Development and characterization of novel edible films based on Cordia dichotoma gum incorporated with Salvia mirzayanii essential oil nanoemulsion

Salvia Mirzaiani essential oil (SMEO) was extracted using hydrodistillation and its GC-MS analysis identified 54 compounds. SMEO nanoemulsion (SMEO-NE) was produced using ultrasound. Then, gum-based films extracted from Cordia dichotoma containing SMEO-NE were prepared at concentrations of 0 (control), 1, 1.5 and 2% (v/v). Addition of SMEO-NE increased thickness, contact angle and elongation at break of the films. It decreased moisture content, water solubility, ultimate tensile strength, water vapor permeability, percentage of light transmission in the visible and ultraviolet range with a significant change in color factors. Formation of new hydrogen bonds between SMEO-NE and film matrix was confirmed by FTIR. Besides, dynamic mechanical-thermal analysis showed a decrease in storage modulus and glass transition temperature of the films. Electron microscope images showed that presence of SMEO-NE led to changes in microstructure of the films. Furthermore, increasing the concentration of SMEO-NE increased antioxidant and antibacterial activity of the films.