Why Espresso Beans Need a Longer Rest Than Pour-Over Coffee (Coffee Degassing Explained)

 It’s widely known that freshly roasted coffee beans are not ideal for brewing right away. During roasting, coffee beans accumulate a large amount of carbon dioxide inside their structure. When too much CO₂ is present, it interferes with hot water’s ability to extract aromas and flavor compounds, resulting in a cup that simply doesn’t taste as good.

Fortunately, carbon dioxide naturally escapes from the beans over time. By allowing the beans to rest, we reduce the amount of CO₂ trapped inside. Once the gas level drops to the point where it no longer significantly affects extraction, it becomes much easier to brew a great-tasting cup of coffee. This resting window is what coffee lovers commonly refer to as the “degassing” or “resting” period.

If you regularly buy whole beans and brew at home, you’re probably familiar with this concept. Beans used for pour-over brewing typically need about 3 to 7 days of rest, depending on the roast level. However, if you’re buying beans intended for espresso, you’ll notice that the recommended resting period is usually several days longer.

Many people find this confusing. After all, coffee beans are coffee beans—so why do espresso beans need more time to rest?

The answer mainly comes down to two factors, the first being roast level.

I’ve mentioned before that coffee beans roasted for espresso are generally darker than those intended for pour-over. The reason is simple: a darker roast increases sweetness and flavor intensity while reducing acidity.

Espresso isn’t just consumed as straight shots—it’s also the base for milk-based drinks like lattes, cappuccinos, and flat whites. If the roast is too light, the coffee flavor won’t be strong enough and can easily be overwhelmed by milk.

On top of that, lighter roasts tend to retain more acidity, which doesn’t always pair well with milk. The result can be a milk drink that tastes sharp or unbalanced. Because of this, many roasters use different roast profiles for the same coffee depending on the intended brewing method.

If a coffee is meant for pour-over, cold brew, or other single-origin brewing styles, it’s usually roasted lighter to preserve floral aromas and fruity notes, allowing you to experience more nuanced flavors. If that same coffee is intended for espresso, the roast will typically be slightly darker to ensure enough intensity to stand up to milk and to create a more harmonious flavor profile.

For example, Ethiopian Gesha is a coffee I often mention. If you’ve ever purchased it from my Taobao or Tmall store, you may have noticed that it’s offered in two roast levels: a light-medium roast for pour-over and other filter methods, and a medium roast designed specifically for espresso.

The darker the roast, the more carbon dioxide the beans tend to contain. Naturally, this means espresso beans—being more deeply roasted—require a longer resting period to release excess CO₂.

At this point, some people might ask: If I use the same coffee and the same roast level for both espresso and pour-over, shouldn’t the resting time be the same?

My recommendation is still to rest espresso beans longer.

This is because carbon dioxide has a much greater impact on espresso extraction than on pour-over. The key reason lies in the brewing method itself.

Pour-over, cold brew, French press, and siphon brewing all take place under normal atmospheric pressure. In these methods, extraction is relatively controllable. You can adjust variables like agitation, brew time, water temperature, and grind size to manage extraction efficiency. Under these conditions, the influence of CO₂ is noticeable but generally manageable.

Espresso, on the other hand, is brewed under pressure. With pressure assisting extraction, we can produce a highly concentrated coffee in a very short amount of time. To achieve this, espresso requires an extremely fine grind and relatively high water temperature, pushing extraction into a very intense and unforgiving zone.

As a result, extraction control is lower, and the negative effects of excess carbon dioxide are amplified.

Because espresso shots are brewed quickly and yield a small volume of liquid, there’s very little opportunity for gas to escape during brewing. When too much CO₂ is present, it becomes difficult to achieve a fully extracted, well-balanced shot without extensive dialing-in. That process consumes both time and beans, making it costly and inefficient.

For this reason, when a coffee is intended for espresso, it’s best to let it rest a few extra days. Once the carbon dioxide level drops to the point where it no longer interferes with extraction, you’ll not only save time and beans during dialing-in, but you’ll also end up with a far more delicious espresso.

Does Expensive Coffee Really Taste Better? The Truth You Should Know

 People often say, “You get what you pay for.”

In many aspects of life, this saying makes perfect sense, and it’s deeply ingrained in the way we think about consumption.

Not long ago, a customer came into our shop for coffee. After looking at the menu, he asked with surprise, “What’s this Emerald Red Label for 75 yuan? It must taste way better than the regular pour-over for 30 yuan, right?”
Clearly, this customer had already equated “expensive coffee” with “good coffee,” assuming that a higher price always means better flavor.
But is that really the truth?

What determines the price of coffee?

1. Variety

Most people know that the coffee beans sold today are broadly divided into Arabica and Robusta.

Arabica includes many sub-varieties—Typica, Bourbon, Caturra, and more. These beans are usually grown at high altitudes above 800 meters. They tend to have a smoother taste and more refined flavor characteristics influenced by the local terroir.
However, Arabica is picky by nature. It demands a high-quality growing environment, has lower yields, is more vulnerable to pests and disease, and can even wither easily. Farmers must invest more time and resources into maintenance, which naturally raises the price.

Robusta, on the other hand, grows mainly below 800 meters. It's hardy—resistant to pests, tolerant of heat and direct sunlight, and suitable for dense planting. Its yield per harvest can be very high, making it widely available across many countries. Because of this abundance, Robusta is commonly used in dark espresso blends and instant coffee at a lower cost.

2. Green Bean Grading

No matter how pricey a cup of coffee is or how it’s brewed, coffee beans are ultimately an agricultural product. And like all agricultural products, each producing country has its own grading standards. The higher the grade, the higher the price.

Globally, coffee grading systems generally fall into three categories:
bean size, altitude (bean hardness), and defect count.

For example:

• Regions like Kenya and Colombia sort beans by size using screens. Larger beans are believed to ripen more evenly and develop better flavor, making roasting more consistent.

• Panama, Costa Rica, and Guatemala grade beans by altitude. Higher altitude means denser beans, richer nutrients, and more pronounced flavor—thus higher value.

• Ethiopia and Indonesia classify beans by defect rate. The fewer defects, the more valuable the coffee. For instance, our PWN Golden Mandheling undergoes machine sorting once and hand sorting three times, reducing defects to a minimum and significantly increasing its price.

Beyond national standards, some well-known estates have developed their own grading systems.
The most famous is Panama’s Hacienda La Esmeralda, whose Geisha beans are labeled Red Label, Green Label, and the exclusive Auction Lot—each grade more expensive than the last, especially the rare auction batches.

3. Yield and Scarcity

There’s an old saying: Scarcity creates value.
Coffee is no exception.

Take Jamaica Blue Mountain, once known as the “Hermès of the coffee world.”
To standardize quality, the Jamaican Coffee Board designated a specific region in the Blue Mountains where only Typica beans grown within that boundary can be called “Blue Mountain Coffee.”
This official growing area is only about 6,000 hectares—just one-third of the entire mountain region.

Typica already has low yields, and the high-altitude environment makes harvesting even more labor-intensive. Add in strict quality control and later hype from Japan, and the price skyrocketed. In the early days—before cafés became common—a single cup could cost over 1,000 yuan.

Today, with direct imports to China, prices have become more accessible. For example, you can now enjoy a classic Blue Mountain pour-over at our shop for 60 yuan.

Higher prices don’t automatically make a coffee “better”

From everything we’ve listed above, it’s clear that industry standards create natural price differences. But for consumers, the value of a cup of coffee isn’t determined by price—it’s determined by whether it suits your taste.

We once had a regular customer who loved dark-roast coffee. One day, she decided to splurge on a cup of our premium Geisha.
But after just one sip, she frowned and said, “Too sour. Not ordering this again.”

Different origins, farms, varieties, processing methods, grades, and roast levels all shape the flavors listed on a bag of coffee. When buying beans or ordering a drink, most people start by choosing what they prefer:

• If you like bright acidity, you can enjoy something affordable like Yirgacheffe—or go all-in with an expensive auction Geisha.

• If you like bitterness or a fuller body, Blue Mountain is an iconic (and pricey) option—but a budget-friendly Brazilian bean can offer similar satisfaction.

That’s why we believe:
Expensive coffee and good coffee are not the same thing.
The best coffee is simply the one that matches your personal taste.