A versatile smart packaging film functionalized with zinc/curcumin-based metal-organic frameworks for maintaining and monitoring peach (Prunus persica) freshness

This study presents the development of a versatile smart packaging film functionalized with zinc/curcumin-based metal-organic frameworks (ZC-MOFs) for preserving and monitoring peach freshness. The synthesized ZC-MOFs have shown enhanced stability compared to curcumin, and they exhibited distinct and stable color changes in response to a wide range of pH levels, and improved antibacterial and antioxidant properties. The ZC-MOFsfunctionalized gelatin/carrageenan (Gel/Carr/ZC) composite films have demonstrated excellent UV-blocking capability (97.82 %), superior radical scavenging activities (99.71 % for ABTS and 90.66 % for DPPH), and effective inhibition of common foodborne pathogens (S. aureus, S. enterica, and L. monocytogenes). Visual and colorimetric analyses have shown that the Gel/Carr/ZC composite films exhibited a distinct color change from deep orange to bright yellow, especially under acidic solution and vapor conditions. When applied to peach packaging, the Gel/Carr/ZC films displayed a noticeable color change from deep orange to light yellow, with Delta E values increasing to 16.76 +/- 2.45 for Gel/Carr/ZC2 % over 16 days, making it a reliable visual indicator of freshness. Additionally, Gel/Carr/ZC films effectively suppressed microbial growth, with TVC and TFC remaining below 4 log CFU/mL and 3 log CFU/mL, respectively, extending the microbial safety of peaches to 12 days for Gel/Carr/ZC1 % and up to 16 days for Gel/Carr/ZC1.5 % and Gel/Carr/ZC2 % films, compared to only 8 days for control samples. These results underscore the dual functionality of Gel/Carr/ZC composite films, offering both freshness monitoring through visible color change and quality preservation by inhibiting microbial growth, supporting their potential as effective smart packaging materials for perishable foods.