Yerba mate extract in active starch films: Mechanical and antioxidant properties

The growing concern on environment preservation and the impact of the packaging from the non-renewable materials improve the interest at biodegradable and active packages development for food applications. The aim was to develop starch films with yerba mate extract (YME) made with water: ethanol (50:50% vol/vol) at 50 degrees C followed by characterization. The YME was applied to the cassava starch films (control, 5, 10, 15, and 20%). The thickness, water vapor permeability (WVP), tensile strength, elongation as well as the Young's Modulus, water solubility, phenolic compounds, antioxidant activity (DPPH center dot), color and opacity and sorption isotherms of the films were characterized. The starch films decrease tensile strength, Young's module and elongation increased as the YME concentration increased. In addition, the sorption isotherms were adjusted to the GAB model (R-2 > 0.96). The moisture absorption by the samples of starch films with 5, 10, and 15%, had similar moisture absorption, higher than the control samples. Practical applications In this research, we developed a biodegradable active film with Yerba mate extract (YME), which is in good agreement with the growing concern in the preservation of the environment through minimization of the environmental impact of packaging from the non-renewable raw material. YME increased the phenolic compounds and antioxidant activity of the starch films. This behavior is good for fatty food applications, since fat acids may undergo oxidative processes and change sensorial and nutritional characteristics; and antioxidants will slow down these reactions. The YME also promoted a plasticizing effect in the cassava starch films, decreasing tensile strength and increasing the elongation. This behavior allows the application of systems that do not need high mechanical efforts.