Incorporation of Thymus vulgaris essential oil and ethanolic extract of propolis improved the antibacterial, barrier and mechanical properties of corn starch-based films

The present study illustrates the influence of Thymus vulgaris essential oils (TEOs), ethanolic extract of propolis (EEP), and their combination on corn starch-based films as antimicrobial packaging materials using the casting method. The FTIR results exhibited no structural change in the composite films after incorporating TEOs and EEP. However, the color properties of composite films were significantly affected by the addition of TEOs and EEP. The addition of TEOs and EEP increased the elongation at break from 5.8 to 13.5 % when TEOs and EEP added together, but tensile strength and modulus of the composite films decreased. The water solubility (SW) of composite films was significantly reduced when TEOs were added in the range of 17.31 % to 16.12 %. Also, the swelling ratio (SR) of all composite films was lower compared to the control film. The incorporation of EEP and TEOs did not change the water vapor permeability (WVP) of composite films significantly. However, the addition of EEP and TEOs in corn-starch films exhibited a synergic effect against Escherichia coli and Listeria monocytogenes. The developed antimicrobial composite films can be utilized in food packaging applications.