Why is my coffee bag puffed up like a balloon?

There are two kinds of coffee bags, one-way valve coffee bags vs. air-tight coffee bags. Which kind of bag will keep your coffee fresher? Let’s look at the pros and cons of each coffee baging system.

Coffee Bean Outgassing

Coffee Outgassing

Right after coffee beans are roasted, they immediately start outgassing Carbon Dioxide (CO2). This outgassing will continue for several days. In of itself, there’s nothing wrong with CO2. In fact, contrary to what the religious environmentalists tell us, CO2 is good for the environment. And it’s especially good for keeping your coffee fresh.

The reason CO2 is good for keeping your coffee fresh is the scientific fact that CO2 is an inert gas and will not chemically interact with your coffee bean’s volatile aromatic gasses. These gasses are the stuff that makes your coffee smell and taste so great.

Coffee Bag Bloating

So, how much CO2 is outgassed by the coffee beans? For dark roast coffee, quite a bit. In fact, most industrial coffee companies burn the living snot out of their beans, leaving behind little more than charcoal. These super dark roasted beans will give off almost double the volume of gas as compared to volume of the beans.

Yet, with a light roast or even a medium brown roast, the amount of CO2 outgassed is minimal. If these light or medium roasted beans were put into an air-tight bag, the bag’s bulge would be barely noticeable.

Will Coffee Mold Make You Sick
Burnt Coffee Beans

Over Roasting

Industrial coffee companies like Yuban, Hills Brothers, Folgers, Charbucks, Kirkland, etc., all buy the cheapest beans that money can buy. This is even true of their self-proclaimed “Premium” brands. Don’t be fooled by their Wall Street marketing. The number one exporter of extremely low grade, bitter, Robusta beans is Vietnam. And their biggest customers are industrial coffee companies in the U.S.

Since these beans are so bad, i.e. bitter, these industrial coffee companies are forced to burn the snot out of the beans so that you can’t tell how bad their beans really taste. And by over roasting their beans, the amount of outgassing is copious. What that means is that if these burnt, outgassing monstrosities, are placed in air-tight bags, the bags could explode or at a minimum, look like they were about to explode.

Puffed Up Bag Solution

50 years ago, the industrial coffee companies solved this problem by packaging their beans in air-tight tin cans. Eventually, for the purpose of saving money, these companies switched from tin cans to plastic and mylar bags, which puffed up like balloons.

To solve the “puffed up bag” problem, they equipped their bags with one-way valves. The one-way valve is supposed to allow the CO2 outgassing to escape the bag, yet not allow oxygen (O2) into the bag. As any good prepper will tell you oxygen is the enemy of freshness. In theory, one-way valve coffee bags seemed like a good solution.

coffee bag one-way valve
Coffee Mold
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cupping costa rican coffee

Do One-Way Valves Work?

One-way valves do let the coffee bean outgassing of CO2 to escape the bag.  Unfortunately, as the valves are letting the CO2 to escape, they're also letting the coffee's oils to evaporate and escape the bag. These oils are essential to the coffee's taste and contain the coffee's bioflavonoids, antioxidants, caffeine, and aroma.

Even worse is the fact that these one-way valves aren't as "one-way" as the industrial coffee companies would like you to believe. If one-way valves actually only worked "one-way", then when your weather’s barometric pressure increased, you’d see the bag collapse. That’s obviously not the case. To prove my point, you can put your lips to the valve and very gently and very easily push air into the bag.

What that means is that these valves also let in a considerable amount of oxygen (O2) into the bag. As any experienced prepper will tell you, oxygen is the enemy of freshness. Even a little bit of oxygen will spoil your beans, creating an environment favorable for the growth of mold and, at a minimum, will make your coffee taste spoiled and bitter, which unfortunately us usually the case with industrial coffee.

The real test is a side-by-side taste test. Even a novice can tell that coffee packaged with a one-way valve will not taste anywhere near as good as coffee packaged in an air-tight container. Obviously, the one-way valve is 100% marketing hype.

Resting Coffee

Many industrial coffee companies, before bagging their beans, will allow their beans to “rest” for a few days. This allows the beans to complete their outgassing. When the beans are completely “de-gassed”, they are placed into their bags.

The problem with allowing the beans to “rest” is that the beans are exposed to oxygen and thus they have several days to lose much of the bean’s oils via escaped outgassing and oxidation. Those oils are where the bean’s flavors, bioflavonoids, antioxidants, and aroma reside. Thus, resting fresh roasted coffee beans is a good way to ruin good coffee.

how to make coffee taste good

Air-Tight Bags

The other option is to go back, roughly 50 years, to an air-tight container. Now we could go back to the air-tight cans. Unfortunately, in today’s world, cans are more costly than bags. The problem with bags, as stated earlier, the beans’ outgassing will cause the bags to bloat and bulge.

All of the industrial coffee companies have decided that the potential of the air-tight bags exploding is a risk that they’re not willing to take. So they stick with one-way valves that don’t work.

Lake City Coffee’s Solution

The trick to keeping coffee fresh is to maintain the environment in which the beans are kept. The only practical solution is to do two things. First, as soon as the beans are cool enough to handle (15 minutes from the roaster) we put the warm beans into heat-sealed air-tight bags.

Secondly, we need to eliminate all the oxygen from the ambient air within the bag. Additionally, we need to eliminate any oxygen residing inside of the beans themselves. Here at Lake City Coffee, we eliminate oxygen by adding an oxygen absorber into every bag of coffee. For details on our research, experiments, and experience with these oxygen absorbers, see our article “How to Keep Roasted Coffee Fresh”.

roasted coffee fresh
cold brew decaf coffee
Fresh Roasted Coffee
fresh roasted coffee

One-Way Valve Coffee Bags vs. Air-Tight Coffee Bags

In side-by-side taste testing, here's what we found.

  1. One-Way Valve Test - When comparing the 3-week-old coffee, preserved in the one-way valve coffee bag, and comparing it to the hours old fresh roasted coffee, the difference was like day and night. The one-way valve coffee was bitter with very little “coffee” taste.
  2. Air-Tight Bag Test - We then compared the 3-week-old coffee, preserved in the heat-sealed air-tight coffee bag along with an oxygen absorber, and then compared it to the hours old fresh roasted coffee. As a professional coffee taste tester, it was almost impossible to tell the difference. I did correctly pick the older bag, but it was a tough arduous decision.
  3. One-Way Valve Coffee Bags vs. Air-Tight Coffee Bags – Obviously, the air-tight bag with an oxygen absorber preserved the coffee much better than the one-way valve coffee bag. There just was no comparison. One tasted fresh and the other tasted like it sat under your porch for 3 weeks.

The percentages below show how good our air-tight bagged coffee with an oxygen absorber tastes as compared to the taste of same day roasted coffee.

  • Cupboard 3 weeks = 98%
  • Cupboard 6 weeks = 95%
  • Freezer 2 months = 95%
  • Freezer 4 months = 95%
  • Freezer 6 months = 90%
  • Freezer 12 months = 90%

Lake City Coffee

As many of you know, I’m obsessed with coffee that's smooth as silk with integrated natural flavors like chocolate, citrus, and nut. I also believe that coffee should be savored like a $100 bottle of fine Bordeaux wine  Here at Lake City Coffee, here is how we do it.

  1. Lake City Coffee only sources premium quality beans. We believe the smoothest (non-bitter) and best tasting beans for the buck come from the Tarrazu Region of Costa Rica.
  2. I loathe burnt coffee. Therefore, I roast the old fashion way, and that would be low-n-slow. Even our dark roast is a very dark brown, never black. The purpose of not over roasting is to preserve the bean’s oils. This is where the bioflavonoids, antioxidants, caffeine, aroma, and flavor reside.
  3. All coffee begins start going stale and bitter the moment they're roasted. That’s why we roast and ship the same day. Additionally, as stated above, we package our coffee in heat-sealed, air-tight bags, which include an oxygen absorber.
  4. Lastly, nearly half of the content of our website is dedicated to teaching you how to make a perfect cup of coffee.

If you have any questions, please contact us. Alisha will get back to you, usually in a few hours and at most a few days.

Russell and Alisha Volz
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