What Is Coffee Bean Degassing Period? Can Coffee Beans Be Sealed for Degassing? Only Concerned About Excessive Expansion

What Is Coffee Bean Degassing?

Start with how flavor changes in freshly roasted beans.

The flavor composition of a coffee is essentially fixed the moment roasting ends. Many people blame a bean's decline on some inevitable daily deterioration, and it's true that every food oxidizes slowly over time. But coffee's changes are unusually noticeable. Freshly roasted beans vent large amounts of aromatic compounds and carbon dioxide through the tiny pores opened during roasting. When you grind the beans, that trapped CO2 escapes into the grinder - and if you brew too soon, the still-releasing gas pushes against the water, disrupting contact between grounds and water and leaving the coffee under-extracted.

As the days pass, the CO2 blanket grows thinner, the water makes better contact with the grounds, and the coffee tastes better and better. That's why many professionals don't call this "resting" at all - they call it degassing, or off-gassing.

Resting, then, is simply the settling and stabilization a coffee goes through after roasting, as the substantial burst of carbon dioxide produced during the roast dissipates.

Coffee beans behave like living things. Just as humans age through cellular oxidation, freshly roasted coffee is immature and hasn't reached its peak. Like people, beans need time to mature - they climb to a flavor peak, and only then do the flavors begin to fade.

Two days after roasting, the beans have already released much of their carbon dioxide and other volatile gases.

Even so, the chemistry inside the beans keeps shifting, which means baristas need to adjust grind settings regularly to keep extracting the right compounds.

If you can't consistently extract the good compounds, you can't hold quality steady - a serious problem for busy cafés serving hundreds of customers a day.

Between days 2 and 6 after roasting, coffee continues to lose aromatics and CO2, but the cup keeps improving: more distinctive, more balanced, better rated with each passing day.

Why Does Coffee Contain Carbon Dioxide?

When coffee is roasted between the first and second cracks, the beans undergo degradation reactions. At roughly 220°C, sugars decompose into several different compounds, including carbon dioxide. The beans turn brown and shrink as they lose moisture. This degradation reaction is the most important chemistry at the end of the roast, because it converts the sugars - and gas is released as that stored energy escapes.

Key Point

Master resting after roasting, choose your equipment well, and above all nail the grind, and you can brew a genuinely good cup at home.

FrontStreet Coffee Recommendation

If you're putting this resting theory into practice, medium-roast beans are the ideal laboratory. FrontStreet Coffee's Brazil Queen Estate is a great place to start: a yellow Bourbon lot from Brazil roasted to a medium level that shows cream, roasted peanut, chocolate, toasted bread, and sugarcane sweetness - a balanced cup with neither sharp acidity nor heavy bitterness, and one that responds beautifully to a proper 4-7 day rest.

For something fruitier in the same roast family, FrontStreet Coffee's Strawberry Candy Geisha Blend combines Panama Geisha with a Costa Rican honey coffee. Roasted medium, it pours out orange-blossom honey sweetness and rounded fruit, and it holds up across pour-over, espresso, and cold brew. If you'd rather taste classic Yunnan character, the FrontStreet 2013 Natural Typica shows nut, brown sugar, black tea, and dried apricot notes at a medium roast.

All FrontStreet Coffee beans are shipped within five days of roasting, which means they arrive right as the flavor window opens - rest them a couple more days if you like, but don't wait too long, because aromatics are always ticking away in the background.