Coffee can be too fresh — here's how to ensure it's not!
A focus on freshly roasted coffees has been a hallmark of specialty coffee education, and for a good reason. When coffee sits around, it slowly loses the aromatics that make it taste so special. Coffee also oxidizes, creating unwanted and stale flavors. No matter how good your storage methods are, coffee consumed within a reasonable window after roasting will taste better and more lively than that same coffee after it has been sitting in your cupboard for eight to 11 months. But, is there such a thing as coffee that’s too freshly roasted? Why yes, yes there is! The solution: degassing coffee.
One byproduct of roasting coffee is the buildup of carbon dioxide inside the roasted coffee beans. This carbon dioxide leaks out of the coffee and starts immediately after the roasting ends. If you’ve noticed a little plastic circle on your flexible packaging of specialty coffee with a tiny hole in it, that’s a one-way valve. It’s there specifically to let that carbon dioxide out without letting much oxygen in. Without that valve, you’d either have unsealed bags letting oxygen in and making the coffee go stale faster, or you would have to deal with the release of the carbon dioxide that would eventually make the sealed bag explode.
The carbon dioxide in ground coffee is also easily observable if you’ve ever brewed coffee in a pour-over, French press, or any other brew method where you can see the water coming into contact with the coffee. Those bubbles that start appearing when the hot water hits the coffee are a result of carbon dioxide. There’s nothing wrong with carbon dioxide being in your coffee, but too much of it does make it harder to make tasty, fresh coffee, and it’s easy to understand why with some very basic physics.
To extract all the tasty stuff we want from coffee roasting, we need water to penetrate the coffee grounds, dissolve those flavor compounds, and get them out into our cup to achieve ultimate coffee freshness. If you have a bunch of gas pushing out from the coffee grounds, it’s simply harder for that water to get in. And if the water can’t get in and can only dissolve particles from the outside of the coffee grounds, it won’t extract evenly, which can potentially lead to cups of coffee with a coffee taste that is both too sharply acidic and too bitter at the same time.
Sometimes when learning how to make coffee, we try to account for this by pouring a little bit of our hot water first, letting some carbon dioxide escape, and then after 30 to 45 seconds continuing with the rest of our water. That process is called a bloom. But a bloom can only do so much if we haven’t let enough carbon dioxide escape between roasting and brewing. And that pre-brewing, resting period we need to let the gas escape is called degassing or off-gassing. Degassing coffee doesn’t involve doing anything special. It simply implies letting the coffee rest on your counter, ideally still in its original bag.
This is especially important if you’re brewing espresso at home, a brew method that has coffee grounds that are packed too tightly and there is not enough time to even allow for blooming coffee. Espresso's flavors are so concentrated that you’ll be able to taste that sharp, uneven extraction immediately. But even for drip coffee, we recommend four days after the roast date as the ideal time to start brewing.
So, when buying fresh coffee (which you definitely should!), getting it any sooner than four days off roast isn’t really a goal worth pursuing if you’re trying to drink it immediately. All it takes is either a little patience or, more to my liking, just making sure you have enough coffee so that you won’t run out until your new bag is four days off roast.
If you’re interested in learning more about coffee degassing, the roasting process, or have simply want to explore coffee brewing tips, visit Trade. From a cup of decaf to a cup of Burundi coffee, we’ve got the answers to all your coffee questions.