Recently I have received some questions from some beginning preppers on what is an oxygen absorber and how you use it.
They are variations of a small bag filled with iron powder and a salt mixture. When they are exposed to air, they immediately start to rust. Rust is a form of oxidation and consumes oxygen. The oxidation will remove the oxygen from sealed container. The oxygen absorbers come in a Mylar bag or special plastic that does not breathe, and have to be protected from exposure to air.
Oxygen absorbers are completely safe, and are non-toxic. They do not create any harmful gases and do not affect the smell and taste of the food. A good oxygen absorber will reduce the oxygen level down reliably to .01% or less. This greatly extends the shelf life of the products and helps to preserve good nutrition. They should only be used in dry foods, like grains, pasta and legumes. Oxygen absorbers are not needed in sugar or salt.
They are a real reliable and inexpensive product when used correctly. I purchase the 300 CC ones for about a dime apiece. A 300 CC absorber is adequate for a number 10 can. I use 5 to 6 of them in a Mylar bag in a five-gallon bucket.
When you first get the absorbers, they will come in a special bag designed to preserve them. While it may look like regular plastic, it is not. Do not store them in plastic bags. After I open the absorbers, I store them, either in sealed Mylar bags or pint mason jars. But I prefer the bags. If you have a question about the condition of the absorbers, it is possible to test them at home. See my blog post Testing Oxygen Absorbers.
I see people trying to make their own absorbers or using hand warmers. This makes no sense to me. Absorbers are inexpensive and reliable; I am not going to risk my food with some homemade or improvised device in an attempt to save a few pennies.