The Effect Of Ph On Yeast Fermentation Essay

1573 Words Jan 25th, 2016 7 Pages
In the observer’s experience apples are less acidic then oranges and both are less acidic then lemons, and this pattern continues with sweetness. Additionally, many cellular processes are affected by the pH of the environment in which they taker place. Because fruits contain a high sugar content, it was theorized that the extracts of these fruits could be used as a source of energy for Saccharomyces cerevisiae. By measuring the rate of fermentation of the yeast given these fruit extracts, the relative acidities of these fruits could be tested. One method to measure the rate of fermentation is to use gas pressure sensors to measure the rate of gas production by the yeast while sealed from the air by oil.

It was hypothesized that the apple would have the highest rate of fermentation and that the lemon would have the lowest rate of fermentation with the orange somewhere in between. Though it is generally accepted that pH effects most cellular functions, it is necessary to know how pH effects yeast fermentation specifically. According to a study published in 2009, the optimal pH of S. cerevisiae is around 4, and their growth falls at either higher or lower acidities ( Arroyo-López, F. N., Orlić, S., Querol, A., & Barrio, E, 124, 2009). This change in rate of growth is likely connected to a change in rate of fermentation. Therefore by raising or lowering the pH from 4 you could raise or lower the rate of fermentation. This change should be observable in fruit extracts, as they…

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