There are many aspects to making beautiful coffee, but one of the most overlooked techniques is resting the freshly roasted coffee beans.
After coffee roasting, it is often recommended to let the beans sit for a few days to allow the CO2 inside them to emerge naturally. Too much CO2 in the beans can cause issues with the flavor and other aspects of the coffee, so, depending on which brewing method you use, it’s something you ought to consider.
But how long should you rest coffee beans without compromising the coffee freshness? What are the effects of not resting the beans? And which brewing methods and roasts are the most affected by allowing the beans to rest before you use them?
This article answers each question so you’ll better know the answers and ensure you get great-tasting coffee.
Why Should You Rest Coffee Beans?
When roasting green coffee, it produces a substantial among of carbon dioxide. Most of that escapes the beans during the roasting process, but a significant amount is trapped inside the beans. As a result, the beans will continue to degas a couple of weeks after packing.
When you brew coffee, more CO2 escapes when hot water reaches the beans. That can interfere with the extraction making quality control more difficult. In some instances, if the coffee is particularly fresh, you may even detect a carbonic acid taste that is unpleasantly sour. Sometimes, if you’re using dark roasted beans, the flavor may even have a smoky tinge.
Because of this, many people suggest resting the coffee beans for several days after roasting to enable much of the CO2 to leave them naturally. Then, when you brew coffee, it’s easier to brew and extract, leading to a far tastier beverage.
However, that isn’t for everyone. Indeed, some people enjoy the taste of extremely fresh coffee, so don’t rest the beans, whereas others prefer to wait about a week or so for the peak flavor. What suits you will depend on factors including taste preferences and lifestyle.
If you decide to rest the coffee beans, there are a few things you need to consider. Let’s take a look at them.
What To Consider When You Rest Coffee
Roast Level
Check the label on your coffee bag to determine whether it’s a light or dark roast. Each roast degree has its own sweet spot.
The lighter the roast, the less CO2 there will be. However, lighter roasted beans are denser, so the CO2 is harder to remove after roasting. Higher-grown coffee is denser still, meaning the degassing occurs even more slowly. In this case, you can rest the coffee for longer.
Daker roasts produce a lot more CO2, but the beans are more porous and brittle so that they can’t hold the gas inside as long as the lighter roasts. They degas much faster.
Brewing Method
The brewing method can be a consideration in the time needed to rest the beans.
For example, if you’re making pour-over coffee with a Hario V60, the first step is blooming, which involves pouring a small amount of hot water on the grounds and letting the gas out of the coffee. The fresher the coffee, the more sizeable the bloom there’ll be. When you brew dark roasted coffee, the coffee bed will rise and expand noticeably. Blooming can reduce the gas efficiently enough for filter coffee.
However, the trapped CO2 is more problematic when you’re using a more intense brewing process, such as pulling espresso. Firstly, espresso usually uses darker roast beans, which have more CO2 and are more porous, allowing the gas to escape from the beans more easily. This means that escaping gas can be an issue in the extraction process when pulling the shot. It’ll also make it more difficult to dial in.
So, on the first day, you can dial in the grind size to achieve the yield in your optimum time. However, on day two, you’ll need to adjust the grind size as the same coffee would yield far more quickly. Another issue is that the crema can be too bubbly when the coffee is too fresh, inhibiting your ability to produce excellent latte art.
As a general rule of thumb, resting coffee isn’t as important an issue when making filter coffee, but it is certainly something to consider when making espresso.
Coffee Storing Temperature
Other factors are also related to the outgassing speed and freshness of the coffee.
For example, if your store your coffee in warmer temperatures, the outgassing will happen more quickly. You can also accelerate other staling reactions, including oxidization.
In general, you should aim to store coffee around a temperature of 68°F (20°C). So, if you live in an area with a warm climate where you’ll struggle to maintain that temperature, it is best not to store and rest coffee for as long because it will degas and age more quickly.
Conversely, if you freeze your coffee, you can extend its shelf life. Not only that, but when you brew espresso, it will still produce a rich crema and taste fresh for longer. So, if you’re storing coffee at a cold temperature – perhaps in a cellar or basement – it is advisable to extend the resting time.
How Long To Rest Fresh Roasted Coffee
Usually, when coffee is shipped to you, it’ll be one or two days after the roast date. So, coffee is often too fresh when it comes to home roasting. In general, between five and 14 days is the best window for enjoying the peak freshness and flavor of most coffees.
Here are some specific recommendations on resting your coffee, depending on the brewing method and roast level.
This chart for the good starting points:
| Roast/Method | Filter Coffee | Espresso |
|---|---|---|
| Light Roasts | 4-7 days | 7-10 days |
| Medium Roasts | 4-5 days | 7-10 days |
| Dark Roasts | 1-2 days | 4-6 days |
Resting Coffee For Filter Brewing
As we mentioned earlier, resting coffee isn’t as significant an issue as filter coffee. After all, if you’re brewing correctly and blooming the grounds, you can make beautiful coffee as early as the day after roasting.
We recommend waiting two days for darker roasts, but for light and medium roasts, we suggest resting it for between four and five days. With very dense light roast coffees, there’s a case for letting it rest for up to 10 days.
Resting Coffee For Espresso
Resting beans for espresso is far more important because the CO2 level in the grounds has a bigger impact on the coffee.
With light or medium roasts, aim to rest the coffee for seven to 10 days. This will be long enough to ensure a consistent shot once dialed in. However, it’s worth remembering that lighter roasts won’t produce rich crema even if the beans are fresh.
For darker roasts, rest the beans for between four and six days. The outgassing will be much faster, so the oil will be exposed to the surface if you leave it for longer. The main concern should be the chance of the coffee going stale rather than CO2 outgassing or the coffee resting correctly.
Resting Coffee FAQ
You may have noticed some holes on the exterior of coffee bags. Inside the bag is a plastic one-way valve that allows gas out but doesn’t let oxygen in. It will burst if you seal the bag of grounds without the valve. If you see a puffy bag, it’s a sign that the valve has failed. However, the coffee will be fresh and fine to use.
No, because once the beans have been ground, they have much more surface area exposed to air and will go stale quickly, so they should be used as soon as possible. You only need to rest whole beans.
No, keep the coffee bag sealed when resting the coffee. The valve in the bag releases CO2 but doesn’t allow air in. Exposing the beans to air will make them go stale far sooner. However, if you roast coffee at home or buy dark roast beans, don’t put the coffee in a sealed bag or a container without a valve. The pressure of the gas emerging from the beans is strong enough to rupture the seal and make a mess.
