While oxygen absorbers are relatively simple to use, there is a lot of misinformation and confusion out there. If you use them the wrong way, your food will be ruined when you need it the most.
This can be fatal to you and your family in a long term disaster because you might end up with spoiled food that could make you sick.
To make sure this doesn’t happen to you, I’ll teach you how to use oxygen absorbers properly to safely store your food for the long term.
Table of Contents
What Are Oxygen Absorbers?
Oxygen absorbers are little packets of salt and iron powder that decrease the level of oxygen within a container or package. to military specifications of less than 2%, thus prolonging the shelf life of the food inside.
They have been used as an inexpensive and harmless method to preserve food since the early 1990s. The primary goal of oxygen absorbers is to reduce residual oxygen levels inside cans or containers.
Why Use Them?
The two primary reasons you will want to use oxygen absorbers will be to prevent oxidation and to inhibit the growth of mold and bacteria.
Both of these things increase the shelf life of the majority of foods dramatically. Oxidation is what causes the deterioration of the color, taste, flavor, nutrition, and texture of foods.
Some foods are more vulnerable to oxidation than others, but as we’ll see later in this article, even these foods can be stored long term with oxygen absorbers if you use the right type of container.
Oxygen absorbers are non-toxic and safe to use. The packet can be discarded through ordinary means and does not require any kind of special method.
Live organisms of any kind cannot live in an oxygen-free environment, including microorganisms.
Lack of oxygen eliminates the chance that any live organisms can survive, and is a barrier against adult insects laying their eggs there.
There are many additional reasons to use oxygen absorbers to store your food:
- It improves the qualities of polyunsaturated oils and fats
- Eliminates the necessity for additives like sulfur dioxide
- Retains the flavor of nuts and coffee
- Stops oxidation of Vitamins A, C, and E
- Absorbs all oxygen that permeates vacuum packaging
- Reduces condensation and oxidation of red pigment on sauces and berries
- Reduces mold on fermented dairy products such as natural cheeses
- Increases the life of most pharmaceuticals
- Inhibits the growth of pathogens
Examples of products that you can preserve with oxygen absorbers include:
| Pastries | Cookies |
| Wheat | Nuts |
| Coffee and Tea | Whole fat dry foods |
| Cured meats | Spices and seasonings |
| Dairy products | Dried fruits and vegetables |
| Flour | Precooked pasta and noodles |
| Vitamins | Birdseed |
| Pet food | Pharmaceuticals |
| Book and Art Preservation | Medical Diagnostic Kits |
| White Rice | Oats |
| Corn | Barley |
The food that you do store with your oxygen absorbers will need to be dehydrated, meaning oil and moisture content reduced less than ten percent. Otherwise, eating the food can result in botulism poisoning, a potentially fatal paralytic illness.
Certain foods such as brown rice or granola bars have a shorter shelf life of 6-12 months because of their oil content.
How Do They Work?
Oxygen absorbers aren’t magical even though the effects seemingly materialize out of thin air. The iron filings inside the packet are activated when they come in contact with air. As the iron oxidizes it absorbs the oxygen and turns into rust.
The oxidation process creates nitrogen, which won’t harm the food within the package. In food preservation oxygen can quickly shorten long-term storage and having an oxygen scavenger to quickly purge is a helpful boon.
What Size of Oxygen Absorber Do You Need?
The size of absorbers that you need is dependent on both the size of your container, and of the void area within the container (or the area within the closed container not taken up by food).
Oxygen absorber packets come in sizes from 20 cc to 2000 cc. These sizes reflect the numbers corresponding to the amount of oxygen that can be absorbed by the packet in cubic centimeters (cc). So a 200cc packet will be able to absorb 200 cubic centimeters of oxygen.
The second thing to keep in mind is that most of the bag itself will be filled with food, whether we’re talking about denser food, or less dense food.
The denser the food, the less air there is left inside for the absorber to process!
So an oxygen packet with a size of 100cc would absorb 100 ml of oxygen that is contained inside 500 ml of air volume.
If you want to avoid doing the math, here are a few examples that you can use as rule of thumb:
| Container Size | Dense Food (flour, grains, etc.) | Less Dense Food (beans, pasta, etc.) |
|---|---|---|
| 1 gallon bag or bucket | 400cc absorber | 600cc absorber |
| 5 gallon bag or bucket | 2000cc absorber | 4000cc absorber |
One thing to keep in mind is that there’s nothing wrong with adding too many oxygen absorbers!
It’s adding too few that’s problematic, because they won’t be able to absorb all of the oxygen, which in turn could spoil your food!
Choosing the Packaging Material
Your packing container must obviously be a food-grade. This means it will not transfer any chemicals, or at least not those harmful to human health, into your food.
This automatically disqualifies many plastic buckets and bins available on the market. Oxygen absorbers work well in bottles, buckets, cans, and films that have strong airtight characteristics, though there are food-grade airtight plastic buckets you can use.
Avoid containers that have inadequate seams or that can’t sustain heavy damage from rough handling.
Pouches, for example, are not airtight, and are not as well protected as a closed can or bucket. A pouch won’t work if your primary preservation method is oxygen absorbers.
Plastic buckets:
- Use only if marked “food grade”.
- Are generally thick and will preserve food 2 to 5 years with oxygen absorbers.
- Oxygen will very slowly be transferred through the plastic (polyethylene) bucket.
Glass jars:
- Will not allow all oxygen to seep in over time through the sides like plastic.
- Jars tend to be smaller, and will not hold as much food.
- They lack the durability of plastic, can crack and allow oxygen inside.
Inspect any container for any holes, cracks, or leakage points prior to using. Inspect seams of plastic buckets and jars to ensure they are tight and won’t allow outside moisture or oxygen to seep inside and ruin your food.
The tightest seal must be between the bottle and the closure; consider using an additional material to wrap around here that you will only open when you need to access the food.
Using Oxygen Absorbers
Using an oxygen absorber is easy once you get the hang of it. Oxygen absorbers are a safe and economical option to keep your food protected and oxygen free. They will keep your food safe long term as long as you follow each step in order.
- Choose the proper packaging container/material.
- Place the appropriate size oxygen absorber inside.
- Seal the lid as tightly as you can over the container.
- Store in a cool place, away from sunlight and moisture.
It can take as long as four days for the inside of the container to become an oxygen free environment.
Oxygen absorbers also have a short life span once taken out of their original packaging. They should be used within 30 minutes after opening the package, to minimize the amount of oxygen they absorb before you seal them.
Ideally, you should have all your containers filled and ready to seal before opening the original packing on your absorbers. Place them inside your container and seal immediately.
In addition, the longer oxygen absorbers are stored in their original packaging the less effective they become.
Use purchased oxygen absorbers in less than six months, and the sooner the better for maximum effectiveness
Leftover oxygen absorbers should be quickly resealed in their original packaging, Ziploc bags are not as airtight, or should be discarded if exposed to air for four hours or longer.
Store in a cool, dark location where temperature is less than 85 Fahrenheit (29 Celsius), preferably less than 70F (21 Celsius).
Foods You Shouldn’t Use Oxygen Absorbers With
Believe it or not there are some foods that you shouldn’t use oxygen absorbers with. Although the list is few, there are some oxygen sensitive items that will degrade quicker with oxygen absorbers.
Salt – Oxygen absorbers will turn sodium into an incredibly hard ball.
Wet Foods – Anything above 10% moisture can grow botulism in the absence of oxygen, a deadly pathogen if ingested.
Sugar – White sugar will go hard, much like salt. Brown and cane sugar have too high a moisture content to use oxygen absorbers in storage.
Baking Soda/Powder – Any products that use these (pancake mix, yeast) may be rendered inert by an oxygen absorber. Some believe that the leavening agents won’t be able to rise.
Questions About Oxygen Absorbers
Let’s answer some basic questions that you might have about using oxygen absorbers for prepping.
Can They be used at Low Temperatures?
The short answer is generally no because the lower the temperature, the slower the oxygen absorption rate will be and this means that the shelf life of your food will not be as long as it could be in moderate temperatures.
At the same time, the activity of any microorganisms will also be dramatically less in lower temperatures, so it’s not a huge risk. Nonetheless it’s always better to be safe than sorry and store your food containers with oxygen absorbers in them in a dimly lit location at a moderate temperature.
This is especially true for a survival situation where you can’t afford anything bad happening to your food.
Why Can the Master Bag of Oxygen Absorbers Feel Hot at Times?
First of all, this is nothing to be alarmed about. When the master bag that contains a type of absorber that is self-reacting is opened up, and as the packets are taken from the bag one at a time, then heat can generate from the oxygen absorber reactions and gather inside the bag.
While this can negatively affect the quality of your oxygen absorbers you can solve the problem by spreading out the packets apart from one another.
Does Repeatedly Opening, Closing, and Re-Opening the Master Bag Affect the Quality of the Oxygen Absorbers?
This is an important question for those who only use small quantities of the oxygen absorbers at a time.
Remember that the absorbers will only last a maximum of four hours out in the open before they’ll need to be resealed in the bag, placed in an airtight container, or discarded.
It’s not a good idea to repeatedly open and close your master bag as the packets inside then repeatedly come into contact with the outside oxygen.
If you are planning to purchase a large quantity of oxygen absorbers but will only use a few at a time, experts recommend buying several smaller bags of packets rather than one large bag of packets.
Is It Safe to Use Oxygen Absorbers with Vacuum Packages?
Defining our terms, vacuum packaging is a type of packaging that removes air from the package before it is sealed.
The amount of air will obviously already be lower in a vacuum package, meaning that you would have to choose a smaller absorber.
In the scenario where there is a strong vacuum ratio, you would need to put the oxygen absorber packet with distance between the food and the packaging material.
Therefore, it is safe to use an oxygen absorber in a vacuum package since a vacuum package cannot eliminate all of the inside oxygen like the absorber packet can.
What is the Shelf Life of Unused Oxygen Absorbers
A pack of unused oxygen absorbers will have a shelf life of between 6 months and 1 year. Once opened you’ll have about 15 minutes to get it where it needs to go before it’s too late and it’ll be ineffective.
Should You Eat Oxygen Absorbers?
Oxygen absorbers should only be used to help preserve bulk foods for long term food storage. You should not ingest them at any age, however small children and pets are susceptible to acute liver toxicity. Consult a poison control center for more information on dealing with that scenario.
Can You Reuse Oxygen Absorbers?
No, unfortunately once an oxygen absorber is spent you cannot use it another time. This is because the chemical reaction is a one time thing as the iron shavings inside will have completely oxidized and turned to rust. These are not the same as moisture absorbers like silica gel which can be “reused” if dried out.
How Can You Tell If Your Oxygen Absorbers Are Still Good?
Oxygen absorbers will take on a hard, rock-like feel when they are fully spent. This means no matter how much you press it won’t budge. If you squeeze your oxygen packet and it’s soft and powdery, then the iron filings are intact and haven’t been oxidized yet.
What are the best containers to use with oxygen absorbers?
Any porous containers will not be suitable for use with oxygen absorbers. This includes many regular plastic bags, jars with non-sealing lids, plastic bottles, and bags with holes in them. Here is a list of great containers to use oxygen absorbers in:
- Mason jars with new lids
- Vacuum-Sealed Bags
- Mylar Bags
- Food-grade sealed buckets
The idea behind this is if you can see light through the container then an oxygen absorber won’t work as there will be a steady influx of fresh air into the bag, even if it’s a pinhole shape.
Start Using Them Today
Food storage needs to be one of your top priorities to prepare for a long term disaster. But improper storage can make good food deadly.
Oxygen absorbers are a fantastic way to keep your stored food edible and safe for very long periods of time. With careful adherence to safety procedures, you’ll be able to keep yourself and your family fed and strong for when disaster hits.
Nick Oetken is a prepper, outdoor enthusiast but, most of all, he is our in-house firearms expert. Look out for his articles on guns to find out which ones you need for your survival.
nick, not sure i understand about putting oxygen absorbers inside a bucket with food that has been
sealed with a seal a meal. can i put the food that was sealed in seal a meal into a myler bag then add a
oxygen aborber ? after that i was going to put the mylar bag into a 5 gallon bucket and then add another
oxygen absorber then seal the bucket.
please advise if i can do this.
thankyou
ron
What about using solar ovens? To me they definitely seem to be one of the different types of cooking equipment that would be desirable to have. The All-American Sun oven seems to be highly rated. It does not seem to be as portable as the Sunflair which is quite light weight. Both have dehydrating shelves. I have just purchased one of each and have not used them yet. They eliminate the need for fuel and can serve the purpose most of the time. Having a propane or other stove when there is not much sunlight could be the backup.
“Live organisms of any kind cannot live in oxygen free environment, including microorganisms.” There are many organisms that exist without oxygen…called anaerobic organisms; for instance: Trichinella Spiralis a larva that causes trichinosis.
Your oxygen volume calculations assume there is no food in the can. Things like beans, peas, kernals, and seeds typically have 37% pore space, so your calculated volume multiplied by .37 should give a reduced volume that needs much less O2 absorbers. Very dense food would have even less pore space.
Well stated Walter. Another one is clostridium botulinum, the organism responsible for botulisim. DO NOT just use oxygen absorbers with just any foods, for you may create the perfect conditions for dangerous anaerobic bacteria to reproduce. The author has made reference to this, but you need more information in order to make use of this information safely. Also, it isn’t the amount of water in the food that is important, but the amount of *available* water, that is water not bound to other molecules. Dried fruits are a good example. They are moist and flexible, but much of that water is bound to the abundant sugar molecules and is therefore not available for use by microorganisms. Googling is your friend here.
I put an 02 absorber AND a moisture absorber in my jars of grain, beans and lintels. I started eleven years ago and those still test as good. If any mealy bugs did hatch, they are pure protein, so yum-yum.