Coffee Degassing: Discovering its Impact on Freshness


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Coffee degassing is the process of releasing the gases that remain inside the beans after being roasted. A one-way degassing valve in a coffee bag helps give appropriate amount of time for carbon dioxide to escape without letting too much oxygen in. If coffee is not degassed, it can taste sour. But if left for too long, it becomes bland.

This guide will answer all your questions about how and why coffee needs to be degassed, the perfect amount of time to leave beans for and why certain roasts take longer than others to degas.

What is Meant by Coffee Degassing?

Degassing coffee means allowing the beans to release the gases inside after being roasted. Gases are formed inside during roasting process. You need to continually release these accumulated gases (primarily carbon dioxide) inside the beans to maximize the coffee’s full potential.

Carbon dioxide makes up around 90% of these gases, and the rest is made of nitrogen and other compounds. When you see a crack in coffee beans, that is the build-up of the gases. After roasting, the majority of the carbon dioxide still remains and needs to escape.

Is Degassing Coffee Necessary?

Degassing coffee allows it to reach its optimal flavor by getting rid of most of the carbon dioxide left in the beans after roasting.

If you do not degas your coffee, it will taste sour. But on the other hand, if you leave your coffee to degas for too long it loses its flavor and becomes stale and bland. So, allowing only the right amount of carbon dioxide to leave the beans ensures the perfect brew.

Although coffee beans need a little bit of carbon dioxide in them to prevent oxidization, leaving too much gas in the beans actually repels the water when making the coffee. This causes the flavor to be of an inconsistent taste and quality.

Brewing coffee too soon after roasting, before the beans have had time to degas, is a common mistake that usually produces the sour taste that can sometimes occur.

How do you Degas Coffee Fast?

To degas coffee, all you need to do is leave the coffee for a certain amount of time to rest to allow the gases to escape from the beans.

If your coffee is in a bag with a valve or appropriate container, you can leave it in this bag before you brew it. Grinding your coffee before brewing speeds up the degassing process by breaking down the structure holding gas.

How Long do Coffee Beans Need to Degas?

According to Perfect Daily Grind, it takes three days to two weeks after roasting. Coffee Statistics claims that 40% of the gas is released within 24 hours, but it takes two days to two weeks. This also depends on brewing method – using a French press means beans could be used after a couple of days as the coffee has more contact with water, yet an espresso has less brew time.

What Affects the Degassing Process?

The method by which coffee beans have been processed can impact on how long the degassing process takes. Natural, or dry, processed coffee beans take a longer amount of time to degas than washed or honey processed beans. This is because the fruit is not removed from the natural beans until the very end of the drying process, yet washed beans will have the fruit removed before they are dried.

What is the Difference Between Degassing Light and Dark Roasts?

Lighter roast beans take longer to degas than darker roasts. This is because darker roasts have been roasted for a longer amount of time, and during that roasting process more gas will have been released.

Darker roasts tend to have more little cracks already which help with quick degassing. Light roast beans are more intact at the degassing stage and so need longer to break down to release carbon dioxide.

What is a Coffee Degassing Valve and Why is it Used on Coffee Bags?

When buying coffee beans from a store or a specialized shop or café, the bag will usually have a degassing valve built into it. The reason for having a valve is to avoid trapping those gases inside the container forever. 

This is a small plastic circle with a hole in that act as a one-way valve. The function of it is to allow the carbon dioxide released by the beans out of the bag without letting too much oxygen in the other way. You can leave coffee beans to degas in this bag.

How Do You Store Coffee to Degas?

If you have bought coffee beans from a store, specialized shop or café they should already come in a bag with a one-way valve. If you are roasting the beans yourself, you will need to store your coffee in a dry container.

Some containers feature a valve that allows the gases to escape. A container with a valve is the most suitable as it allows carbon dioxide to escape without letting oxygen in.

There are airtight containers that don’t have degassing valves. However, these containers are good at protecting the coffee against moisture, light and heat. An airtight container prevents air from getting in.

So, the best thing you can do after the beans are roasted is to let it sit for just a couple of minutes to degas. Then you can store the beans inside the container to keep it fresh. Don’t expose your beans to air for a long time as it will degrade the quality.  

What Happens if Coffee Is Degassed for Too Long?

Although degassing coffee is to get rid of gases, you do not want them all to be released. Leaving coffee too long will cause it to go stale as too much oxygen gets into the beans. This means your coffee can be bland and you may need to use more coffee than you usually would to get enough flavor.

Coffee Degassing: Impact On Freshness And Extraction - Samo Smrke

In Summary

Coffee degassing involves allowing coffee beans to release the gases that remain inside after being roasted. If coffee is not degassed it can taste sour, but if left for too long becomes bland. The tips above should help you brew the optimal flavored coffee.

Leave your coffee beans in a bag with a one-way valve for between two to fourteen days after roasting. Grinding your coffee before brewing speeds up the degassing process. Remember that natural, or dry, processed coffee beans take a longer amount of time to degas than washed or honey processed beans. Also, lighter roast beans take longer to degas than darker roasts.

Like this Article? You might to read: What Is Honey Processed Coffee?