How is matcha made? From tea field to stone mill

What is the difference between tencha and matcha?

Matcha is a powder made from one specific raw tea: tencha. That is the name for the shaded, steamed and dried tea leaves that matcha is ground from.

The plant is the same as for sencha, Japan's everyday green tea, or for black tea: Camellia sinensis. What makes the difference is how the tea is grown and processed. The table gives the overview, and below we explain each step.

Why are the tea bushes shaded?

A few weeks before harvest, the tea fields are covered, traditionally with reed mats and straw, today also with cloth. A two-stage cover is widely used in Uji: it first blocks about 80 percent of the sunlight, and about 98 percent after 8 to 10 days. Around 20 days or longer is common. Our matcha is shaded for about 4 weeks.

The reason is plant chemistry. In sunlight, the tea plant converts part of its theanine into catechins. Theanine is an amino acid that shapes the umami taste. Catechins make tea bitter and astringent.

In the shade, more theanine stays in the leaf and the plant builds more chlorophyll. The result is dark green leaves with more umami and less bitterness.

When is the tea for matcha harvested?

High-quality matcha comes from the first spring harvest (ichibancha). In Uji it is picked from late April to late May, for tencha often by hand. The second harvest follows from late June to early July.

Leaves from later harvests in summer or autumn are older. Matcha made from them usually tastes more bitter and looks less green. What exactly changes between harvests is explained in First spring harvest vs. later harvests.

What happens right after picking?

The fresh leaves are steamed briefly. This stops oxidation: the leaf stays green instead of darkening like black tea. So matcha is not fermented.

Then air blows the leaves up several times. This cools them down and removes the water on their surface.

Why is tencha not rolled?

For sencha, the leaves are rolled after steaming. Tencha stays flat because it will be ground anyway.

Instead, the leaves dry in an oven that can be about 10 metres long. Radiant heat and warm air dry them on several conveyor belts until less than 5 percent water remains in the leaf.

Why are stems and veins removed?

After drying, the leaves are cut into small pieces. Air flow and sieves then separate stems and veins from the leaf flesh. These parts are too tough to grind finely between stones.

What remains is tencha: flat pieces of dark green leaf. Only these go into the mill.

How much matcha does a stone mill grind per hour?

Very little. Two granite stones turn slowly against each other and rub the tencha into powder. One mill makes around 40g per hour.

For scale: 40g is enough for 20 servings of 2g. So one serving takes the mill about 3 minutes, and a 60g pouch about an hour and a half.

The upside: the powder comes out very fine and even. A Japanese study measured an average particle size of about 11.5 micrometres for regular matcha, just over a hundredth of a millimetre.

Is machine-milled matcha worse?

Not automatically. Machines grind faster and more evenly. One industrial method for cooking-grade matcha makes around 10kg per hour, about 250 times as much as a stone mill.

For baking or large volumes, that makes sense. In our experience, the quality of the leaves matters more than the mill: late-harvest, bitter leaf will not become good matcha on granite either.

Is every green powder matcha?

There is no binding international definition. A Japanese study compared 25 green tea powders sold in the US, priced from 4.30 to 160 US dollars per 100g. The expensive matchas contained more chlorophyll and more free amino acids such as theanine. Many cheap powders had a different composition but were sold as matcha too.

The researchers therefore call for an international definition. Until there is one, concrete information on the pack helps, such as harvest and origin. What else to look for is in How to spot good matcha.

Why is matcha so sensitive after grinding?

As a fine powder, matcha has a huge surface area. Oxygen and heat therefore act faster than on whole leaves.

A Japanese storage study shows how much temperature matters: sealed matcha kept good quality for 24 weeks at 4°C. At 37°C it was clearly worse after only 3 to 4 weeks.

That is why matcha is packed airtight and protected from light. Every one of our packs carries a best-before date, one year from sealing. Our 60g pouch is resealable. How to store an open pack is explained in How to store matcha after opening.

Where does our matcha come from?

We buy directly from a producer family in Uji that works with the tea farmers and mills the matcha itself. Our organic matcha comes from the first spring harvest and is ground on granite mills. It is so fine that it needs no sifting. As is traditional for matcha, it is a blend of two tea cultivars.