Supercritical CO2 impregnation of Gelatin-Chitosan films with clove essential oil and characterization thereof

Supercritical CO2 impregnation process was used for the first time to fabricate biodegradable gelatin-chitosan (G/Ch) films containing dove oil (CO) for potential use in active food packaging. All the impregnations were carried out at moderately low temperature (40 degrees C). Aiming to maximize CO loading in the films with acceptable morphological, structural and thermal properties, CO2 pressure, impregnation time and G:Ch mass ratio were varied. Gelatin fraction in the films of 25-50 wt. %, scCO(2) pressures of 10-20 MPa and impregnation time of 2-6 h impregnation favoured the CO loading. Processing of the film with equal gelatin to chitosan mass ratio (G/Ch(50:50)) at 10 MPa for 2 h yielded sufficiently high loading (56 mg CO/g(film)) without an adverse effect on morphological properties. The G/Ch(50:50) film was therefore chosen for structural and thermal analyses. ATR-FTIR analysis confirmed successful CO incorporation into the G/Ch(50:50) and its interaction with the film. Plasticizing effect of scCO(2) and CO on the film was evidenced by DSC. Incorporation of 56 mg CO/g(film) into the G/Ch(50:50) didn't affect thermal stability of the film. Beside environmental benefits, supercritical impregnation process enables fast fabrication of G/Ch bio-composite films containing CO, thermally stable to 110 degrees C, which is suitable for most of food packaging applications.