Cyclodextrin-grafted nanoparticles as food preservative carriers

Photocatalytic properties of titanium dioxide nanoparticles (TiO₂ NPs) have encouraged their use as fillers in polymer-based nanocomposites for application in food packaging. The surface modification of TiO₂ NPs with cyclodextrins (CDs) can improve their functionality in a large extent. With this purpose, sorbic acid (SA) and benzoic acid (BA), commonly used as antifungal and antibacterial food preservatives, respectively, have been encapsulated in CD-grafted NPs. Inclusion complex formation of SA and BA with α and βCDs in water has been assessed first by means of ¹H NMR and UV-Vis spectroscopy to determine the affinity of the preservatives for the macrocycles and the stoichiometry of the complexes. The association constants of both preservatives were found to be lower for βCD, however, the loading efficiency in βCD-grafted NPs was higher than that exhibited by αCD-NPs. Release kinetics from the CD-grafted NPs have been carried out. In the case of SA, the αCD-grafted NPs showed a prolonged and sustained release profile, suggesting its application as microbial growth inhibition system if incorporated into packaging materials.