Effect of Immobilization in Alginate on the Stability of Freeze-Dried Bifidobacterium longum

抄録

Bifidobacteriumlo ngumR O23 was immobilized in calcium alginate gels and freeze-dried. The effects of immobilization, storage temperature and composition of the protective solution were studied. High mortality (two log reduction in viable count) was observed when a concentrated culture was immobilized and immediately freeze-dried. Such and immobilization procedure also reduced stability during storage at 20° C. This feature was strain/species related, as immobilization in alginate beads was not detrimental to the survival of Lactococculsa ctisR O58 and Lactobacillusrh amnosus RO11 to freeze-drying, but influenced negatively Streptococctuhse r mophiluRsO 57. Alginateand calcium chloride, used in the immobilization process, were not responsible for the high mortality of immobilized B. longum RO23. Bifidobacteria grown in the alginate beads did not produce high post-lyophilization mortality, suggesting that freeze-drying the culture immediately following immobilization was the cause of the high mortality, and exposing the cells to a growth medium between immobilization and freeze-drying may allow recovery. Whey-based protective solutions that are mixed to the alginate beads were more effective than milk-based solutions in protecting the immobilized cells against mortality during freeze-drying.