Evaluation of the Effect of Oregano Essential Oil and Emulsifier Ratio on the Physicochemical, Mechanical, and Antioxidant Properties of Corn Starch Films Based on Gel Matrices

In this study, the oregano essential oil (OEO) was extracted and physiochemically characterized in order to assess its effect on starch films formed from gel matrices. Ten formulations were proposed, in which the amounts of OEO and the emulsifier Tween^® 80 (Tween80) were varied in order to determine the OEO and Tween80 (<i>w</i>/<i>w</i>) ratio that would allow us to obtain a stable colloidal dispersion (without the physical perception of OEO) with an adequate incorporation of OEO. The effect of the inclusion of OEO on the rheological, physicochemical (color, thickness, and density), mechanical, water vapor permeability (WVP), and antioxidant properties of the starch-based gel films were evaluated. The formulations indicated that an OEO/Tween80 ratio of 0.0046/0.0010 g g^-1 was the appropriate formulation for the formation of starch films from gel matrices with physical and mechanical properties suitable for being applied to food. This ratio could be ideal for obtaining films with greater mechanical properties and lower hydrophilicity (lower WVP) for packaging for foods that do not require high WVP levels.