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-flushed and vacuum-sealed.
What does Nitrogen Flushed mean anyways?
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?
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.