Influence of prebiotic and coating materials on morphology and survival of a probiotic strain of Lactobacillus casei exposed to simulated gastrointestinal conditions

Inulin type fructans are among the most studied prebiotics that contribute to enhance gastrointestinal system conditions. To improve the survival and stability of probiotic Lactobacillus casei, native inulin, long-chain and short-chain inulin, were separately incorporated into alginate and chitosan coated alginate beads during the microencapsulation of bacteria. Morphology, particle size and viability of different beads were measured before and after exposure to simulated gastro-intestinal condition. Application of inulin, with different chain lengths, did not alter the shape and size of alginate/inulin beads (2.25–2.28 mm) but slightly increased the size of chitosan-coated beads (about 2.9 mm), while the diameter of micro particles containing alginate alone was 2.2 mm. When alginate beads were exposed to the simulated gastric solution, their size was significantly decreased (by about 0.2 mm), while the size of chitosan-coated beads was not affected. Using inulin and chitosan-coating, the survival of co-encapsulated cells in simulated gastro-intestinal condition was improved with only 2.7–2.9 logs reduction for L. casei and long-chain inulin showed the highest survival rate (2.7 log reduction).