Oxygen Absorbers: Their Function and Use
June 7, 2013
Oxygen absorbers are little packets of iron powder packaged in a material that keeps the iron in, but allows oxygen and moisture to enter and be absorbed. The iron absorbs the oxygen causing the iron to rust. As it rusts, or oxidizes, it absorbs any oxygen that may be present.
Why do I need Oxygen Absorbers?
Oxygen and moisture are two factors that destroy the value of dehydrated and freeze-dried foods. Theses elements have a detrimental effect on color, flavor, vitamin content, and fats of stored foods. Oxygen will enhance the growth of insects, bacteria, mold, and yeast in your food, accelerating spoilage.
Oxygen absorbers help to remove the oxygen in your container, leaving nitrogen. Dry foods are protected against spoilage and bacteria growth in a nitrogen environment. A “nitrogen flush” is often used to force the oxygen out of a product before it is sealed for storage. But even when a nitrogen flush has been done, it's still wise to include an oxygen absorber inside the container to help eliminate any remaining moisture.
During the freeze-drying or dehydrating process, much of the moisture causing molding or spoilage is eliminated. An oxygen absorber will help to mitigate any moisture that remains once the food is packaged. Foods with a high moisture or oil content should not be stored in reduced oxygen packaging because it can cause botulism poisoning. Only store foods with in low moisture (10% or less) with oxygen absorbers.
Oxygen absorbers actually remove oxygen more effectively than vacuum packaging because they only remove the oxygen rather than all the air.
What Type of Containers do I Need?
[Metallized cans] with seamed lids, [metallized bags], PETE plastic bottles with airtight, screw-on lids, and glass canning jars with metal lids and gaskets all do well with oxygen absorbers. Do not use plastic containers that are not identified as PETE or PET under the recycling triangle on the bottom of the container. Metallized cans and bags prevent light, another source of spoilage, from reaching your food with the added help of your oxygen absorbers.
Oxygen absorber packets come in different sizes, two of the most common are 500cc and 2000cc. To decide which size is right for you, consider the size of the container you'll store your food in and the amount of empty space between the food particles and between the top of the food and the lid of the container.
Some companies that manufacture absorber packets rate them according to their oxygen absorption capacity in milliliters, while others do so by the equivalent air volume (the actual total amount of air between the product pieces).
How do I Preserve the Life of my Absorbers?
Store unused absorbers in small glass jars that have a lid and ring seal. A one-pint jar will hold 25 absorbers. You can also heat-seal them back into the bag they came in. Or you can store them in plastic freezer bags, but you must use them within the next few months because the plastic will slowly admit oxygen and shorten the lifespan of your absorbers.
When using a combo like the Do-it-Yourself Superpail Kit, do not plan to package more food than you can in 20 minutes. Prolonged exposure to air in the room will speed up the demise of your absorbers.
Instead, place the number of absorbers you expect to need for one batch of packaging on a tray . Use one absorber per package of food, and work as quickly as possible to preserve the life of the absorbers. When you are ready to do another batch, remove enough absorbers from their bag or jar for that batch.
You'll know the lifespan of your oxygen absorber by its color. Some absorber packages turn pink when they're working properly and are still absorbing the oxygen in your can. Some turn purple or blue when they're used up.