Bio-based composite edible films containing Origanum vulgare L. essential oil

Biocomposite films based on fish gelatin and chitosan containing Origanum vulgare L. essential oil (OEO) at 0.4, 0.8, and 1.2% (w/v) were prepared by a solvent casting method and their physicochemical and antimicrobial properties were examined. The results showed that the incorporation of OEO caused a significant decrease (p < 0.05) in tensile strength (TS) and elastic modulus (EM), although no significant change was observed in elongation-at-break (EAB). Water vapor permeability (WVP) and solubility of films containing OEO increased as the amount of oil increased (p < 0.05). Oregano essential oil-loaded films displayed superior barrier capability to ultraviolet light. Fourier transforms infrared (FTIR) spectra indicated that the interaction between polymer matrix and essential oil was occurred. The properties of the films were related with their microstructure, which was observed by scanning electron microscopy (SEM). Atomic force microscopy (AFM) images showed that the surface roughness of the films was influenced by the inclusion of oil. OEO-incorporated films also exhibited higher antimicrobial activity against the gram-positive bacteria (Staphylococcus aureus and Listeria monocytogenes), and lower for gram-negative bacteria (Salmonella enteritidis and Escherichia coli). This study showed that OEO has the potential to prepare active edible films.