Antimicrobial and magnetically removable tannic acid nanocarrier: A processing aid for Listeria monocytogenes treatment for food industry applications.

An innovative core-shell nanocarrier, combining the magnetism of surface active maghemite nanoparticles (SAMNs, the core) and tannic acid (TA, the shell) was self-assembled by simple incubation in water. Due to the drastic reorganization of SAMN surface, the prepared magnetic nanocarrier (SAMN@TA) resulted as one of the most robust nanomaterial bearing TA to date. Nevertheless, the ferric tannates network, constituting the SAMN@TA shell, and the free tannic acid display comparable chemical behavior. The antimicrobial properties of SAMN@TA were tested on Listeria monocytogenes in comparison with free TA, showing similar bacteriostatic effects at relatively low concentrations. Besides the preservation of the TA inhibitory activity toward L. monocytogenes, the possibility of being magnetically removed leaving no residues into the matrix makes this nanocarrier an innovative processing aid for surface treatments. Thus, SAMN@TA can be used as an effective, low-cost and environmentally friendly antimicrobial nanomaterial for the food industry applications.