Evaluation and modeling of scavenging performances of active multilayer PET based films for food preservation

This work deals with the design, production and evaluation of the effectiveness of multilayer active systems based on PET, suitable for food packaging applications. Symmetrical 3-layer structures were produced by using a cast co-extruder laboratory-scale equipment. The oxygen scavenger (OS), copolyester based and approved for direct food contact, was added to the central layer. Two multilayer active films were obtained by keeping constant the thickness of the active layer and with different thicknesses of the inert layers. Active single layer and neat films were also produced for comparison. Oxygen absorption measurements in continuous were performed by means of a luminescence lifetime detection device. The scavenging performances, in terms of scavenging activity, exhaustion time and residual oxygen concentration in the package were investigated; in particular, their variation as function of the thickness variation of the inert layers was analysed. Preliminary shelf life tests were also conduced on Brassica oleracea florets, in order to point out the effectiveness of the OS systems in inhibiting vegetables senescence. Finally, a mathematical model, developed during previous studies, was applied to the data set in order to validate it and verify its effectiveness in predicting the transport phenomena occurring in the multilayer active systems.