More or less? Testing the Ethanol Levels of Saccharomyces cerevisiae When Mixed with Sucrose, Starch, and Dextrose

Cazzady Griffith, Coree' Green, Jared Croston, Heather Hampton, Teri Cocke


Yeast, more specifically Saccharomyces cerevisiae, plays a vital role in various different processes, such as making baked goods, beer, as well as industrial ethanol. Yeast breaks down many sugar compounds in order to create an increase in the amount of CO2 being produced. The increase in the amount of CO2 being produced leads to there being an increase in the amount of ethanol produced and also an increase in the rate of fermentation. We hypothesized that monosaccharides, such as dextrose, would have a greater increase the overall production of ethanol when compared to disaccharides (sucrose) and polysaccharides (starch) because it is a simple compound that allows the yeast to easily break it down. In order to test the hypothesis, we mixed 2.0 g of each type of sugar into 78 mL of deionized water adding 160 μL of 0.5M sodium phosphate as well as 2 mL of S. cerevisiae. A total of 9 fifteen-minute trials were run, 3 trials for each type of sugar. Our hypothesis was not supported as it showed sucrose, the disaccharide, had the highest rate of ethanol production when compared to dextrose, the monosaccharide, and starch, the polysaccharide.

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