Alginate and chitosan functionalization for micronutrient encapsulation.

A new method for encapsulation of micronutrients was successfully developed. The encapsulation matrix consisted of two polymers (alginate and chitosan), which were functionalized by acylation with palmitoyl chloride. The structural modifications of polymers were confirmed by Fourier transform infrared (FTIR) spectroscopy. Beads were formed by ionic gelation, and their mechanical and physical characteristics (puncture strength and deformation, viscoelasticity, water vapor permeability, and rate of gel swelling) were evaluated using beads or films made of bead-forming solutions. Functionalization increased elasticity and water impermeability of polymer films. Stability of selected encapsulated micronutrients (ferrous fumarate, ascorbic acid, and beta-carotene) was also evaluated under two levels of temperature (23 and 45 degrees C) and relative humidity (56 and 100%) for 6 months. Encapsulation strongly increased the stability of micronutrients. No difference was observed in the encapsulated micronutrients' stability between nonfunctionalized and functionalized beads. Finally, a release study in gastrointestinal media was conducted. Results showed that beads were not susceptible to enzymatic and acidic attacks during stomach transit. This research demonstrates the potential of a new encapsulation method to protect bioactive molecules from temperature, moisture, and acidic conditions.