FOOD AND PACKAGING INTERACTIONS - DETERMINATION OF THE KINETIC-PARAMETERS OF OLIVE OIL DIFFUSION IN POLYPROPYLENE USING CONCENTRATION PROFILES

The penetration of olive oil into polypropylene was studied in order t o allow a complete modellization of food and packaging intel actions. Oil concentration profiles through polypropylene food trays were deter mined by FTIR-microscopy measurements along the thickness at various t imes. Calculations of the relevant parameters characterizing Fickian d iffusion, namely constant diffusivity, coefficient of convective mass transport on the surface and concentration at equilibrium were carried out. This way of working has proven to be considerably shorter and mo le accurate than the method consisting of recording the global absorba nce of the substance absorbed especially when the amount of diffusing fat is low. Major conclusions are: that absorption of olive oil is str ongly influenced by convection; the diffusion coefficient of olive oil in polypropylene is constant. Possible consequences to simplify globa l migration testing are discussed.