Melanoidins

What a drinker notices

• Colour — appearance
• Body and texture — a tactile sensation

Colour first: an amber-to-mahogany cast that deepens with the length of the roast and sits differently in the cup from an oxidised brown, which is redder. Then weight — a roasted tea feels rounder and denser on the tongue than the same leaf unroasted, and part of that fullness is this fraction being in solution rather than any change in how much leaf was used.

How much of it there is matters: A long even gradient rather than a threshold. Every additional hour of low roasting pushes colour and fullness further in the same direction, until the point where the roast character stops being a layer over the tea and becomes the only thing left — the standard complaint about an over-roasted Tie Guan Yin.

What it is

Two entirely different processes turn a tea liquor brown, and tea writing merges them constantly. One is oxidation and microbial fermentation, which builds theaflavins, thearubigins and theabrownins from polyphenols — that is what makes a black tea and a shou pu-erh dark. The other is heat acting on sugars and amino acids, the same chemistry that browns bread crust and coffee, which builds these. Hojicha is the clean demonstration: it is a green tea, unoxidised, whose leaf has never had an enzyme allowed near it, and it pours amber. Nothing was oxidised. Something was baked. Once a reader has that distinction, a whole class of confident sentences about roasted oolong 'being partly oxidised by the roast' stops being persuasive.

Chemically: Large, brown, nitrogen-containing polymers built during Maillard browning — an operationally defined fraction rather than a defined structure.

Where it occurs in the plant

Not present in any leaf, at any stage, until heat is applied. What the plant supplies is the sugar and the amino acid, both of which are highest in young shaded leaf and in stem — which is why stem teas brown so readily and so sweetly under a fire that would barely mark a coarse mature leaf.

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.

Charcoal roasting — Creates it

The classical route, and the one that builds this fraction most unevenly, because a charcoal bed heats a basket of leaf from one side. That unevenness is not a fault — it is a large part of why a charcoal roast reads as layered where an oven roast reads as flat.

Electric baking — Creates it

The same chemistry under a temperature controller. An electric bake builds this fraction predictably and reproducibly, which is exactly the argument for it and exactly the complaint against it: the colour and the weight arrive on schedule and so does everything else.

Hojicha roasting — Creates it

The clearest case in tea. A finished green tea, never oxidised, goes into a hot drum and comes out amber. Everything darker about hojicha than the sencha it was made from is this fraction, and none of it is oxidation.

Re-firing — Raises it

A light bake on already-finished tea to drive off absorbed moisture, and it is never only that. Each re-fire adds a little more of this fraction, which is why a stored oolong re-fired every year or two darkens steadily in a way that has nothing to do with age.

Pulling the old fire (la lao huo) — Creates it

Intense heat applied for a second or two at a time. The surface browns far ahead of the interior, so this fraction is built at the outside of each leaf — the reason the technique gives colour and roast aroma without the leaf tasting cooked through.

Two-stage drying (mao huo and zu huo) — Creates it

The second of the two passes is where most of this arrives, because it runs on drier leaf where surface temperature climbs faster. The cooling interval between passes is what stops the first from doing it.

Basket drying (hong gan) — Creates it

Long, low and gentle, which builds this fraction slowly enough that colour arrives without the toasted aroma taking over. It is the setting that separates a warm-tasting tea from a roasted-tasting one.

Resting between roasts (tui huo) — Leaves it broadly alone

Resting between roasts changes nothing about this fraction and a great deal about how it reads. Moisture redistributes and the harsh edge of a fresh roast settles, so the same colour and the same weight come across as integrated rather than raw.

How brewing brings it out

Extraction rate: Moderate

Comes out readily in hot water and carries its colour with it. A roasted tea brewed cool pours noticeably paler than the same leaf brewed hot, which is a useful check on whether a dark liquor is a roast or an oxidation.

Across infusions: Persistent. Where the roast aroma fades over three or four infusions, the colour and the fullness hold much longer, which is why a late infusion of a roasted oolong can look strong and smell of almost nothing.

Water: Alkaline water deepens the colour further and flattens the aroma sitting over it, so a hard-water roast reads darker and duller at once. Softer water is the standard remedy for a roasted tea that looks stronger than it tastes.

Leaf, ratio and agitation: Because this fraction sits at the leaf surface on a fast-fired tea, a rinse pulls a surprising amount of colour before any of the tea has really begun. That first dark rinse is not a sign of strength.

What you can change

• Brew cooler to hold the colour back
• Rinse briefly if the first pour comes out too dark
• Give a heavily roasted tea a few months to settle before judging it
• Use softer water if it looks stronger than it tastes

Teas this compound defines

• Hojicha
• Kuki hojicha
• Kyobancha
• Tan Bei oolong
• Nong Xiang Tie Guan Yin (roasted)
• Muzha Tie Guan Yin
• Da Hong Pao

Read next

• Theabrownins — The dark, water-soluble polymers of ripe pu-erh and other dark teas — why a shou is almost black and almost never drying.
• Pyrazines — The roasted, nutty and toasted aromas — compounds that do not exist in a tea leaf until heat makes them.
• Soluble sugars — Present in small amounts, tasted only faintly, and indispensable as the fuel for every roasted aroma in tea.
• Strecker aldehydes — Malt. The group made when firing spends the leaf's own amino acids against its own sugars, and the reason the maltiest teas are the ones with the most amino acid to spend.
• Epimerised catechins — What roasting actually does to a tea's catechins: not destroys them, flips them. The same molecules, mirrored at one carbon, sitting differently on the tongue.