Development of pH-Indicative and Antimicrobial Films Based on Polyvinyl Alcohol/Starch Incorporated with Ethyl Lauroyl Arginate and Mulberry Anthocyanin for Active Packaging
Antibacterial and pH-responsive composite films for active food packaging were fabricated based on polyvinyl alcohol (PVA), cassava starch, ethyl lauroyl arginate (LAE), and mulberry anthocyanin. With the incorporation of LAE and mulberry anthocyanin, the PVA/starch blend films exhibited a less compact and more heterogeneous surface structure. The tensile strength and elongation at break of the active films were not significantly affected when the mulberry anthocyanin content was less than 20%. Moreover, the incorporation of mulberry anthocyanin effectively improved the UV barrier property of the blend films. Notably, while mulberry anthocyanin showed obvious color changes in buffer solutions with different pH values, the changes were indistinguishable for the PVA/starch/mulberry anthocyanin films. By contrast, the color changes of the PVA/starch/LAE/mulberry anthocyanin films were more noticeable, indicating the addition of LAE increased the pH sensitivity of the blend films. Furthermore, the PVA/starch/LAE/mulberry anthocyanin films efficiently inhibited the growth of both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) due to the strong antibacterial activity of LAE. According to the spoilage test, the active films containing 5% mulberry anthocyanin and 5% LAE effectively indicated and slowed down the spoilage process of dairy milk. Our results demonstrate that PVA/starch/LAE/mulberry anthocyanin films have high potential as bioactive packaging materials applied in the food industry.