Home » Oxygen Absorbers: Why You Need Them For Emergency Food Storage

Oxygen Absorbers: Why You Need Them For Emergency Food Storage

Oxygen absorbers are a big part of the long-term storage of dry foods like white rice, wheat berries, dried beans, and other grains. Combining oxygen absorbers and packaging that provides an oxygen barrier, like Mylar bags, is hands down the best and most modern method of preserving food for a massive shelf-life. I practice what I preach I have hundreds of pounds of dry staples stored using oxygen absorbers, Mylar bags, and food-grade buckets.

You need oxygen absorbers to package dry foods like white rice to protect food from oxidation which spoils food quicker by breaking down food’s quality, color, and nutritional value. Also, removing oxygen with oxygen absorbers hinders bacterial growth and kills all bug life within two weeks.

Up next, what is an oxygen absorber?

2000 cc oxygen absorbers
2000 cc Oxygen Absorbers for 5-gallon buckets of dry foods

What Is An Oxygen Absorber?

An oxygen absorber is a sealed sachel or packet filled with Ferrous iron oxide. Absorbers are sealed inside containers that provide an oxygen barrier to remove oxygen, such as Mylar bags.

The oxygen-free environment also kills bugs, eggs, and pupae within 2 weeks, so freezing dry foods before repackaging isn’t necessary.

Oxygen absorbers reduce the amount of oxygen in a package to less than 0.01 percent, as compared to traditional preservation methods such as gas flushing and vacuum packing, which reduce headspace oxygen to only about 0.50 percent.

*Sources, Study Of The Use Of Oxygen-Absorbing Packaging Material To Prolong Shelf-Life Of Rations

Next, let’s examine how oxygen absorbers work.

How Do Oxygen Absorbers Work?

Oxygen absorbers work by chemical reaction. An oxygen absorber contains iron powder and sodium that interacts with oxygen in a sealed food package. The rusting iron and oxygen molecules turn into a single iron oxide substance trapping the oxygen in the packet.

The reason oxygen absorbers are available in various sizes is that more iron powder is needed to eat up the oxygen in a larger container.

Can Oxygen Absorbers Be Reused?

Oxygen Absorbers can not be reused. Once exposed to oxygen, the iron dust in the package will begin to rust. When it reaches capacity, the packet will turn hard and no longer remove oxygen.


Absorbers won’t kill you; everything about them is food-grade. The one dangerous thing is using them in foods that have more than 10% moisture content. This is why they are only used with dry foods. Storing wet foods with more than 10% moisture may lead to botulism, a rare but deadly bacteria that cannot be seen, smelled, or tasted.

Type of Food to Store with Oxygen Absorbers

Absorbers are used with dry goods or dry staple foods like white rice and wheat, typically foods with less than 10% moisture content and low in fat.

Top 10 Foods Stored with Oxygen Absorbers

  1. White Rice
  2. Dried Hard Grains
  3. Dried Soft Grains
  4. Dried Dent Corn or Field Corn
  5. Low-fat Powdered Milk
  6. Dried Pasta and Macaroni
  7. Rolled Oats
  8. Steel Cut Oats
  9. Dried Beans and Legumes
  10. Freeze-dried foods (Not the same as dehydrated food, which is higher in moisture content)

Don’t Use Oxygen Absorbers With This Food

High moisture and high-fat foods should not be stored with absorbers (oxygen-free storage). They create the perfect environment for anaerobic bacteria like botulism to form, so you should not use them with these types of food.

Foods Not To Store With Absorbers

  1. Any Foods with 10% or more moisture content
  2. Foods high in fats
  3. Nuts and foods with nuts such as granola
  4. Dehydrated food(s) processed at home (food should snap, not bend)

Up next, how long does it take for oxygen absorbers to work?

How Long Does It Take For Them To Work?

When the chemical reaction starts (the absorber is exposed to oxygen), the absorber will get warm to the touch and expend the capacity to remove oxygen within 4 hours.

Picking the proper size of the oxygen absorber for the size of the container, headspace, and the density of the food is important because once an absorber is expended, it will no longer remove O2.

Up next, why do oxygen absorbers come in different sizes?

Why Oxygen Absorbers Come in Different Sizes

An oxygen absorber is sized by its capacity to remove oxygen indicated in ccs or cubic centimeters. Said another way, you need a specific size of oxygen absorber or oxygen absorbers (ccs of oxygen absorption) to remove all of the oxygen determined by container size and food type.

Oxygen Absorber(s) for Container and Food Type

For the container size, the oxygen absorber required is based on the volume of the container when filled, and for food type, it is based on how compact the food is. For instance, beans have more airspace between each bean and are less compact than white rice so beans need more ccs of oxygen absorption than rice.

Up next, the easiest way to figure out oxygen absorber requirements is to look at a chart. Let’s take a look.

Chart #1: Oxygen Absorber Chart: Mylar Bags

Following is an oxygen absorber chart for each size of Mylar bag. The chart indicates how much oxygen absorption to use based on the dimensions of the Mylar bag and the type of dry food stored. Let’s examine the chart.

Mylar Bag SizesWheat/Flour/Grains/Rice
More Compact/’Less Air
Pasta Beans
Less Compact/More Air
20″x30″ (4.25,5,6-gal bucket(s) 2000cc2500cc to 3000cc
18″x28″ (4.25,5,6-gal bucket(s)2000cc2500cc to 3000cc
14″x20″ (2 gal)1000cc1500cc to 2000cc
14″x18″x6″ (2 gal)1000cc1500cc to 2000cc
12″x18″ (1.5 gal)800cc1200cc
12″x16″x6″ (1.5 gal) 800cc1200cc
10″x14″ (1 gal)400cc400cc
8″x12″ (1/2 gal)200cc400cc
6″x10″ (1/4 gal)100cc200cc
6″x8″ (1/4 gal)100cc200cc
Information Compliments of USA Emergency Supply.
*Note, these are average amounts at sea level. You may need more or less depending on your individual conditions and the remaining residual volume of air. There is no danger in adding too many as this does not affect the food.
Oxygen represents 20% of the total volume of air, and the number in cc’s above represents the amount of oxygen that would be absorbed. Conversions: 1cc = 1ml. 1000ml = 1 Liter. 3.78 Liters = 1 gallon.

Next, let’s examine the oxygen absorber chart for Mason jars and common food storage containers.

Chart #2 Oxygen Absorber Chart: Mason Jars & Containers

Chart #2 is an oxygen absorber chart for what oxygen absorber to use or how much oxygen absorption to use in cubic centimeters by container size. Let’s take a look at the chart.

Glass/Mason Jar SizeWheat/Flour/Grains/Rice
More Compact/’Less Air
Pasta Beans
Less Compact/More Air
1 Gallon
4 Quarts
8 Pints
16 Cups
128 oz.
1 Quart
2 pints
4 cups
32 oz.
64 Tbs
50cc50 cc
1 Pint
2 cups
16 oz.
32 Tbs
1/2 Pint
8 oz.
1/4 Pint
4 oz.
The smallest Oxygen-absorbers I tend to have on hand is the 100cc. For smaller packages like a pint, I would use these. You can’t use too many oxygen absorbers, only too few ccs.

How to Store Oxygen Absorbers

Store leftover oxygen absorbers in a mason jar with the lid tightly in place or seal them in a small Mylar bag. Left in open air an oxygen absorber will activate and continue to take oxygen from the ambient air until it is used up. You’ll know they are working because they get warm. Once they turn hard, it’s too late the absorber is no longer useful for oxygen removal.

Are they Safe for Food Contact?

Oxygen absorber packets filled with Ferrous iron oxide are 100% food safe and you can’t use too much oxygen absorption, only too little.

Next up, can oxygen absorbers be used in the freezer or refrigerator?

Can Oxygen Absorbers Be Refrigerated Or Frozen

Oxygen absorbers should not be refrigerated or frozen before they are done removing oxygen because they will not work properly.

Side Note: Most foods stored in the freezer or refrigerator have high moisture, high oil content, or both, so the foods are not appropriately stored using absorbers.

Do Oxygen Absorbers Kill Bugs?

Oxygen absorbers don’t kill bugs but an oxygen-free environment does. If foods are packaged properly, oxygen does kill bugs, but indirectly, by creating an oxygen-free environment inside the food storage container.

By using the treatment of oxygen absorbers inside the proper food container (Mylar bag) bugs at all stages of life, including eggs, pupae, and adults, are dead within two weeks.

Up next, should absorbers be hard?

Should Oxygen Absorbers Be Hard?

A hard oxygen absorber is ready for the trash because it no longer has the capacity to remove oxygen from a food container. If you have some hard oxygen absorbers it is probably because you didn’t store the in an airtight container like a ball jar or the package they came in is torn or damaged.

Next, let’s examine if oxygen absorbers get hot.

Do Oxygen Absorbers Get Hot?

An Oxygen absorber gets hot because of a chemical reaction between ferrous-iron-oxide powder and Oxygen in the air. This is the same chemical reaction you get when you use hand warmers. You know an oxygen absorber is doing its job of scavenging oxygen when it gets warm. If you are packaging foods properly, you won’t experience the warmth because the absorber will already be sealed in the container you package the food in.

Thanks for visiting Ready Squirrel. If you have any questions please leave them in the comments.

Keep on prepping!

Best Regards, Scott

Leave a Comment