It may sound counter-intuitive. With food and drink we are used to the idea that fresher is always better. With specialty coffee the rule is a little different. Brew a coffee that was roasted only a few hours ago and you will most likely get a foaming extraction, an empty body and a sharp, unpleasant acidity. Why? The answer lies in the chemistry of roasting and a process called de-gassing.

What happens inside the bean during roasting?

During roasting, complex chemical reactions take place inside the cells of the bean under high heat. One of the main by-products of those reactions is carbon dioxide. When the coffee leaves the roaster drum, that gas stays trapped inside the porous structure of the bean. In the days right after roasting the coffee is, quite literally, full of it.

Why is CO₂ the enemy of good extraction?

When hot water meets coffee that is too fresh, the reaction is violent: the coffee blooms rapidly. The gas forms a physical barrier between the water and the soluble compounds in the coffee. The water cannot get deep into the particles to draw out the lovely lipids, sugars and acids we want in the cup. The result is an under-extracted coffee: watery, with aggressive sour notes and no balance.

How long should coffee rest?

The resting time depends on the brewing method and the roast profile:

• For filter methods (V60, Chemex, AeroPress): the coffee is ready 5 to 7 days after the roast date. Filter methods are gentler and cope more easily with the remaining gas.
• For espresso: espresso is brewed under high pressure, usually 9 bar, which amplifies the effect of the gas and produces an unstable, bitter, overly airy crema. For the best balance, sweetness and a steady flow on the group head, we recommend resting the coffee 12 to 18 days after the roast date.

In short: every one of our bags carries the exact roast date. Do not rush it — give the bean a little time to breathe and it will repay you with its full sensory potential.