Effect of high pressure treatments on the properties of EVOH-based food packaging materials

The effects of different high pressure processing (HPP) treatments on EVOH-based packaging materials were studied and they were compared with the morphological effects produced by a more traditional food preservation technology, i.e. sterilization. The samples were high pressure processed at 400 and 800 MPa, during 5 and 10 min at two different temperatures, 40 and 75 °C. Sterilization was carried out in an autoclave at 120 °C during 20 min. Oxygen barrier and morphological properties of the treated packaging structures were analyzed and compared with those of the untreated samples. The results proved that HPP scarcely affects packaging materials, especially when compared with the detrimental consequences of retorting. Although commercial food products are being high pressure processed packaged in flexible packaging materials relatively little information is available regarding the impact on high pressure. This paper addresses critical issues such as pressure effects on permeability and morphology of EVOH-based packaging structures which are essential to be able to assure food safety during pressure treatment and storage. A slight increase in crystalline morphology resulting in better barrier properties could be found after pressure treatment.