Do Coffee Beans Need Resting Before Brewing?

Freshly roasted coffee beans benefit from resting, because roasting leaves a popcorn-like aroma and smoky notes along with a large amount of carbon dioxide trapped inside. Brewing immediately can trap that gas as a barrier, blocking water from reaching the flavour compounds and causing under-extraction or uneven extraction.

Resting lets carbon dioxide escape and unpleasant roast odours fade while the coffee's own flavours come forward. The aroma of freshly roasted beans lasts about two to three weeks, and the 8 to 25 day window is when it shows most clearly. How long to grind coffee beans stays a separate question: grind close to brewing, since ground coffee stales quickly.

When you've just bought coffee beans, you'll often hear baristas suggest letting them "rest" before drinking, as the flavor will be better. But why exactly do coffee beans need to rest? How long is the resting period? And how long can freshly roasted beans be stored? These questions puzzle many coffee enthusiasts. From the perspective of Front Street, this article discusses the principles behind bean resting: freshly roasted beans carry a popcorn-like aroma and smoky notes, and are rich in carbon dioxide, which hinders extraction; resting is precisely the process that allows the gas to slowly release and the flavors to gradually emerge. It also shares how to judge a bean's condition through the swelling dome during blooming, and why it's worth drinking while observing the changes after receiving your beans.

When buying coffee beans, you'll often hear baristas remind you: don't rush to use freshly roasted beans, let them rest first and the taste will be better. So do coffee beans really need resting? If so, how long do you have to wait? And how long can fresh coffee beans be stored? Today Front Street will briefly talk about the matter of bean resting.

Do fresh coffee beans need resting?

Freshly roasted coffee beans carry a popcorn-like aroma produced by the Maillard reaction, mixed with some smoky notes. If you grind and brew them right away, these less pleasant flavors will end up in your coffee. Moreover, freshly roasted beans contain a large amount of carbon dioxide inside, like a barrier that hinders water from extracting the flavor compounds in the coffee, easily causing under-extraction or uneven extraction, resulting in less than ideal flavor.

But at the same time, we also suggest drinking the coffee beans as soon as possible after receiving them—so why is that?

The aroma of freshly roasted coffee can last two to three weeks, and especially in the 8–25 day window, the aroma is at its best and the flavor characteristics are at their most intense.

The purpose of resting is to let the coffee beans slowly release carbon dioxide while carrying away the unpleasant odors produced during roasting; in this process, the coffee's specific flavors also gradually emerge. This duration is not fixed, so the resting period is unstable. Starting to drink as soon as you receive the beans lets you slowly feel the subtle daily changes in flavor, and truly understand the difference between beans that have rested well and those that haven't rested enough.

Since you can't taste and judge whether the beans have rested enough before brewing, what should we rely on to understand the condition of the beans?

In fact, you can use the swelling dome during blooming to make a simple judgment of whether the beans have rested enough. Blooming is meant to release the carbon dioxide inside the coffee grounds and saturate them so as to extract better. If during blooming the coffee grounds easily form a "hamburger"-shaped dome, it means there is more carbon dioxide in the grounds and the beans are fresh; if during blooming the coffee bed changes little and doesn't swell much, then the beans may not be very fresh.

The blooming dome after being stored for a period of time (roast date: 6.18)

(both coffees are 90+eleta, brewing date is July 9)

Of course, the blooming dome can only roughly help us observe the condition of the beans; in the end, you still have to taste the specific flavors to truly judge whether the beans have rested enough.

There is also technology that adds nitrogen to extend the shelf life, which to some extent can maintain the release of coffee flavor compounds; this technology was originally developed to solve the preservation problem of beans during ocean shipping. Now, with the rise of specialty freshly roasted coffee, rather than emphasizing how to preserve it, it's better to just buy fresh beans in small quantities for the short term and drink them as soon as possible—wouldn't that let you better appreciate the flavor of coffee?

Front Street Coffee

No. 10, Bao'an Front Street, Yandun Road, Dongshankou, Yuexiu District, Guangzhou, Guangdong Province

The above content is compiled by CoffeeHunters, a coffee news website.