Many of us have been sold the belief that fresh is best.

To a certain extent, this is true, but not nearly to the black-and-white degree we might think. It’s also true that oxidization and other effects that make coffee stale are the ultimate killjoy. However, we do coffee (not to mention our fellow humans) a great injustice by equating a certain age with “stale”; in fact, by dismissing a coffee that’s x weeks past its roast date, we may miss out on the best, sweetest, richest coffee we’ve ever had.

There’s fresh. There’s stale. And there’s a magical window in-between we call rested.

Jump ahead:
What is resting?
Why is resting your coffee important?
How long should you rest your coffee?
Is it well-rested, or is it (frankly) old?
Super-fresh? Aged beyond optimal? We've got brew guides!

What is resting?

To answer this question, follow the CO₂! 

When we roast green coffee, the various chemical transformations that occur produce quite a lot of carbon dioxide (CO₂) as a byproduct — by some estimates, as much as 10 litres per kilogram of coffee. As the green coffee releases moisture and expands, it develops microscopic pores that trap CO₂ inside the bean. Most of it escapes during or soon after roasting, and the rest seeps out slowly thereafter. 

Exactly how slowly depends on a few factors:

• Density: Certain coffee varietals, as well as coffee grown at high altitudes, have a sturdy, compact cellular structure that retains CO₂ for longer.
• Roaster: According to Scott Rao[1], drum roasters (which use conductive heat and rigorous motion) tend to weaken the outer layers of the beans more than air (or fluid bed) roasters do, and the resulting porousness of the coffee allows for more rapid CO₂ release.
• Roast Level: Dark roasts produce way more CO₂ than light roasts to begin with, since the CO₂-producing processes carry on for longer. The darker the roast, the weaker the cell walls of the beans, and the easier it is for CO₂ to escape — so even though darkly roasted beans accumulate more CO₂ in the beginning, they release it more quickly over time.
• Environment: Elevation, temperature, humidity, exposure to light and oxygen all affect the rate of degassing, not to mention staling. We can't emphasize enough the impact of proper storage.

Put simply, resting is giving coffee time to release CO₂ that would otherwise interfere with extraction.

Why is resting your coffee important?

If we brew coffee right after roasting (theoretically, at its freshest), the stored carbon dioxide will come rushing out as soon as hot water hits the grinds.

The subsequent mushroom cloud pushes the water and the grinds around, disrupting the flow rate and direction. This is true for both filter and espresso, and both end up tasting sour, hollow, and underdeveloped.

After a period of resting, however, the change is remarkable:

• Those harsh, astringent flavours soften and give way to a clearer, brighter expression of the coffee’s profile.
• The release of CO₂ during extraction is gentler — blooming delicately, in the case of filter brewing, and emulsifying smoothly into crema in espresso.
• Shot times and brew times are often more consistent.
• The flavour in the cup is consequently much more balanced, nuanced, and full.

So you see, good rest is sorely underrated!

How long should you rest your coffee?

As mentioned above, the rate at which CO₂ escapes any given coffee will vary. The ideal rest time also depends on your chosen brew method.

As a starting point, we recommend at least..

• 1-2 weeks' rest for filter coffees;
• 14+ days' rest for espresso.

This is not to say a coffee that’s rested for longer is past its prime; these are more like bare minimums. Many of our cafe partners rest their beans for closer to 6 weeks or more before serving, and report tasting incredible espressos that turned out to be 3 months off-roast (or more)!

Proof that coffee doesn’t suddenly expire, but simply evolves — especially when stored and treated with care.

Is it well-rested, or is it (frankly) old?

At some point, freshness does start to fade. But a coffee past its peak isn’t necessarily done for!

Though it may have lost some vibrancy; once-bright acidity may be quieter; the crema may be thinner and the profile more gentle... You may actually prefer certain coffees that way! 

Try a well-aged filter coffee on espresso. See how it tastes as a flash brew. Or, give some of the suggested tweaks below a go — you might discover new life in something you’d otherwise discard.

Super-fresh? Aged beyond optimal? 
We've got brew guides for that!

Now that you know what’s happening with all that carbon dioxide, and how it affects extraction, you can rest and brew accordingly. Even so, not every coffee will be optimally rested when you want to brew it.

For those times, here’s our guide to brewing by age:

• For lightly-rested coffee (less than 1-2 weeks off-roast):
  Extend your bloom time to about 45-60 seconds, using 2-3 times the weight of your coffee dose in water, then brew the rest in one long pour. This disperses most of the CO₂, decreasing any interference with extraction.  You can also try grinding the coffee and waiting 15-20 minutes before brewing.
• For very rested coffees (6+ weeks off-roast):
  Push extraction further than usual to maximize aroma and clarity. Use a high water temperature, split the brew into multiple pours to increase contact time, and grind slightly finer than a typical V60 consistency.

Looking for rested coffee, ready to brew right now? Check out our selection here and surprise yourself with something exceptionally, deliciously nuanced.

[1] Scott Rao, 2023: Resting Roasts: Is Fresher Better?