Substance able to chemically absorb oxygen in the surrounding air
An oxygen absorberThe contents of an oxygen absorber from a packet ofbeef jerky
Oxygen scavengers oroxygen absorbers are added to enclosedpackaging to help remove or decrease the level ofoxygen in the package. They are used to help maintain product safety and extendshelf life.[1]There are many types of oxygen absorbers available to cover a wide array of applications.[2][3]
The components of an oxygen absorber vary according to intended use, the water activity of the product being preserved, and other factors. Often the oxygen absorber or scavenger is enclosed in a poroussachet or packet but it can also be part of packaging films and structures.[4] Others are part of a polymer structure.[5]
Oxygen absorbing chemicals are also commonly added toboiler feedwater used in boiler systems, to reduce corrosion of components within the system.[6]
The first patent for an oxygen scavenger used an alkaline solution ofpyrogallic acid in an air-tight vessel.[7][8]
Modern scavengersachets use a mixture of iron powder andsodium chloride.[8] Oftenactivated carbon is also included as itadsorbs some other gases and many organic molecules, further preserving products and removing odors.
When an oxygen absorber is removed from its protective packaging, the moisture in the surrounding atmosphere begins to permeate into the iron particles inside of the absorbersachet. Moisture activates the iron, and it oxidizes to formiron oxide. Typically, there is required to be at least 65% relative humidity in the surrounding atmosphere before the rusting process can begin. To assist in the process of oxidation, sodium chloride is added to the mixture, acting as a catalyst or activator, causing the iron powder to be able to oxidize even with relatively low humidity. As oxygen is consumed to form iron oxide the level of oxygen in the surrounding atmosphere is reduced. Absorber technology of this type may reduce the oxygen level in the surrounding atmosphere to below 0.01%.[2][3] Complete oxidation of 1 g of iron can remove 300 cm3 of oxygen in standard conditions. Though other technologies can remove more, iron is the most useful as it does not cause odor like sulfur compounds orpassivate like aluminium compounds. Many other alternatives are not food safe.[8] The moisture requirement of iron-based scavengers makes them ineffective in moisture sensitive applications.
The performance of oxygen scavengers is affected by ambient temperature and relative humidity.[9]Newer packaging technologies may use oxygen scavenging polymers to prevent accidental ingestion of oxygen scavengers.[8]
Typical reasons to use a non-ferrous variant would include the packaging of products intended for international shipping where metal detection would pose a problem; a desire to reduce the odor associated with ferrous carbonate; or dietary products where contact with iron should be avoided.[11]
Potassium metabisulfite is often used in the wine industry to both scavenge oxygen and provide a layer of gas that separates wine from oxygen.[citation needed]
^Miltz, J.; Perry, M. (2005). "Evaluation of the performance of iron-based oxygen scavengers, with comments on their optimal applications".Packaging Technology and Science.18:21–27.doi:10.1002/pts.671.S2CID97578421.
^abTewari, G.; Jayas, D. S.; Jeremiah, L. E.; Holley, R. A. (2002). "Absorption kinetics of oxygen scavengers".International Journal of Food Science and Technology.37 (2):209–217.doi:10.1046/j.1365-2621.2002.00558.x.
^US 5660761, Katsumoto, Kiyoshi, "Oxygen scavenging layer consisting of oxidizable compound, second, separate layer consisting of oxidation catalyst", published 26 Aug 1997
^US 96871, Virgil W. Blanchard, "Improvement in preserving fruits, meats and other substances."
^abcdYam, K. L., ed. (2009).Encyclopedia of Packaging Technology. John Wiley & Sons. pp. 842–850.ISBN9780470087046.
^Braga, L. R.; Sarantópoulos, C. I. G. L.; Peres, L.; Braga, J. W. B. (2010). "Evaluation of absorption kinetics of oxygen scavenger sachets using response surface methodology".Packaging Technology and Science.23 (6):351–361.doi:10.1002/pts.905.S2CID96850090.
^Kerry, Joseph; Butler, Paul (May 23, 2008).Smart Packaging Technologies for Fast Moving Consumer Goods. Wiley & Sons. p. 1.
^Brody, Aaron L.; Strupinsky, E. P.; Kline, Lauri R. (June 8, 2001).Active Packaging for Food Applications. CRC Press. p. 20.
^Dave, Rajiv I.; Shah, Nagendra P (1996-10-19). "Effectiveness of ascorbic acid as an oxygen scavenger in improving viability of probiotic bacteria in yoghurts made with commercial starter cultures".International Dairy Journal.7 (6–7):435–443.doi:10.1016/S0958-6946(97)00026-5.
