Thermoplastic starch/whey protein isolate/rosemary essential oil nanocomposites obtained by extrusion process: antioxidant polymers

Abstract

Active substances are added to polymers to act as a barrier to external elements, protecting the product. This article evaluated the effect of the addition of sodium montmorillonite (MMT) nanoparticles and the antioxidant activity of rosemary essential oil (EO) in thermoplastic starch/whey protein isolate (TPS/WPI) nanocomposites obtained by extrusion. X‐ray diffractograms showed dispersion/exfoliation of the MMT in the TPS/WPI matrix. The nanocomposites presented rough surface with the presence of porosity as shown by scanning electron microscopy images. Thermogravimetric analysis revealed that the combination between MMT and rosemary EO increased thermal stability of nanocomposites. The addition of rosemary EO became the films less rigid, weaker and had an antioxidant effect as shown by mechanical properties and 2,2‐diphenyl‐1‐picrylhydrazyl assay. The optical properties showed in opaque greenish yellow nanocomposites. Therefore, the addition of rosemary EO in nanocomposites showed an alternative for use as antioxidant polymers in packaging material.