Fabrication of pH-Sensitive Poly(vinyl alcohol) Films with <i>Clitoria ternatea</i> Extract and Zinc Oxide for Antibacterial Applications

In this study, <i>Clitoria ternatea</i> flower extract, obtained via ultrasound-assisted maceration, was incorporated into a zinc oxide/poly(vinyl alcohol) (Ex-ZnO/PVA) film via the solution-casting method. The obtained films were characterized through XRD, FTIR, FE-SEM, EDS, UV-vis, and stress-strain curve. The results reveal that Ex-ZnO/PVA was fabricated successfully with the incorporation of the extract, a uniform distribution of ZnO particles, excellent mechanical properties, and a moisture content of 9.68%. The antibacterial performance of Ex-ZnO/PVA is higher than that exhibited by the film with ZnO embedded and without the incorporation of the extract for the <i>Pseudomonas aeruginosa</i> and <i>Staphylococcus aureus</i> strains. The obtained films were applied for the preservation of <i>Lap xuong,</i> a fatty food with high protein content, which is vulnerable to microbial activity. The preservation results reveal that after 14 days at 30 °C with an average moisture content of 80%, patches of molds were developing on the studied <i>Lap xuong</i> sample preserved with Ex-ZnO/PVA, meanwhile, these patches appeared shortly after 7 and 9 days for the <i>Lap xuong</i> samples preserved with pristine PVA and ZnO/PVA films, respectively. In addition, Ex-ZnO/PVA also exhibits the ability to alter its color in response to changes in the pH of the environment. The obtained results reveal the potential application of the Ex-ZnO/PVA film as a biocompatible food wrapper and indicator.