Celik, Omer F.2013-10-182013-10-182013-07https://hdl.handle.net/11299/158514University of Minnesota M.S. thesis. July 2013. Major: Food science. Advisor: Daniel J. O'Sullivan. 1 computer file (PDF); vii, 101 pages.Using trehalose as the cryoprotectant, a freeze-drying protocol with almost no loss of viability was developed for stress-sensitive strains of bifidobacteria. The resilience of B. animalis subsp. lactis Bb-12, a common probiotic used in food products, to a wide range of storage conditions was demonstrated while a stress-sensitive strain, B. longum DJO10A, required optimum conditions of frozen storage, water activities controlled between 0.11 and 0.22 and replacement of oxygen with nitrogen to maintain viability. The predicted models based on genome sequences for the folate biosynthetic abilities of several bifidobacteria were examined and the accuracy of these models for the tested strains was functionally evaluated. This study indicated that some bifidobacteria have potential to supplement folate while some can act as folate scavengers, including strain Bb-12. To maintain adequate dietary folate intake it may be conceivable to include additional folic acid in foods containing high levels of folate depleting bifidobacteria.en-USThesis or Dissertation