A closure that is able to prevent oxygen from entering the container upon which the closure is attached. Preferably, the closure is comprised of one piece wholly molded of plastic, oxygen scavenging or anti-oxidant compounds, and catalysts homogenously mixed therein. More preferably, the closure is a composition of polypropylene or high-density polyethylene with an oxygen scavenger and catalyst intergrated within the polypropylene or high-density polyethylene.