GAS PERMEABILITY AND THERMAL BEHAVIOUR OF POLYPROPYLENE FILMS USED FOR FRESH-CUT POTATOES PACKAGING: A CASE STUDY

This work reports some results of an experimental study on the permeability and thermal behaviour of commercial Polypropylene (PP) film used for fresh-cut potatoes packaging. The permeability of PP material was tested and studied using O2, CO2 and N2 pure gases and different mix of them, normally used for modified atmosphere packaging (MAP) in comparison to Air, in order to understand if it will be possible to extend the shelf life of food product designed for catering field. The temperature influence (from 5 to 40°C) on permeability data, was analyzed before and after 4, 8, 12, 15 and 20 days of food contact, pointing out the dependence between temperature and gas transmission rate (GTR), solubility (S), diffusion coefficient (D) and time lag (tL) parameters. The activation energies of the permeation at the tested different gases were determined. Moreover, the thermal behaviour of packaging was studied by Differential Scanning Calorimetry (DSC) and Thermogravimetric analysis (TG) to well understand the structural stability of the polymer used in the experiments. Moreover, FTIR/ATR spectroscopy analysis was also performed, in order to study the eventual influence of the food contact on the chemical characteristics of the polymer films.