Changes of properties of polymer packaging films during high pressure treatment

The effect of high pressure on the polymer packaging materials was studied. Seven single material films as well as seven laminates suitable for high pressure preservation of food or commonly used as food contact layer were pressurized using the pressure 600 MPa for 60 min. The effect of pressure treatment on the change of following film parameters were evaluated: mechanical properties (tensile strength and seal strength), transparency (absorbance at 450 and 600 nm), water vapour permeability, global migration characteristics into fat food simulants (95% ethanol and isooctane) and the transfer of food simulants (water and olive oil) into packaging materials. The obtained results confirmed the influence of high pressure treatment on functional properties of tested films, in some cases in rather significant level (loss of heat sealability, changes of migration levels, etc.). The obtained results need further confirmation by tests done in closer cooperation with packaging materials producers, which enables better understanding of film changes. (C) 2003 Elsevier Ltd. All rights reserved.