Chitosan as a potential microencapsulation carrier for ascorbic acid stabilization in heterodisperse systems

Abstract

ABSTRACT: Objective: The purpose of this work is to assess the ionotropic gelation of chitosan as a new method to encapsulate and increase the stability of ascorbic acid (AA). Methods: Chitosan was employed for the encapsulation of AA employing the technique of ionotropic gelation with sodium lauryl sulfate. The encapsulation process was made by two processes, homogenization and sonication-homogenization, respectively Ionotropic gelation was carried out by mixing chitosan and sodium lauryl sulphate solutions at 0.5, 1.0 and 1.5 % (w/v) concentrations with ~20 mg of AA. Results: The two processes rendered spherical microcapsules with a narrow particle size distribution and particle size (0.7-2.1 μm), but only sonication-homogenization rendered less cohesive microcapsules. The encapsulation efficiency depended on the processing conditions and levels of parent materials and ranged from ~14 to 90% and ~14 to 72% for sonication-homogenization and homogenization, respectively. In both processes, runs with the lowest levels of chitosan (0.5%) were selected as optimal due to the spherical morphology, high encapsulation efficiency and less cohesive behavior. The addition of AA microcapsules into heterodisperse systems such as emulsions, semisolid systems and aqueous dispersions improved their thermal stability at 45°C rendering a shelf life (t90) of 17.6, 21,1 and 3.3 days, respectively. Conversely, the products containing free AA had a shelf life of 1.8, 3.1 and 0.9 days, respectively. Conclusions: The ionotropic gelation of chitosan with sodium lauryl sulfate improved the functionality, stability and shelf life of AA in heterodisperse systems.