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Vacuum PACKED: Why do coffee bags have a little valve?

Vacuum PACKED: Why do coffee bags have a little valve? - Coffee Life, a blog by EspressoWorks

Why the Valve?

If you’ve ever bought a large amount of coffee beans, you’ll likely have noticed the presence of the coffee bag valve. This valve, though very important to the health of your coffee beans, may seem counter-intuitive at first. Why would there be a valve in your coffee bag? Well, we’ll find out if this is the case, or if coffee bag valves are a little more sophisticated than that.

Get to Know Your Beans

Coffee beans require a certain set of conditions in which they will remain fresh and fragrant for the longest period of time. Roasted coffee beans need a dry environment to stop them from getting soggy, an airtight seal to prevent oxygen and bacteria from getting in, and they need to be able to release carbon dioxide – a natural byproduct from the roasting process. How do coffee bag valves solve any of these problems? Let’s find out.

The Value of the Valve

Now that we know what type of conditions roasted coffee beans thrive under, let’s take a look at how coffee bag valves actually permit those conditions to exist. Firstly, it’s important to note that coffee bag valves are not two-way. This means they do not allow air to get in and out of the bag. Instead, they are one-way valves that allow carbon dioxide to be pushed out but do not permit air to enter. This accomplishes three important things: 

1. Moisture can’t get in

Since the coffee bag-valve only lets carbon dioxide escape, no moisture can get in from outside, ensuring that your beans remain dry and safe from mold. 

    2. No outside air can get in

    Oxygen is the enemy of roasted coffee beans. The minute the beans are exposed to oxygen, you essentially begin the countdown to your beans reaching their expiration date. Oxygen causes beans to turn stale and can introduce unfriendly bacteria that will ruin the beans over time.

      3. Carbon Dioxide can escape

      What’s the big deal about letting carbon dioxide escape, you might wonder. Well, considering coffee bags are airtight, there has to be a way to let the natural buildup of carbon dioxide dissipate - or else you’re going to have a coffee bag that could explode at a moment’s notice! It’s one thing to want your coffee to have explosive flavor, but no one wants a literal coffee explosion on their hands!

        A Window to the Best Coffee

        Surprisingly, there is another little perk to purchasing coffee that comes in a bag with a valve. We all want the freshest coffee possible, but when your beans are locked in an airtight bag that may be opaque, how can you know if the beans you’re buying are fresh? Well, the answer actually lies in the coffee bag valve, which acts as a little window to the coffee within. However, instead of using your eyes to determine freshness, you’ll be using your nose. Gently squeeze the bag and breathe in deep. If you get a strong aroma of coffee, you know that the beans within are still degassing and are fresh. However, if you get barely a hint of coffee, you’ll know the beans have been kept inside for too long, and have almost completely degassed. This lack of coffee smell indicates that this bag of beans will stay fresh for a far shorter duration, or may even already be stale.

        What to do If you Rupture your Coffee Bag?

        In the likely scenario that you accidentally render your airtight coffee bag no longer airtight, what can you do? Well, one of the easiest methods is to simply use a bag clip. Bag clips let you reseal open bags in a way that’s totally airtight. Just make sure you push out all the air before sealing. Use a scoop to get out the coffee you need and then reseal your bag as you like. 

        Alternatively, you can move your coffee beans into an airtight canister. Unlike coffee bags, airtight canisters are built to last. There’s no easy way to poke a hole in a metal canister, so these make a great second home for your coffee beans if your coffee bag is starting to let air in. 

        Not Just a Bunch of Hot Air

        Let’s go through a quick recap of why coffee bag valves are so important to the health of your coffee beans, and how you can use them to pick out the best beans for your coffee collection. Seek out coffee bags with valves so that you can ensure that moisture, oxygen, and bacteria are kept out, but carbon dioxide does not build up within and cause your bag to expand and potentially explode! When picking out your beans, squeeze the coffee bag lightly and make sure a strong coffee aroma seeps through the coffee bag valve. A powerful coffee scent is an indicator of fresh, long-lasting beans!