Roast date
Degassing What happens inside the bean after roasting.
A lot of discussion revolves around coffee freshness, the importance of the roast date and the best way to store coffee so it doesn’t age too quickly. While freshness is undeniably crucial, it is essential to understand that too much freshness isn’t desirable either. Why? Because freshly roasted coffee holds a considerable amount of gas that works against an optimal brew.
During roasting, various gases — mainly carbon dioxide — form inside the coffee bean. These gases are trapped inside the bean and are released gradually over the days following the roast. That’s why coffee bags have a valve that lets the gas escape without letting oxygen come into contact with the beans. A bag without a valve can swell as the beans gradually degas, and may even burst.
CO2, harmful and protective A gas you have to get right.
Brewing coffee with beans that are too fresh can cause an excessive release of carbon dioxide during extraction, disrupting how the grounds interact with the water. In the cup, this translates into an uneven and shallower extraction, resulting in more pronounced astringency and a loss of the flavours specific to each coffee.
That said, carbon dioxide isn’t only harmful. Heavier than oxygen, CO2 blocks the oxidation of coffee, acting as a barrier against oxygen around the beans. Oxidation has the effect of dulling the flavours in the cup. The protective layer of CO2 also holds in the volatile aromatic compounds developed during roasting.
Our recommendation A delicate balance.
So, should you let the CO2 escape? Yes, but not too much. It’s a delicate balance. We want to give the coffee time to degas so we can fully enjoy its aromatic compounds, but we don’t want all the gas to escape, which would dull the coffee’s flavours. The optimal degassing time depends on several factors, such as the processing method, the roasting techniques and the brewing method. At Zab, we recommend a degassing period of 3 weeks after the roast date, a recommendation based on our specific roasting methods.
Past its peak Storing your coffee well to slow the decline.
Once the resting time is over, the coffee reaches its peak. After that, our precious beans gradually lose their aromas. The decline is inevitable, but you can slow it down by storing your coffee the best way possible: in an opaque, oxygen-free container (one that keeps oxygen out, or even lets you remove it), kept in a cool, dry place.
If you buy more coffee than you drink in a week, split the bag into one-week portions stored in separate containers, so oxygen doesn’t creep in a little more each day as you scoop out beans. If you’re using fresher coffee, favour a method with a longer contact time, such as full immersion (French press, Aeropress, etc.). Immersion brewing methods give the water and coffee more contact time, allowing better flavour extraction. For espresso, waiting is even more important because of its very short contact time, which is particularly sensitive to an excessive amount of gas in the bean.
I know that waiting three weeks can be hard sometimes, but keep in mind that if you drink your coffee before or after the recommended three weeks, the result won’t be bad — simply not at its peak. I encourage you to try the experiment; I’m convinced you’ll notice the difference!
Coffee storage A vacuum canister, and time works for you.
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