| 1. |
- Hjortmo, Sofia, 1978, et al.
(författare)
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Biofortification of folates in white wheat bread by selection of yeast strain and process
- 2008
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Ingår i: International Journal of Food Microbiology. - : Elsevier BV. - 1879-3460 .- 0168-1605. ; 127:1-2, s. 32-36
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Tidskriftsartikel (refereegranskat)abstract
- We here demonstrate that folate content in yeast fermented food can be dramatically increased by using a proper (i) yeast strain and (ii) cultivation procedure for the selected strain prior to food fermentation. Folate levels were 3 to 5-fold higher in white wheat bread leavened with a Saccharomyces cerevisiae strain CBS7764, cultured in defined medium and harvested in the respiro-fermentative phase of growth prior to dough preparation (135-139 mu g/100 dry matter), compared to white wheat bread leavened with commercial Baker's yeast (27-43 mu g/100 g). The commercial Baker's yeast strain had been industrially produced, using a fedbatch process. thereafter compressed and stored in the refrigerator until bakings were initiated. This strategy is an attractive alternative to fortification of bread with synthetically produced folic acid. By using a high folate producing strain cultured a suitable way folate levels obtained were in accordance with folic acid content in fortified cereal products.
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| 2. |
- Hjortmo, Sofia, 1978, et al.
(författare)
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Growth rate and medium composition strongly affect folate content in Saccharomyces cerevisiae
- 2008
-
Ingår i: International Journal of Food Microbiology. - : Elsevier BV. - 1879-3460 .- 0168-1605. ; 123:1-2, s. 93-100
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Tidskriftsartikel (refereegranskat)abstract
- Folate content in a Saccharomyces cerevisiae strain was monitored during aerobic batch fermentation in synthetic growth medium, yeast peptone dextrose medium, and a molasses based medium. During growth in the synthetic medium large differences in intracellular folate content was observed at different phases. Specific folate levels, expressed per unit biomass, were highest during respiro-fermentative growth (120 mu g/g) and decreased during the respiratory and stationary phases. Thus, the physiological state of the cells clearly affects the folate content. This was confirmed in chemostat Cultures where total intracellular folate content increased linearly with increasing growth rate (r(2) = 0.998), indicating high growth rate i.e. respiro-fermentative growth to be most favourable to obtain high specific folate content. In complex media however, much lower folate content (15-40 mu g/g) was found throughout the batch growth. Only minor growth-phase related differences were detected. This shows the impact of cultivation medium on folate content in yeast. To further investigate which components that influence folate content, batch experiments in synthetic medium with addition of specific components were performed. Adding a raw mixture of peptides and amino acids (peptone) decreased folate levels extensively (90%) whereas adding amino acids one-by-one only had minor effects on the intracellular folate content. Furthermore, supplementing synthetic medium with pABA, folate or nucleotides did not change the intracellular folate content. This work constitutes the first steps towards an optimised process for production of natural folates for fortification Purposes, as well as an effort to gain fundamental understanding of folate requirements in yeast in relation to environmental conditions.
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