Effect of some formulation and process variables on properties of alginate -poly L lysine-alginate beads containing Lactobacillus acidophilus

Abstract

Objective: The objective of present study is to evaluate effect of the different parameters on physicochimical properties and viability of Lactobacillus acidophilus in Alginate-Poly l lysine-Alginate beads. Methods: Alginate beads with different concentrations of Alginate were prepared using extrusion method. Poly-l-lysine and Algiante as second and third coats were incorporated on the surface of Alginate beads using immersion technique.The morphological charactristics and the integrity of the prepared beads were investigated using lights microscope and SEM. Bacterial loading was obtained by camparison of bacterial counts in the Alginate gelant and prepared beads.The viability of L. acidophilus with and without coat after exposure to SGJ (pH of 1.5 and 2) before and after lyophilization were investigated. Growth preperties of the beads were also investigated by bacterial counting after exposure to simulated intestinal juice (SIJ) (pH=6.8). Results: Optimum conditions for preparation of circular beads with high integrity and loading (98.7%) were achieved. Survival petcentages after 3hours exposure to simulated gastric juice (SGJ) with pH of 1.5 and 2 were 72 and 79% respectively in camparison with no surviaval in uncoated bacteria. A good growth of bacteria from the beads in SIJ (pH=6.8) was observed with more than 2.5 (log cfu/g) increase during 24 hours. Lyophylized beads showed suitable viability after 3hours exposure to SGJ (69%), followed by a good growth in SIJ (pH=6.8). Conclusion: Preparation of beads of Lactobacillus acidophilus with alginate-poly l lysine-alginate can effeciently protect the bacteria from harsh conditions of GI tract.