Interfacial mass transport properties which control the migration of packaging constituents into foodstuffs
Résumé
Interfacial mass transport properties, such as partition coefficients (K), mass transfer coefficients (h) and diffusion coefficients (D) were estimated from controlled desorption kinetics at 40 degrees C, which would be realistic of extreme conditions of use of the packaging materials in contact with a liquid food. The experiments were carried out on formulated pieces of low density polyethylene (LDPE) with variable thicknesses (50, 100 and 150 mu m) dispersed in ethanol, in controlled conditions of stirring, with Biot mass number between 5 and 10(3). The 3 transport properties for 8 homologous molecules (n-alkanes and n-alcohols), 2 antioxidants and 2 fluorescent tracers were estimated from a set of 78 desorption kinetics. Concentrations in ethanol samples were measured by GC-FID. The uncertainty related to analytical errors was quantified by Monte-Carlo sampling consisting in adding an arbitrary white noise to results in the range of experimental errors. The physical interpretation of the external transport resistance is finally discussed.