Studies on the Acid-base Tolerances and Release Propertiesf Lactic Acid Bacteria Encapsulated in Polysaccharidesnder Simulated Gastrointestinal Conditions
Date Issued
2009
Date
2009
Author(s)
Wang, Chen-Gang
Abstract
In this study, sodium alginate, cellulose acetate phthalate (CAP) and chitosan wereused for encapsulating Lactobacillus plantarum, one species of the lactic acid bacteria(LAB). Survival ratio of the encapsulated LAB in simulated gastric fluid and intestinalenvironments were examined. Improvements of survival ratio were expected from encapsulation of LAB. There were two types of encapsulated products. One was calcium alginate-chitosancomplex beads. The effects of cell load, beads with alginate double coating, different encapsulating methods, different molecular weight of chitosan and concentrations of calcium chloride were investigated. It was noted that raising in cell load could increase the number of survival LAB after 2 hour incubation in simulated gastric condition, but the survival ratio would decrease. If the encapsulated beads were coated with one more alginate layer, viability of encapsulated LAB could further increase. The calcium alginate beads coated with chitosan could significantly add chitosan in the beads, so LAB encapsulated in these beads would have higher viability after incubated inimulated bile solution. The different concentrations of calcium chloride would also affect the survival ratio of encapsulated LAB after gastric and bile test. The encapsulated LAB in all types of beads would release in intestinal environment after about 6 to 10 hours. The other type of encapsulated products was double-layer powder. The inner layer of powder was used CAP or chitosan, and the outer layer was CAP or sodium alginate. The sedimentation abilities of inner layer materials, CAP and chitosan, were investigated, and the survival ratio of encapsulated bacteria was evaluated under simulated gastric and intestinal environments. The result showed CAP and chitosan could also coprecipitate with bacteria, increasing the load of LAB in powder. The increment of concentration of coating CAP could increase the survival ratio after 2 hour incubation in simulated gastric fluid. Moreover, sodium alginate, which was the same as CAP, could also protect encapsulated LAB in gastric environment, and the sodium alginate had better result than CAP. After 2 hour in simulated bile solution, the powder used chitosan as inner layer had better survival results of encapsulated LAB. In addition, the encapsulated LAB could release in simulated intestinal solution after 4 to 6 hours.
Subjects
lactic acid bacteria
sodium alginate
cellulose acetate phthalate
chitosan
encapsulation
Type
thesis
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