Comparing The Performance Of Barrier Coated Vs Multilayer Pet Containers For Oxygen Sensitive Products

Trials of different types of PET beer bottles were carried out by Crown Cork & Seal. Bottles covered with PPG "Bairocade", a patented epoxy/amine barrier coating, which on the basis of the generally accepted models of gas permeation were expected to give beer only a short shelf life (as it was predicted that sufficient oxygen would enter the bottle to cause serious deterioration within a few weeks) were actually found to achieve a degree of flavour stability similar to that of beer in glass bottles, the quality of beer stored for 9 months in coated PET being no worse than beer from the same batch stored in glass for the same period under the same conditions, while the oxygen content of beer stored in coated PET was likewise much lower than predicted. Multilayer bottles, combining two layers of PET with one layer of Crown Cork and Seal's patented "Oxbar" oxygen scavenging material, proved to give even better production against oxidative deterioration, but when "Oxbar" was used alone, the shelf life of the beer was limited by loss of carbonation (dissolved carbon dioxide content decreased by 10% in 4 months), although this could be rectified by adding a barrier coating as well. The "Bairocade" coating is claimed to be over 99% removable by a suitable washing/separation process before recycling, but procedures for the removal of barrier layers from between layers of PET are stated to be still under development.