Dual-functional smart indicator for direct monitoring fruit freshness

Innovative smart packaging systems that inhibit bacterial growth and monitor food quality change are urgently needed in food industry. A dual-functional polyvinyl alcohol/polyethyleneimine/methylene blue (PVA/PEI/MB) nanofiber film was prepared for inhibiting bacterial growth and monitoring freshness of fruit. The nanofibers exhibited excellent mechanical property, breathability, water resistance and biocompatibility as characterized by the tensile test, air permeability test, water contact angle and cytotoxicity experiment. In vitro antibacterial experiment showed that the nanofibers had strong antibacterial activities against Escherichia coli and Staphylococcus aureus, and the antibacterial activities were improved under light irradiation. Nanofibers showed color variation from blue to colorless under bacterial infection in a range of 10(1)-10(10) CFU/mL, which can be used to detect the freshness of fresh-cut fruit. Effectiveness of nanofibers for freshness keeping and monitoring was confirmed via fruit tests, which suggests that the dual-functional nanofibers could potentially be used in food packaging.

Automated summary

In this study, a dual-functional nanofiber film was prepared to inhibit bacterial growth and monitor fruit freshness. The nanofibers exhibited excellent mechanical property and biocompatibility, and the antibacterial activities were improved under light irradiation. The color change of the nanofibers could be used to detect fruit freshness, and fruit tests confirmed their effectiveness in freshness keeping and monitoring.