β-Cyclodextrin-based nanosponges as carriers for gallic acid: A sustainable strategy for gallic acid separation and food preservation

The adsorption and the eventual encapsulation of gallic acid (GA) in β-cyclodextrin-based nanosponges offer a method to separate GA from vegetable feedstocks avoiding harmful chemicals, ensuring high selectivity, and minimizing its exposure to adverse conditions. Furthermore, the encapsulated GA can directly be used in food packaging, providing its controlled release to extend the shelf life of food industry products. In this view, GA has been encapsulated in β-cyclodextrin-based nanosponges (βCD-NS) functionalized with diamines having 6 or 12 methylene groups, to form complexes (βCD-NS-GA) whose synthesis has been confirmed by 1H NMR. FTIR spectra and SEM analysis confirmed the successful adsorption of gallic acid on both the adsorbent materials used. The optimum pH for GA adsorption was found to be 4.0 for the both NSs, da6-CD-NS and da12-CD-NS, with adsorbed amounts of 10.80 and 24.22 mol kg−1, respectively. The βCD-NS-GA complexes were also studied as regards the adsorption mechanism, kinetics and equilibrium. An effective desorption protocol was developed changing the pH of the medium, thus ensuring milder conditions and a reduced environmental impact. A significant antibacterial and antioxidant activity of βCD-NS-GA complexes indicate the CD-NSs as good candidates for application in the food field.