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

This work report an experimental study on the permeability and thermal behaviour of commercial Polypropylene (PP) film used for fresh-cut potatoes packaging. The permeability was tested using oxygen, carbon dioxide, nitrogen, mix of these three gases, normally used for modified atmosphere packaging (MAP) and Air, to understand if it would be possible to extend the shelf life of this food product designed for catering field in respect to the packaging behaviour. The temperature influence on permeability data, from 5 to 40°C, 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 (E) of the permeation process were determined with the different gases used in the experiments. The thermal behaviour of PP film was studied by Differential Scanning Calorimetry (DSC) and Thermogravimetric analysis (TG) to well understand its thermal stability. FTIR/ATR spectroscopy was also performed in order to study the influence of the food contact on the chemical characteristics of the polymer film. The results obtained were discussed and compared each other. Studied samples showed, for all investigated gases, an increase of gas permeability and S values at higher temperature.Heat resistance classification among the sample as it is and stored in modified atmospheres was made. Finally all performed experiments have showed a good polymer stability for the shelf-life storage potatoes under study.