At-Home Fermentation

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FERMENTATION LAB

PART A – MEASUREMENT OF THE FERMENTATION RATE IN YEAST

SECTION A: ALCOHOL FERMENTATION IN YEAST

This At-Home Procedure replaces the procedures found in your Lab Manual, Lab 7: Fermentation Lab pg. 4 – 6 . To complete the lab this week, you must conduct ONE of the following exercises: Substrate Variation OR Environmental Influence and take photos of your experimental setup (as requested in the procedures). These two photos will be uploaded to Blackboard (jpg or PDF only). You will then graph the results of your experiment and scan and upload that graph (pdf). If you were unable to complete one of the At-Home experiments, you may graph the results of the experiment shown in the lab manual and PowerPoint instead.
Regardless of which option you chose, make sure to read the PowerPoint, watch the Video, and attempt to answer the questions in your lab manual on p. 7 of 13.

QUESTIONS to consider after completing the experiments:

  1. What kind of organism is yeast?
  2. When comparing the yeast and sugar mixtures in differing temperatures, which water temperature produced the best results? How could you tell? What would happen if you left the glass with the cold water + yeast + sugar on the counter for another ½ hour?
  3. Compare the three yeast solutions of plain water, sugar and sugar substitute.

a) Did any of the solutions not ferment at all? Explain why this is the case.

b) Did you expect any fermentation in the sugar substitute? Based on its chemical structure, should fermentation have occurred? Why might some have occurred? (hint: read the ingredients list of your chosen substitute)

  1. Why did we cover the glass tops with Saran wrap? (hint: what must be absent for fermentation to occur)  
    OPTION A: SUBSTRATE VARIATION IN ALCOHOL FERMENTATION IN YEAST

PROCEDURE:
Choose one Sugar and one Sugar Substitute. Record your choices here:
Glass #2 Sugar: __________
Glass #3 Sugar Substitute: ____________

The three test solutions will consist of yeast combined with #1 – water only, #2: sugar + water and #3: your chosen sugar substitute + water. What do you predict, with respect to comparative fermentation rates, for each of the three yeast solutions? Consider the chemical formulae you’ve been given.

Materials:
Drinking glasses – 3 small clear glasses
Non-permanent marker (or eyeliner pencil)
Plastic wrap/saran wrap (3 pieces big enough to cover your sample glassware)
3 Spoons to stir samples
Measuring cup (1/4c or 60mL) and teaspoon (5mL)
Ruler with mm-scale
Sugar ( ½ tsp)
Yeast (1.5 tsp) – active or instant dry yeast
Sugar substitute (1/2 tsp of Twin, Equal, Splenda, etc…)

Procedure:

  1. Tear off three pieces of saran/plastic wrap that are big enough to cover the top of each of your chosen glasses (three pieces required)
  2. Label 3 glasses with non-permanent marker or tape (#1, #2, #3).
  3. To each glass, add ½ tsp (2.5mL) yeast.
  4. To glass #1, don’t add anything else.
  5. To glass # 2 add 1/2 tsp (2.5 mL) of white sugar.
  6. To glass # 3 add 1/2 tsp (2.5 mL) of Sugar Substitute.
  7. To each glass, add ¼ cup (60ml) of warm water (~37°).
  8. Use a clean spoon to stir the contents of each glass (don’t cross contaminate between glasses!).
  9. Cover each glass with a piece of plastic wrap.
  10. Use a NON-permanent marker and draw a line at the level of water on the glass.
  11. Take a picture of your glasses at 0 minutes. Set a timer for 5 min.
  12. After 5 min, use the ruler to measure the thickness of the foam layer. Record this in Table 1.
  13. Reset your timer for another 5 min, and measure thickness of the foam every 5 min for an additional 25 min and write your results in Table 1.
  14. Take another picture of your glasses after 30 min. These will be uploaded into your online lab report. Combine the two photos into ONE file (put both into Word) and save as a PDF.
  15. Plot a line graph of the depth (mm) of the foam layer (y-axis) for each condition vs. time (x-axis) on the graph paper provided. Title it, label each axis and provide a legend to indicate which line represents which glass number. Your title should start with the phrase: Option A(Substrate): _____

RESULTS:

Table 1. Option A: Volume of liquid displaced by fermentation in water of chosen solutions.

Time (min.) mm of liquid displaced (foam layer)
#1: H2O + yeast #2: Warm H2O, yeast + sugar #3: Warm H2O, yeast + sugar substitute
0
5
10
15
20
25
30

Title: Option A (Substrate): ___________________________

OPTION B: ENVIRONMENTAL INFLUENCE ON ALCOHOL FERMENTATION IN YEAST

PROCEDURE:

The three solutions consist of yeast combined with #1 – cold water and sugar, #2: hot water and sugar and #3: warm water (~37°C) and sugar. What do you predict with respect to comparative fermentation rates for each of the three yeast solutions?

Materials:
Drinking glasses – 3 small clear glasses
Non-permanent marker (or eyeliner pencil)
Kettle, pot, or microwave to boil water
Plastic wrap/Saran wrap (3 pieces big enough to cover your sample glassware)
Spoon to stir samples
Measuring cup (1/4c or 60mL) and teaspoon (5 mL) or ½ teaspoon (2.5mL)
Ruler with mm-scale
Sugar
Yeast – instant or active dry yeast

Procedure:

  1. Tear off three pieces of saran/plastic wrap that are big enough to cover the top of each of your chosen glasses (three pieces required)
  2. Label 3 glasses with non-permanent marker or tape (#1, #2, #3).
  3. Boil 1 cup of water.
  4. Add ½ tsp (2.5 mL) of sugar to each glass.
  5. Add ½ tsp (2.5mL) yeast to each glass.
  6. To glass # 1 add ¼ cup of COLD water.
  7. To glass # 2 add ¼ cup of BOILING water.
  8. To glass # 3 add ¼ cup of WARM/body temperature water (warm to touch).
  9. Use a spoon to stir the contents of each glass.
  10. Cover each glass with a piece of plastic wrap. Make sure the top is sealed.
  11. Use a NON-permanent marker and draw a line at the level of water on the glass.
  12. Take a picture of your glasses at 0 minutes. Set a timer for 5 min.
  13. Once 5 min has elapsed, use your ruler to measure the thickness of the foam layer on each glass. Record this in Table 1.
  14. Reset your timer for another 5 min and measure the thickness of the foam every 5 min for an additional 25 min recording each measurement in Table 1.
  15. Take another picture of your glasses after 30 min. These will be uploaded into your online lab report. Combine the two photos into ONE file (put both into Word) and save as a PDF.
  16. Plot a line graph of the thickness (mm) of the foam layer (y-axis) for each condition vs. time (x-axis) on the graph paper provided. Title it, label each axis and provide a legend to indicate which line represents which glass number. Your title should start with the phrase: Option B(Environmental):

RESULTS:

Table 1. Option B: Volume of Liquid Displaced by Fermentation in Water.

Time (min.) mm of liquid displaced (foam layer thickness)
#1: Cold H2O, yeast + sugar
#2: Hot H2O, yeast + sugar
#3: Warm H2O, yeast +sugar
0
5
10
15
20
25
30

Title: OptionB(Environmental):_____________

OPTION C: ALCOHOL FERMENTATION IN YEAST – Lab Manual and PowerPoint Experiment

PROCEDURE:
See Lab Manual – Lab 7: Fermentation Lab, Page 4 of 13. Also see the PowerPoint on Blackboard and the Alcohol Fermentation Video linked in the Accessory Materials folder.

Choose one Sugar and one Sugar Substitute.
Choose one sugar substitute. Record your choices here:

Cuvette #2 Sugar: __________
Cuvette #3 Sugar Substitute: ____________

The three test solutions consist of yeast combined with #1 – water, #2: sugar and #3: your chosen sugar substitute. What do you predict, with respect to comparative fermentation rates, for each of the three yeast solutions? Consider the chemical formulas you’ve been given.

Follow along with the Lab Manual, PowerPoint and Video. Complete Table 1 in your Lab Manual (p. 6 of 13) with results from the PowerPoint.

Graph your data (Procedure step 10, p. 5 of 13): Plot the volume displaced (mL) (y-axis) for each condition vs. time (min) (x-axis) on graph paper provided. Use a line graph and make sure to use appropriate axis labels. The Title of this graph should start with: Lab Manual Experiment:

Title: Lab Manual Experiment:______________________

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