Investigation the physical, antioxidant and mechanical properties of active pectin film containing Peppermint and Fennel essential oil

In this research, peppermint and fennel essential oil (0.5, 1.5, and 1.5%) was used separately and in combination in pectin film to change the functional properties of films. The results showed that the addition of peppermint and fennel essential oil to the film caused a significant decrease in solubility and moisture content of the film (p<0.01). The effect of fennel essential oil on reducing the solubility was higher than peppermint. By increasing the concentrations of essential oil in the film, the opacity of films was increased from 0.72 Au.nm-1 to 5.97 Au.nm-1, but the use of the combination of essential oil in the film formed homogeneous emulsion and had less effect on opacity. The FTIR analysis showed a new interaction between essential oils and pectin. The most antioxidant activity was found in films containing 1.5% fennel essential oil, the phenolic compounds confirmed the antioxidant activity of the essential oil, the phenolic compounds content was (385/71 mg/g Gallic acid) for fennel and peppermint (322/83 mg/g Gallic acid). Water vapor permeability was decreased 50% by adding essential oil in films. In the results of mechanical properties, the elongation percentage of pectin films increased significantly by addition the essential oil (p<0.01), but the tensile strength and elastic modulus decreased. In terms of color changes, light absorption by phenolic compounds of essential oil decreased the yellowness index compared with the control sample, total color difference in the film containing essential oil, was higher than control films due to the presence of essential oil, the yellowness index and white index in the films containing essential oil decreased and increased, respectively.