Antifungal and ultraviolet–visible barrier properties in starch films reinforced with CuO nanoparticles

Abstract

AbstractStarch materials are subject to loss of initial characteristics due to the retrogradation degenerative effect, high hygroscopicity, and favoring the growth of the microorganisms, which reduces the shelf life of packaging. In this sense, the insertion of nanoparticulated CuO was evaluated for the best performance. CuO is a semiconductor that can improve optical, mechanical, and antimicrobial properties, enabling excellent promotion of starch films. The hot injection precipitation method was used to obtain CuO nanoparticles in the nanometric scale rapidly. The films were carried out from the starch homogenization in water and urea under temperature, followed by thermopressing at 120°C. As a result, the 1% CuO (w w−1) increased tensile strength from 0.87 ± 0.40 to 1.92 ± 0.09 MPa. Furthermore, the films containing nanoparticles showed a barrier property against radiation in the ultraviolet–visible spectrum, not observed for the micrometric scale. Such results were attributed to the superior opacity of the films generated by nanometric reinforcement. Concerning antimicrobial activity, the films containing CuO showed a fungistatic effect (33%) for the Alternaria alternata fungus, a microorganism very susceptible to carbohydrate‐rich sources. Thus, the CuO‐reinforced starch films improved physicochemical and biological properties, making them promissory candidates for commercial application.