Lactobacillus acidophilus NCFM is a probiotic culture widely added to dairy products and dietary supplements. The bacterium has been linked with immune modulation, cold prevention in humans, and relief of gut pain via a morphine like mechanism in animals. Industrially, the target for delivery of viable cells in a 6 oz. serving of yogurt at the end of a 52 day shelf-life is 2 x 106 CFU/g. Survival studies with an industrial yogurt formulation showed that counts of NCFM fell to less than 102 CFU/g at the end of shelf-life. The objective of this study was to investigate the reasons for the dramatic loss of viability during shelf-life, and define a solution that could maintain viability throughout shelf-life. Levels of NCFM were followed in fermented yogurts at pH 4.1, 4.7 and 5.0. Results showed that with inoculation levels of 108 CFU/ml, NCFM added at the outset of fermentation maintained survival in yogurts acidified at pH 4.7 and 5.0. NCFM showed poor survival in yogurts acidified to pH 4.1, exhibiting a 3 log loss after 48 days. The possible effects of cell injury in lyophilized Lb. acidophilus NCFM cells were also investigated. Cells subjected to a 60 minute resuscitation period in MRS media, prior to addition to acidified yogurt base at pH 4.1, showed only a ~1.5 log loss after 42 days. Survival of NCFM in yogurt was compromised at acidic conditions below pH 4.7 and a recovery period of the lyophilized cells can greatly improve survival.
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-11072008-084635 |
| Date | 02 December 2008 |
| Creators | Trahan, Caitlin Elizabeth |
| Contributors | Dr. Ilenys M. Perez-Diaz, Dr. Trevor G. Phister, Dr. Todd R. Klaenhammer |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-11072008-084635/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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