My matcha powder has gone dull green or khaki

In short

Colour is the one quality signal in matcha a drinker can read directly, and it fades faster than in any other tea because milling has exposed an enormous surface area to air and light. The fading is not reversible, so every cause below is really a question about storage from the moment the tin was opened.

Likely causes, in order

Most likely first. Answer the question under each one before moving on — several of these look alike in the cup and are told apart only by what was done to the leaf.

1. 1. The tin has been open at room temperature for weeks

   Storage

   Check: When was it opened, and where has it been kept since?

   Fix: Keep opened matcha sealed and refrigerated, and buy in 20–30 g tins rather than 100 g ones. Ground tea has far more exposed surface than leaf and degrades on a scale of weeks rather than months.

2. 2. Light exposure through a clear or part-clear container

   Storage

   Check: Has it been decanted into a glass jar, or kept anywhere lit?

   Fix: Use an opaque airtight container. Light drives the colour loss directly, and a jar on a worktop will dull a good matcha in a fortnight.

3. 3. Condensation from taking a cold tin straight into a warm kitchen

   Storage

   Check: Do you open it immediately after taking it out of the refrigerator?

   Fix: Let the sealed tin come to room temperature before opening it. Moisture condenses on cold powder and both dulls the colour and clumps it permanently.

4. 4. It was a culinary or lower grade to begin with

   Leaf quality

   Check: Was it vivid on the day the tin was opened, or has it always been olive?

   Fix: Later-harvest and stem-heavy material mills to a duller powder from the start, and shading depth affects it too. If it was never bright, this is grade rather than storage, and it will also taste more bitter.

5. 5. Heat from being stored beside the hob or on top of the kettle

   StorageInferred by TeaHQ, not established

   Check: Where in the kitchen does the tin actually live?

   Fix: Move it. Repeated warming accelerates every degradation route at once, and the top of an appliance is the warmest shelf in most kitchens.

Tea types this applies to

• Green tea

Brewing methods this applies to

• Whisking (bowl-prepared powdered tea) — Powdered leaf suspended in water rather than steeped and strained — the only common preparation in which the leaf itself is consumed rather than discarded.
• Koicha (thick matcha) — Matcha prepared thick enough to pour like paint rather than to whisk into foam. It is not a stronger version of everyday matcha but a separate preparation with its own motion, its own grade of powder and, in chanoyu, its own place in the sequence — and it is the older of the two.

When this cannot be fixed

Colour loss in matcha cannot be reversed. Dulled powder is still usable in a latte or in cooking, where milk and sugar cover the flattened aroma, but it will not make a good bowl again.

Guides covering this

• Choosing a matcha without a grading system to lean on — There is no regulated matcha grading, no certifying body and no agreed vocabulary. What there is: a small set of things a seller either tells you or does not, and each omission means something.

Related problems

Sharing a cause category, a tea type or a brewing method with this one.

• My Japanese green tea tastes of seaweed or fish — A sencha, gyokuro or matcha reads as marine — seaweed at best, distinctly fishy at worst — and it is not clear whether that is the tea or a fault.
• My matcha is harsh and I think it is a cooking grade — A matcha bought to drink is dull-coloured, gritty and aggressively bitter, and the tin says culinary, cooking or ingredient grade — or says nothing at all.
• I bought a big bag to save money and it was stale before I finished it — A large quantity bought at a good unit price faded well before it was drunk, so the saving turned into waste.
• My tea goes damp within weeks and I live somewhere humid — Leaf that arrived loose and crisp becomes soft, slightly clumped and quiet within a few weeks, and the aroma flattens long before any best-before date is close.
• I have too many teas open and most of them are going stale — A dozen or more packets are open at once, three or four get drunk regularly, and the rest fade quietly on the shelf until they are thrown away.

Sources