What You Really Need to Know About Degassing Valves

Soon after roasting, coffee begins to release carbon dioxide (CO₂) as a byproduct of sugar and carbohydrate breakdown. This off-gassing process is strongest in the first 12–24 hours post-roast but continues for days or even weeks after.

The rate and volume of off-gassing depend on a few key factors:

• Roast level: Darker roasts are more porous, resulting in a faster release of gases. Conversely, lighter roasts are denser beans, which make for a slower, longer off-gassing process.

• Grind size: Ground coffee releases gas rapidly—think hours, not days.

• Processing method: Natural vs. washed vs. honey—each has its own off-gassing profile.

• Resting period: Letting coffee rest before packaging it helps, but doesn’t eliminate the need for off-gassing management.

Once you seal a coffee bag, any gas released inside has nowhere to go. Without a valve, that pressure builds up. Over time, it can warp the packaging or even cause it to burst. Not great for shelf life or brand perception!

A degassing valve is a one-way vent installed in the wall of a coffee bag. Maybe you've squeezed a bag of coffee before and enjoyed the wonderful aroma that comes through the valve. However, the true purpose of this feature is less about scent, and more about protecting the freshness and quality of your beans.

Here's how it works. Once pressure inside the bag hits a specific threshold, the degassing valve allows CO₂ to escape while blocking oxygen from getting in. Oxygen is the enemy of freshness, so this one-way functionality is crucial.

It’s important to note that even bags with degassing valves are prone to puffing up, but don’t be alarmed. Valves only engage when there’s enough pressure from inside the bag. If the coffee has already off-gassed significantly, there might not be enough pressure to trigger the valve. That doesn’t mean it’s faulty—it means your coffee is stable and staying fresh.

Inside the valve, there’s typically a small mesh filter to catch micro-particles during pressure release. At Roastar, our valves are ultrasonically applied (not glued), so it has a minimal effect on the bag and its artwork. That means you can design freely without worrying about warping or obstructions created by the valve.

Short answer: If you’re packaging coffee within a few days of roasting, adding a degassing valve is critical.

It’s especially important to include a valve when:

• You're sealing coffee soon after roasting

• You're working with darker roasts or high-CO₂ varietals

• You're shipping product long distances

• You want a longer shelf life (without freezer storage)

• Your brand depends on consistent, professional presentation

On the flip side, you might be okay without one if:

• You’re packaging a single serving of pre-ground coffee.

• You’re packaging instant coffee, which does not degas.

• You’re packaging green, unroasted coffee, which also does not degas.

• You’re using a low-barrier package that is permeable to oxygen.

That said, you’re safest adding a degassing valve, especially if you’re scaling or experimenting with roast styles or fulfillment methods. The small extra investment (3 cents per valve) is definitely worth it to prevent any future headaches.

Degassing valves may be industry standard, but they’re not all created equal. Roastar’s are:

• Ultrasonically applied for a clean seal and low profile

• Quality tested with cutting-edge technology to ensure consistent pressure engagement

• Artwork-friendly so they don’t interrupt your design aesthetic

• Durable and discreet—no bubbling, no peeling, no performance drop-off over time

Your customers might not even notice the valve, but you’ll appreciate the performance.

Roastar offers industrially compostable and store drop-off recyclable degassing valves designed to work with our sustainable materials.

As a bonus, unlike other valves on the market that must be removed before disposal, ours are fully compatible with industrial composting and Trex recycling processes (same for our zippers.) This means the entire bag can be processed for disposal—not just a certain percentage like a lot of our competitors. This makes disposal a breeze for your customers.

If you’re taking the time to dial in roast profiles, optimize rest periods, and manage freshness in every other part of your process, don’t let your packaging fall short.

A degassing valve doesn’t just save your bags from bursting. It saves your coffee from staling. It adds polish. It supports consistency. And in today’s competitive market, that kind of detail matters.

Still have questions about degassing valves, or want to add some to your next order? We’re glad you asked. Reach out to our team or start your quote.