Investigation of physicochemical properties of Lactobacillus ruteri microorganism coated with two layers of sodium alginate and mastic gum( Pistacia atlantica subsp. kurdica)

The aim of this study was to microencapsulate Lactobacillus reuteri using two-layer extrusion technique consisting of sodium alginate and mastic gum at concentrations of 0.2, 0.4, 0.6 and 0.8%. Physicochemical properties and survival ability of free and microencapsulated form during the storage and similar gastrointestinal conditions were evaluated. The results showed that, the produced beads were spherical in shape. By increasing the concentration of the mastic gum, the diameter of the beads increased significantly, but the L* parameter decreased. All free and microencapsulated form were reduced at 72° C. While, the beads had a longer shelf life than the free bacteria. The free bacteria and the microencapsulated form decreased during the storage and under the simulated gastrointestinal conditions. The reduction of the free form was 6.2 Log CFU/ml, which was much higher than the beads )2.58 Log CFU/ml(. Free bacteria had a minimum of 106 CFU/ml probiotic bacteria in the MRS broth after 20 days. While this time for the beads was 30 days in 4° C. The results of this study showed that the use of mastic gum could increase the shelf life of Lactobacillus reuteri under harsh conditions.