Use of dual ligands for functional Zn-MOF fabrication for fruit quality monitoring and freshness maintenance

Abstract

Functional Zn-based metal-organic frameworks (Zn-MOF) were developed using a dual-ligand approach for active and intelligent packaging applications. The dual-liganded Zn-MOF was prepared using dual ligands of terephthalic acid and resazurin (Zn-MOF@T-R) via a one-pot solvothermal method and characterized by scanning electron microscopy, Fourier transform infrared, and X-ray diffraction analyses. Smart packaging films were prepared by incorporating Zn-MOF@T-R into the binary blend of carrageenan/polyvinyl alcohol (C-P/Zn-MOF@T-R). The composite film inhibited the growth of L. monocytogenes, S. enterica, and S aureus by 100 %, whereas E. coli by 91.6 % after 12 h of incubation. The C-P/Zn-MOF@T-R film also exerted 79.3 % neutralization of ABTS radicals, enhancement in the tensile strength by 46.0 %, and exhibited 73.2 % blocking of UV-B and 66.5 % blocking of UV-A light. The C-P/Zn-MOF@T-R films showed strong colorimetric responses to acetic acid and pH changes, and the color changes of these films with pH changes could successfully track the quality changes of pineapple juice. The C-P/Zn-MOF@T-R film as an active packaging system can reduce microbial spoilage and nutrient loss and extend the shelf life of freshly cut pineapple stored at 4 °C for 12 days. Therefore, the multifunctional properties provided by C-P/Zn-MOF@T-R have the potential for quality monitoring and preservation of pineapple.