Experimenting With Yeast Fermentation Using Temperature

Methodology and Procedure & Discussion and Analysis-Rosemary Cornella
Introduction & Data and Results-Annie Gipson

Introduction-Annie Gipson

The purpose of this lab is to show how different temperatures affect the fermentation of yeast. The definition of fermentation is the chemical breakdown of a substance by bacteria, yeasts, or other microorganisms. It results in the breakdown of carbohydrates and other substances into simpler substances. Yeasts get their energy from fermentation. Yeast fermentation results in bread, wine, and beer. Our experimental question was "Will different temperatures affect the fermentation of yeast?" The independent variable in this experiment was the yeast solution. The dependent variable was the level the yeast solution was at after every test. Our control variable was the yeast solution level before it fermented, which was 7cm. Our hypothesis was "If we put the yeast solution fermenting at different temperatures, then the level of the solution will change." Overall, the point of this experiment was to test how different temperatures affected the amount of yeast fermentation there was at the end of 10 minutes.

Methodology and Procedure

Procedure-Rosemary Cornella

-Test #1

Measured 3g of yeast
Poured the yeast into the test tube
Poured in 25 ML of H20
Mixed solution
Measured 2g of sugar
Poured the sugar on top of solution
Mixed solution
Put two drops on top of solution
Marked when the solution ended on the test tube
Placed solution in room temperature beaker for 15 minutes

-Test #2
Measured 3g of yeast
Poured the yeast into the test tube
Poured in 25 ML of H20
Mixed solution
Measured 2g of sugar
Poured the sugar on top of solution
Mixed solution
Put two drops on top of solution
Marked when the solution ended on the test tube
Placed beaker on hot pad until boiling
Placed test tube in boiling water for 15 minutes

-Test #3
Measured 3g of yeast
Poured the yeast into the test tube
Poured in 25 ML of H20
Mixed solution
Measured 2g of sugar
Poured the sugar on top of solution
Mixed solution
Put two drops on top of solution
Marked when the solution ended on the test tube
Placed test tube in ice cold beaker for 15 minutes

-Test #4
Measured 3g of yeast
Poured the yeast into the test tube
Poured in 25 ML of H20
Mixed solution
Measured 2g of sugar
Poured the sugar on top of solution
Mixed solution
Put two drops on top of solution
Marked when the solution ended on the test tube
Placed beaker on hot pad on low (not boiling but warm) for 15 minutes

Data and Results-Annie Gipson

Written Observations:

• in test 2 the change in solution did not change, and was zero changes in the volume
• when the test tube was warm, the yeast fermented the best
• at ice cold, the yeast barely fermented
• at room temperature, the yeast fermented a little bit, but not as much as the warm test tube.

Discussion and Analysis-Rosemary Cornella

Analysis
The hypothesis was supported by the end results. The results were predicted. The hypothesis was: If the yeast fermentation is tested in different temperatures the level of the solution will change. The results of the experiment show when the temperature of the solution changes the level of solution changes. When the temperatures were extreme-boiling or ice cold- the solution either didn’t change or barley changed. The biggest changes in solution levels were when the temperature the solution was tested at was mildly adjusted-warm not boiling & room temperature. The experiment didn’t have a source of error because the end results supported the hypothesis. Some factors, such as, how old the yeast or sugar was & how long it was exposed to the oxygen were factors out of our control.
New Questions
Why does the temperature change the level of yeast? Why did some solutions rise more than others? What could have made the solution go down?

Works Cited

1. "Fermentation ." How Stuff Works . N.p., 21 Oct. 2008. Web. 13 Feb. 2014. <http://science.howstuffworks.com/dictionary/biology-terms/fermentation-info.htm>.