Problems of food protection by polymer packages

Following a book [Vergnaud, J. M.; Rosca, I. D. Assessing Food Safety of Polymer Packagings; Smithers Rapra Ltd.: Shawbury, Shropshire, UK, 2006] written on this subject, problems arising in food protection by polymer packages are examined in this survey, from both a theoretical and a practical point of view. The process of release of the polymer additives into the packaged food is established: the transfer is controlled either by transient diffusion through the thickness of the package or by convection at the package-food interface and through the food as well. As recycling of old polymer packages in new polymer packages is now common, the time of protection of the food is evaluated when the new package consists of two layers, the virgin polymer layer being in contact with the food. Active packages able to deliver an antimicrobial agent in the food are also briefly examined. Finally, an attempt is made to define the operational conditions of a standardised test as well as the best way to calculate the diffusivity and convection coefficient.