Plastic bottles are widely used for soft drinks as an alternative to glass; however, their use for beer requires anoxygen-barrier layer. High-performance resins and barrier layers can prevent oxygen from entering PET containers and retain carbon dioxide. There are an estimated 17 different barrier formulations, some of which are discussed in this article. SurShield from Owens-Illinois uses SurShot multilayer injection technology to supply the exact amount of barrier material for each wall. Constar's product, Oxbar, provides up to 110 days of shelf life for beer, and more than a year for citrus juices. Other companies manufacturing barrier containers include Amcor PET Packaging and Evalca. Voridian, a division of Eastman Chemical, has a Web page (the Oxygen Limited Shelf Life Calculator) that enables customers to model shelf life for new PET containers. Information is given on two tests for assessing barrier effectiveness.
