Supercritical CO2 Impregnation of Piper divaricatum Essential Oil in Fish (Cynoscion acoupa) Skin Gelatin Films

Abstract

Films with antioxidant properties using acoupa weakfish skin gelatin (Cynoscion acoupa) were obtained after supercritical solvent impregnation with Piper divaricatum essential oil, in order to produce active food packaging. The impregnation process was carried out using CO2 as supercritical solvent, in an autoclave, at 35 °C, pressures of 100, 150, and 200 bar, and times of 60, 90, and 120 min. The film that presented the highest percentage of antioxidant activity was obtained at 100 bar and 60 min (41.63 ± 1.6%). Scanning electron microscopy (SEM) showed that the essential oil had a heterogeneous distribution within the film, confirming its impregnation. The analysis of Fourier-transform infrared spectroscopy (FTIR) showed that the structural properties of the film changed after the process, in which the interaction of the essential oil and the film proteins was confirmed. Impregnation resulted in a film presenting less tensile resistance, greater flexibility, and greater opacity when compared with control film. Thermogravimetric analysis indicated that thermal stability decreased after the impregnation process. The film obtained presented characteristics that suggest its potential as an active packaging for food products.