Bioactive multilayer film based on the sage seed gum-gelatin, TiO₂ and electrospun zein fibers encapsulating pomegranate peel extract

Despite the desirable features, electrospun fibers are mechanically fragile. To enhance their usability in packaging applications, these fibers need to be supported on a substrate. In this research, bio-based electrospun multilayered films were developed based on the strong sage seed gum-gelatin film as the outer layers and an electrospun zein-pomegranate flower extract (0, 20, 40, 60, and 80 g.m^-2) as the middle layer. The findings revealed that the developed multilayer films exhibited a thickness ranging from 0.18 to 0.25 mm. Increased electrospun layer thickness enhanced interfacial adhesion, resulting in a denser film structure, which subsequently improved tensile strength (from 60.8 to 70.2 MPa) and elastic modulus (from 279.9 to 379.2 MPa). These modifications led to a reduction in water vapor and oxygen permeability by 72.4 % and 82.6 %, respectively. Additionally, the opacity of the film >200 %. Increasing the thickness of the electrospun layer also resulted in an increase in total phenolic content (TPC) and antioxidant activity by 899 % and 547 %, respectively. The FTIR analysis revealed molecular interactions between the different layers of the multilayer film. Furthermore, X-ray diffraction (XRD) analysis indicated that the multilayer film possesses a semi-crystalline structure, with an increase in crystallinity observed as the thickness of the electrospun layer increased, which consequently enhanced the thermal stability of the multilayer films. A reduction in water solubility, moisture content, and swelling ratio, as well as an increase in antimicrobial activity, was also observed with the increasing thickness of the electrospun layer. Release kinetics results showed that the lowest release rate occurred in the fatty food simulant. This research advances the development of bio-based electrospun multilayered films to improve their mechanical strength and barrier properties for packaging. It highlights the potential of these materials in sustainable packaging and paves the way for future innovations in environmentally friendly practices.