How long should roasted coffee rest before you sell or brew it?

Coffee straight out of the roaster isn't at its best. For a few days it keeps releasing carbon dioxide, and that gas gets in the way of brewing. Resting means leaving it alone long enough for most of it to escape.

What the gas does

In espresso, too much CO2 makes the shot gassy: channelling, an uneven extraction, a crema that looks great and tastes thin. In filter, the bed bubbles up as you pour and the water doesn't contact the coffee evenly, so the cup tastes sharp or empty.

Wait too long, though, and the coffee starts to go flat. The aromatics fade, and the sweetness and acidity dull.

Common starting points

These are ranges many roasters use, not rules:

• Filter: about 4 to 10 days after roasting.
• Espresso: about 7 to 14 days, sometimes more for very light or dense coffees.
• Dark roasts: they degas faster, often within a few days, and go stale sooner because they're more porous.

Darker roasts release gas sooner. Lighter, denser coffees release it slowly and often improve for longer.

How to find the window for your coffee

The best method is the plainest: roast one batch, then taste it over time.

1. Brew the same coffee the same way on days 2, 4, 7, 10 and 14.
2. Take a note each time: how it tasted, and for espresso how the shot ran.
3. Write the day you liked it best.

The log in your roast notes is a good place for it. After two or three coffees you'll see your own pattern, and you can print a "best from" date on the bag.

Packaging matters

A one-way valve bag lets gas out without letting air in, so you can bag the coffee early and let it rest in the bag. Without a valve, let it degas first, or the bag will puff up.

Keep it away from heat and light. Sealed and cool, roasted coffee holds for a few weeks. After that, it's slowly losing what you worked for.

What to tell customers

Don't promise "roasted yesterday" as if it were the selling point. Put the roast date on the bag, plus a note on when it's at its best. People then brew it when it's ready, and the coffee gets the reputation it deserves.