Alcoholic fermentation is a metabolic pathway primarily used by yeasts and some bacteria (Kenyon 142). In it, glucose forms three products: Ethyl alcohol (ethanol), carbon dioxide and ATP. This process is enzyme catalyzed and so the outcome can be dependent on any of the three factors that affect enzyme activity.
The purpose of the experiment was to measure the fermentation rates of a malt extract and compare this with the rates of the highly concentrated corn syrup. The experiment calls for use of a single-celled fungus that contains is capable of breaking down glucose by alcoholic fermentation (yeast). In the first setup, corn syrup was to be the substrate and by mixing variable amounts of each, the rate of alcoholic fermentation was recorded by the amount of carbon dioxide collected. The other setup used malt extract in variable amount similar to the ones used in the corn syrup. Before the experiment, it was hypothesized that the malt extract with the most yeast suspension would produce the most CO2 product because of maltose’s chain of dual glucose molecules.
Materials and Methods
We needed six fermentation setups which would give us three for corn syrup and three for maltose. Each tube was labeled and set aside to prevent confusion later on. A tub filled with hot water was needed to catalyze fermentation. In order to transport the carbon dioxide from the fermentation tube to the water-filled tube, we inserted the end of a plastic tube into one of the test tubes designated for collecting carbon dioxide. That tube was later submerged in the hot water. The apparatus used to hold the test tube was a test tube holder. The water level was affirmed to be 1 cm from the bottom of test tube so as to keep the pressure inside the test tube. Before recording began, it was necessary to check the plastic tubes for kinks and rectify it. The tubes were filled with varying amounts of extract and water. Tube 1 contained 4mL of water and 0mLyeast suspension. All the tubes for the corn syrup experiment contained 3mL of corn syrup. Tube 2 contained 3mL of water and 1mL yeast suspension. Tube 3 contained 1mL water and 3mL yeast suspension. The exact same amount of each constituent and tubes were used in the maltose version of the lab (substituting maltose for the corn extract). The test tubes were then agitated to mix the reactants and then plugged with a rubber stopper to exit any remaining water out of the tubing. The beginning level of the water in the CO2 collecting tube was marked as the baseline to begin recording data. The experiment was 30 minutes long for both the corn syrup and the maltose extracts. At 5 minute intervals, the distance from the baseline to the water level was marked and recorded. All data was in millimeters. After 30 minutes, the tubes were measured for the final distance and recorded in the subsequent tables.
Results
The results from the corn syrup experiment can be found in table 1A. It was discovered that the amount of carbon dioxide was dependent on the amount of yeast suspension in the solution. The control tube proved to be useless with no fermentation recorded. Table 1B contains the maltose results. From these figures, we see an increase in fermentation as the yeast amount is increased as well. Again, we see the control tube garner no carbon dioxide for the 30 minute experiment.
Table 1A – Results of Fermentation Experiment (Corn Syrup)
Table 1B – Results of Fermentation Experiment (Malt Extract)
Figure 1A – Results of Fermentation Experiment (Corn Syrup)
Figure 1B - Results of Fermentation Experiment (Malt Extract)
Discussion
The experiment was carried out with little to no flaws and whatever one group member may have overlooked was caught by the others. In looking at the results, it complements both the literature findings and our hypothesis. The tubes with the greatest carbon dioxide readings had more yeast to break down the glucose in the mixtures. Inversely, the control tubes were setup in order to verify this assumption that the yeast is the cause of fermentation. No readings were found on both the 0mL corn syrup and the 0mL malt extract.
The question posed by this particular experiment was whether or not the malt with 3mL yeast would ferment faster and collect more carbon dioxide. According to our data, it doubled the numbers found in the corn syrup experiment. This can probably be attributed to the maltose property of two glucose molecules per link and mathematically, our results are sound. Overall, the higher concentration of yeast yielded the higher carbon dioxide product made.
We hypothesized that the malt extract with the 3mL of yeast would produce the most CO2 product and we were correct. The trend from the graph shows that any amount greater than zero would have yielded some carbon dioxide so it was appropriate to state an estimate amount in our hypothesis.
Works Cited
Kenyon, Lisa O. 2003. Symbiosis: Introductory Biology Laboratory Manual. Pearson
Custom Publishing, Inc., Boston.
Campbell, Neil A. 1996. Biology. The Benjamin/Cummings Publishing Company, Inc.,
California.