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 an absorber and oxygen barrier packaging like Mylar bags is hands down the best and most modern method of preserving food for longer shelf life.
I did a lot of research trying to decide how to package food. Here are some things I learned. I hope it helps you plan your emergency food stores.
It is necessary to package dry staple foods like white rice with oxygen absorbers to protect food from oxidation which breaks down the quality, color, and nutritional value of food. A lack of oxygen also hinders bacterial growth and kills all bug life within two weeks.
Benefits In Food Storage
Inhibit the formation of aerobic pathogens, spoilage organisms, and mold. Delays non-enzymatic discoloration, prevents oxidation of water and fat-soluble vitamins, minimizes the need for additives and preservatives, [kills bugs, eggs, and pupae when used in a container that provides oxygen barrier.]Simon Cichello, Nutritionist, Wholesale Group International Pty Ltd
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, such as Mylar bags, to remove oxygen.
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
How They Work?
Oxygen molecules interact with iron particles, and they begin to rust. Sodium is added to the pack to act as a catalyst so iron will rust in the low humidity environment inside a sealed food container. The rusting iron and oxygen molecules turn into a single iron oxide substance reducing oxygen.
Can You Use Oxygen Absorbers In?
Use oxygen absorbers to store bleached white flour for a 5 to 10-year shelf-life.
Do not use O2 Absorbers for Whole Wheat Flour. Due to the fat content from the husk, whole wheat flour will only last 8 to 12 months regardless of how it is stored.
It’s best for emergency and survival purposes to store hard white or red wheat berries with the husk removed. They will store for 30+ years in an oxygen-free container such as a trifecta of Food-grade bucket and lid, lined with a Mylar bag and an oxygen absorber.
Mason or Glass Jars
Use O2 absorbers in Mason jars, they provide and excellent oxygen barrier.
The only downside to ball jars is they allow light to touch the food. Light oxidizes food breaking down nutrition over time. So if you are going for a 30 years shelf life, it is better to use a container such as Mylar that protects food from light.
Do not use absorbers in plastic containers without using Mylar. Plastic is not an effective oxygen barrier.
Plastic containers, which go for food-grade buckets and PET bottles, will allow oxygen into a container even if sealed with a lid.
Plastic slows oxygen transfer but is unfit for foods that have decades of shelf-life. Food-grade buckets are often lined with a Mylar bag which provides a true oxygen barrier.
Avoid using Oxygen absorbers with white granulated sugar. It will turn into a concrete brick. Also, don’t store brown sugar this way because it has too much moisture for O2-free storage.
For sugar storage you don’t need an Oxygen-barrier store it in a 5-gallon bucket without a Mylar bag.
White rice is one of the best candidates for absorber use. Stored and packaged in store-bought packaging, white rice will last 5 years if it isn’t infested with bugs. In an O2 free container, it will last 30 years.
Do not use O2 absorbers with brown rice because the lipid or fat content is too high. It will go rancid within 8 months regardless of how it is stored.
There are two reasons not to store beef jerky with O2 absorbers, 1. the moisture content is too high (above 10%), and the fat content is too high. So there is a chance of botulism or rancidity without the benefit of a long shelf-life.
Side Note: When you purchase beef jerky at the store the little packet inside is a desiccant to remove moisture, not an O2 absorber.
Can They Be Reused?
Oxygen Absorbers can not be reused. Once exposed to oxygen, the iron dust in the package will begin to rust. When it’s reached capacity, the packet will turn hard and will no longer remove oxygen.
What Can Be Dangerous About Using Them With Food?
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 higher than 10% moisture may lead to botulism, a rare but deadly bacteria that can’t be seen, smelled, or tasted.
What Kind Of Food Do You Use Them With?
Absorbers are used with dry goods or dry staple foods like white rice and wheat, typically foods that are less than 10% moisture content and low in fat.
9 Foods Typically Stored With Oxygen Absorbers
- White Rice
- Dried Hard Grains
- Dried Soft Grains
- Dried Dent Corn or Field Corn
- Low-fat Powdered Milk
- Dried Pasta and Macaroni
- Rolled Oats
- Steel Cut Oats
- Dried Beans and Legumes
- Freeze-dried foods (Not the same as dehydrated food, which is higher in moisture content)
Are There Foods I Shouldn’t Store With Oxygen Absorbers?
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.
List of Foods You Should Not Store
- Any Foods with 10% or more moisture content
- Foods high in fats
- Nuts and foods with nuts such as granola
- Dehydrated food(s) processed at home (food should snap, not bend)
How Long Does It Take For Them To Work?
When the chemical reaction starts (absorber is exposed to oxygen), the absorber will get warm to the touch and expend its capacity to remove oxygen within 4 hours.
Picking the proper size of oxygen absorber for your 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.
Sizing Oxygen Absorbers For Food Storage
Oxygen Absorbers are sized by their capacity to remove oxygen from a hermetically sealed container in ccs or cubic centimeters. Each container and food type needs a specific amount or cc capacity for oxygen absorption. I tend to use absorbers that are too big for the package to be safe because you can’t use too many oxygen absorbers.
Chart 1: Oxygen Absorber Size For Mylar Bag Size and Food Type
|Mylar Bag Sizes||Wheat/Flour/Grains/Rice|
More Compact/’Less Air
Less Compact/More Air
|20″x30″ (4.25,5,6-gal bucket(s)||2000cc||2500cc to 3000cc|
|18″x28″ (4.25,5,6-gal bucket(s)||2000cc||2500cc to 3000cc|
|14″x20″ (2 gal)||1000cc||1500cc to 2000cc|
|14″x18″x6″ (2 gal)||1000cc||1500cc to 2000cc|
|12″x18″ (1.5 gal)||800cc||1200cc|
|12″x16″x6″ (1.5 gal)||800cc||1200cc|
|10″x14″ (1 gal)||400cc||400cc|
|8″x12″ (1/2 gal)||200cc||400cc|
|6″x10″ (1/4 gal)||100cc||200cc|
|6″x8″ (1/4 gal)||100cc||200cc|
*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.
Chart 2 Mason Jar Size: Oxygen Absorber(s) Required
|Glass/Mason Jar Size||Wheat/Flour/Grains/Rice|
More Compact/’Less Air
Less Compact/More Air
|1 Gallon |
How To Store Leftovers After Opening
Once absorbers are exposed to air, the clock starts ticking, so it’s a good idea to have all of your containers filled with dry goods and ready to seal before you open your package of O2 absorbers. Doing this will keep them fresh longer.
Store leftover oxygen absorbers in a mason jar with the lid tightly in place or seal them in a small Mylar bag. Left open, they will activate and continue to take oxygen from the ambient air until they are expended. 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.
Can Oxygen Absorbers Be Refrigerated Or Frozen
Oxygen absorbers should not be refrigerated or frozen because they will not work properly. Instead, package foods in a Mylar bag, seal them with the proper oxygen absorption and put them in the freezer the next day once the absorber is spent.
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.
Can Oxygen Absorbers Kill Bugs?
You may not know that almost all foods have allowable amounts of gross stuff in them. Dry foods stored for long-term storage are no exception. Most Hard and soft grains, including wheat berries, white rice, and rolled oats, have bug eggs when you get them. This is why we repackage foods for long-term storage. So we can remove the oxygen not only to preserve food but to kill bugs.
Oxygen absorbers can’t kill bugs. In the Oxygen-free environment they create when sealed in a high barrier container like Mylar bags, bugs at all stages of life, including eggs, pupae, and adults, are dead within two weeks. Oxygen-free storage also kills the dreaded weevil, the bain of hard and soft grain storage.
Should They Be Hard
Oxygen absorbers turn hard when they have reached their capacity for removing oxygen. Once hard, they are no longer useful for oxygen-free food storage.
Do They Get Hot?
Oxygen absorbers get hot when the chemical reaction between Ferrous iron oxide powder and Oxygen in the air starts. You know the 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 choose.
*Study Of The Use Of Oxygen-Absorbing Packaging Material To Prolong Shelf-Life Of Rations, Elena Castell and H.-J. Sue, Texas Engineering Experimental Station, Defense Logistics Agency, College Station Texas Link
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