An oxygen scavenging system comprising a free radical scavenger (e.g., .alpha.-tocopherol, trimethylhydroquinone, ubiquinol, carotenoids, flavonoids, etc. and mixtures thereof) and a transition metal (e.g., iron (II), copper, manganese, cobalt, etc. and mixtures thereof) in a medium is generally provided. The medium containing the antioxidant and the transition metal has been thermally processed by heating to at least about 150.degree. F. for at least about 10 minutes. Methods of removing oxygen from an environment surrounded by a medium containing the oxygen scavenging system and methods of making the oxygen scavenging system in a medium are also provided
