Why Do Coffee Beans Need Resting? Is Bean Resting Necessary? Why Do Darker Roasts Require Longer Resting Time?

The Art of Coffee Bean Resting: Understanding "Degassing"

Freshly roasted coffee beans require several days of resting to develop richer flavor experiences, a process we call "degassing." While degassing isn't strictly mandatory, FrontStreet Coffee still recommends letting fresh coffee beans rest to reduce extraction issues and ensure more delicious coffee.

The resting time depends on the roast level of the coffee beans. Lighter roasts require shorter resting periods, while darker roasts need longer resting times! This is especially true for dark-roasted beans used for espresso, which require even longer resting periods.

Why Do Dark Roasts for Espresso Need Longer Resting?

Many friends might wonder: dark-roasted beans have a more porous texture, so logically, their resting period should be shorter than light roasts. While that reasoning seems correct, have you considered that dark-roasted beans contain more carbon dioxide?

1. Instability Caused by Carbon Dioxide

This is the first reason why dark-roasted beans need extended resting periods: higher carbon dioxide content. Although dark-roasted beans have a more porous texture, they contain higher levels of carbon dioxide and require a longer release cycle. For the particularly sensitive extraction method of espresso machines, excessive carbon dioxide is detrimental.

When carbon dioxide levels are too high, it not only hinders the release of aromatic compounds but also reduces crema quality. Under the pressurized extraction of espresso machines, abundant carbon dioxide is compressed into rich, golden crema! However, while this crema may be thick, its surface is extremely rough, it dissipates quickly, and is prone to clumping. Such crema is unappealing whether for latte art or tasting.

Additionally, as FrontStreet Coffee mentioned, espresso extraction methods are extremely sensitive and can cause extraction variations due to subtle changes in the beans! In the period immediately after roasting, coffee beans continuously release large amounts of carbon dioxide (compared to the amount released after proper resting)! Therefore, extraction parameters you painstakingly adjusted in the morning might become unusable just a few hours later due to massive carbon dioxide release.

The loss of carbon dioxide significantly increases debugging costs, and overall instability multiplies. Therefore, to achieve more stable espresso extraction, we generally choose to let coffee beans rest for longer periods.

2. Allowing Coffee Beans to Develop Oils

There's a second reason: letting the beans develop oils! This primarily applies to medium-dark roasted coffee beans. Medium-dark roasted coffee beans will have varying amounts of oils on their surface, and these oils are essentially the water-soluble fats from the beans.

Before roasting, coffee beans have a tight structure with oils encapsulating the fiber matrix. When roasting begins, the continuous heat from the roaster causes the beans to expand, and the pores in the cell walls of the green beans are gradually opened by these heat waves, which is when carbon dioxide enters. As roasting completes, coffee beans return from the high-temperature environment of around 200 degrees to normal temperature and pressure, causing carbon dioxide to gradually release and oils to gradually seep to the bean surface!

Many coffee beans have only slight oiliness or none at all when fresh out of the roaster, but after several days of resting, they become beautifully oily. These oils that have migrated to the bean surface not only help create more stable crema but also add body to the coffee, making the overall taste rounder and fuller.

Therefore, considering both factors, dark-roasted coffee beans for espresso should ideally rest for appropriate longer periods. This allows the extracted coffee to taste better! FrontStreet Coffee recommends letting medium-dark roasted espresso beans rest for about 10 days (counting from the roasting date), and for darker roasts, you can decide whether to extend the resting time based on their condition.

Of course, excessive oiliness isn't always good. Too much oil accelerates the oxidation of coffee beans! Therefore, once beans reach their peak condition, we should consume them as quickly as possible to avoid excessive rancid flavors from oxidation. If you can't finish them all, you can seal them in airtight containers to extend their optimal tasting period!

Important Notice :

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FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

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