Physicochemical and antibacterial properties of psyllium gum/sodium-alginate edible films as affected by incorporating CuO nanoparticles and Heracleum persicum essential oil

In the current study, after analyzing synthesized films using various ratios of psyllium gum (PG) and sodium-alginate (SA) through different physical, barrier, mechanical, and structural properties, the best ratio of PG/SA (25:75) was selected and applied in the preparation of films incorporated with 0–3% of CuO nanoparticles (CuO NPs) and 0–1.5% of Heracleum persicum essential oil (HEO). The results suggested that although adding CuO NPs and HEO as individual additives could result in films with different drawbacks, incorporating a combination of 3% CuO NPs and 1% HEO with PG/SA film (PG/SA-1H-3C) could result in films with significant (p ≤ 0.05) enhancements in water resistance (≈ 32%) and water vapor barrier ability (≈ 55%). Although there were no significant changes observed in the thickness of the films (ranged 83–86 µm), PG/SA-1H-3C sample demonstrated a significant improvement in its elongation at break, increasing from 14.99 to 16.13%. Additionally, its tensile strength significantly improved from 28.90 to 30.43 MPa (p ≤ 0.05). The structural features of PG/SA films were analyzed using XRD and FTIR spectroscopies. Moreover, the scanning electron micrographs revealed that the addition of CuO NPs and HEO did not have any adverse effects on the smoothness and compactness of the surfaces of the films. Finally, antimicrobial results illustrated that the sample with 3% CuO NPs and 1% HEO had a significantly higher impact on inhibition of the growth of four different pathogens, with inhibition zone diameters against E. coli, S. aureus, and V. parahaemolyticus and S. typhimurium of 9.76, 12.59, 11.73, and 10.25 mm (p ≤ 0.05).