Food Packaging Materials for Irradiation
Irradiation of packaging materials-in most cases, plastic-generally leads to the formation of free radicals and ions, which eventually result either in cross-linking or in chain scission. The latter leads to the release of volatile radiolysis products that may induce off-odors in the polymers, thereby altering the migration characteristics of packaging materials. Irradiation also affects polymer additives, which change the specific migration behavior of polymer additives and additive-related decomposition products. Both migration and sensory changes of presterilized packaging materials strongly affect the quality of packaged goods and consumer safety. Radiation processing is widely used for medical product sterilization and food irradiation. Moreover, the use of irradiation has become a standard treatment to sterilize packages in aseptic processing of foods and pharmaceuticals. Nowadays, packaging consists of natural or synthetic plastics; therefore, the effect of irradiation on these materials is crucial for packaging engineering. The effect of ionizing radiation on polymeric materials has been found to manifest itself in two ways: (i) as a molecular weight increase (cross-linking); and (ii) as a molecular weight decrease (chain scission degradation). The ability of radiation to process the packaged material, compared to the ineffectiveness of chemical treatments, is a critical advantage over the others. The most important applications of polymer irradiation are: (i) sterilization of medical disposables, syringes, and tubing; and (ii) food and food packaging irradiation. © 2010 Elsevier Inc. All rights reserved.