Effect of sorbed oil on food aroma loss through packaging materials

Mass transport of six food aroma components, D-limonene, n-decane, ethyl ca proate, phenylethanol, 1-hexanol, and hexanal, through three sealable polym er films suitable for direct food contact, ultralow-density polyethylene (U LDPE), ionomer (ION), and modified polyester (mPET), was analyzed by permea tion experiments. Transport was characterized by the permeability coefficie nt and its two contributing factors, the diffusion coefficient (related to kinetics) and the solubility coefficient (related to equilibrium). The resu lts show that ULDPE is more permeable to aromas that ION, which is more so than mPET. Differences in diffusivity are mainly responsible for barrier im provement. With aromas, nonpolar compounds permeate faster than polar ones through ULDPE. The effect of sorbed oil on the behavior of these materials as food aroma barriers was investigated. The sorption of oil apparently res ulted in polymer swelling, increasing the solubility of aromas into the pol ymer matrixes. Little or no effect was found on the values of the diffusion coefficient. The permeability coefficient was affected as a consequence of changes in solubility. When aromas were compared, the transport of nonpola r penetrants showed a considerable increase while permeability values for t he polar ones were either unaffected or even reduced. This behavior has bee n discussed in terms of polymer/oil/aroma compatibility.