Porous metal-organic framework (MOF) Carrier for incorporation of volatile antimicrobial essential oil

The increasing demand for safety and quality in food products has stimulated research on developing natural preservatives and their carrier systems as a novel preventive control strategy. In this study, metal-organic framework (MOF) was investigated, for the first time, as a carrier for volatile antimicrobial essential oils. Zinc metal-organic framework (Zn@MOF) was synthesized with zinc nitrate hexahydrate and 2-aminoterephthalic acid in N, N-dimethylformamide (DMF). Thymol was then loaded into the Zn@MOF at a loading rate of 3.96% as measured by thermogravimetric analysis (TGA). The crystal structure of porous MOF was confirmed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Antibacterial activity of thymol loaded Zn@MOF (T-Zn@MOF) with active thymol loading of 0.029 g/100 g was assessed against a three-strain cocktail of E. coli O157:H7 in a tryptic soy broth (TSB). E. coli O157:H7 growth in T-Zn@MOF exhibited growth inhibition without an exponential growth phase after 24 h of incubation, which could be attributed to the sustained release of thymol by incorporating it in the porous Zn@MOF through noncovalent interactions. This research demonstrates that Zn@MOF loaded with the essential oil thymol is an effective antimicrobial and may have potential indirect applications in food.