Apple Fermentation Essay

1573 Words 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
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As seen in figure 2.1 and 2.2, the mean rate of fermentation for the apple extract was .033, for the orange was .023, and for the lemon extract was zero. The hypothesis was also supported by the qualitative data. The bubbles seen in the test tubes were carbon dioxide, one of the byproducts of alcoholic fermentation, so the production of more of them would indicate a higher rate of fermentation. This would seem to indicate that lower pH leads to lower rate of fermentation. This would suggest that their is an optimal pH for the fermentation of sugars by yeast, and that any other pH would negatively affect its rate of fermentation. This is supported by a study by Arroyo-López, F. N., Orlić, S., Querol, A., & Barrio, E which found the optimal pH of S. cerevisiae to be around 4 ( Arroyo-López, F. N., Orlić, S., Querol, A., & Barrio, E, 124, 2009). Additionally, the FDA marks the pH of apples at 3.4-4.0, of oranges at 3.1-4.1, and of lemons at 2.2 - 2.4 (FDA, 2015). The results collected would indicate that the orange was on the lower end of orange pH as its rate of fermentation was significantly lower, that the apple extract likely had a pH right around 4 because it had such a high rate of fermentation, and that the lemon was likely on the low end of its pH as no fermentation was observed. This also supports the observer’s opinion that apples are less acidic …show more content…
The first way would be to simply repeat the investigation with more replicates. This would likely lead to anomalous data, such as apple extract replicate 3, to have a much smaller effect on the end result, and would increase the significance of the data. Another way would be to test more fruits to see whether they also follow the trend. This would be especially interesting in the fruits with a pH greater than 4, as all fruits tested had a pH less than 4 or equal to 4.
Evaluation:
Evaluating the procedure – this paragraph section discusses how well your experimental design helped answer your experimental question. What worked well (and why) and what did not work well (and why). This must be a worthwhile evaluation of the method chosen, rather than a superficial commentary on poor lab techniques and sloppy work. “I should measure more accurately” is a problem with your practical skills, rather than the method of investigation.
Did you record any anomalies in your practical work? How did they affect your results and what did you do to minimize their adverse effects?
What weaknesses were present in the method chosen for the investigation and how could they have affected the

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