The improvement of the physicochemical properties of Lactobacillus reuteri probiotic by dual layers extrusion microencapsulation with sodium alginate and basil mucilage

In this study, two-layer extrusion method was performed on Lactobacillus reuteri. The first layer was sodium alginate and the second one basil seed mucilage in five concentrations (0.2, 0.4, 0.6, 0.8 and 1 percent). The image was provided from microencapsulated form to determine the diameter of the layers and microencapsulated color components L*, a*, b*, whiteness and yellowness. Thermal, salt, acid survivability, growth and acid production of free and microencapsulated bacteria in MRS medium were investigated. The results of this research showed that as increasing the percentage of mucilage gum used as the second layer can cause a significant change in the outer layer diameter. The b*, whiteness, and yellowness parameters increased but the L* parameter decreased significantly (p≤ 0.05). Microencapsulated containing 1 precent basil seed mucilage can survive for 5 min at 72 °C, above minimal probiotic concentration limited (6 log CFU/g) based on regression curve. But the free-living bacterium only survived for 0.6 min at this limited. As the basil seed mucilage concentration increased, the bacterial survivability was increased under salt and acidic conditions. The microcapsulated form survivability time (7.5 min) was greater than free form (2.5 min). The rate of acid production and bacterial growth in the microencapsulated form was slower than the free bacteria.