Science behind making beer
Purpose
The purpose of this laboratory exercise on October 31, 2012, was to understand the biochemical and physiological processes that produce beer from the model yeast Saccharomyces cerevisiae.
We made homemade beer using a kit commercially available from a business in Austin, TX. The beer is now fermenting on a table in a conference room outside of Dr. Dan Ebbole's office. A beer tasting is planned for the last day of class on November 28, 2012, when we will also present PowerPoints on our unknowns projects. Could make for an interesting day - if not presentations! More pics and details of this exercise to follow!
Directions for making beer:
Directions for making beer:
Results
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| Liquid malt extract tastes a little like dark Karo syrup. |
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| In go some more ingredients. Pictured (left to right) are Wenwei, Sheila and Danny. |
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Stirring
and stirring to dissolve everything. Pictured (left to right) are Wenwei, Xin,
Dr. Dan Ebbole, Pei-Cheng, Danny and Maxwell. Notice the time on the clock on the wall. Yes, it is never too early in the day to MAKE beer at least. |
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Pei-Cheng (back, left to
right), Charity and Xin look on as Chris (front, left) and Wenwei pour the brew
into a carboy.
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| In goes the S. cerevisiae. Shan did the honors. |
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| Microscopic view of S. cerevisiae added to our brew (40X). Photograph cropped and enlarged to show detail. |
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| Making sure we did it right. Checking the specific gravity. The density is spot on. I swear this picture was not posed, but notice the first aid kit in the background. I hope we will not need medical attention from drinking our brew in a few weeks. Sterility was key in making the beer so that we do not grow bacteria along with the yeast. We want the yeast to grow and produce ethanol through a process called fermentation. |
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Time for a
taste. Chris looks on in the background as Sheila takes a swig...
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...and so
does Wenwei from the graduated cylinder used to check the density of the beer. And it wasn't even Noon yet. Remember the clock on the wall?
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A picture
says a thousand words. Shan's face expresses how she liked the taste of beer
made with malted barley and hops, which is not so much. Sorry for the blurry
picture, but she did not stand still for this one.
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Fermenting
in the "dark" in Dr. Ebbole's office. Perfect portrait of a
"headless" brew, especially since this picture was taken on
Halloween. But we are hoping the fermentation will solve that problem.
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| Fermentation was slow to start but had begun within 2 days. Notice the foam on top of the brew from carbon dioxide, which in addition to ethanol is a product of fermentation. See diagram of a S. cerevisiae cell and the biochemical process of fermentation in the Discussion section of this blog. |
Figure 1. Diagram of a S. cerevisiae cell and the biochemical process of fermentation. http://www.responsiblebusiness.eu/display/rebwp7/Yeast+physiology+in+ethanol+production
In addition to making beer and learning about fermentation, we learned about carbon status regulation of gene expression, the sensing of glucose outside a cell, the TCA cycle, a number of terms (basal expression, repression, de-repression, uninduced, induced) and the KEGG Pathway database (http://www.genome.jp/kegg/pathway.html). KEGG stands for the Kyoto Encyclopedia of Genes and Genomes.
In addition to making beer and learning about fermentation, we learned about carbon status regulation of gene expression, the sensing of glucose outside a cell, the TCA cycle, a number of terms (basal expression, repression, de-repression, uninduced, induced) and the KEGG Pathway database (http://www.genome.jp/kegg/pathway.html). KEGG stands for the Kyoto Encyclopedia of Genes and Genomes.
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