The food applications of cyclodextrin-metal-organic frameworks (CD-MOFs) with typical edible, renewable and biodegradable characteristics have been recently reviewed by two groups [1,2]. CD-MOFs have gradually attracted the attention of researchers in the food industry due to their high specific surface area and good biocompatibility properties.
The strategy of CD-MOFs as carriers of bioactive compound to improve the solubility and stability of bioactive compound is emphasized. In addition, the potential applications of CD-MOFs in the food industry are reviewed, such as carriers of bioactive compound used as food additives, antibacterial compounds used in food packaging, controlled release nanosystems for active compounds, nanofillers for food packaging materials, food nanoreactors, food substance nanosensors, stabilizers and immobilizers for active compounds and enzymes, and extractors of food contaminants. Both groups agree on the the problem that non-renewable, some times non-food grade reagents are added during the preparation process of CD-MOFs which restrict the use of CD-MOFs in food applications. A partial solution for this problem ithe application of gamma-CD-based MOFs.
Metal organic frameworks (MOFs), highly ordered porousmaterials (e.g. high surface area, high porosity, and tunability), are constructed through the self-assembly of different organic ligands and metal ions. MOFs are porous materials in which the network structure is formed of organic ligands and metal ions by self-assembly.MOFs can form a periodic structure with an infinite network through coordination bonds or covalent bonds. Metal ions and ligands have rich geometry and connectivity. Consequently, the physicochemical properties of MOFs can be artificially designed and adjusted to various applications. The physical and chemical properties of MOFs have led many researchers to apply them in the food industry. Therefore, MOFs have good prospects for future applications in the food industry, such as in food monitoring, food preservation, food hygiene and food packaging. With good biocompatibility and nonreactivity with the host reported by many studies, MOFs have become a very promising application material in the food industry. With the wide application of MOFs in the food industry, such as entering the food supply chain, the toxicity evaluationof MOFs and the avoidance of health problems caused by their long-term use are important issues. In most cases, MOFs are synthesized by a solvothermal method, which generally adopts heating a mixture of a metal salt and organic ligand in solvents. In addition to conventional solvothermal methods, synthesis techniques including microwaves, mechanochemistry, sonochemistry, electrochemistry, and so on, are also good synthesisoptions. Nevertheless, all MOF preparation processes are not recyclable, and with the high toxicity of synthetic components (such as metal ions and organic ligands) or the high toxicity of selected chemical reagents, these unfavorable factors greatly limit the use of MOFs in the food industry. Therefore, using biocompatible metal ions such as Ca, K, Ti and organic ligand linkers (peptides, carbohydrates, amino acids, and CD derivatives) within a biologically acceptable range can promote green MOF production to reduce the unfavorable factors of MOFs, promoting their use in the food industry.
 M Shen, D Liu and T Ding (2021) Cyclodextrin-metal-organic frameworks (CD-MOFs):main aspects and perspectives in food applications. Current Opinion in Food Science 2021, 41:8–15. https://doi.org/10.1016/j.cofs.2021.02.008
 A Magri, M Petriccione, TJ Gutiérrez (2021) Metal-organic frameworks for food applications: A review,
Food Chemistry, 354,129533, https://doi.org/10.1016/j.foodchem.2021.129533.
Featured image: Indranil Roy, J. Fraser Stoddart Cyclodextrin Metal–Organic Frameworks and Their Applications. Accounts of Chemical Research Pub Date : 2021-02-01 , DOI: 10.1021/acs.accounts.0c00695