Why Do Coffee Bags Have Vents? (Mystery Solved)

Last Updated on June 26, 2023 by Barry Gray

I’m a coffee lover, and I’m always on the lookout for the freshest beans. However, that’s not always something that’s possible.

And yet, there’s one thing that has stood out in my quest for the freshest coffee beans, and perhaps you have noticed it as well.

One thing I’ve noticed is that most coffee bags have a small vent in them. I’ve always wondered why that is, so I decided to do some research.

You see, I already knew that handling coffee was a tricky task. It turns out that coffee is significantly more fragile than most people are aware of, which poses problems.

So, is that the reason why coffee bags have vents?

There are two main reasons why coffee bags have vents. The first reason is to allow the coffee to degas. The second reason is to maintain the bag’s shape to ensure the coffee inside is not damaged. Too much gas could also lead to the bag exploding, which nobody wants.

You can see from that answer that the most important thing to think about with coffee in bags is the emergence of gas.

And yet, I know this also confuses people. Let’s face it, you don’t look at coffee and immediately think about gas being released, do you?

But that’s exactly what goes on, and understanding this will make a massive difference to your understanding of what is happening with your coffee and how vents help it to maintain its freshness for just that bit longer.

coffee bags

What Gases Will Coffee Beans Release?

When coffee beans are roasted, they release carbon dioxide. 

This gas needs to be able to escape, or it will build up inside the bag and eventually cause it to burst. The vent allows the CO2 to escape without letting any oxygen in, which would spoil the coffee.

This is crucial for your coffee to remain as fresh as possible. 

Carbon dioxide is a major enemy of coffee. It will speed up the process by which coffee deteriorates, and you will then have a poorer experience as a result.

But gas build-up can also lead to another major problem: destroying the bag itself.

Let’s say there was no vent in the bag. The coffee would still produce gas as it’s something it will do naturally.

But the difference with no vent is that the gas has nowhere to go, and that’s a huge deal.

At that point, the gas is restricted by the bag. The gas would build, putting more pressure on the bag itself until it got to the point where it would eventually burst.

Now, that would be a disaster, so a vent is included in the bag to help regulate the gas and to preserve your coffee for longer. 

In short, the vent is there for protection and no other reason, but it’s not just a regular vent.

Instead, it’s a degassing valve, and it’s more intelligent than you would have perhaps expected.

How Do Degassing Valves Work?

So, your coffee bags come with degassing valves, but how do they work?

The problem is that people often believe that valves or vents will allow oxygen through, and that would be terrible for your coffee. Oxygen will quickly get to work, destroying coffee and breaking down its flavor and aroma.

Nobody wants that to happen at any point, but degassing valves are not designed to act that way.

Degassing valves are one-way valves that allow carbon dioxide to escape from a coffee bag without letting oxygen in. They are typically made of plastic or metal and are about the size of a pinhole.

This small vent makes a considerable difference to your coffee.

The valve works by allowing the CO2 to expand and push against the diaphragm. The diaphragm is held in place by a spring, and when the CO2 pressure exceeds the spring force, the diaphragm opens and allows the CO2 to escape. 

Once the CO2 pressure has decreased, the diaphragm closes, preventing oxygen from entering the bag.

You see, degassing valves are an essential part of coffee packaging because they help to preserve the freshness of the coffee. Without a degassing valve, the CO2 would build up inside the bag and eventually cause it to burst. 

This would allow oxygen to enter the bag, which would spoil the coffee. Also, this would happen quickly, and before you know it, your coffee is ruined and no longer as enjoyable.

I’m not too fond of that idea, so I’m glad the coffee industry knows what it’s doing and puts those vents in the bags.

But are they able to last an indefinite length of time? 

How Long Do Coffee Bags Last?

coffee beans in a bag

The shelf life of coffee beans in a bag with a degassing valve depends on a number of factors, including the freshness of the beans when they were packaged, the storage conditions, and the type of valve.

In general, coffee beans will stay fresh for about 2-4 weeks after being roasted. However, if they are stored in a cool, dark place, they can last for up to 6 weeks.

There are other things you can do in an attempt to extend the lifespan of your beans. Freezing them is one option, but I know not every coffee lover actually feels this is something you can do.

However, I sort of disagree with that point of view. I feel freezing coffee beans in small quantities can extend the freshness, and you will still get a decent cup of coffee at the end of it all. 

The Type of Valve Changes Longevity

The type of degassing valve also affects the shelf life of coffee beans. Yes, even the quality of the valve that has been used on the coffee bag is capable of making a huge difference. 

Valves made of plastic typically allow more CO2 to escape than valves made of metal. This means that coffee beans in bags with plastic valves will stay fresh for a shorter period of time.

But it’s evident that cheaper coffee will come with more inexpensive valves. After all, they want to keep the costs down, so they will hardly go to extra expense in order to keep the coffee fresher for longer.

Instead, they will simply want you to go out and buy more of their coffee in a couple of weeks, and I sort of understand what they are attempting to do.

Do Vents Actually Work in Coffee Bags?

ground coffee from a bag

But here’s an important question I feel I need to answer: Do the vents actually work?

So, I carried out an experiment. However, I know it’s not a precise experiment as I had no idea of knowing when the coffee beans in the bag were roasted, so I didn’t have an accurate starting point.

But this is how I got around that particular problem.

I got two packs of the same beans. I kept one in the bag with a vent, and the other I opened and put in a vacuum-sealed bag.

And then, I had to be patient and give the beans a couple of weeks in the same conditions to see which one ended up tasting best. Finally, I had an answer.

The vacuum-sealed beans still gave a decent cup of coffee, but the beans in the bag with the vent were a slight winner. 

I felt the difference was small, but there was a certain freshness and crispness about the beans that were allowing gas to escape. 

I then really understood why coffee companies include those vents, as I do feel it would keep the beans slightly fresher for slightly longer.

But it then also opens up another question I feel I need to answer: how to successfully store coffee beans to extend their freshness as much as possible.

How to Store Coffee Beans

vacuum seal coffee

Storing coffee beans is more involved than people realize. I know I was unaware of how fragile coffee beans can be at the start of my coffee journey, so I understand how people can make mistakes.

But there are some things you can do that will help keep your beans fresh for as long as possible.

Store in a Cool, Dark Place

Your coffee needs to be stored in a cool, dark place. Coffee hates the light, which will speed up the deterioration process leading to poorer coffee.

This applies even if you are keeping the beans in their bags. There’s a reason why coffee bags are not clear as it’s to keep out as much light as possible.

I have a cupboard that is basically my coffee cupboard. I keep everything in there with beans and ground coffee from around the world.

It’s away from any heat source, and that means no chance of condensation or moisture getting to the coffee. This is another important point, as moisture will also ruin your coffee if it gets the chance. 

Consider an Airtight Container

An airtight container is another option when it comes to storing your coffee, but it’s not my first port of call.

The key here is to eliminate oxygen getting to the coffee, as that alone will make a huge difference to how long it will stay fresh for. 

But again, you need to keep it away from light if you want to do the best possible thing for your coffee.

My Recap on Why Coffee Bags Have Vents

I found it interesting to do some research into those small vents that appear on coffee bags, and at least I came across an explanation as to what’s going on.

But here’s my recap covering the key points I’ve brought up over the course of the last few minutes.

  • Vents are used to prevent gas from building up
  • They deal with CO2 in your coffee
  • They also stop oxygen from getting to your coffee, which would make it go stale
  • They do actually work and make a difference in the freshness
  • Keep your coffee away from direct sunlight
  • Keep your coffee away from direct heat sources
  • Without vents, the bags would expand and eventually burst

So, this small thing makes a huge difference, and I’m glad they’ve included it to allow me to continue enjoying my coffee for some time to come.

My Conclusion

Coffee bags with vents are an important part of keeping coffee fresh. The vents allow the CO2 to escape, which prevents the bag from bursting and allows the beans to expand without breaking the bag. 

Degassing valves are also an essential part of coffee packaging because they help to preserve the freshness of the coffee.

By following the tips in this article, you can keep your coffee beans fresh for weeks to come and enjoy delicious, flavorful coffee every time you brew.