Since bioactive molecules are extremely sensitive to a number of external factors and are often unstable, they must be protected and stabilized by encapsulation methods such as spray drying and electrostatic extrusion. Myrtle (Myrtus communis L.) has long been known for its beneficial therapeutic effects on disorders of various organic systems. Its essential oil is obtained by distillation of the leaves and contains various terpenoids, with 1,8-cineole, myrtenyl acetate, and α-pinene predominating. Alginates isolated from brown seaweed are often used as carriers for encapsulation due to their gel forming property in the presence of divalent cations such as calcium where alginate solution containing bioactive compounds is first dispersed into small droplets and then solidified by gelation. Therefore, the aim of this study was to investigate the possibility of stabilization of myrtle essential oil by the formation of brown algae alginate beads.
Myrtle essential oil beads were prepared by electrostatic extrusion encapsulation and the effect of the concentrations of sodium alginate as carrier (0.5, 1 and 1.5%) and calcium chloride as recipient (3 i 5%) on the yield and physical properties of the beads was studied. Myrtle essential oil (5%) was added to sodium alginate solutions together with 0.5% Tween 20 as emulsifier and homogenized with a mechanical stirrer at 10,000 rpm for 4 min. Droplets were formed by extrusion on Büchi encapsulator by applying electrostatic potential of 500 V, frequency 80 Hz with 1 mm needle tip. Yield (Figure 1) was calculated as percentage of wet beads weight and showed significant differences between formulations. The lowest yields were obtained for the samples with the lowest concentration of Na-alginate (0.5%). For both CaCl2 concentrations an increase in encapsulation yield was observed with increasing Na-alginate concentration with the highest value determined in the sample prepared with 3% CaCl2 solution. Largest beads (Table 1) were produced with 1.5% alginate and 5% CaCl3 while 3% CaCl3 caused less variation between samples. Sphericity improved greatly with the addition of higher levels of Na-alginate.