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Good matcha comes down to two things you cannot see on the label: how the leaf was made, and how the finished powder behaves in a drink. Real matcha is shade-grown leaf, steamed and dried without rolling into tencha, then stone-milled into an ultra-fine powder, and the steps that take time and money (shading, slow stone-milling, grinding right before shipping) are exactly the ones that decide whether your matcha stays bright green, dissolves cleanly, and holds its flavor in a latte. For the drink side of that, see our matcha latte ratios and method guide.
I'm Hiroshi Asami, and I source and export matcha directly from farmers across Japan through Japanomars. This is a supply-side guide to what actually makes matcha good, and how to test it before you commit to a wholesale order.
Key takeaways
Not a binding one. No government legally defines "matcha," so the word alone guarantees nothing. The closest things to a standard are voluntary: Japan's tea industry published a definition in 2019, and ISO issued a technical report (ISO/TR 21380:2022, April 2022). Both describe matcha as stone-milled tencha, but neither can stop anyone from labeling a cheap green powder "matcha."
Here is what the international standard actually says. ISO/TR 21380:2022 defines matcha as tea from shade-grown Camellia sinensis, steamed to inactivate enzymes, dried without rolling the leaves, then finely ground into powder. It also draws the line on adulteration: real matcha is "made from pure tea leaves and is free from any additives including colouring agents and flavourings," and it explicitly excludes flavored, blended, decaffeinated, and instant matcha. Japan's Japan Tea Central Council labeling standard (March 2019) says the same in fewer words: matcha is tencha, shade-grown, steamed, dried without rolling, and stone-milled.
The catch is in the document types. Japan's is a voluntary labeling guideline with no legal force, and ISO's is a Technical Report, informative rather than certifiable. So "matcha" remains, in trade terms, an honest-supplier word, not a regulated one. This matters because a lot of what is sold as matcha does not meet even the voluntary bar. Japan's standard has a separate term, "food-processing tencha," for powders made from open-grown leaf, machine-cut and ground in a pulverizer instead of a stone mill. It is perfectly legal, and some is fine for blended drinks, but it is not ceremonial-quality matcha, and on a spec sheet it still just says "matcha." Knowing the real definition lets you ask the one question that separates them: is this stone-milled tencha, or food-processing tencha?
New in 2026: the industry starts to define "matcha." On June 8, 2026, the newly formed International Matcha Association (IMA), a non-profit established in Tokyo on April 22, 2026, published its first labeling and classification guidelines. It defines matcha exactly as ISO and Japan's standard do, frames it as a voluntary "common language" and a starting point for dialogue, and flags four product types buyers keep confusing: shade-grown tencha matcha, beverage and processing powders, commercial-grade leaf, and other variants. Logo shown for reference. Logo © IMA.
Every step that makes matcha expensive is a step you can taste. Matcha starts as the same plant as sencha, then four things set the good stuff apart: weeks of shade before harvest, steaming to lock in green, drying the leaf flat and unrolled into tencha, and slow stone-milling into powder. Skip or rush any of them and it shows up as duller color, weaker umami, grittier texture, or flatter aroma in the glass.
Shading is where flavor is built. For the final stretch before harvest, the best tencha fields are covered. ISO/TR 21380 spells out how serious it gets: top "two-step" shading blocks 70 to 80% of light at first, then rises to 95 to 98% for the last days, with shoots plucked after 20 to 30 days. Starving the leaf of sunlight does three measurable things: it raises chlorophyll (deeper green), raises L-theanine (umami and sweetness), and lowers catechins (less bitterness). That is why heavily shaded matcha tastes round and sweet while open-field "matcha" tastes thin, grassy, and sharp. The color and the umami are literally grown in.
Steaming, then drying without rolling, is what makes it tencha. Within 2 to 3 hours of picking, high-grade leaf is steamed for 15 to 30 seconds at 100 degrees C to deactivate its enzymes and lock in the green (China pan-fires instead). Then comes the fork from sencha: sencha is rolled as it dries, but tencha is dried flat and unrolled in a brick-walled dryer (tencha-ki) at 150 to 220 degrees C. Drying it flat lets the stems and veins, which cannot be milled to fine powder, be cleanly removed in finishing. Leave them in and the powder turns harsh, gritty, and dull.
Stone-milling, done slowly and cool, is what makes it usable behind the bar. High-quality matcha is ground on a purpose-built tencha stone mill into a powder with a mean particle size of 10 to 30 microns (median under 20). That fineness is what lets matcha stay suspended in water and milk instead of sinking. ISO is precise about the catch: grinding generates heat that creates matcha's aroma, but excess heat ruins the color, aroma, and taste, so the grinding room is air-conditioned to about 20 to 25 degrees C. Cheaper normal-grade powder is ground in a ceramic ball mill or jet mill instead, faster and hotter. This is also why matcha is ground close to shipping: ISO notes quality "deteriorates immediately after grinding," so a recent grind date is a freshness signal worth asking for.
Because matcha is one of the most fragile ingredients behind your bar, and most "bad matcha" is really mishandled or low-spec matcha. Its bright color and sweet aroma come from chlorophyll and amino acids that degrade quickly when exposed to light, heat, moisture, or oxygen. Bright green fades to olive, sweet umami goes flat, and ultra-fine powder draws moisture and clumps. Knowing the failure modes tells you both what to buy and how to store it. On the storage half of that, see how long matcha keeps once opened.
Color fade has a name in the chemistry. A vivid, saturated green means high chlorophyll: young, well-shaded leaf, freshly milled and stored cold and sealed. ISO/TR 21380 is specific about what goes wrong: poor storage degrades the chlorophylls to pheophytins, turning the powder from bright green to olive. That dull, yellowish-olive tint is the clearest single sign of matcha that is old, badly stored, or open-grown, which is why color is the first thing a tea taster checks.
Clumping is partly a quality sign and partly a handling problem. Genuinely fine, stone-milled matcha (10 to 30 microns) clumps a little because the tiny particles attract each other statically; perfectly free-flowing "matcha" is often coarsely ground or cut with anti-caking agents, which a pure matcha by ISO's definition cannot contain. The fix is not a coarser powder; it is sifting before use and keeping moisture out. The real ISO-grade test is what the powder does in water: quality matcha whisked into hot water stays suspended, without agglomeration or sedimentation. Matcha that sinks, or stays gritty after sifting, is the red flag.
Flavor that "disappears" in a latte is what matters most for a cafe: whether the shaded-leaf character survives heat, milk, and sugar. ISO names the markers a taster looks for: bright green color, umami taste, a greenish shaded-leaf aroma, the right level of bitterness, and a smooth mouthfeel. A high-spec matcha carries that color and flavor through a steamed latte; a thin one washes out to a beige, vaguely grassy drink. This is exactly why you should test matcha in the format you will actually sell.
You do not need a lab; you need a sample, a sieve, a whisk, and a few minutes. Steps 1 to 4 mirror the official ISO/TR 21380 sensory method (evaluate the dry powder, then whisk 2 g in 100 ml of just-boiled water and judge suspension, froth, and taste); step 5 adapts it to how you will actually sell. It catches the difference between real stone-milled tencha and cheaper food-processing tencha faster than any grade word on the bag.
Score a few samples this way and you will quickly build an internal benchmark, sourcing on what is in the tin, not on the marketing. For how leaf type, harvest, and supply-chain length set the price behind these traits, see our guide to matcha grades.
Across drinks, food, and garnish, and each use asks slightly different things of the powder. In a cafe, matcha mostly shows up three ways: whisked and drunk neat (usucha, or a clean matcha latte ordered for the flavor), blended into milk drinks and baking (the volume driver: lattes, sweetened iced matcha, soft serve, cookies), and occasionally as a visual finish (a dusted, vivid-green garnish). Knowing the use tells you which trait to weight.
For neat drinks, color, fine texture, and sweet umami matter most; this is where true first-flush, stone-milled tencha earns its premium. For lattes and baking, resistance (holding flavor and color through heat and milk) and batch-to-batch consistency matter more than the last increment of sweetness. The practical move is to match grade to use: pay up for a high-spec matcha on the drinks tasted on their own, and use a solid mid-grade where milk and sugar carry the cup, without dropping to a washed-out powder that makes your whole program taste cheap. For why high-spec supply is tight and getting tighter, see our 2026 market outlook.
From the sourcing floor
When we run this bench test with cafe owners, the color and suspension steps decide it before anyone tastes anything: a fresh, well-shaded first-flush tencha throws a fine jade froth and holds it, while a tired or open-grown powder sinks and greys out within a minute. We grind our lots close to shipping and send the grind date with every sample, because on ISO's own point (quality deteriorates immediately after grinding) that date is the single number most suppliers will not put in writing.
No. There is no binding legal definition of matcha in Japan or major export markets. Japan's tea industry published a voluntary definition in 2019, and ISO issued a technical report (ISO/TR 21380:2022); both describe matcha as stone-milled tencha, but neither is enforceable. In June 2026 the new International Matcha Association issued its first voluntary labeling guidelines to address exactly this confusion. Any green powder can still legally be sold as "matcha," so you have to verify quality yourself.
By Japan's standard, real matcha is stone-milled tencha: shade-grown, steamed, unrolled leaf with stems and veins removed, ground on a stone mill, with no added colorings or flavorings. "Food-processing tencha" is the industry's term for cheaper powder from open-field, machine-cut leaf ground in a ball or jet mill. It is legal and can work in blended drinks, but it is not ceremonial-quality matcha, even though the label may just say "matcha."
A little clumping is normal and even a good sign: genuinely fine stone-milled matcha (10 to 30 microns) clumps because the tiny particles attract each other statically. The fix is to sift it before use and keep moisture out. The real quality test is in water: per ISO, good matcha whisked into hot water stays suspended without clumping or sinking. Worry about matcha that stays gritty after sifting or sediments to the bottom.
Storage degradation. Matcha's bright green comes from chlorophyll, which breaks down to pheophytins when exposed to light, heat, moisture, and oxygen, turning the powder olive and the flavor flat. ISO advises storing it in sealed, nitrogen-flushed aluminum foil with minimal air, kept at 5 degrees C or below, and using it within a few weeks of opening for the best color and taste.
It matters for texture and aroma. A purpose-built tencha stone mill is run in a 20 to 25 degrees C room to protect the color, producing an even 10 to 30 micron powder (median under 20) that suspends smoothly. ISO notes normal-grade matcha may instead use a ceramic ball mill or jet mill, faster and hotter, which can dull the color and aroma. For drinks where matcha is tasted, stone-milled is worth specifying.
Sealed, opaque, cool, and dry. Light, heat, moisture, and oxygen all degrade matcha's color and flavor, so keep it airtight and light-blocking, refrigerated (ISO suggests 5 degrees C or below), and away from steam and humidity behind the bar. Buy in sizes you will use within a few weeks of opening rather than one large tin that sits half-used and fading.
"Matcha" is not a regulated word, so good matcha has to be recognized, not assumed. What makes it good is the same thing that makes it cost more: shade-grown tencha, stems and veins removed, slowly stone-milled to a fine, bright powder, and ground fresh, every step protecting the color, umami, texture, and staying-power you will taste in the cup. The fastest way to buy well is to ignore the grade word, ask whether it is stone-milled tencha, and run a quick color-sieve-whisk-latte test before you commit.
We export premium first-flush matcha directly from named Japanese regions and work with cafes on long-term supply, not one-off orders. Request a sample set, with leaf type, harvest, region, grind date, and current wholesale pricing spelled out, so you can run the bench test yourself and source on substance.
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