My matcha is harsh and I think it is a cooking grade

In short

Grade words on matcha are not defined by anybody. Ceremonial, premium and culinary are marketing terms with no standard behind them, so the same word means different things between two brands. What is real is what the terms are gesturing at, and those are observable properties you can check on the tin in front of you.

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 grade vocabulary is unregulated and cannot be relied on

   Leaf quality

   Check: Are you assuming that a tin marked ceremonial is necessarily better than one marked culinary from another brand?

   Fix: There is no body defining these words and no test behind them. Comparing them across brands tells you nothing. Within one careful producer's range they usually do mean something, and that is the only context where they carry information.

2. 2. The real variables are harvest, shading and leaf position

   Leaf quality

   Check: Does the tin say first harvest, and does it say anything about shading?

   Fix: Early-harvest shaded leaf makes sweet, savoury, vivid matcha; later harvests from less-shaded or coarser leaf make the bitter, duller powder sold for cooking. Those are the facts underneath the grade word, and a producer who has them will state them.

3. 3. Colour is the cheapest check and it works

   Leaf quality

   Check: Is the powder vivid, almost fluorescent green, or is it olive, yellowish or khaki?

   Fix: Shaded early leaf is intensely green and coarser or older material is not. Colour does not separate a good drinking matcha from an excellent one, and it separates both from a cooking grade immediately. Note that dullness also indicates a fresh matcha that has staled, which is a different problem with the same appearance.

4. 4. It is doing the job it was made for

   Leaf quality

   Check: Are you drinking it as usucha, or putting it in milk, ice cream or a cake?

   Fix: A cooking grade is built to survive dilution by sugar and dairy, which needs a stronger, more bitter, more assertive powder. In a latte it does its job and a delicate ceremonial powder would be wasted. The mismatch is between the grade and the use, not necessarily a defect in the tin.

5. 5. The harshness might be the whisking rather than the powder

   Technique

   Check: Is the water near boiling, and is the dose large?

   Fix: Rule this out before rejecting the tin. Matcha whisked with water much above 80 °C turns harsh whatever the grade, and there is a separate record for that. Try it sifted, at 70 to 80 °C, at a modest dose, before deciding.

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.

Related problems

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

• My matcha latte is lumpy and the powder sinks — Whisked straight into milk, the matcha forms lumps that will not break up, and within a minute a green layer has settled at the bottom of the glass.
• Leaves stick to the cup, the pot and my teeth — Fine leaf clings to the inside of the vessel, comes through into the cup, and ends up in the last mouthful.
• My bamboo whisk is losing tines — Fine bamboo tines snap off during whisking and turn up in the bowl, and the whisk feels stiff and splayed.
• 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 lumpy, gritty or will not foam — Undissolved lumps float on the surface, powder settles at the bottom, and no fine foam forms.

Sources