Theaflavins
The bright orange-red pigments oxidation builds from catechins, and the compounds the tea trade means by briskness.
What a drinker notices
- Astringency — a tactile sensation
- Colour — appearance
- Bitterness — a taste
Brightness of colour and briskness of texture — a lively, clean grip that reads as quality rather than as fault, plus some bitterness. It is the difference between a black tea that snaps and one that is merely dark.
How much of it there is matters: Theaflavins peak partway through oxidation and then fall as they polymerise onward into thearubigins. A tea taken too far loses brightness and gains only depth, which is why oxidation is stopped by judgement rather than by a clock.
What this gets credited for, wrongly
Strength in a black tea is credited to theaflavins routinely. They give briskness and brightness; the weight and colour depth belong largely to the thearubigins that come after them.
What it is
When a rolled leaf's cells rupture, its own oxidase reaches its catechins, and pairs of them couple into theaflavins — orange-red pigments with a distinctive ring system that does not exist in the fresh leaf at all. There are four principal ones, differing in whether one, both or neither half carries a gallate group. They are what makes a good black tea look bright and coppery rather than dull brown, and briskness — the tea trade's word for a lively, clean, mouth-catching quality — is attributed to them directly. The theaflavin-to-thearubigin ratio is used as a working quality index in black tea assessment, which is unusually direct for a chemical measure in this industry.
Chemically: Benzotropolone pigments formed by oxidative coupling of a catechin-type and a gallocatechin-type unit.
Where it occurs in the plant
Absent from the fresh leaf. They exist only as a product of processing, which is what makes them the clearest demonstration on this site that a tea's compounds are made rather than found.
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 — Creates it
- Formed here and nowhere else. The tea maker's judgement about when to fix is a judgement about theaflavins: too early and there are few, too late and they have already gone on to something else.
- Rolling and shaping — Creates it
- Rolling is what makes oxidation possible, by rupturing cells so the enzyme and its substrate meet. The degree of rupture — orthodox versus CTC — decides how fast and how completely theaflavins form.
- CTC (crush, tear, curl) — Raises it
- Maceration gives the fastest and most complete cell rupture in tea, which produces a rapid, high theaflavin yield. It is why CTC liquors are so brisk and so quick to develop colour in a mug.
- Controlled-environment oxidation — Raises it
- Cool, humid, well-aired conditions favour theaflavin formation and slow the onward march to thearubigins. Hot, dry oxidation pushes past them.
How brewing brings it out
Extraction rate: Moderate
Readily soluble in hot water and much less so as it cools — which is why they cause the most visible phenomenon in tea. On cooling they associate with caffeine and drop out as the cloud known as tea cream, and a strong black tea left to go cold hazes for this reason and no other.
Across infusions: Out quickly. A black tea gives most of its brightness in the first infusion, which is part of why black tea is traditionally brewed once and oolong many times.
Water: Very sensitive to water. Alkaline or hard water darkens and dulls the colour immediately — the same tea can be coppery in soft water and muddy brown in hard, with no change in what was dissolved except how it looks.
Leaf, ratio and agitation: Brewing strong and cooling is the standard route to a hazy iced tea. Brewing slightly weaker, or adding a little acid, keeps it clear.
What you can change
- Use soft or filtered water for brightness of colour
- Add lemon to clear a hazy iced tea — acid keeps them in solution
- Cool quickly rather than slowly to reduce clouding
- Brew once and fully, rather than repeatedly
Where this gets misdescribed
That black tea is 'fermented'. Nothing microbial happens: this is the leaf's own enzyme acting on the leaf's own catechins in air, and the products are these pigments. Fermentation in tea means the microbial work that makes dark tea, and it is a different process producing different compounds.
Teas this compound defines
Read next
- Thearubigins — The largest fraction of a black tea liquor, responsible for its depth and body, and not actually a compound at all.
- 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.
- EGCG (epigallocatechin gallate) — The most abundant catechin in green tea, and the clearest single demonstration that astringency and bitterness are different things.
- Caffeine — Tea's principal alkaloid, bitter at concentration, and the compound most often blamed for a drying sensation it does not cause.
- 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
This record describes pigments formed during oxidation, what they do to colour and texture, and how brewing and water change them. It makes no statement about what they do 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.