Evaluatuion of physical, structural and antioxidative properties of potato starch edible film containing zedo gum and salvia officinalis essential oil and its effect on the oxidative stability of virgin olive oil

the aim of this study was to investigate some of the physicochemical and antioxidant properties of the active edible film prepared from starch and zedo gum and salvia officinalis essential oil and its effect on oxidative stability of olive oil. For this purpose, Edible films based on potato starch were prepared with two variables zedo gum at different levels (0.5%, 1% and 1.5% w/w) and salvia officinalis essential oil at three levels (0, 250 and 500 ppm). Spectrophotometric results indicate the formation of CH, CH2 and CH3 bonds between starch and  zedo gum, as well as aromatic compounds of the essential oil of the salvia officinalis (C-H and C=C) bonds. With increasing concentrations of zedo gum and different concentration of salvia officinalis essential oil, the film thickness increased and increased the opacity and reduced light transmission rate of the films. Samples containing 1.5% zedo gum and 500 ppm essential oil of Salvia officinalis showed the highest thickness and opacity among other samples. As the essential oil concentration increased, the antioxidant properties of the films increased so that the sample containing 1.5% zedo gum and 500 μl of essential oil of the salvia officinalis had the highest antioxidant activity of 68.3%. The results of stability test against oxidizing virgin olive oil based on tests such as acid number, peroxide number and thiobarbituric acid showed a significant difference (P<0.05) between essential oil containing 500 ppm with a synthetic antioxidant (TBHQ). Due to its relatively good antioxidant activity, edible film prepared from starch and zedo gum and salvia officinalis essential oil plays a positive role in reducing the oxidation process of olive oil and can be a good alternative to the use of synthetic antioxidants.