Microbiology and Biochemistry: Difference between revisions
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==Saccromyces dominance== | ==Saccromyces dominance== | ||
After the pH falls below ~4.5 and the alcohol content rises over ~2%, Saccromyces species take over as the dominant organisms in the wort, though Saccromyces is present in large numbers well prior to the dissapearance of the enterobacteria. Saccromyces will remain dominant until at least 8 months into fermentation, and | After the pH falls below ~4.5 and the alcohol content rises over ~2%, Saccromyces species take over as the dominant organisms in the wort, though Saccromyces is present in large numbers well prior to the dissapearance of the enterobacteria. Saccromyces will remain dominant until at least 6-8 months into fermentation, and will maintain a presence, though no longer active, throughout fermentation. Despite Saccromyces' importance to the fermentation of Lambic, its concentrations remain below 10^7 cells per mL of wort, which is considerably lower than the 10^8 cells/mL found in commercial beers [6]. | ||
As in controlled fermentation, Saccromyces is responsible for most ethanol production and attenuation in lambic. The yeasts consume all the major sugars found in lambic wort (glucose, maltose, and | As in controlled fermentation, Saccromyces is responsible for most ethanol production and attenuation in lambic. The yeasts consume all the major sugars found in lambic wort (glucose, maltose, and some maltotriose). By the end of the Saccromyces phase around 8 months, the ethanol content of the beer stabilizes at 5-7% by volume and will remain around that value until the end of fermentation[5,7]. Attenuation after Saccromyces fermentation reaches 60-65%, which is known as the "attenuation limit" for conventional beers. Despite being responsible for most of the ethanol in Lambic, yeasts of the Saccromyces genus are not responsible for most of the aroma and flavor compounds that give Lambic its distinct sensory characteristics. | ||
Other bacteria and yeasts also thrive during the Saccromyces phase. Kloeckera and ____ both survive in considerable numbers alongside Saccromyces. In the case of Kloeckera, the growth begins prior to Saccromyces in the first days of fermentation, but are overgrown by Saccromyces in the following weeks. | Other bacteria and yeasts also thrive during the Saccromyces phase. Kloeckera and ____ both survive in considerable numbers alongside Saccromyces. In the case of Kloeckera, the growth begins prior to Saccromyces in the first days of fermentation, but are overgrown by Saccromyces in the following weeks. |