Development and characterization of biopolymer edible film based on gelatin and chitosan incorporated with kesum (Persicaria minus Huds.) Essential oil nanoemulsion

High concentration of essential oils (EOs) in edible films and their instability under environmental stressors, have led to the development of nanoemulsion delivery systems for improved stability and bioactivity. Kesum essential oil (KEO) offers antimicrobial and antioxidant properties, making it suitable for edible film packaging. This study incorporates KEO nanoemulsion (KEO-NE) into gelatin-chitosan (GL-CH) edible films. The physicochemical and antibacterial properties of KEO-NE were investigated. The impact of KEO-NE on the films' physicochemical, barrier, and mechanical properties was also evaluated. KEO-NE exhibited a particle size of 67.6 nm, a zeta potential of -33.1 mV, and a polydispersity index (PDI) of 0.219, indicating high stability and uniformity. Antibacterial assays demonstrated greater efficacy of KEO-NE against Staphylococcus aureus ATCC 29,213 and Salmonella enterica, with larger inhibition zones (15.67 mm) and lower MIC values (7.5 mg/mL). TEM analysis confirmed the nano-sized droplet distribution in KEO-NE. Incorporating KEO-NE into GL-CH films increased thickness (0.213 mm) and opacity (1.038 Amm- 1). Mechanical properties remained acceptable for edible films (tensile strength of 4.295 MPa, elongation at break of 76.211%, and Young's modulus of 0.055 MPa). These findings highlight the potential of KEO-NE to enhance food preservation and functionality. High pressure homogenizer was able to produce KEO-NE with smaller particle size, good stability and uniformity.KEO-NE demonstrated greater efficacy of antibacterial activity compared to KEO-CE.KEO-NE into GL-CH films increased thickness and opacity.Mechanical properties remained acceptable for GL-CH films incorporated with KEO-NE.