You may be more familiar with oxygen absorbers than you think. Even if you haven’t used them for food storage in your own home, you’ve likely seen them in food packaging before or eaten food that was stored with oxygen absorbers. That’s because oxygen absorbers are an important step in the food preservation process. If you are planning to buy Mylar bags for food storage, you should also consider using oxygen absorbers along with these bags. In this article we’ll explain oxygen absorbers, why they work, and how you can use them for long term food storage. 

What are Oxygen Absorbers?

These little packets are filled with iron powder. Iron powder absorbs oxygen - up to 99% of the oxygen in a sealed container (such as a jar or airtight bag). Whatever is left in the air is completely inert and won’t degrade it. When packets are removed from a sealed container, they start absorbing O2, which will react with the iron powder to form iron oxide. When packets are placed in a sealed container, almost all of the oxygen will be removed. What’s left in the air is ideal for long-term storage. 

While the oxygen is absorbed, the powder in the packet remains secure and separate from the food in a package. Because of that, oxygen absorbers can be placed directly in containers with edible items. Interestingly, they tend to be warm to the touch, since they work using a chemical process that’s similar to disposable hand warmers. They will warm and take about 4 hours for oxygen absorbers to remove the O2 from sealed containers or bags. 

Why Use Oxygen Absorbers? 

There are multiple reasons why people use these items. The most common reason is to increase the shelf life of dried foods. If you dehydrate food at home, you can use these to store them for longer periods of time. If you buy dried food at the store, you can leverage oxygen absorbers to keep the foods longer. 

Oxygen absorbers are especially helpful for people who want to avoid processed food. Often, foods are preserved with additives or chemicals which make the food last. Most pre-packaged foods available make use of these preservatives. With oxygen absorbers, you can choose more natural food items and keep them around for longer. They also prevent pathogens from growing in food. Many organisms or mold particles are unable to survive in an environment without oxygen. Simply put, by keeping oxygen out, you are able to keep your dry foods safe and edible in the future. 

The Biggest Oxygen Absorber Error

For the most part, these little items are handy and easy to use. However, there are a few things to know to ensure they work properly. 

The most important information to note is that, similar to disposable hand warmers, they begin working immediately. If you open them before your food is ready to store, the packets will start to absorb the air and will have less capacity for preserving food. In this way, you may end up using packets that are no longer effective. Some companies provide little pill-type items that change color based on whether or not the absorbers are active (for example, pink means active, but purple means they are no longer effective). However, you can also test them on your own by placing the packet in your hand and checking for loose powder. If you can feel the powder, it’s an indicator that the packet is ready to use. If the substance feels hard or solid, chances are good that the active substances will no longer work. That makes it even more important to store oxygen absorbers properly. Being diligent will maintain the life of these packets. The better you are able to preserve them, the less likely you are to need to replace them. 

How to Use Oxygen Absorbers

There are a few simple steps one should follow to properly use oxygen absorbers to preserve food. 

  1. Review your needs and decide how many packers you’ll be using in your food. More on that below…
  2. Prepare your food and place it in the long term storage container of your choice (bag, can, etc). 
  3. You should have a container nearby where you’ll place the leftover packets as soon as  you’re finished. Remember that as soon as you open the bag, you’ll have to place leftovers in a properly sealed container asap. Some people like to use the original bag and simply seal it with a hot iron. 
  4. Be ready to seal the food container immediately after putting the packet inside. 
  5. Keep packages in a cool, dark, and dry place. 

Which Containers Work Best for Storing Food? 

There are plenty of options for storing food with oxygen absorbers. There are a lot of versatile choices that seal well and are easy to use. We’ve found these materials to work best: 

Obviously which container you’ll use will depend on how much food you’re storing. For small amounts, a jar should work. In this case, simply fill the jar and then place the packet on top, closing it up with the ring and the lid. The absorber will essentially seal the jar by taking the oxygen out. For larger quantities, a Mylar bag or food-safe bucket will work better. In this case, fill the containers but leave a little room at the top. For bags, close the top and then seal it using a hot tool. Some people place several bags into a bucket with a lid for extra protection, especially against rodents. Remember to check on the recommended number of packets or cc’s - one packet may not be enough for a large bucket. 

How Many Packets Should I Use? 

You can’t just throw one packet into every container you use. To use oxygen absorbers effectively, you need to understand how many to use. To figure this out, you need to know how much oxygen your chosen container holds and the type of food you’re dealing with. 

Here’s a basic formula that can be used to calculate the oxygen absorbers required (in cubic centimeters). 


Container Volume – Food Volume = Residual Air Volume

1 gram (g) = 1 cubic centimeter (cc)

We suggest adding on a few extra cubic centimeters in your calculations, since it’s better to be on the safe side where food is concerned! 

You can find oxygen absorbers in several sizes but the most commonly used are 500cc or 2500cc. Here are some example calculations: 

  • 1 pint up to 1 quart Mason jar = 50cc
  • 1 gallon Mylar bag = 300cc
  • 5 gallon bucket with low air volume (think rice and flour) = 1000cc
  • 5 gallon bucket with high air volume (think pasta) = 2000cc

Remember you can also combine packets to reach the correct quantity of cubic centimeters for the volume that you’re working with. 

Which Foods Work Well with Oxygen Absorbers? 

Oxygen absorbers are very versatile, but they do work better with some foods than others. The rule of thumb is to store foods that have 10% moisture or less. Think about which type of dried foods you might store and that you want to make sure won’t deteriorate. The most common foods are: 

  • Beans
  • Legumes
  • Dried fruit
  • Dried vegetables
  • Grains
  • Popcorn kernels
  • Oatmeal
  • Flour
  • Cereal
  • Pasta 
  • Instant coffee

It’s worth noting that you should never add these packets to sugar or salt. That’s because neither of those items actually need to be preserved. They are often the ingredients used to preserve other items. If they are placed in sugar or salt, they’ll harden into a brick and be rendered useless.

Do Oxygen Absorbers do the Same Job  as Vacuum Packaging or Freezing? 

Some people mistakenly believe freezing their food is the best way to preserve it. The truth is that most food items do last longer in cooler temperatures, so the freezer is a good bet in many cases. However, an oxygen-free environment is better for a wider range of dry foods. 

Vacuum packaging is helpful in many circumstances, but it doesn’t do the job of an oxygen absorber. That’s because air is approximately 20% oxygen and 80% nitrogen. Some people think, because there may still be air present in containers with oxygen absorbers, that they aren’t as effective. However, absorbers remove oxygen and then leave nitrogen in the air. Nitrogen isn’t harmful to food. The goal should be to remove the components that are actually bad for the food - which is the oxygen. 

Other Things to Keep in Mind

Oxygen absorbers alone aren’t a food preservation strategy. If you want to be really successful in storing food long term, plan to account for these: 

  • Light - Don’t store products out in the open where they can be exposed to sunlight. Dark, dry cabinets are your best bet for food storage. Basements can also work well as long as you can keep food off the ground and the space doesn’t get too damp. 
  • Temperature - Foods need to remain at or below room temperature. The ideal is 40 or 50 degrees F if you can accomplish that. In general, dry goods will be safe below room temperature and away from direct sunlight. Avoid temperatures over 90 degrees entirely. 
  • Moisture - If your food is in a moist environment, then condensation is likely. Condensation will cause food to spoil more quickly. Store food in as dry a location as possible. It’s also worth noting that foods high in oil may not be “dry”. 

Follow these tips and use the correct amount of oxygen absorbers, and you’ll have a great foundation for storing food well into the future. Browse our website for more food storage tips and the highest quality food storage products.