My green tea goes yellow or brown in the cup

In short

Some of this is normal and unavoidable, and some of it points at water and temperature. Separating the two matters, because the normal version is not worth chasing and the water version is a genuine and fixable fault.

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. Ordinary oxidation of the brewed liquor

   Technique

   Check: Does it happen slowly, over ten or fifteen minutes, in an open cup?

   Fix: Brewed tea darkens on standing in air. This is expected and affects colour far more than flavour; drink it sooner or accept it.

2. 2. Alkaline or hard water

   Water chemistryInferred by TeaHQ, not established

   Check: Does it darken almost immediately, and does the cup also look dull with a surface film?

   Fix: Alkaline water shifts the colour of green tea sharply and flattens its aroma at the same time. Filtered or low-mineral water is the fix, and the colour change is a useful visible indicator of a problem you can also taste.

3. 3. Water too hot

   Temperature

   Check: Was the water at or near boiling?

   Fix: Use 70 to 80 °C. Excessive heat produces a duller, more yellow liquor as well as the bitterness that usually accompanies it.

4. 4. The leaf is old

   Storage

   Check: Is the dry leaf dull olive or yellowish rather than fresh green, and how old is it?

   Fix: Green tea fades within a year and the dry leaf shows it before the cup does. No brewing adjustment recovers a faded green tea.

5. 5. Lemon or another acid was added

   Technique

   Check: Is there citrus in the cup?

   Fix: Acid lightens tea liquor visibly and quickly. That is chemistry rather than a fault, and it works the same way on black tea, which is why lemon tea looks pale.

Tea types this applies to

• Green tea

Brewing methods this applies to

• Western brewing (teapot or mug) — A small amount of leaf in a large volume of water, steeped once for a few minutes and then strained off. The approach most English-speaking drinkers already know, and the one most teas sold in the West are made for.
• Mug infuser brewing — Loose leaf in a basket inside a mug — the most common way loose tea is actually made, and the method most often responsible for people concluding that loose leaf is not worth the trouble.

Guides covering this

• What colours a tea liquor, and why colour is a poor guide to strength — Four groups of compounds account for nearly all the colour in a cup, and none of them tracks how much material is dissolved. Judging strength by eye is one of the commonest brewing errors and this is the mechanism behind it.

Related problems

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

• I bought a water filter for my tea and it changed nothing — A filter jug or tap filter was bought specifically to improve the tea, and the cup tastes the same as it did before — with the same dullness, the same film and the same scale in the kettle.
• My green tea tastes flat and looks dark in this house — A delicate green tea that tasted bright elsewhere comes out dull and heavy here, with a darker, browner liquor than it should have and none of its aroma.
• My leaf floats on top and will not sink — Dry leaf sits on the surface in a dry-looking raft, and the tea underneath is pale long after it should have been ready.
• My tea gets drier and harsher as it cools — The first mouthful is balanced and the last one, several minutes later, grips the tongue and feels rough — from the same cup, with nothing added.
• 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.

Sources