Development of Alginate-Chitosan Bioactive Films Containing Essential Oils for Use in Food Packaging

The effect on the physical, mechanical, and antibacterial properties of films composed of alginate-chitosan with the incorporation of oregano (EOO) or thyme (EOT) essential oils was evaluated. These films showed a thickness between 37.7 and 38.2 mu m, with no significant differences for essential oil content. Water vapor permeability decreased from 4.03 (oil-free film) to 1.65 (g/msPa) x 10-9 in 3% EO. Mechanical properties reflected a reduction in tensile strength (TS) from 73 (oil-free films) to values between 34 and 38 MPa with 3% EO, while elongation (E%) increased from 4.8% to 10.4-11.8%. Regarding antibacterial capacity, as the concentration of essential oil increases, the antibacterial capacity also increases. On average, the increase from 1.0% to 3.0% of EOO increased the antimicrobial capacity against Gram-negative and Gram-positive bacteria. EOO outperformed EOT against E. coli and L. monocytogenes. In addition, films with 2-3% EOT showed a significant dark yellow color compared to the control. These results suggest that films with the addition of oregano and thyme essential oils can be promising for food packaging applications with the ability to improve food safety and increase product shelf life by achieving functional packaging characteristics.