The Airscape range of coffee canisters do allow CO2 to escape and that's actually by design. To understand why this matters, it helps to know what CO2 is doing inside your coffee beans in the first place and why a canister that handles it correctly makes a meaningful difference to how your coffee tastes.
Why Freshly Roasted Coffee Produces CO2
During roasting, coffee beans undergo a series of chemical reactions that produce carbon dioxide as a byproduct. That CO2 gets trapped inside the bean's cellular structure, and after roasting it slowly begins to escape in a process called degassing. For the first few days after roast, the release is quite rapid. It then slows gradually over the following weeks.
This is why most specialty coffee bags have a one-way valve on the front. Without it, a sealed bag would balloon and eventually burst from the pressure of CO2 building up inside. The valve lets gas out without letting air in, which is a practical solution for the roastery's packaging needs.
CO2 in coffee isn't just a packaging inconvenience though. It plays a role in how your coffee extracts. When you pour hot water over freshly roasted grounds, the CO2 escaping from the coffee creates what's known as the bloom, that foamy, bubbling rise you see at the start of a pour over brew. The presence of CO2 indicates freshness, and in espresso it contributes to crema. Coffee that has fully degassed tends to extract differently, often faster and can taste flatter in certain brew methods.
How the Airscape's Two-Way Valve Works
The Airscape uses a two-way valve built into the plunger lid. When you press the plunger down onto your beans, air is forced out through this valve. The valve then closes to prevent oxygen from re-entering the canister. This is the core mechanism that makes the Airscape more effective than a standard airtight container.
The two-way valve also allows CO2 to escape passively over time. As your freshly roasted beans continue to degas inside the canister, that CO2 can exit through the valve without disrupting the seal or allowing oxygen back in. The canister doesn't trap CO2 under pressure, and it doesn't require you to manually release anything.
This is an important distinction. A truly airtight container with no valve at all would trap CO2 inside along with the remaining oxygen, which could eventually create enough pressure to compromise the seal. The Airscape's valve design avoids this while still doing the primary job of keeping oxygen out.
What This Means for Freshly Roasted Beans
The practical implication is that you don't need to wait for your beans to fully degas before transferring them to the Airscape. The valve will handle ongoing CO2 release without issue.
That said, there is still a reasonable case for letting very freshly roasted beans rest in their original roastery bag for the first day or two before transferring them. In the first 24 to 48 hours after roasting, CO2 release is at its most rapid and significant. Roastery bags are specifically designed to handle this initial surge, and leaving beans in the bag for that short window before moving them to the Airscape is a sensible habit, particularly if your beans arrived on roast day or the day after.
From day two or three onwards, transferring to the Airscape makes sense. The initial degassing surge has slowed, the Airscape's valve can comfortably manage what remains, and from that point you're getting the full benefit of reduced oxygen exposure for the rest of the bag.
Does CO2 Loss Affect Coffee Freshness?
CO2 and freshness are related but not the same thing. CO2 loss is a useful indicator of how fresh your coffee is, because it's escaping alongside the aromatic compounds that give your coffee its flavour and complexity. But it's oxygen exposure that does the most direct damage to flavour. A coffee can have very little CO2 remaining and still taste excellent if it has been stored well, while a coffee with plenty of CO2 can taste poor if it's been exposed to a lot of oxygen.
The Airscape's strength is in managing oxygen, not CO2. The fact that it allows CO2 to escape is a feature rather than a flaw, because the alternative, trapping CO2 under pressure, would create problems without adding any meaningful benefit to flavour preservation.
The Airscape allows CO2 to escape through its two-way valve, which is intentional and correct. Freshly roasted beans will continue to degas normally inside the canister without creating pressure issues, and you don't need to leave the lid open or take any extra steps to manage it. If your beans are very freshly roasted, a day or two in the roastery bag before transferring is a reasonable practice, but it's a minor detail rather than a strict requirement.
What the valve doesn't do is let oxygen back in. That one-directional quality is what makes the Airscape genuinely useful for coffee storage, and it's the reason the canister continues to do its job every time you seal it, regardless of how much CO2 your beans are still releasing.
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