Coffee degassing: How much time to let the coffee rest after the roasting process?

For many coffee enthusiasts, the enticing aroma of freshly roasted coffee beans is irresistible. However, despite the allure of freshly roasted beans, there is an important issue when it comes to brewing the perfect cup: the degassing of the coffee - the initial phase right after the roasting and packaging process. Coffee beans need time for gases such as carbon dioxide, created by roasting, to escape. Therefore, before it reaches its full flavor potential, the coffee must rest after roasting. How long should this period be?

Understanding the coffee roasting process:

Coffee beans undergo a significant transformation during the roasting process. When they are heated, they undergo physical and chemical changes that directly affect their flavor, aroma and overall quality. Some of these changes include caramelization, the Maillard reaction and the development of volatile compounds responsible for the coffee's aroma.

Why does coffee need to rest after roasting?

Coffee beans emit carbon dioxide (CO2) during the roasting process as a natural byproduct of the chemical reactions taking place in the beans. It is trapped in the bean's cellular structure, and immediately after roasting, the beans release an intense amount of the gas, creating what is known as the "degassing process." This phase is where the grains are most sensitive in terms of flavor and aroma. The rapid release of CO2 can result in undesirable qualities if the coffee is brewed too early.

The rest period serves several important purposes:

1. Stabilization of flavors: After roasting, coffee beans undergo a series of volatile flavor changes. A resting period allows the beans to stabilize and consolidate these changes. During this phase, the beans may be unstable when it comes to the brewing process and receiving flavor
2. Aroma Development: The resting period is crucial to the development of a coffee's aroma. In the first few days after roasting, the coffee may have a strong "grassy" aroma, which gradually gives way to distinctive aromas that highlight the coffee's region of origin and level of roasting.

How long should the coffee be aged?

The optimal aging period for coffee beans can vary depending on factors such as roast level, bean density and origin. A darker-roasted bean gives off CO2 faster than a lighter-roasted coffee, so we can drink darker-roasted coffees sooner than the roast date. Hence, the tendency is that after opening a coffee bought at the local supermarket, the first brews will be quite good, while the quality of the brew will drop drastically due to long aging and rapid oxidation after opening the package.

We also notice that from the store extreme (coffees sitting on shelves for several or more months) we are moving dangerously close to the other extreme, where we want to get coffee almost on the day it is roasted. However, this is not optimal in terms of experiencing depth of flavor and aroma. Experiments have been conducted where high-quality coffee was tested precisely in terms of the length of resting time after roasting. The results were astonishing. The coffee tasted mediocre until the 20th day from the roasting date, while after the 20th day it obtained the fullness of flavor and hidden aromas.

Therefore, we should not be concerned about taking coffee whose roast date goes back 3-4 weeks. However, it should be remembered that once opened, the oxidation process begins and care should be taken to protect the beans from too much contact with air by all means. For this reason, many coffee packs have a one-sided valve that allows you to squeeze out the air inside the bag when it is closed, while protecting the coffee from the negative effects of oxygen.

In summary, the resting period after coffee roasting is an essential stage for the perfect cup. It allows the beans to stabilize, release CO2 and develop their aromatic and flavor properties. While there are general guidelines for resting time, the final decision should be based on personal preference and experimentation to find the golden mean that will make your coffee perfect.