Is fresher always better when it comes to roasted coffee? Not exactly. Right after roasting, coffee beans go through a degassing phase—a short period where they release trapped gas. This step can make a big difference in how your coffee brews and tastes. But what is degassing, and how long should you wait before brewing?

What is Coffee Degassing?

Degassing is the period after roasting when coffee beans are left to rest so they can release built-up carbon dioxide (CO₂). During roasting, beans undergo a series of chemical reactions—like the Maillard reaction and caramelization—that create flavor, color, and aroma. But these same reactions also produce gas.

In the first few days after roasting, that CO₂ begins to escape. If you brew right after roasting, the trapped gas can create bubbles that interfere with water flow, causing uneven extraction and muddled flavors. This is why “degassing” is a common term in the coffee world—it’s not just resting, it’s an essential step toward a better brew.

How Green Coffee Resting and Aging Differ from Degassing

Before roasting, green coffee also goes through its own form of resting—but it serves a very different purpose than post-roast degassing. 

In this context, aging refers to the long-term storage of green beans—typically from several months to one or two years—to intentionally develop specific flavor characteristics. This is common with certain origins or processing styles, such as aged Sumatra or monsooned coffees.

Resting, on the other hand, is a short-term stage that usually happens after drying. Its purpose is to allow moisture to redistribute evenly throughout the beans and stabilize their condition before export or roasting.

Aside from these intentional processes, green coffee also undergoes natural changes over time during storage and transportation.
This is why coffee professionals often classify green beans based on how long they’ve been stored.

• New Crop: Freshly harvested and processed in the current season. These beans are usually vibrant green, with 10–12% moisture and bright, fruit-forward flavors.
  

• Past Crop: Beans from the previous harvest cycle, stored for several months. Moisture content is slightly lower, and the color may shift toward yellow-green. Flavors become softer, and acidity tends to mellow.
  

• Old Crop: Green coffee stored for over a year. Over time, the beans may lose aroma and develop a flatter flavor profile. If stored improperly, they may also take on “baggy” notes.
  
  

**These categories describe the natural aging of green beans in storage—not to be confused with intentional resting, aging or degassing.

How Long Does Degassing Take After Roasting?

There’s no universal rule for how long coffee should degas after roasting. Some coffees settle within 3 to 5 days, while others may need up to two weeks. The ideal rest time depends on several factors:

• The coffee species (e.g., Arabica vs. Robusta)

• The processing method

• The roast level

• Whether the coffee is kept whole or ground

Species: How Arabica and Robusta Differ in Degassing

The chemistry inside different coffee species affects how they degas. Studies suggest that Robusta beans usually produce more total gas after roasting than Arabica. This difference can influence the degassing process and ultimately change how long the beans need to rest before brewing.

Processing Method: How It Impacts Degassing Speed

The way coffee is processed—from fruit to green bean—also affects degassing time. Washed, natural, honey, and anaerobic coffees all behave a little differently after roasting. In practice, washed coffees tend to degas more quickly because they contain less mucilage, leaving the bean structure cleaner and more uniform.

Roast Level: How Light, Medium, and Dark Affect Degassing

Roast level has a direct impact on how quickly beans release CO₂. Heat change the cell structure of the coffee, altering its porosity:

• Light roast: Dense structure with fewer pores. Degassing is slower, often taking 7–14 days.
  
  

• Medium roast: Moderate porosity and a mid-range degassing window of about 5–10 days.
  
  

• Dark roast: Looser structure with more pores. Degasses quickly, usually within 2–7 days.

These numbers are only general guidelines. Actual resting (degassing) time varies depending on species, processing, roast style, and even equipment. When in doubt, check the roaster’s recommendation or the packaging notes.

Related: A Guide to Coffee Roasting

Grinding: Why Ground Coffee Degasses Faster

Grinding dramatically speeds up degassing. One study found that freshly roasted beans, once ground, can release as much as 75% of their CO₂ within just 90 seconds.

The trade-off is that grinding also exposes far more surface area to oxygen. Along with gas release, fragrances dissipate and oxidation accelerates, shortening the coffee’s shelf life. That’s why degassing is typically done with whole beans—this helps preserve flavor and extend freshness.

In special cases, such as when you need to brew right after roasting, grinding and letting the grounds sit briefly can help release excess gas. But this is more of a workaround than a standard degassing practice.

How Degassing Impacts Coffee Flavor

When ground coffee comes into contact with hot water, CO₂ is released.

If there’s too much gas trapped in the beans, bubbles form during brewing. These bubbles disrupt water flow, leading to uneven extraction and unstable flavors. In espresso, excess CO₂ can interfere with flow rate and consistency; in pour-over, it can weaken the bloom and disturb the coffee bed, causing fines to rise to the surface and making extraction uneven.

On the other hand, if beans rest for too long, they lose freshness. Aromatic compounds fade, acidity flattens, and the cup becomes dull and lacking in complexity.

It’s worth noting that CO₂ isn’t always a bad thing. The rich crema on espresso, for instance, forms through the interaction of CO₂ with oils and other compounds. The key is balance—giving the beans enough time to degas, but not so long that the coffee turns flat or stale.

How to Rest Coffee Properly

So how should freshly roasted beans be rested? The principles are similar to general coffee storage: keep them dry, protect them from humidity, and avoid direct sunlight or strong light exposure.

The best option is to use bags with a one-way degassing valve. These allow CO₂ to escape while preventing oxygen and moisture from entering, which helps protect flavor and extend shelf life.

Related: How to Store Ground Coffee for Maximum Freshness

How Long Do Beans Stay Fresh After Degassing?

Once degassing is complete, coffee enters a “sweet spot” for flavor. Typically, the 2–4 weeks that follow are when aroma is most vibrant and the cup shows the best balance and complexity. Over time, both fragrance and acidity start to fade, and the flavor profile flattens.

That said, properly stored beans remain safe to drink within their shelf life. The real threats are moisture, oxidation of oils, and spoilage—these factors matter more than the calendar date alone.

For store-bought roasted coffee, always check the roast date and the best-by date on the packaging. Ground coffee, with its much greater surface area, stales faster than whole beans. Choosing whole beans and storing them correctly will help preserve freshness for longer.

Femobook Electric Coffee Grinders

After the right degassing (resting) period, all that stands between you and a great cup is grinding and brewing. The Femobook A68 Electric Grinder delivers commercial-grade performance in a compact design. It features quick-release parts for easy cleaning and a wide range of grind settings, with excellent grind consistency. Its short grind path minimizes retention, delivering a clean dose every time—free from stale grounds that can dull flavor.

Femobook also offers a lineup of grinders to suit different needs—whether at home, on the go, camping outdoors, or even in a commercial setting. The compact A2 is perfect for travel, the A5 is an excellent everyday grinder for home brewing, and the A68 can easily meet the demands of a café.