The Effects of pH level on the Ethanol Emission of Baker’s Yeast

Blake Chlouber, Bailey Beach, Lindsie Bortka, Jie Ren


Our investigation began with the sole purpose to discover how the change in pH level effects the growth rate of Baker’s yeast (Saccharomyces cerevisiae). The change we decided to test was the pH level on the ethanol emission of the yeast. In our procedure, we had our control, which consisted of 0.13 grams of Baker’s yeast (0.33%) and 2.00 grams of table sugar (5%) mixed with 40 ml of deionized water with a neutral pH level of ~7.09. Our experimental group included the change in the pH level by increasing and decreasing the added solution to ~8.99 and ~5.07 respectively, and used the same mixture of 0.13 grams of Baker’s yeast, 2.00 grams of table sugar and 40 ml of the new solution was then added to the small biochamber. The results of our experiment have shown that there was no significant change in ethanol emission when a solution with a pH level of ~8.99 was added and a lower pH level of ~5.07 actually sped up the process of fermentation and produced a higher amount of ethanol emission of the course of 20 minutes. The results concluded that a higher pH level actually slows down or completely stops the process of fermentation all together while a lower pH level will both increase the ethanol emission of yeast and speed up the process of fermentation.

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