What Does Bean Degassing Mean? Is Unrested Pour-Over Coffee Really That Unpleasant?

FrontStreet Coffee - Introduction to Coffee Bean Degassing

Simply put, degassing is a "gas release" process, commonly known as "bean awakening" or "bean resting."

Freshly roasted coffee beans contain approximately 2% carbon dioxide by weight. This substantial amount of carbon dioxide is released depending on storage conditions, equipment, or methods, creating pressure in the packaging that exceeds atmospheric pressure. This pressure helps aromatic compounds fuse with oils, bringing all internal aromatic substances to a state where they can be easily extracted.

The degassing process of coffee beans typically begins about 3 hours after roasting is complete. Coffee beans that haven't released any carbon dioxide produce very inconsistent flavors when brewed. If you've ever poured hot water over freshly ground coffee immediately after roasting, or used it to make an Espresso, you'll notice a sharp, stimulating taste with over-extracted bitterness and noticeable acidity—hardly reminiscent of the smooth, sweet flavor profile we desire.

What is the Purpose of Degassing?

Although the flavor composition of roasted coffee beans is largely determined, many people attribute flavor changes to the natural daily evolution of coffee beans. In reality, everything undergoes slight deterioration through oxidation, which affects taste. While this might not be as perceptible with fruits, coffee distinctly shows noticeable flavor changes.

Don't underestimate the importance of proper degassing—I've personally experienced the unpleasant taste of improperly rested coffee! Insufficiently degassed coffee beans have a "harsh" quality, which is the residual smoky taste from high-temperature roasting that remains trapped within the beans. This requires a period of maturation and carbon dioxide release to eliminate. Allowing the beans to rest for several days during the degassing period results in cleaner flavors and more prominent characteristics~

How to Degas Coffee Beans? How Long Should They Rest?

After all this explanation, how exactly should you degas coffee beans? Have you noticed the round object with several small holes on bags of roasted coffee beans? We commonly call this the "one-way degassing valve." The best degassing method is simply keeping the beans in their original bag with this valve intact. Place unopened coffee beans in a cool, dry, dark environment away from strong odors. After the degassing period, simply seal the one-way valve (transparent tape works fine).

As for how long the degassing period should be, it's best to ask the roaster. Every roaster has different techniques, varying roast depths, and different impacts on coffee bean structure, so there's no standard answer for degassing time. However, we can primarily determine the degassing duration based on the roast level of the coffee beans.

Generally, medium to dark roasted coffee requires shorter degassing time than light roasted coffee, with a typical period of about 3 days. Of course, some argue that no resting is needed and coffee can be brewed immediately. Due to different techniques among roasters, there can be significant variations. Perhaps one roaster's beans have a higher maturation rate than others, eliminating the need for resting.

Key Point: To reduce degassing, extend the resting time, allowing the oxidation reaction of coffee beans to gradually stabilize, which also results in more balanced flavors.

In Summary

FrontStreet Coffee is a dedicated coffee research establishment, enthusiastic about sharing coffee knowledge with everyone. Our comprehensive sharing aims to help more friends fall in love with coffee. Additionally, we hold three discount coffee events monthly because FrontStreet Coffee wants to offer the best coffee at the lowest possible prices—this has been our mission for six years!

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473