Viability of L. casei during microencapsulation in chitosan-Ca-alginate microparticles and in simulated in vivo conditions

Viability loss of probiotics in pharmaceutical and food products and during the passage in the upper gastrointestinal tract has always been an obstacle for effective delivery of bacterial cells able to colonize the intestine. Microencapsulation has shown to be efficient method in preserving probiotic’s viability. The aim of this study was to evaluate the survival rate of L. casei during microencapsulation and in simulated in vivo conditions after incorporation in chitosan-Ca-alginate microparticles enriched with fructooligosaccharide as prebiotic. The initial cell population before encapsulation was 2 x 1011 cfu/g. High cell entrapping, within the therapeutic value, in the particles was achieved (3,2 x 1010 cfu/g). Narrow size distribution of the particles was observed (d50% of 18,42 μm; PDI 0,155), with production yield of approximately 40%. When comparing the viability of L. casei after spray-drying alone or with alginate and fructooligosaccharide, increased survival in the microparticles for 4 log was observed. After incubation in simulated gastric (3h) and intestinal juices (6h), the number of viable cells decreased for 3,8 log and 3,6 log for microencapsulated cells, and for 7,2 log and 6,3 log for the free cells, respectively. No significant difference in viability between the free and encapsulated cells in simulated colonic pH was observed. The presented microencapsulation method and formulation of microencapsulated L. casei shows potential for effective preservation and targeted release of viable cells in the colon. Further studies are needed for optimal formulation to be prepared and in vivo effects of the probiotic to be confirmed.