Fabrication of pH-Sensitive Poly(vinyl alcohol) Films with Clitoria ternatea Extract and Zinc Oxide for Antibacterial...

In this study, Clitoria ternatea 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 Pseudomonas aeruginosa and Staphylococcus aureus strains. The obtained films were applied for the preservation of Lap xuong, 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 Lap xuong sample preserved with Ex-ZnO/PVA, meanwhile, these patches appeared shortly after 7 and 9 days for the Lap xuong 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.