Stone milling

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

Matcha is defined by this step. A granite mill turns at around thirty revolutions per minute and yields roughly forty grams of powder an hour, which is the main reason good matcha is expensive. The slow speed matters because it keeps the leaf cool: friction heat degrades the aroma compounds and dulls the colour, so faster industrial milling produces a visibly duller, flatter powder from identical leaf.

Also transliterated as: ishiusu biki.

What it does to the leaf

Reduces tencha to a particle size of a few microns without heating the leaf enough to damage its aromatics or colour.

What it does to the cup

Determines texture and suspension as much as flavour; poorly milled matcha is gritty, settles fast and tastes flat.

Variants that matter

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

Ball milling

Fast and cheap, used for culinary and industrial powder. Heat damage is visible as a khaki rather than jade colour.

Other steps at the Rolling and shaping stage

• Blending to a standard — Combining lots so that a named tea tastes the same in March and in October, which is a manufacturing step performed on finished tea and not a compromise applied to it afterwards.
• Cloth-ball rolling — Wrapping leaf tightly in cloth and repeatedly kneading and unwrapping it until it forms tight spheres.
• CTC (crush, tear, curl) — Leaf passed through counter-rotating toothed rollers that cut it into small uniform granules.
• Curling and down-raising (cuo tuan xian hao) — Rubbing warm leaf between the palms into loose balls and breaking them apart repeatedly, which curls the leaf into spirals and lifts its down to the surface.
• De-stemming and de-veining — Separating stem and leaf vein from the leaf blade after drying, usually by air separation.
• Flat shaping — Pressing leaf flat against the side of a heated wok by hand during pan-firing.
• Needle shaping (li tiao) — Shaking fixed leaf along heated parallel grooves until each piece straightens into a needle, rather than twisting it into a curl.
• Orthodox processing — The older manufacturing route, in which leaf is twisted and rolled rather than cut, so it survives largely intact.
• Pearl forming (chao gan cheng yuan) — Working rolled leaf against the wall of a heated pan through successive pans until each piece closes into a hard sphere, drying and shaping in the same operation.
• Refining (shiage) — The second factory. Japanese green tea leaves the producer as aracha, an unfinished trade good, and is cut, sorted and separated elsewhere into the several named teas one intake contains.
• Repeat rolling and roll-breaking (fu rou) — Rolling is done in two or three passes with the compacted lumps broken up and sifted between them, because one long pass tightens the outside of a ball of leaf and never reaches the middle.
• Rolling and shaping — Working the leaf to rupture its cells and give it a form that governs how it later brews.
• Rotorvane maceration — A screw press with internal vanes that macerates withered leaf continuously, sitting between orthodox rolling and CTC rather than belonging to either.
• Sorting and grading — Separating dried tea by particle size, density and colour into the grades it is sold as — a sorting operation, not a quality judgement.
• Stalk picking (jian ti) — Hand removal of stalk and yellow leaf from finished oolong, done between roasts rather than at the end — which is why it is an ordering fact and not a tidying-up one.
• Strip rolling — Rolling leaf into long twisted strips rather than compressing it into balls.

Teas that go through this step

• Matcha
• Matcha koicha grade
• Matcha usucha grade

Guides covering this step

• Ceremonial grade, and the other words nobody defines — A group of terms on tea packaging look like classifications and are not: no body defines them, no audit checks them, and any seller may use any of them. Knowing which words are in this group, and what to look at instead, is most of label literacy.
• Energy and fuel in tea processing — Making tea is mostly an exercise in removing water, and removing water takes heat. The drier, and whatever is burnt to feed it, is usually the largest single energy load in the whole business of producing tea — and the least discussed.
• What matcha should cost, and what you are paying for — Matcha spans roughly two orders of magnitude in price, and almost all of the difference is decided before the leaf reaches the mill. Here is where each cost sits, and which of them a drinker can actually taste.