Cinnamaldehyde-loaded chitosan nanoparticles: characterization and antimicrobial activity

Abstract

Due to its wide spectrum activity and low toxicity, chitosan has shown to be a promising molecule to be applied in food science and technology. Meanwhile, cinnamaldehyde (the main component in cinnamon flavor) has shown potential uses as a strong antimicrobial compound. To improve the antimicrobial activity of chitosan, we have prepared N-acylated chitosan nanoparticles, with cinnamaldehyde as acylating reagent. The properties of the modified material were compared against the ones of the unmodified chitosan nanoparticles. Modification of the material was characterized by means of FT-IR spectroscopy with the identification of the imine group formed due to the addition of cinnamaldehyde (soft band appearance in the range of 1630-1660 cm-1 ). Meanwhile, 1H NMR analysis was used to quantify the modification. Nanoparticles of both, the modified and the unmodified chitosan, were characterized by TEM and DLS analysis showing a higher diameter size and a reduced zeta potential for the cinnamaldehyde loaded material than the chitosan nanoparticles. Finally, their activity was tested against E. coli and L. monocytogenes by measuring the minimal inhibitory concentration, showing a greater activity when the nanoparticles were functionalized (with an observed increase of the activity with the higher loading of cinnamaldehyde). This works evidence that the N-acylated chitosan nanoparticles have promising and potential use in food preservation.