SMB AT Kegging

Filtering, fining, bottling, etc

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Ancient Abbey
German Brewing
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Re: SMB AT Kegging

Postby Ancient Abbey » Sun May 08, 2016 7:34 am

There is a difference between using oxygen as the final electron receptor in respiration and using oxygen to produce double bonds to make unsaturated fatty acids for their cell membrane. Crabtree is independent of sterol production.

narcout wrote:Isn't all yeast reproduction in wort anaerobic due to the Crabtree effect? I know some older texts say otherwise, but I thought they had been shown to be incorrect.


If yeast are constantly in anaerobic respiration due to crabtree, then they must be capable of reproducing without the presence of oxygen. Budding is not oxygen limited, but UFA limited. However, crabtree is often misquoted as a absolute on the forums, when its really a continuum. Both the type of sugar and the concentration of the sugar can affect whether the crabtree system is yeast is up-regulated. In any given batch of yeast, not all of the cells can express the crabtree effect. So, during aerobic conditions, there is a large mix of what is going on in the wort, and not all cells will be utilizing the crabtree system. While the proposed mechanism for why this happens has been altered in recent times, my understanding is that the use of the term crabtree simply denotes ethanol being produces during aerobic conditions.

http://www.microbiologyresearch.org/doc ... 2060254A69

http://www.rpi.edu/dept/chem-eng/Biotec ... rload.html

https://www.google.com/url?sa=t&rct=j&q ... 1273,d.cWw
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