Prepper Basics: Oxygen Absorbers

by Gaye Levy

When I first started getting serious about food storage, I found myself facing an entirely new vocabulary of food storage terms. It should come as no surprise that one of those terms was “Oxygen Absorber.”

Now I am pretty sure that you have heard about oxygen absorbers. But do you know what they are and that they are a necessary component when sealing up dry goods for the long haul? Oxygen absorbers are a mystery to many, so today I will provide you with the basics – just enough to get you started on the road to storing your bulk foods for the long term.

Learning about Long-Term Storage

The very first item I purchased for my food storage pantry was a 25-pound sack of pinto beans. Of course back then, I thought I would simply store the big bag in the garage and let it sit there until I needed it – you know, set it and forget it. Luckily, I did my research and learned first and foremost that beans indeed have a shelf life and will turn as hard as rocks if not properly packaged and maintained in a cool, moisture free environment. Who knew?

The light bulb really came on as I was reading John Hill’s book How to Live on Wheat. It was this little book that taught me not only about wheat (living and dead) but about storage containers, Mylar bags, desiccants, and yes, oxygen absorbers. Seriously, I wanted – no, I needed – to know what was in these little packets and how could I learn to use them effectively for long-term food storage.

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What are oxygen absorbers made of?

Oxygen absorbers are smallish little packets that hold an iron powder. Through the magic of technology – or so it seems to me – the outer wrapper lets oxygen and moisture in. At the same time, the outer wrapper is strong enough to prevent leakage of the the powder back out into the packaged food.

How do they work?

In the process of sucking up moisture, the iron in the absorber starts to rust. This creates oxidation and, before you know it, in a well-sealed container, 99.99% of the oxygen is used up. Any space or air left in the container is nitrogen – not oxygen – which is not a bad thing because insects cannot thrive in pure nitrogen.

So, in simple terms, the little packet sucks up all of the oxygen from the air within the container in which it is placed.

Factoid: Air is about 21 percent oxygen, 78 percent nitrogen and 1% other gasses. Did you know that?

What about storage containers?

Still with me? We are getting to the hard part. As you do your research, you will hear over and over again that you should use oxygen absorbers in sealed Mylar bags. And yes, it is true that they work extremely well when used with sealed Mylar bags.

But – and this is a big but – they can be used successfully to block out oxygen with other types of packaging, too. All of the following will work:

  • Metal cans with sealed lids. Great if you have access to a canner or a local community kitchen. For most of us, however, this is not a realistic and cost-effective solution.
  • Mason jars with proper canning lids. This is one of my favorites especially since I have a special attachment for my food saver that allows me to vacuum seal the mason jars quickly and easily. And, just a personal thing, but I love looking at all of the products peeking out of those glass jars.
  • Mylar bags. These are heavy duty foil bags lined with a special plastic.
  • Vacuum sealed bags (such as the Food Saver bags). While not as heavy as the Mylar, these are much easier to handle especially if you already have the Food Saver machine itself.
  • Plastic buckets with gamma seals. These can be used alone or in combination with other Mylar or other bags such as those from the food saver.
  • PETE plastic bottles with airtight, screw on lids.

What is the proper way to use oxygen absorbers?

There are just a few precautions that you need to be aware of when using oxygen absorbers.

  • The most important precaution is to limit the unused packets from exposure to the air. Take out only what you are going to use in the next 15 minutes or so and seal the rest up in a jar with a screw top lid. Don’t put them in a zip lock bag because they will immediately suck up the residual oxygen and become useless.
  • A good rule of thumb is to use one 300 cc oxygen absorber for each gallon of product. For larger containers, you can purchase larger, 2000 cc oxygen absorbers which are ideal for 5 or 6 gallon buckets.
  • Be mindful of the little pink pill. Most reputable vendors will include a little pink pill with their package of absorbers. If the pill is blue, the absorbers are toast so don’t use them. However, if they are just starting to turn – not quite pink and not quite blue – they are probably okay since the change of color can happen in as little as 10 or 15 minutes.
  • Another good test of their viability is to pick one up and hold it. It may feel warm. It will also feel soft and powdery, like a little pillow. If it gets real hot and uncomfortable, it is in full-out working mode and has probably been exposed to the air for too long to be usable. In this case it may also start to feel hard and brick like. Toss it.
  • Oxygen absorbers themselves have a limited shelf life, even when sealed. Only purchase an amount that you will use within a year.

Help Me! I Am Confused!!!

If you start to do some research on your own, prepare to be confused. You will find that some sources feel you should use a larger quantity of oxygen absorbers when packaging dried pasta and beans versus packaging grains, flours, and rice. The reason for this is that the latter are more dense so there is less oxygen to get rid of.

You can come to your own conclusion, but the overwhelming advice I received from respected vendors was that 300 cc per gallon or 2000 cc per bucket would do just fine.

A few other pointers

Almost anything can be packaged using oxygen absorbers and they are so inexpensive, there is no reason not to use them. There are some things, however, that should be packaged without them. They are sugar and salt. Why? Well the sugar will turn to a brick of concrete and the salt simply does not need anything special to keep it preserved. It, too, may clump.

In addition, sprouting seeds need oxygen to stay alive (and ultimately germinate) so you would be defeating your purpose if you sealed them up with an oxygen absorber.

A bag sealed with product plus an oxygen absorber may or may not turn brick like in a day or two or even up to a week. The ability to fully compress is dependent upon factors such as head room and the amount of air that was sucked out during the sealing process. This is not a problem in spite of what you may read on the Internet. If you have used an oxygen absorber sufficient for the size of your packaging, the oxygen will be gone. The extra air is simply nitrogen and it will not harm your food. Of course, if it makes you feel better, you could open the package and start all over again but that is not really necessary for anything but your peace of mind.

The Final Word

Using oxygen absorbers (or Mylar bags, a Food Saver or even buckets) does not have to be a big mystery. All you really need is someone to explain it to you, right?

Seriously, though, my eBook, The Prepper’s Guide to Food Storage, covers what food to store, how to store it and a whole lot more. For the basics, though, keep checking back as I will do my best to explain the mysteries of food storage – in very plain terms – at Backdoor Survival.

For an interesting technical discussion of Oxygen Absorbers, read A Guide to Oxygen Absorbers.

Enjoy your next adventure through common sense and thoughtful preparation!

Gaye started Backdoor Survival to share her angst and concern about our deteriorating economy and its impact on ordinary, middle-class folks. She also wanted to become a prepper of the highest order and to share her knowledge as she learned it along the way. She considers her sharing of knowledge her way of giving back and as always, we at Natural Blaze are grateful for her contributions. If you would like to read more from Gaye Levy, check out her blog at  You can also visit her Facebook page or sign up for updates by email by clicking on Backdoor Survival Updates.

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