When Life Gives you Lemons, Add Them To Yeast. The Effects of varying pH Additives on Saccharomyces cerevisae.

Carlie Caldwell, Noah Brown, Jacob Martin, Sarah Belden, Ryan Grewe


Saccharomyces cerevisiae is a type of yeast which is used for brewing alcohol. We wanted to study the effects of differing pH on the production of ethanol from the yeast. We predicted that at a lower pH, the yeast’s production of ethanol would be inhibited, consequently not forming ethanol. To test this, in all trials we mixed small concentrations of water, sodium phosphate, sugar, and the yeast in a biochamber, for our experimental trials we added lemon juice to lower the pH and baking soda to heighten the pH. Our final pH values in the experimental groups were 4 for the lemon juice trials and 10 for the baking soda trials, as compared to 6 for the control groups. Using an ethanol probe, we measured the amount of ethanol production over our time intervals of 15 minutes after a 5 minute lag period. Our results showed us that at lower a pH, an acidic environment, the yeast produces more ethanol, approximately 0.0058 ppm, which opposed our hypothesis. In the future, our research could be used to study the exact process of fermentation at varying pH levels as well as to study how yeast could be utilized as a biofuel. 

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