of it. Yellow tea is not green tea that faded — it is green tea in which this loss was arranged on purpose.
Wet-blank and dry-blank yellowing — Lowers it: Whether the smothering runs on damp leaf straight from fixation or on part-dried leaf decides how fast this happens, because the reaction needs the moisture. A wet blank yellows quickly and can overrun; a dry blank yellows slowly and is far harder to push too far — which is the main axis separating one yellow tea from another.
Drum fixation — Locks it in place: A heated rotating cylinder brings the leaf to enzyme-killing temperature in a continuous pass rather than in batches, and how completely it does that decides the colour of everything downstream. Under-fixed leaf keeps working and dulls; the tumbling contact also browns a little at the surface, which is why drum-fixed greens look slightly warmer than steamed ones.
Spreading and cooling (tan liang) — Locks it in place: Heat that stays in the leaf keeps working on the pigment after the operator has stopped. Spreading the leaf out to cool immediately is what makes a fixation step end when it is supposed to, and skipping it is the commonest reason a green tea comes out of a good pan looking khaki.
Steam softening before pressing (zheng ya) — Lowers it: The few seconds of steam that make dry leaf compressible are also a few seconds of heat on a pigment that has already been through everything else. A cake steamed a little too long has begun to lose its green before it is pressed, which is one of the ways a young sheng can look older than it is.
Pearl forming (chao gan cheng yuan) — Turns it into something else: Extended heat converts it to pheophytin, which is most of why a gunpowder pellet is a duller grey-green than an open-leafed pan-fired tea and why the liquor is darker than its category suggests.

How brewing brings it out

Extraction rate: Not extracted by water at all

Essentially insoluble in water at any temperature. No brewing decision extracts it, and this is the single most under-explained fact about green tea's appearance.

Across infusions: Not applicable to a steeped tea — it stays in the leaf from first infusion to last.

Water: Acid conditions convert it to pheophytin, which is olive-brown rather than green. That reaction is why a green tea liquor left standing, or made with markedly acidic water, drifts from green towards khaki — and why a squeeze of lemon in green tea dulls the colour immediately.

Leaf, ratio and agitation: The only way to consume it is to consume the leaf: matcha, koicha, powdered green tea in cooking, or eating the spent leaf, which is ordinary practice in parts of Japan and China.

What you can change

Whisk ground leaf rather than steeping it, if colour is the point
Judge a matcha's colour dry, before water touches it
Store green tea cold and dark to slow the fade

Where this gets misdescribed

That the colour of the liquor tells you how green the tea is. It tells you about the soluble pigments, which are not the green ones. A pale gold gyokuro can come from leaf far greener than a bright green cup of something else.

Teas this compound defines

What this page does not say

This record describes a pigment, what it does to the appearance of leaf and cup and why it does not dissolve. It makes no statement about what it does in a body.

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.

How TeaHQ handles sources