TeaHQ

Kill-green (fixation)

Heating the leaf to stop oxidation — the step that makes green tea green.

杀青Stage 5 of 13: FixationAlso called fixationAlso called fixingAlso called de-enzyming

The categories this step defines

In tea, processing is not a modifier applied to a category — it is what creates the category. These are the types that exist because this step exists.

  • Green tea — Kill-green (fixation) applied before meaningful oxidation can develop.

What it is

Applying enough heat, quickly enough, denatures the enzymes that would otherwise brown the leaf. Everything downstream then happens to a leaf that has stopped changing colour. The method matters as much as the fact: steam and dry heat leave very different signatures, which is most of why Japanese and Chinese green teas taste so unlike each other despite sharing a category.

Also transliterated as: shaqing, sha qing, sha-ching.

What it does to the leaf

Denatures polyphenol oxidase and related enzymes, arresting enzymatic oxidation.

What it does to the cup

Steaming preserves marine, umami and seaweed-adjacent notes; pan-firing contributes toasted, chestnut and nutty character through contact with hot metal.

Variants that matter

Ways this step is carried out that produce genuinely different results, rather than regional names for the same thing.

Steaming (Japanese standard)
Seconds of steam. Duration is itself a style axis — longer steaming gives a deeper, softer, more broken-leaf cup.
Pan-firing (Chinese standard)
Tumbled in a heated wok or drum, often by hand for high-grade teas.

Where this gets misdescribed

Kill-green is often described as 'stopping fermentation'. It stops OXIDATION, which is enzymatic. Fermentation in tea means microbial activity and is a different process entirely — one that mostly happens after manufacture, in dark tea.

Other steps at the Fixation stage

  • Drum fixation — Kill-green in a heated rotating cylinder that leaf passes through continuously, which is how most Chinese green tea is now fixed.
  • Pan-firing (Chinese fixation) — Fixation by direct contact with a heated wok or drum, which halts oxidation and toasts the leaf at the same time.
  • Spreading and cooling (tan liang) — Getting the heat out of the leaf immediately after a hot step, because heat that stays in the leaf keeps cooking it after the operator has stopped.
  • Steaming (Japanese fixation) — Fixation by live steam rather than dry heat — the choice that separates Japanese green tea from Chinese.

Teas that go through this step

Guides covering this step

  • What is green tea? — Tea whose oxidation is stopped before it starts, by heat applied within hours of picking. The method of heating — steam or pan — splits the category into two families that taste almost nothing alike.
  • The six categories are six answers to the same set of questions — Every tea in the world comes from a leaf that arrived at a factory in the same condition. What separates green from black from oolong from pu-erh is a short series of decisions taken in the hours after that, and each one has a knowable consequence.
  • Why green tea is the hardest category to make well — Green tea has the fewest steps and the least margin. There is nothing in the process that hides a mistake, no oxidation to build over a weak start and no roast to cover a flat finish, and every error is still in the cup at the end.
  • What heat does to a tea leaf, from ambient to char — Almost every operation in tea manufacture is a decision about temperature. Reading the whole process as one ladder of heat — from a wither at room temperature to a roast that chars — makes the reasons behind each step visible at once.
  • Green tea and dark tea want opposite storage, and this is the fact to keep — One category is stored to stop it changing and the other is stored to make it change. Almost all confusing storage advice comes from a writer who has not said which of the two they mean.
  • Why the order matters more than the steps — There are perhaps a dozen operations in tea manufacture and every category uses most of them. What separates green from black from oolong is almost entirely the sequence, and once you can see the sequence you stop needing to memorise the categories.
  • Drying, firing, baking, roasting: four words and one machine — Heat is applied to tea at least four times in some routes, for four different purposes, sometimes in the same basket over the same charcoal. The words overlap badly, and the way to tell them apart is by where they sit in the sequence.

Sources

  • TeaHQ editorial synthesis — TeaHQ

This page is TeaHQ’s own synthesis of well-attested production practice. No external technical document stands behind it, so it describes what producers do rather than asserting measured process parameters.

How TeaHQ handles sources

Written comparisons

Where TeaHQ has set this step against something it is routinely confused with, and argued the differences out in full.

  • Kill-green vs oxidation — Every category of tea is decided at one fork: whether heat arrives before the leaf browns, or after. Kill-green and oxidation are the two branches, and the whole six-category structure follows from where a producer puts that heat.
  • Withering vs kill-green — Two early steps that both happen to freshly plucked leaf and that pull in opposite directions. Withering lets change begin; kill-green stops it. Which one comes first — or whether the other happens at all — is what separates white tea from green tea.