What Are Oxygen Absorbers?
If exposed to oxygen, even non perishables like beans and rice will eventually start to go bad. If you want to store food long-term, you’ll have to protect it from oxygen. Luckily, there’s a cheap and easy solution: oxygen absorber packets.
Oxygen absorbers are little packages containing iron. When you put the oxygen absorber (OA) into an airtight container, the oxygen molecules “stick” to the iron. OAs can reduce the amount of oxygen in a container to less than 0.01%. (1)
Keep in mind that air is about 78% nitrogen, 21% oxygen, and about 1% other gases. Oxygen absorbers only remove the oxygen. However, nitrogen does not cause food to spoil.
Good quality products with great customer service.Discount Mylar Bags
*See the section on botulism in the FAQs
To store food with oxygen absorbers, you will need to put the food and oxygen absorbers in an air-tight container. If the container leaks air, then it is pointless to use oxygen absorbers. There are four main containers which can be used for long-term food storage with oxygen absorbers.
Mylar is a metallic-looking material which doesn’t allow air or humidity through. Mylar bags are very cheap and durable, which makes it one of the best long-term storage packages for dry food.
To store food in it, you will fill up the Mylar bags with dry foods, add oxygen absorbers, and then seal the bags. You can then put the Mylar bags in buckets with lids. This will keep food safe against virtually any disaster. Some people even do “Mylar bag parties” with friends so they can seal a lot of food in one go.
Pros
Cons
For detailed instructions, see our post on mylar bags for food storage.
For storing smaller amounts of food long-term, you can put the food in canning jars or Mason jars (jars with a two-part lid). Just add the right amount of oxygen absorber to the jar and then screw on the lid. You’ll know the oxygen absorbers are doing their job because the jar lid will get sucked down.
Other jars can also be used with oxygen absorbers. However, the lids on these jars are much more likely to leak. To play it safe, it’s best to stick to canning jars.
Pros
Cons
The simplest way to use oxygen absorbers with large amounts of food is to put them into food-grade buckets. You fill up the bucket with dry foods, add the right amount of oxygen absorbers, and then close the lid.
The downside is that most buckets will leak air inside. This includes the cheap HDPE 5 gallon food-grade buckets. They slowly leak air, so you could still use them with oxygen absorbers – just not for long-term storage. You are much better off with a gamma-seal lid bucket. These buckets cost more but actually do create a tight seal.
Also note once you open the bucket, you will expose the food to air. If you want to reseal the bucket, you’ll have to add more oxygen absorbers.
So, this method isn’t good if you plan on rotating through your food stockpile. Personally, I’d only recommend using buckets as a short-term solution until you are able to get enough food stockpiled to have a “Mylar bag party.”
Pros
Cons
A lot of emergency foods – like butter powder from Augason Farms or Mountain House’s scrambled eggs – are packaged in #10 cans (pronounced ten pound cans). If you get a can sealer, it’s possible to store your own food in these cans at home too.
Using #10 cans for food storage is actually pretty simple. You just put your dry food in the cans, add oxygen absorbers, and seal the can. The seal is completely air-tight and the cans are tough enough to withstand almost any disaster.
The downside is that the cans and the sealer are pretty expensive. If you are lucky enough to know someone who already has a can sealer which you can borrow, then you only have to worry about the costs of the cans.
Pros
Cons
Oxygen is in the food container in two places:
If you want to keep the food safe for long-term storage, you’ll need to remove virtually ALL of this oxygen. This means making sure you use enough OAs.
Below is a general guideline of how many oxygen absorbers you will need. However, the amount can vary depending on things like whether your batch of beans is uniform in size (lots of air space between the beans) or varying in size (less space between the beans).
If you really want to know exactly how many OAs you need, you’ll need to do some math. I’ve included the math in the dropdown for those who are interested.
As Fresh Pack points out, there can be a surprising amount of oxygen within certain foods. For example, dry foods like TVP contain a lot of air inside of them. The same goes with dry beans.
They also point out that there is mistaken information about how density affects air amount. The idea that “items with small particles (like flour) are ‘dense’ and have less air volume” is FALSE. Here is why:
“A pool filled with marbles will have the same interstitial air volume as one filled with basketballs. Yes, the basketballs will have much larger pockets of air, but there are far fewer of them. Think of a checkerboard with just 2 large black squares and 2 large white squares… ½ of it’s area is black and ½ white. What if it had 100 small black squares and 100 small white ones? 1000? Even with tiny squares it is still ½ black and ½ white as long as the squares are all a uniform size.
What does matter is particle size distribution, or in other words, whether you have particles that are all a uniform size or if you have a lot of particles of different sizes. If you have a pool filled with basketballs AND marbles, the marbles can fill in all the large pockets of air. So, products with uniform particle sizes will have more interstitial air than products with a greater distribution of particle sizes.”
Calculating How Much Air is in the Container
To figure out how much air will remain between the food spaces in a filled container, you can do this test:
With this information, you can do a fairly exact calculation of how many oxygen absorbers you need. This requires some more math:
*Some products like beans contain a lot of air inside of them. For the water test to work, you have to let them sit for at least 6 hours so they absorb the water. Note also that beans require a lot more oxygen absorbers than typically shown in charts.
Top Tip
It is always best to play it safe – use more oxygen absorbers than you think you need! Using extra oxygen absorbers won’t impact the food. OAs are cheap, better to spend an extra 25 cents on an additional oxygen absorber than throw away 5 gallons of food when it’s needed most.
Just about any dry and low fat food can be stored with oxygen absorbers. This includes foods like:
Note: Not all foods are oxygen sensitive. For example, whole grains, peas, and beans aren’t too sensitive to oxygen. If you plan on using the foods within 5 years, there won’t be too much difference in freshness regardless of whether you use an OA or not.
However, oxygen absorbers do protect against pests and have other benefits like preserving nutrition. Since OAs are pretty cheap, I recommend using them with all dry foods you want to store for 12+ months.
Most home dehydrated fruits and veggies usually aren’t suitable for long-term storage. They simply contain too much moisture. If the moisture level is too high, you could even risk botulism poisoning (more on that below).
To safely store dehydrated food with OAs, the food must be so dry that it snaps when bent. Or, for round foods like corn or peas, it should shatter when pressed with a spoon.
*Read Expert-Level Food Dehydrating
Storing nuts and seeds with oxygen absorbers will extend their shelf life. However, because they contain so much oil, they will eventually start to go rancid.
Most people put the shelf life of nuts/seeds with OAs at about 2 years. However, nuts and seeds can last longer than this even when exposed to oxygen. The key is keeping the temperature and humidity low.
*Granola also has a lot of oil in it and won’t store long-term.
Botulism is usually only talked about in regards to home canning. However, because the botulism bacteria grows in no/low oxygen environments, it could also grow in Mylar bags packaged with oxygen absorbers.
Botulism requires moisture of 35% to grow. However, to play it safe, virtually all food preservation guides will say that food must have 10% or less moisture to be packaged in airtight containers with oxygen absorbers. (2)
This shouldn’t scare you away from self-storing foods with oxygen absorbers. Just make sure you aren’t storing any moist foods in sealed containers with oxygen absorbers.
The good news is that botulism toxin (which causes the disease) can be easily destroyed by boiling for 10 minutes. The CDC states, “Despite its extreme potency, botulinum toxin is easily destroyed. Heating to an internal temperature of 85°C for at least 5 minutes will decontaminate affected food or drink.” This page also has good info on deactivating botulism. Many of the foods which get stored for long-term need to be boiled anyway (dry beans, dry grains, etc.), so this in theory would kill any contaminants.
However, that doesn’t mean you should eat any foods which you suspect are contaminated with botulism.
Warning: If the package is bulging (a sign that bacteria or toxins are growing inside), then don’t eat its contents!
Remember that OAs only protect against oxygen. You’ll also want to protect your food against heat, light, and physical damage.
The following table gives you general guideline of what shelf life you can expect when packaging food with oxygen absorbers.
*Dehydrated fruits and vegetables must have less than 10% moisture to be safely stored with OAs. They will snap when bent or (with round food like corn) shatter when pressed with the back of a spoon.
The moment you take oxygen absorbers out of the package, they will start to absorb oxygen. After around 2-4 hours, they’ll have absorbed their maximum capacity of oxygen.
It is important that you have a plan on what to do with any unused oxygen absorbers before you begin working. Ideally, you will reseal oxygen absorbers in the packaging they came in. Then you vacuum seal them.
If this isn’t an option, you can also store unused oxygen absorbers in a mason jar. Fill up any extra space in the jar with marbles (or something similar). The less air that is in the jars, the less air the unused OAs will absorb. Be sure to seal the jar tightly!
If you buy OAs from a reputable company, they should be good. We like the supplier DiscountMylarBags, they are the cheapest around and provide good quality products. They also sell on Amazon if you prefer to shop there)
They will arrive in a vacuum-sealed package. Most oxygen absorbers have a “margin for error” added into their abilities (DiscountMylarBags use ShieldPro absorbers they absorb 200 to 300% of their rating). So, they will actually absorb more than specified.
This is so you can have a good 10-20 minutes to work with the OAs and not have that air exposure count against you.
Here’s how you can check:
Oxygen absorbers will absorb oxygen. Desiccants will absorb moisture. OAs actually require a small amount of moisture for them to activate. Thus, it’s generally not recommended to use both OAs and desiccants together.
There are some exceptions to this rule though. Some foods (like home-dehydrated fruits) may contain a lot of moisture. Since moisture is one of the things which makes food spoil, adding a desiccant can help the food last longer.
In this case, it’s best to use silica gel desiccants because they don’t absorb so much moisture that it will interfere with the OA. Some more advanced types of desiccants can reduce the moisture to practically zero, which means they would stop the OAs from doing their job.
*When using both oxygen absorbers and desiccants, put the desiccant on the bottom of the package and the OA on the top.
Oxygen absorbers and vacuum sealing both work by removing air from packaging. However, vacuum sealing doesn’t remove all the oxygen like OAs do. Also, the vacuum seal bags are actually not air-tight and will slowly leak air into the package over time. Thus, vacuum sealing is NOT suitable for long-term food storage.
There’s also no reason use oxygen absorbers and vacuum sealing together: OAs do their job well enough without any need to first suck out air. Further, the vacuum sealer will remove nitrogen from the packaging (oxygen absorbers only remove oxygen). If you add an OA to a vacuum-sealed bag, the bag may get so “sucked in” that sharp edges on foods like rice could tear through the bag.
This doesn’t mean that vacuum-sealing isn’t good for food storage. Vacuum-sealing can increase shelf life of foods by 3-5 times. It’s also great for storing foods which aren’t suitable for OAs, such as moist foods. But, when it is long-term storage that you want (5+ years), then sealed containers with oxygen absorbers is the way to go.
I’ve recently come across many guides and videos about gas purging (aka nitrogen flushing) Mylar bags. The basic idea is that you use a special machine to force nitrogen gas into the package. The nitrogen flushes out any oxygen. Then you seal the package so only nitrogen remains.
Nitrogen flushing is used by some food manufacturers to keep their greasy foods (such as chips) fresh for a long time. That’s why bags of chips are puffy when you get them.
However, unless you have access to professional equipment, nitrogen flushing is very difficult to do! You have to displace all of the oxygen and make sure none gets back into the bag before you seal it.
Packaging with oxygen absorbers is much easier, and leaves just nitrogen in the packaging. Don’t mess with what works – use oxygen absorbers for your home food storage and leave nitrogen flushing to the experts. (3)
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good overall article >>>
but you have a mis- Q within the article >> it first indicates the 02 absorbers can prevent bacteria growth – then later it corrects itself by discussing moisture % and botulism >> not good
you included what is often left out !!!!
*When using both oxygen absorbers and desiccants, put the desiccant on the bottom of the package and the OA on the top.
Hence why I wrote after the bacteria line “most bacteria require oxygen to grow.” 🙂 Botulism is the exception. I’ll edit the article to make sure this is clearer. Thanks.
Can you revitalize o2 absorbers by putting them in a freeze dryer?
Thanks for the info.
As far as I know, no – oxygen absorbers can’t be revitalized. They go through a chemical reaction when exposed to oxygen and the reaction can’t be reversed. Well, maybe there is some high-tech way a chemist could do it… In any case, even if you could reverse the process in OAs, I wouldn’t risk it; they are cheap and you don’t want your food to go bad because you took a chance with reusing old OAs.
I recently put different types of beans and rice in glass jars with the locking clamp. Then added a oxygen absorber packet to each jar. I also put the extra absorbers in a glass jar. When I went to get one before, the inside of the jar was warm. Is that normal? Can I use OA to store dry pasta in jars?
It’s normal for OAs to produce a bit of heat as they work. The heat will go away after a while. If the jars are still hot days afterwards, the I don’t know what’s going on 😀
Yes, you can use jars for storing dry foods like pasta, so long as the jars have a tight-fitting lid. However, I don’t advise on it. You can’t really fit that much pasta in a jar and jars can break. You are better off getting Mylar bags IMO. Save the jars for items you only need in small quantities, like spice packets.
Have you ever used(or heard about) vacuum sealed mylar bags? I bought some on Amazon. Just wondering what your thoughts are on these.
I personally haven’t done it, but I have seen hacks on YouTube which show how you can vacuum seal Mylar bags. The issue is making sure you get a proper seal on the Mylar bag since it is thicker than standard vacuum bags.
With so many mylar bags on market. Do you have it written somewhere what yo look for? I know mil thickness are important. Some bags you get that say mylar you. An see through still. Thanks
We’ve got recommendations in this post https://www.primalsurvivor.net/mylar-bags-food-storage/ As for thickness, the thicker ones are more durable but can cut your fingers (they have sharp edges!) and don’t bend as much, so not as much food will fit in them. As a general rule, use slightly thicker bags for pointy things like rice and thinner bags for other stuff. If you put the sealed bags in buckets after you are done then you don’t really have to worry about the bags tearing or breaking.
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What Are Oxygen Absorbers?
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