Vacuum Sealed vs. Nitrogen Flushed Coffee

coffee bags being packaged

When you’re shopping for coffee, you will find that it comes in all kinds of different packages, including cans, vacuum packs and bags with valves. Each of these packages has its benefits and drawbacks, but the main goal is always to preserve the freshness of the coffee.

However, there are two types of packaging you will find most often on the store shelf: vacuum-sealed packages and nitrogen-flushed bags with valves. Which of these is better for maintaining the delicious, fresh-roasted aroma and flavor of coffee? Well, we’ll tell you. But first, let’s talk a bit about what we mean when we say nitrogen-lushed and vacuum-sealed.

What does Nitrogen Flushed mean anyways?

Coffee being filled with nitrogen during the packaging process.
Coffee being Nitrogen Flushed during packaging

Nitrogen is an inert gas that is both odorless and food-safe. It is also abundantly available. Roughly 78% of the earth’s atmosphere is made up of nitrogen gas, so it’s relatively inexpensive to produce. Nitrogen is also heavier than oxygen, the molecule that causes coffee and many other foods to go stale. So it turns out it’s a great gas to use to flush out oxygen from coffee bags that have just been filled with freshly roasted coffee. A quick seal of the bag with a one-way valve and you have a flavor- and aroma-saving package that will keep your coffee in great shape for when you’re ready to brew the perfect cup.

But why the valve, you might be asking?

That’s a good question, for sure. Companies that nitrogen-flush their coffee use a one-way valve on these bags for one simple reason: Coffee off-gasses carbon dioxide for many days after roasting! If we seal the bag and don’t give the gas a path to leave, we will get coffee bag balloons, exploding your freshly roasted coffee all over the place. Nobody wants that. And remember we mentioned that nitrogen is heavier than oxygen? This is important because when all the carbon dioxide — which contains oxygen molecules — starts coming off the beans, it gets pushed out of the bag first. The fact that the valve is one-way means that oxygen can’t get back in.

So what about vacuum-sealed coffee bags?

When coffee is vacuum-sealed, manufacturers remove the air and, thus, oxygen from the coffee bag to protect the flavor and aroma of the coffee; this is the same goal as with Nitrogen-flushed bags. But there is one key difference. With vacuum-sealed bags, manufacturers need to wait for the coffee to off-gas before they vacuum seal the bags. It can take anywhere from 24 – 48 hours for coffee to complete most of its CO2 off-gassing, and during this time, the coffee is exposed to oxygen and going stale. Some manufacturers have devised ways to get around this, including roasting into large super sacs that have one-way valves that allow the coffee to gas off for a few days before being vacuum packaged, but this is the exception rather than the rule.

So which is better for preserving freshly roasted coffee?

You can argue the merits of both processes for preserving freshness, but we think the nitrogen-flushed method is the clear winner. That’s why we use this method for our coffee packages. Your coffee gets bagged right out of the roaster, and the one-way seal allows all the freshness-damaging carbon dioxide to leave the package while keeping the aroma and flavor of the coffee in.

Not convinced yet? Next time you’re shopping for coffee, pick up one of each type of bag and taste to see which you feel preserves the coffee’s freshness better. Leave your test results in the comments below.

About The Author

Gary Goodman

3 COMMENTS

  1. john cassel | 10th Oct 20

    Gas Man here again. When pressure builds and the relief valve operates it is due to pressure alone and whatever gas is closest to the valves is going to come out. Be it CO2, N2 or O2. Your premise would be true for lighter gases like methane at 16 or He at 4 or H2 at 2 if the valve was at the top and there was somehow separation rather than gas mixing. Take it from the youngest gas mixer in the U.S. at 18 for Matheson that when gases mix they do not ever separate. So the notion that heavier or lighter gases escape from the mid package located valve after the bag has been saturated with N2 and then CO2 (and is probably mixing quite well as this is not like making a cocktail pouring one on top of the other but more like a thousand pours from a thousand different locations in the bag- da beans/CO2. To a bag saturated with N2). Pressure does not care who is at the door. No this is not a fart or shart reference. Summary: gases mixed come out mixed. Gases separated can come out separated but only under controlled conditions. A pressure relief valve is not a controlled condition it merely opens when pushed hard enough and cares not who be pushing. Sorry for the grammatical wreck!

  2. john cassel | 10th Oct 20

    Gas Man here again. When pressure builds and the relief valve operates it is due to pressure alone and whatever gas is closest to the valves is going to come out. Be it CO2, N2 or O2. Your premise would be true for lighter gases like methane at 16 or He at 4 or H2 at 2 if the valve was at the top, there was somehow separation rather than gas mixing. Take it from the youngest gas ixer in the U.S. at 18 for Matheson that when gases mix they do not ever separate. So the notion that heavier or lighter gases are from the mid package located valve after the bag has been saturated with N2 and then CO2 is released evenly throughout the bag probably mixing quite well as this is not like making a cocktail pouring one on top of the other but more like a thousand pours from a thousand different locations in the bag- da beans. Pressure does not care who is at the door. No this is not a fart or shart reference.

  3. john cassel | 10th Oct 20

    Gas Man here. The molecular weight of Nitrogen is 14 and a stable Nitrogen atom has two Nitrogen (N2) molecules and weighs 28.0134 compared to Oxygen at 16 mole weight and at 32.00 as a stable atom of O2. Soooo, O2 is heavier. Carbon Dioxide does not contain Oxygen the gas. CO2 is a compound that contains carbon and oxygen atoms as components. Unless there is a chemical reaction it stays stable and there is no Oxygen ever released from it. Check yo self befo you reck yo self.

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