Preparation of Chitosan-Alginate Nanoparticles for Trans-cinnamaldehyde Entrapment

Trans-cinnamaldehyde incorporated chitosan-alginate nanoparticles were synthesized using the ionic gelation and polyelectrolyte complexation technique. Alginate, chitosan, calcium chloride, and trans-cinnamaldehyde at predetermined concentrations were complexed electrostatically to optimize particle size and loading efficiency. A final methodology using optimized processing parameters (for example, stirring time, homogenization time, equilibration time, and droplet size) was developed. The best working alginate to chitosan mass ratio was determined to be 1.5:1 at a pH dispersion of 4.7. Particle size (166.26 nm) and encapsulation efficiency (73.24%) were further optimized at this mass ratio using an alginate:calcium chloride mass ratio of 4.8:1, alginate:trans-cinnamaldehyde mass ratio of 37.5:1, a 18 gauge syringe needle, stirring times of 90 min, 15 min of homogenization at 21000 rpm, and equilibration time of 24 h. Optimized nanoparticles showed increased stability (6 wk) and translucency in solution. The final radical scavenging effect of loaded particles in apple juice was 62% and trans-cinnamaldehyde was just as available to react in free form as it was in inclusion complexes. The final nanoparticle system with modified and optimized processing parameters reduced the size by 43.6% and increased entrapment efficiency by 17.2%. Nanoparticles resembled a spherical shell and core type arrangement (that is, spherical, distinct, and regular) and were in the size range of 10 to 100 nm.

Nanoencapsulation of lipophilic antimicrobial and antioxidant compounds has the potential to improve their effectiveness and efficiency of delivery in food systems. Determining a standard nanoparticle synthesis methodology and optimizing entrapment efficiency and particle size prior to characterization studies allows for improved understanding of nanosystems and substantiates results. This study demonstrates the potential to improve current nanoparticle preparation techniques to fine tune critical physical parameters. The results presented in this study can aid in developing new and simple ways to improve nanoparticle formulations and prompt further studies to validate entrapment of lipophilic compounds combinations.