A Comparative Study on the Structural, Physicochemical, Release, and Antioxidant Properties of Sodium Casein and Gelatin Films Containing Sea Buckthorn Oil

The aim of this study was to compare the effect of increasing concentrations (0, 1, 2, 4%) of sea buckthorn oil (SBO) on the structural, physicochemical, release, and antioxidant properties of glycerol-plasticized sodium casein (NaCAS) and gelatin (GEL) films. Ultrasonic treatment ensured effective homogenization of SBO in both types of emulsions, resulting in yellow-tinted semi-opaque films with relatively low micro-roughness. Generally, GEL films demonstrated lower UV barrier properties and solubility but exhibited higher compactness, crystallinity, transparency, surface hydrophobicity, oxygen barrier performance, strength, and antiradical activity compared to their NaCAS-based counterparts. In a concentration-dependent manner, SBO decreased the solubility and water absorption of the gelatin-based film and enhanced its oxygen permeability. Conversely, SBO improved the water vapor barrier properties of both films in a concentration-independent manner. At the highest SBO concentration, the tensile strength of NaCAS- and GEL-based films decreased by 27% and 20%, respectively, while their antiradical activity increased by 9.3× and 4.3× (based on the time required for the half-neutralization of 2,2-diphenyl-1-picrylhydrazyl radicals). Migration studies showed that at the lowest concentration, SBO was released (into 95% ethanol) approximately 2× faster from the GEL-based film than from the NaCAS film, whereas at higher concentrations, the trend reversed.