At present, people know a lot about the benefits of functional foods, and a large part of the food bazaar has been allocated to this group of foods. The functional foods which contain probiotic microbes are more favourable. To achieve the beneficial effects, a minimum of 6 Log cfu/mL should be colonised in the epitellial cells in colon. Microencapsulation technology is one of the suggested methods to protect the probiotics, against the harsh conditions of food process, storage and gastrointestinal fluid. Simulation of different stresses' effects during the food processing on the microcapsules seems necessary to estimate the usability of the microcapsules in different products and during the storage time. Because of this, selection of a suitable bed with specific characteristics similar to the food should be considered. Also it is essential to study the survival ability of native species against the processing stresses to improve the beneficial effects of peobiotics on the consumers. In this project, after optimization of the microencapsulation method, the microcapsules were prepared and photographed by Reflection optical microscopy and Scanning electron microscopy (SEM) to characterise their morphological characteristics, and finally the optimum process parameters were introduced. Afterwards native Lactobacillus plantarum A7 and commercial Lactobacillus casei ATCC 39392 were simultaneously encapsulated and then 1g of both microencapsulated cultures were separately transferred to distilled water and skimmed milk to evaluate their stability and release rate of the cells to different processing environments. At the same time Non-encapsulated cells with the same ratio were studied too. The results showed that 200 rpm, 20' aggitation time for emulsion forming and 5' aggitation time for capsules forming, were the best. The microcapsules had spherical shape with a smooth surface. Totally L. plantarum had a good stability to different processing conditions and during storage period compared with the commercial L. casei. In this study skimmed milk medium because of its protein and sugar contents had better protective effects to the stresses (except homogenization)in comparison with distilled water. Since skimmed milk is the base of dairy products, It could be said that dairy products are appropriate beds for the encapsulated probiotics. This bed can also protect the structure of microcapsules. Among the exerted stresses 90ْ C and pH 3 were the most fatal stresses
