An oxygen absorber is a specially formulated and packaged chemical that removes all or a significant percentage of oxygen in an appropriately sized and sealed space. These packages are used primarily as a preservative measure to prevent the development of mold, insect infestation, and all other oxygen-related degradation in sealed foodstuffs. They may also prevent oxidation on non-food-related items stored for protracted periods. The active agent in oxygen absorber packs is typically a iron oxide powder packaged in a material which retains the powder but allows air and moisture to penetrate. Oxygen absorbers are available in a range of sizes suitable for differing storage container capacities.
Long-term storage of foodstuffs can be problematic due to the negative effect protracted exposure to oxygen can have. Food develops mold, become rancid, and is infested by insects when exposed to oxygen-rich air. In addition, metallic non-food items rust when stored for long periods. These issues can, to a large degree, be prevented if the goods are stored in vacuum sealed packaging. This is not always practical or even possible, and other solutions have to be found to preserve goods in long-term storage and to prolong the shelf life of retail products.
Oxygen absorber packs are generally a simple and cost effective way of removing almost all the oxygen from goods contained in sealed packaging. These packs consist of a fine iron oxide based powder in a bag or package which prevents the powder from spilling out but allows moisture and air to penetrate. When the powder is exposed to moisture in the air, an oxidization process begins which causes it to absorb up to 99% of the oxygen in a suitably sized container. The emphasis here is on suitably sized because each oxygen absorber size is rated for a maximum storage container capacity.
Generally the oxygen absorber is formulated in such a way that it changes color, typically from bright pink to dark blue, when exposed to oxygen. This gives a good visual indication that the absorber is working correctly. Oxygen absorber packs may be used to remove oxygen from whole fat dry foods, processed and cured meats, dried fruit, nuts, spices, flour, and grains and pasta products. They are also often used to prevent oxygen degradation of pharmaceutical products and medical diagnostic kits. The absorbers are available in a range of sizes which are rated to function correctly with storage containers of different capacities.