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Nitrogen Flushing: Killing Oxygen, Creating Fresh Coffee, And Other Facts

Nitrogen Flushing: Killing Oxygen, Creating Fresh Coffee, And Other Facts

Fresh and flavorful: These are “holy grail” words for those of us in the coffee roasting business. We’re continually seeking ways to extend the shelf life of our coffee roasts and ensure a product that customers love and keep coming back for. 

This quest occupies our time because of the great coffee roasting conundrum: While roasting coffee brings out the aroma, color, and flavor of the beans, those same beans can become stale and flavorless if exposed to air for too long. And, for ground coffee, the beans’ oils are exposed, and they emit gases that over time diminish the flavor of the final brew. 

Add to this the effects of degassing. Immediately following roasting, coffee releases carbon dioxide. Whole bean coffee releases carbon dioxide relatively slowly compared to ground coffee. Once you grind coffee, carbon dioxide is liberated from the beans, which accelerates degassing and staling.

So, once the coffee beans are roasted or ground, the clock begins to tick and the race is on to package up our product quickly and efficiently for that fresh-roasted taste — and that’s where nitrogen flushing (aka gas purging or modified atmosphere packaging) enters to save the day.

Nitrogen flushing is a hot (and quite subjective) topic, so let’s talk about why nitrogen is used, what nitrogen flushing is, its role in producing fresh coffee with a longer shelf life, and how it all works, plus answer some basic questions.

Why Nitrogen?
First, a quick science lesson: Nitrogen is an inert, non-reactive gas that is odorless and food-safe. And given that approximately 78% of the earth’s atmosphere is made of nitrogen gas, it’s easy to come by and is pretty inexpensive. Also, nitrogen is heavier than oxygen, a very reactive gas that most of us know causes coffee and many other foods to go stale. 

So, it turns out that nitrogen is a great gas to flush out oxygen from coffee bags that have just been filled with freshly roasted or ground coffee. By eliminating oxygen and moisture, nitrogen also prevents bacterial growth. 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 your customers are ready to brew themselves the perfect cup. 

And by the way, nitrogen is just as effective for K-cups. We get this question a lot, and we always tend to have at least a few sealing machines (or combination filler and sealer machines) that have the nitrogen flushing option integrated into their operating systems. All you need to do is supply the nitrogen cylinders that you obtain from your local gas company or co-op, and then connect them to the nitrogen supply port on your equipment.

What Do You Mean By Nitrogen Flushing and How Does It Work?
The term does exactly what it sounds like: It flushes out oxygen and replaces it with nitrogen. Pretty simple. And it’s a practice widely used across various industries but is most recognized for keeping packaged food from going rancid. Think of chip bags, most of which use nitrogen both to preserve and protect food from damage during shipping and storage. (Yep, this is why the bag is only half full of chips.)

Here’s how it works: Most coffee bags are packaged using a vertical form and fill system. Coffee grounds or beans are fed into an overhead hopper. Bags are fed into the dispenser where they are flushed with food-grade nitrogen as the bag is filled with coffee from the overhead dispenser. Finally, nitrogen is flushed until the bag is sealed, assuring that the coffee will remain fresh for months.

The process is similar for K-cups: K-cups are placed in special pods in K-cup filler and sealer equipment. The pods are filled with ground coffee, the film lid is placed on top, and then nitrogen flushed and vacuum sealed. 

How Does the One-Way Bag Valve Help?

It’s a good question and there’s a simple answer: We’ve already mentioned that coffee degasses carbon dioxide for a number of days post-roasting. If you seal the bag and don’t give it a way to escape, your coffee bags will balloon and eventually explode. And nobody has time for that! The one-way bag-valve — nitrogen flushing’s trusty sidekick — allows this gas to get pushed out of the bag with no way to get back in.

Another way a bag that has been nitrogen-flushed helps: Vacuum-sealed bags are constantly fighting the positive pressure outside the bag, which can lead to the potential for leaks. Flushed, zero-pressure bags are at an equal pressure to the environment around them, so there is no battle to keep the seal.

Let’s Talk Numbers: Is there a Certain Level of Oxygen You Still Want in the Bag?
Lab tests have shown that oxygen levels above 5% can cause greater oxidation and affect coffee’s freshness and quality within days of packaging. As a result, the minimum recommendation is no more than a 3% residual oxygen level. Some roasters will push for lower levels to protect their coffee’s flavor and freshness for an extended amount of time — especially ground coffee that is more sensitive to oxygen degradation. Being able to achieve lower than the minimum recommendation will open the door for more opportunities to a contract or private label roaster. More often than not, when bidding on a contract, especially with bigger competitors, the required residual oxygen level must be consistently 2% or below. Having the ability to achieve this level could be the difference of getting a lucrative contract or not.

Do I Need Special Nitrogen Flushing Equipment? Where Do I Get Nitrogen From?
Nitrogen flushing is a function that is built into your coffee bag or K-cup sealer; it is not something that requires a separate piece of equipment.

You can get nitrogen from outside suppliers like your local gas company or co-op. If you are a larger operation, you can produce nitrogen on-site with a nitrogen generator, which simplifies your operations, improves safety, can be cost-effective, and is environmentally friendly. CoffeeTec doesn’t sell nitrogen generators but a simple web search can point you in the right direction. 

Does Nitrogen Flushing Change The Flavor of My Coffee Product?
No. Nitrogen is odorless, colorless, tasteless, non-irritating, and completely food-safe. It does not impact the taste of your coffee beans beyond the fact that it will keep your coffee tasting fresher for longer.

How Long Does Nitrogen-Flushed Coffee Stay Fresh?
Sealed nitrogen-flushed coffee can stay fresh for up to six months after the “roasted on” date printed on the bag. However, once the bag is opened, it’s recommended that the coffee is used immediately over the next 7-10 days. And if you’re an avid coffee drinker like we are, then that’s usually not a problem!

What Are Additional Benefits of Nitrogen-Flushed Coffee?
We can think of three benefits, besides greater flavor and freshness:

Time Savings: You might be wondering: “Why not just stick with good old-fashioned vacuum sealing? That process removes ‘Enemy Oxygen’ too!” Ah, this is true, but there is one key difference. If you’re using a simple vacuum sealing method, you must wait for your coffee to off-gas before you can vacuum seal your bags. This waiting period can take anywhere from 24 to 48 hours, and during this time, the coffee is exposed to oxygen and going stale. Nitrogen-flushing your coffee product puts time on your side, allowing you to go from roasting to packaging with no time lost.

Expanded Customer Base and Potential Income: Another benefit? Nitrogen packaging allows you to potentially expand your business by extending your geographic reach because a longer shelf life means your coffee product can be transported far and wide. You might even be able to attract more foodservice and hospitality clients since they typically need a product that remains fresher than retail packaging. In fact, more and more stores, food service, and hospitality companies are requiring their vendors to package their coffee in nitro-flushed bags.

Better Company Reputation and Customer Experience: By providing a consistently fresh and flavorful coffee product that is rarely stale, you’ll build a strong reputation, help ensure better customer experience, and build brand loyalty.

Any Drawbacks to Nitrogen Flushing?
So, just as nitrogen gas flushes oxygen out of a coffee bag or K-cup, it can displace oxygen from a room. If a leak were to occur, employees wouldn’t be able to tell since it has no smell, odor, or color. A leak could push so much oxygen out of the air that you could suffer respiratory problems or worse. To help prevent this, invest in an oxygen sensor to continually monitor your space’s oxygen levels. 

Additionally, there is the cost of your equipment that includes the nitrogen-flushing function, the cost of nitrogen cylinders or a nitrogen generator, and related costs. For this reason, plus some subjective opinions that nitrogen flushing doesn’t make a huge difference (do your own research!), some coffee roasteries may prefer to bypass nitrogen flushing. 

At the end of the day, whether you decide to nitrogen flush your coffee product really comes down to how you probably make most of your business decisions — weigh your distribution and volume goals with your own research about what makes for a superior product, assess market demand, and then determine if you have the budget to spend to achieve that payoff. 

Have Additional Questions?
We’re here for you and would love to help you make the best purchasing and design or layout decisions for your coffee roastery’s operations. No matter where you are in your coffee journey, we want to see you succeed. Check out our consulting and education services. Perhaps you’re interested in financing or are considering the option and benefits of buying used. We’ve got you covered for both. Finally, feel free to explore our FAQs, and if you still don’t have answers to your questions, contact us. 

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Julio Gil - July 13, 2023

Dear Sirs,

Excellent article regarding nitrogen. I have done extensive testing in using nitrogen in packaging and found it is the best way to maintain the quality and freshness of the coffee.

The article only lacks addressing the equipment to measure the oxygen levels in the final product and assure that the remaining percentage of oxygen is on the target define by the packer. In my products I used 2% as the maximum allowed oxygen level.

Also, on the “time savings” it is mentioned that there is no need for degassing the coffee. This is not true if the packaging does not have a one way valve. Otherwise the package will be inflated. That is my experience while packaging coffee PODs with a nitrogen flush.

Let me know if I can be of any assistant or help in any area regarding coffee.

Best Regards
Julio Gil

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