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Originally Posted by gweed
Will the yeast increase my yield levels or not?
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Quote:
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Originally Posted by gweed
My yield levels means the amount I end up with
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Are you asking if the yeast will give you more consumable beer (yield) as an end result?
The yeast produce two main things, ethanol and carbon dioxide [C6H12O6 → 2 C2H5OH + 2 CO2]. The yeast are eating sugars dissolved in an aqueous solution. These sugars add X amount more volume. Lets look at CO2 and C2H5OH separately. When the yeast produce carbon dioxide they consume X amount of volume of sugar and produce Y amount of CO2 gas which will eventually come out of solution and create a lesser total volume. Now the ethanol. When the yeast consume X amount of sugar, they'll produce Y amount of ethanol. Since ethanol is less dense than water, Z amount of ethanol (in weight) takes up more volumetric space than Z amount (in weight) of water or beer. This will account for a larger total volume. Since [(CO2)Y
volume] ≠ [(ethanol)Y
volume], it isn't an even exchange. But, since the amounts are negligible, I'd say the answer to your question is no. If anything you'll lose more due to the aqueous nature of the yeast cake at the bottom of the fermenter.
I figure I must also point out the yeast themselves and the space that they take up. During the aerobic respiration cycle, the yeast replicating like crazy. All these new yeast cells take up space. Thus creating a larger volume. But they eventually fall out of suspension, and form the cake at the bottom of the fermenting vessel. I'd like to reference this handy graph:
Now, if you can imagine a mirror image of the graph where the line is in a rightward downward slope. This will account for the total amount of yeast in suspension over time as you let the beer sit after anaerobic respiration has come to an end. The volumetric space that the yeast take up in your beer gets lesser and lesser as they fall to the bottom and form the "cake". Again, the results are almost negligible. So my answer is still no.