Rest times for fresh roasted coffee

[Mad Dawg]

From the Daily Coffee thread:

Originally Posted by Bobbystbob

La Minita, with 3, excellent. The additional days rest really smoothed it out. Good cup

This gets right to something I've been thinking about rather a lot lately. I typically don't rest my coffee more than 24 hours, and my norm is more like 12 hours - roast in the afternoon for consumption the following morning.

To be sure, I've done the experiments myself. I've roasted a couple of pounds of coffee at a time and brewed it over 7+ successive days so as to track the evolution of the flavors and overall impressions as rest time is increased. A few observations follow.

The amount of foam that the ground coffee generates when the hot water hits it decreases steadily with increasing rest time. This is a no-brainer. Roast coffee throws off gas (mostly CO2) after it's roasted, and eventually, all of the gas is gone. I've heard people assert that coffee that is still offgassing is not yet ready to drink, but that (to my tastes) is bullshit. Once the gas is gone, the coffee is stale. All canned coffee is pre-staled so that it won't generate gas once it's sealed in the can. If it weren't, BOOM!

Flavors change as rest times increase. To my tastes, some rest is required. I've ground and brewed coffee warm from the roast, and I don't find it pleasant at all. But...that's exactly what professional coffee tasters do. Frankly, how they see past that to what a coffee will taste like when it's rested is beyond me.

How much rest a coffee needs is the key, and I believe that's a matter of individual tastes. At the kind of short rest times I typically use, the brewed coffee has a kind of prickly edge to it; I've come to like that. After 2-3 days, most coffees will have lost that prickliness, and smoothed out considerably. That's fine, but I've had coffees where flavor components that I love (e.g., blueberries) disappear with that much rest. Deciding how much rest is needed to smooth out the cup without sacrificing key flavors is a kind of a tricky business.

But it's also part of what makes roasting your own coffee so much fun.

Discuss!