Yeast and Ethanol Production: How Different Amounts of Sugar Affect the Ethanol Output

Lauren Walley, Dakota Taylor, Oakley Winters, Sarah Hileman


Yeast produces ethanol in an anaerobic process called fermentation, and many outside factors, such as sugar, have an effect on how much or how little ethanol is produced during this process. Our hypothesis stated that increasing the amount of sugar (dextrose) added to yeast would in turn increase the production of ethanol, yet if too much sugar was added (>1.6g), the ethanol output would begin to decrease due to the denaturing of the amino acids in the yeast. We predicted that lowering the concentration of water yet keeping the sugar concentration the same will positively affect how much ethanol is produced. If our hypothesis is supported, this can greatly impact how we produce biofuels in the future using yeast and ethanol production. Our experiment included starting with a control group of yeast in 250mL of water with no sugar added and then testing other groups with various amounts of the sugar, dextrose, added in to see how this affected the output of ethanol. We also ran trials with various different amounts of water, keeping our sugar concentration constant, to see if this changed the production of ethanol. Our results supported our hypothesis, showing that up to a certain point, excess sugar added increased the ethanol production in the yeast. When the sugar concentration became too high or exceeded 1.6g, the output of ethanol began to decrease with higher amounts of sugar added. Our research also supported our prediction that the lower the water concentration, the higher the ethanol output. This research provided results that will help future studies about how the production of ethanol in yeast could help further the production of functioning biofuels. Our research is novel due to the fact that along with testing the effects that the sugar concentration has on yeast and ethanol output, we also tested the effects that various concentrations of water had on the production of ethanol.

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