Selenium (Se) is an essential element. Supplementation of Se as yeast-Se in animal and human diets has been proven to have beneficial health effects. The goal of this study was to add a maximum amount of Se in yeast metabolism in order to optimize its incorporation in amino acids. A bakery yeast strain of Saccharomyces cerevisiae (S. cerevisiae) was studied for its tolerance to Se when the latter was incorporated at different levels. Fermentations were run at 27°C for 8 h and 24 h. The maximum Se incorporation was achieved when 12.6 mmol of Se, as sodium selenite salt, was added to the culture medium and fermented for 24 h. A final Se concentration of 1550 +/- 35 mug/g yeast was obtained by this treatment. / Different yeast strains of S. cerevisiae were also studied for their capacity to incorporate Se. Five yeast strains of wine and four yeast strains of beer were fermented for 24 h and tested for their capacity to incorporate Se. The amount of 12.6 mmol Se was added in the growth medium. A maximum of 642.6 +/- 3.6 mug Se/g yeast was found to be incorporated in Uvaferm BC wine strain. Uvaferm windsor of beer strain was able to incorporate a maximum of 826.8 +/- 10.4 mug Se/g yeast. These yeast strains could be used as alternatives for Se supplementation. / Se speciation was carried out on the bakery yeast strain containing 1550 +/- 35 mug Se/g yeast, using Fast Phase Liquid Chromatography (FPLC) and amino acid analysis. Out of 1550 +/- 35 mug Se/g yeast, 57.5% Se was present as selenoaminoacids. The yeast extract contained 147 +/- 14 mug/g of SeCys, 248 +/- 13 mug/g of SeCyst and 295 +/- 17 mug/g of SeMet. Yeast cell walls contained 65 +/- 8 mug/g of SeMet; 69 +/- 5 mug/g of SeCyst and 67 +/- 9 mug/g of SeCys. These selenoaminoacids are known for their beneficial health effects. The produced Se-enriched bakery yeast could be used, after evaluated to be toxicologically safe, as an efficient dietary supplement.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.37890 |
| Date | January 2001 |
| Creators | Ferhane, Akila. |
| Contributors | Chan, H. M. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Food Science and Agricultural Chemistry.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001847605, proquestno: NQ75631, Theses scanned by UMI/ProQuest. |
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