Fabrication of low environment-sensitive nanoparticles for cinnamaldehyde encapsulation by heat-induced gelation method

The current study was devoted to preparing biopolymer nanoparticles stable to harsh environment (extreme pH, high ionic strength and high temperature) to improve the protection of cinnamaldehyde. Cinnamaldehydeloaded nanoparticles (NPs-C) were prepared by heating electrostatic complexes of whey protein isolatedextran conjugate (WPI-Dex) and chondroitin sulfate (ChS) in the presence of cinnamaldehyde. Results showed relatively high encapsulation efficiency and loading capacity (76.57% and 19.02% respectively). The particle size was around 185 nm and the polydispersity index (PDI) was 0.22. Both hydrogen bonding and hydrophobic interactions facilitated the successful entrapment of cinnamaldehyde into the nanoparticles. The NPs-C were stable over the pH range of 1-10 in the absence or presence of various NaCl concentrations (1-4 M). Moreover, the nanoparticles remained stable against a combined effect of different pH, different ionic strength and heating (90 degrees C, 30 min). Interestingly, the result indicated that the addition of NaCl improved the heat stability of NPs-C especially at pH 2. Results have also revealed that cinnamaldehyde encapsulation has improved its storage stability, where nanoparticles have effectively protected cinnamaldehyde during storage for 6 weeks both at 4 degrees C and 25 degrees C. The WPI-Dex/ChS nanoparticles fabricated in this research have a promising prospect to protect essential oils or bioactive compounds against harsh environmental stresses in food, nutraceutical and pharmaceutical industries. Furthermore, the sustained antimicrobial activity endows NPs-C with a great potential application in the aforementioned industries.