How Nitrogen Flushing Is Used for Food Preservation

View inside and open potato chip bag
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Americans consume a lot of processed foods every day. They're convenient and easy to transport and store. Processed foods need a lot of protection, from the processing plant to the grocery store, and to your kitchen. Plus, you may need to store them for awhile before you use them.

Dry foods are usually packaged in bags and boxes. The key to long-term preservation is removing oxygen from the containers because the oxygen exposure causes the food to deteriorate. The fats will go rancid, discoloration of the food occurs, and the product spoils and goes to waste. There are two ways to accomplish this, either vacuum packaging or nitrogen flushing.

Vacuum Packaging

The first step in vacuum packaging is to get the food into a bag. Next, the bag is connected to a vacuum, and the air is removed, which of course, takes the oxygen along with it. The bag is sealed, and the product is ready to be labeled and shipped.

Regular vacuum packaging works fine for sturdy solid foods like beef jerky and fresh meat, but it doesn't work well for foods that are delicate, like snack chips and crackers. These foods need protection during transportation so that they won't be crushed or broken. Foods like coffee beans that have a lot of surface area and can't be squished down into an airless lump may need something more than vacuum packaging too.

Nitrogen Flushing

When you pick up a bag of snack chips, you can hear and feel the chips banging around, and it seems like there's much more air in the bag than actual chips. But it isn't really like the air you breathe because the package doesn't contain oxygen. All that 'air' is nitrogen gas.

Chip and snack bags are not filled with nitrogen gas just so they look bigger. The bags are designed that way to protect the delicate foods inside from both oxygen exposure and physical damage. The nitrogen replaces the oxygen in the bag, and it cushions and protects the contents.

And no worries about the nitrogen gas. It's completely safe. In fact, you're exposed to nitrogen constantly because it makes up about 78% of the air you breathe.

Nitrogen flushing is a method used to preserve and protect food from damage during shipping and storage. Nitrogen replaces the oxygen in a food storage bag, and it cushions the contents. Unlike oxygen, nitrogen doesn't react with foods or affect the flavor or texture, so they stay fresher longer.

How It Works

First, the food is added to an open package, something like a plastic or mylar bag. Next, food manufacturers use machines that force the regular oxygen-rich air out of the bags and immediately fill them with nitrogen gas. Then, before the nitrogen has a chance to escape, a machine seals the bags tightly. The bags are placed in large boxes and shipped to grocery stores, convenience stores, and restaurants.

The nitrogen-filled packages help to protect the delicate foods inside for as long as the bag is sealed. Of course, once you open the bags, the nitrogen escapes and is replaced by regular air that's about 20% oxygen. That means the food inside is no longer protected and will start to deteriorate and the oils or fats will start to go rancid. You can maintain some of the freshness by keeping the package closed with a twist tie or clip, or by placing the food in a resealable container and putting it in the fridge, but it's best to consume the food products within a short time.

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Article Sources
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  1. Ajita T, Jha SK. Effect of Nitrogen Gas Enriched Packing on Quality and Storage Life of Pearl Millet Based Fried Snack. J Biosyst Eng. 2017;42(1):62-68. doi:10.5307/JBE.2017.42.1.062

  2. Agarwal D , Mui L , Aldridge E , Mottram R , McKinney J , Fisk ID. The impact of nitrogen gas flushing on the stability of seasonings: volatile compounds and sensory perception of cheese & onion seasoned potato crispsFood Funct. 2018;9(9):4730–4741. doi:10.1039/c8fo00817e

  3. U.S. Food & Drug Administration. Code of Federal Regulations, Title 21, Volume 3, Subchapter B, Part 184-- Direct Food Substances Affirmed as Generally Recognized as Safe. Subpart B, Sec. 184.1540 Nitrogen. Updated September 19, 2019.

  4. Marasca E, Greetham D, Herring SD, Fisk ID. Impact of nitrogen flushing and oil choice on the progression of lipid oxidation in unwashed fried sliced potato crisps. Food Chem. 2016;199:81-86. doi:10.1016/j.foodchem.2015.11.136

  5. National Aeronautics and Space Administration. 10 interesting things about air. Published September 12, 2016.