Antioxidant activity and some physical properties of gelatin films incorporated with thyme oil

In this study film thickness, film solubility, tensile strength and elongation at break, light transmittance and color (CIE L *, a *, b *) total amount of phenolic compound and antioxidant activity values (DPPH, ABTS and metal chelating activity measurement) of gelatin based films incorporated with thyme oil (Thymus vulgaris L.) at different ratios (2%, 4%, 6% and%8) were determined. It has been observed that thyme oil gelatin-based film samples, cause increase in the total phenolic substance content and antioxidant activity values. GC-MS showed that the majör volatile components of thyme oil were α-pinene, carvacrol and thymol. Thymol and carvacrol were determined by high performance liquid chromatography and the concentrations of thymol and carvacrol were determined as 1325.13-5347.27 and 58.82-686.22 respectively. Scanning electron microscope (SEM) images of gelatin-based films containing thyme oil were obtained. The addition of thyme oil at increasing concentrations (2%, 4%, 6%, 8%) decreased the melting point (Tm) and enthalpy ∆H (J/g) while the glass transition temperature (Tg) values have gradually increased. These values were determined by differential scanning calorimetry (DSC). Strawberry samples were coated with gelatin-based films incorporated with thyme oil and stored at +4°C at refrigerator and their sensory properties were evaluated. All the results were evaluated statistically (P<0.05).