Antibacterial and antioxidant properties of hydroxypropyl methylcellulose-based active composite films incorporating oregano essential oil nanoemulsions

Hydroxypropyl methylcellulose (HPMC) was combined with oregano essential oil nanoemulsion (ORNE) at concentrations of 0–7.5% (v/v) to produce active composite films. The mechanical, optical, water vapour barrier, antimicrobial, and antioxidant properties of the composite films were evaluated. The composite films containing 5.0% (v/v) ORNE showed increased elongation at break compared to the control films, although their tensile strength and Young's modulus were lower. In addition, these composite films showed greater opacity and decreased UV and water vapour transmittance, indicating that incorporation of ORNE resulted in enhanced barrier properties. Furthermore, the composite films were effective against all tested bacterial strains, particularly against Salmonella typhimurium, as evidenced by the large inhibition zone attained (47.5 mm) in the disc diffusion test. Antioxidant activity was assessed by the DPPH and ABTS assays, with the composite films containing 5.0% (v/v) ORNE showing values approximately 69% and 46% higher than those of the control, respectively. Therefore, the developed composite films could potentially be used as active packaging with antibacterial and antioxidant properties.