Isoreticular metal-organic framework-3 post-synthetic modification: Application in a new active film based on sodium alginate and carvacrol for pork preservation

To achieve long-term effective protection of food by continuously controlling the release of active substances in an active film, IRMOF-3 was post-synthetic modified with benzoic acid (BA) to obtain BA-IRMOF-3. This modification enhanced the loading capacity of carvacrol (CA) and slowed down its release rate. Research on IRMOF-3 synthesis has found that increasing the proportion of metal nodes can improve its crystallinity. The post-synthesis modification of IRMOF-3 through amide reaction successfully enhanced the binding energy with CA from -5.1 kcal/mol to -6 kcal/mol, resulting in an improved CA loading rate of 28.62% +/- 0.15% and delayed release. Furthermore, the BA-IRMOF-3/CA assembly was added to the sodium alginate matrix to prepare the active film BMC@SA, which improved the mechanical and physical properties of the film. The release and antibacterial/antioxidant properties were investigated. The results demonstrated that the active film BMC@SA exhibited significant sustained-release properties and antibacterial/antioxidant activities, reducing the growth of E. coli and S. aureus by 61.95% and 49.33% respectively. In refrigerated pork experiments, the film BMC@SA slowed down the color, weight, pH changes and inhibited microbial growth of fresh pork effectively, and extended the shelf life of pork from 6 d to 12 d, which demonstrated the potential application of active film BMC@SA in food preservation.