The Effects of Ethanol Production on Different Sugar Complexities in Yeast

Thomas McGrath, Kinslee Jones, Braydn Little, Luke Marshall, Bobby Bowser


Baker’s yeast, through the process of fermentation, utilizes sugars to produce ATP, and in the process releases ethanol and CO2. Many other factors can also influence ethanol production in yeast, such as 02 availability and sugar complexity. We hypothesize that more complex sugar molecules will result in decreased ethanol production, because during 10-minute time trials the yeast will break down complex sugar molecules less efficiently. Our experiment started with our control group, which was the yeast in deionized water with no sugar. This is considered a negative control and assured our equipment was working properly. In the control, we added 0.13 grams of yeast to 40 mL of deionized water after it agitated for one minute and then collected ethanol production over a 10-minute period for three trials. The 0.13 grams of yeast made a 0.325% yeast per 40mL solution. After this, we began testing ethanol production based on sugar complexity. We added 0.13 grams of yeast to 40 mL of dextrose, lactose, and starch solutions, and measured each sugar’s ethanol production for three 10-minute trials. The dextrose solution saw an increase in ethanol production because of its less complex sugar molecules, while the lactose and starch had very little ethanol production because of its increased sugar complexity. Our results supported our hypothesis, but there was not a statistical significance between the control group, lactose, and starch. In our bar graph, the standard deviation bars showed that the dextrose was significantly different from starch and lactose, suggesting that the more complex sugars, starch and lactose, were harder for the yeast to utilize and turn into ethanol.

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