Microencapsulation effect on the survival rate of Lactobacillus casei in simulated gastric and duodenal conditions and heat treatment

It has been proved that microencapsulation by probiotics have positive effect on the abilityof tolerating the simulated gastric and intestinal condition. One of the most important factors in reducing the viability of probiotics passing through the stomach and digestive system is the presence of proteases and bile salts and also lowpH. To enhance the viability of Lactobacillus casei PTCC 1608in the condition of human intestinal system, it was microencapsulated by calcium alginate and covered by chitosan. To determine the size of microencapsulates, the average size was measured using an image analysis software. Microcapsules wereput in simulated conditions at intervals of 0, 15, 30, 60 and 120 minutes at 37 °C. The amount of viability was calculated. The results showed that microencapsulation with calcium alginate reduces the amount of damage to the bacteria in the presence of pepsin in the simulated gastric conditions ((pH: 2, followed by simulated intestinal conditions in the presence of pancreatin and bile salts (pH= 7/5). Microencapsulation with calcium alginate and chitosan coating caused the population of microencapsulated bacteria get to 108 cfu/ g after passing the simulated condition to stomach and intestine system, though thin number for the free bacteria in this condition was 104cfu / g (p< ./ 05). Also the thermal resistance of free bacteria and encapsulated bacteria at 50 °C had no significant difference, but at 55 and 60 degrees maximum in less than 15 minutes, microencapsulation can have a protective effect on bacteria .Considering the swelling of the microencapsulated particles, particles dried via freeze drying had arate of inflation higher than those dried particles exposed to the airAnd alginate particles have more water absorption and inflation rare compared to alginate particles coated with chitosan.