One of the steps in storing food long term is removing the oxygen from the container that the food is being stored in. Oxidation will ruin food, so the oxygen has to be removed somehow to keep the food from spoiling. To do this we can use oxygen absorbers, also called O2 absorbers. They come in little packets that can safely be added right in with the food.
One of the best methods for storing food long-term is to store the food in Mylar bags. Once sealed, a Mylar bag will be air tight and the oxygen absorber will remove any remaining oxygen inside the bag. Then the bag can be put in a food storage bucket for additional protection from light, moisture, oxygen, and pests.
We’ll talk more about Mylar bags and food storage buckets in separate articles. For now let’s just focus on oxygen absorbers for food storage – what they are, how they work, and what foods we can use them with.
What are oxygen absorbers?
Oxygen absorbers are little packets that contain iron powder. The packet itself is designed to allow oxygen and moisture into the packet without letting the iron out.
How do oxygen absorbers work?
Moisture activates the iron causing it to oxidize and rust. In the process of oxidizing the iron reduces the oxygen levels in the surrounding atmosphere or in the bag you’re storing your food in. Once the iron has completely oxidized its absorbing action stops.
If you have your food storage bag or container sealed properly and you’re using the right amount of oxygen absorbers, they should use up 99.99% of the oxygen that’s left in the container and thereby extend the shelf life of your food. Any remaining air will be in the form of nitrogen, not oxygen, and insects can not survive without oxygen so it will also keep them from thriving in your food.
Desiccants are not oxygen absorbers
Don’t get oxygen absorbers mixed up with desiccants, they’re not the same thing. Desiccants just absorb moisture. They can be used when storing food with a higher water content. They’re also used in a lot of other applications as well where moisture levels need to be reduced.
How long do oxygen absorbers last?
Oxygen absorbers usually have about a 12 to 18 month shelf life. So don’t purchase any more than what you plan on using within the next year.
How many oxygen absorbers do you need?
Oxygen absorbers are measured in CC’s (cubic centimeters). The amount of cc’s you will need depends upon the food you’re storing and the size of the Mylar bag you’re storing it in. As a general rule, a lot of sources will say to use a 300 cc’s per gallon or 2000 cc’s for a 5 or 6 gallon bucket.
How to tell if oxygen absorbers are still good
To make sure your oxygen absorbers are still good before you use them, feel the absorber. It has iron powder in it so it should feel soft and powdery if it’s still good. Once the iron powder has oxidized or turned to rust it hardens into a solid block.
Another way to test them is to set one of them out of the bag for a few minutes exposed to the air. If it’s still good it should get warm to the touch within a few minutes.
Some vendors will throw in a little pink indicator pill with their oxygen absorbers to help you determine if they’re still good or not. If the pill is still pink then the oxygen absorbers are supposedly still good, but if it’s turned blue then they’ve gone bad. Don’t pay much attention to these indicator pills because even if it’s still pink it doesn’t mean that all of the oxygen absorbers are still good. It’s more of an indicator of the oxygen levels in the bag and even if they’re is only one good oxygen absorber left in the pack it could keep the pill from turning blue.
You can also come back and check your Mylar bags a few days after you’ve sealed them with the food and oxygen absorber inside. If the oxygen absorber is working you’ll probably notice a slight reduction of the air inside the bag. The bag will have more of a vacuum-packed looked to it. That doesn’t mean that all of the air will be gone, just the oxygen. If you’re storing your food in mason jars, a good oxygen absorber will cause the lid to get sucked down.
Why not just vacuum-pack the food instead?
Oxygen absorbers are actually more effective at removing all of the oxygen than vacuum-packing. Vacuum packing will squeeze the food together real right, but there is still air and oxygen in the spaces between the food. You really don’t need to remove all of the air anyway, just the oxygen which makes up about 20% of the air, and oxygen absorbers do that quite nicely.
How to use oxygen absorbers for food storage
Oxygen absorbers become active very shortly after being exposed to oxygen. You need to move quickly once you’ve removed them from the package they came in because you don’t want to use them up on the oxygen in the room before you get them into the bags.
First you want to have your Mylar bags filled with food and ready for the oxygen absorbers. Only do a few bags at a time so you’ll have enough time to seal them before the oxygen absorber gets used up. Have a clothes iron or hair straightener nearby so you can quickly seal them after you insert the oxygen absorbers.
Open the package of oxygen absorbers and grab out the amount you need. Drop them into the Mylar bags and get the bags sealed up with a clothes iron or hair straightener.
How to store left over oxygen absorbers
You can store your left over oxygen absorbers in a mason jar. You should put what you’re not using in a mason jar at the same time that you’re putting what you are using in your bags of food. Then you can seal your bags shut. If the jar has a lot of empty space in it, you can add something like rice to reduce the amount of air and oxygen in the jar. You should already have the rice added though so you can just put the left over oxygen absorbers on top of the rice where they’ll be easier to get to.
Alternatively, if you don’t have a mason jar to store the left over oxygen absorbers in, you might be able to reseal them in the bag they came in using your clothes iron or hair straightener.
What kind of foods can you use oxygen absorbers with?
This long-term storage method works great for dry foods like beans, rice, grains, flour, sugar, macaroni, etc. The foods stored this way should have a low moisture and oil content.
Where to buy oxygen absorbers for food storage?
You can purchase them many places online, from long-term food storage companies, and even from Amazon.
That’s really all you need to know about how to remove oxygen from food. I do recommend you use oxygen absorbers with Mylar food storage bags. Over time, air can make its way into some bags more so than others, not so much with Mylar bags though which were made for this purpose. Finally, don’t forget to store you bags of food in food storage buckets for added protection.