What goes wrong

The bag inflated, or the container pressurized

Updated October 2026

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It is not spoilage Which means the fix is upstream Ground coffee does it faster and harder In a rigid container it is a handling issue Darker roasts degas more Record the rest time References

A swollen bag or a lid that resists coming off means the coffee was still degassing when you sealed it, and the package had no way to vent.

It is not spoilage

Nothing has gone wrong with the coffee. Carbon dioxide produced during roasting is leaving the bean and has accumulated in a sealed space. The product inside is usually fine and the package is telling you about your timing.

Which means the fix is upstream

Either rest the coffee longer before packing, or pack into something that can vent. Those are the only two options and they trade against each other: resting costs freshness and space, venting costs the simplicity of a plain airtight container.

Ground coffee does it faster and harder

Grinding releases the gas much more quickly, so a ground product packed immediately after grinding will pressurize within hours rather than days. If the problem appeared overnight rather than over a week, this is why.

In a rigid container it is a handling issue

A pail or canister that has built pressure can open abruptly and throw product. It is not dangerous in the way a fermenting bottle is and it is enough to make a mess and startle somebody, which at a counter is worse than it sounds.

Darker roasts degas more

More of the reaction has happened, so there is more gas to release. A resting period that is adequate for a light roast may not be for a dark one, which is a reason to set resting times per profile rather than as one house rule.

Record the rest time

Roast date, pack date and the gap between them, per batch. Without those three you cannot tell an inadequate rest from a packaging failure, and they are the same two numbers that answer most freshness questions.

References

21 CFR 101, Food Labeling, which carries the general requirements that apply here in the absence of a standard of identity: the statement of identity, net quantity, ingredient list and the name and place of business of the responsible party. law.cornell.edu

Written from federal regulation and from the published physics and chemistry of staling, not from a laboratory. There is no standard of identity for coffee or tea, so most of what governs a product here is the general requirement that labels be truthful and claims be substantiated. Anything here is a starting point for a conversation with your state department of agriculture, not a determination that you comply.