Microencapsulation of eugenol in polyelectrolyte complexes of chitosan and alginate

Abstract

Eugenol is widely used in several applications such as food activity packaging to prolong shelf life of fruits and vegetables because of its antimicrobial activity. However, eugenol is easy to decompose, leading to reduce its activity. In this work, we prepared eugenol loaded alginate-chitosan microparticles in order to solve this problem and controlled release essential oil using ionic gelation technique. The effect of concentration of eugenol (0.1-0.5 g), calcium chloride (0.5 – 8 %W/V) and surfactant (2-10% W/V) was investigated. The results showed that the optimum condition was eugenol 0.1 g, calcium chloride 2% W/V and surfactant 4% W/V. The SEM image of alginate-chitosan microparticles as ration 1:1 showed a regular distribution and spherical shape with the size of 1 mm and after loading eugenol into the beads, it was still spherical in shape. FTIR spectrum showed the interaction between carboxylic group of alginate and amine group of chitosan. According to the release profiles, it was found that release rate of eugenol loaded alginate-chitosan microparticles was higher than that of eugenol loaded alginate microparticles. In addition, strawberries were selected as a fruit model for evaluation of antimicrobial properties of eugenol loaded alginate-chitosan microparticles. The results showed that eugenol loaded alginate-chitosan microparticles could inhibit microbial in strawberries and prolong shelf-life up to 12 days. The measurements of color, lightness (L*), hue angle (h°), weight loss, and total soluble solid during storage at 0, 4, 8 and 12 days confirm that there are no significantly difference between treatment group of strawberries and control. However, the firmness of treatment group increased, which might be due to the beads could adsorb moisture, which is a major factor related to their firmness.