Recognizing When Matcha Has Declined

The printed date says nothing about the current state, particularly after opening.

Four things to check.

1. Color

Matcha's green comes from chlorophyll, which breaks down under light, heat, and air, shifting toward yellow and brown.

Remember the shade when you opened it and comparison is simple. Color is the most legible indicator.

One exception: products containing coloring agents hold their appearance regardless. Check the ingredient list to know whether this applies.

If the smell on opening has weakened, volatile compounds have gone.

Heat and time drive them off. No aroma at all, or something resembling oxidized oil, indicates the process is well advanced.

Powder that was free-flowing and now feels damp or caked has taken on moisture.

Light clumps can be broken up and used. A solid block should not be.

Flat, chalky, or all vegetal note with no depth.

Bitterness and astringency remaining while umami disappears is another version of the same decline.

Those are safety issues rather than quality ones.

Best-before dates indicate quality. Passing one does not create a hazard.

Powder that has dulled in color and aroma may still work in baking or cooking, where it is not the sole focus.

Easier than learning to judge: avoid the conditions.

Away from light, away from heat, sealed against air and moisture. And buy what you can finish — 300 g at 20 g per serving is 15 cups.