Sodium alginate-based nanocomposite films with strong antioxidant and antibacterial properties enhanced by polyphenol-rich kiwi peel extracts bio-reduced silver nanoparticles

Sodium alginate (SA)-based films with excellent antioxidant and antibacterial activities were prepared, which was modified by polyphenol-rich kiwi peel extracts (PE) bio-reduced silver nanoparticles. In detail, PE was employed as reducing and capping agents to self-assemble silver@PE nanoparticles (Ag@PE NPs), which was further used to modify SA film in its functionality. In addition, the effects of the Ag@PE NPs amount on the physicochemical and biological performances were investigated. Results showed that SA-based films had strong tensile strength, water vapor resistance and good UV barrier properties. The incorporation of Ag@PE NPs drove a color change of SA-based films to redness and yellowness, while still showing good transparencies. Besides, Ag@PE NPs modified SA-based films showed a significant enhancement of antioxidant property, as well as an obvious improvement of antibacterial activity against Staphylococcus aureus and Escherichia coli. Therefore, this study provided a new insight for the reutilization of kiwi peels and a green, cheap and easy approach to prepare multifunctional SA-based food packaging films.

Automated summary

The study successfully improved the antioxidant and antibacterial properties of sodium alginate-based films by modifying them with silver nanoparticles bio-reduced by polyphenol-rich kiwi peel extracts.