Development and characterization of amaranth protein-based edible films incorporating Satureja khuzestanica essential oil

• Amaranth protein-based films containing S. khuzistanica essential oil were developed. • Physicochemical and antibacterial properties of developed films were evaluated. • Films showed appropriate antioxidant, antibacterial, and physicochemical properties. The current research aimed to investigate the physicochemical and antimicrobial characteristics of the edible film based on amaranth protein containing Satureja khuzestanica essential oil. Different edible films were developed by adding varying concentrations of S. khuzestanica essential oil, including 0% (control), 1%, 2%, and 3%, to amaranth-based films. The following properties were evaluated for developed films: physical characterization (thickness, moisture content, water solubility, and water vapor permeability), mechanical properties (tensile strength and elongation at break), sensory evaluation (color), antioxidant activity, and antimicrobial activity (against Staphylococcus aureus, Bacillus cereus, Salmonella typhimurium , and Escherichia coli ). The results revealed that an increase in the concentration of essential oil increased antioxidant activity by DPPH scavenging (4.53 to 51.64%) and thickness (0.20 to 0.28 mm) but decreased water solubility (8.04 to 6.31%), moisture content (7.98 to 4.76%), water vapor permeability (3.63 to 2.16 g. m/m 2 . s. Pa), tensile strength (0.84 to 0.40 MPa), and elongation at breaking (95.33 to 68.13%). Also, increasing the essential oil concentration significantly (p < 0.05) affects the film's color parameters. The increased order of sensitivity of bacteria against different treatments was as follows: S. typhimurium > E. coli > B. cereus > S. aureus . Scanning electron microscopy (SEM) was employed to examine the microstructure of the developed films, and results showed that increasing essential oil concentration formed more porosity in the film structure, making the film rougher. Our findings suggest that amaranth protein films incorporating S. khuzestanica essential oil could provide antioxidant and antimicrobial packaging material for food applications.