BIOL 1 Fermentation of Yeast with Real and Artificial Sugars

1. Fermentation of Real and Artificial
Sugars With Yeast
Jessica Ibbetson, Luvdeep Bal,
Julyandra Mendoza & Bianca Medina

2. What is Fermentation?
● Fermentation is a chemical process in which sugars are broken down
anaerobically by microorganisms such as yeast.
○ Food and drinks include: Cultured milk and yogurt, wine, beer and apple cider vinegar.
● Yeast is a type of eukaryotic fungi, it is a facultative anaerobe which means
it can perform in aerobic and anaerobic respiration.
○ During aerobic respiration yeast converts carbohydrates into carbon dioxide and
water.
○ During anaerobic respiration (fermentation) yeast converts carbohydrates into carbon
dioxide and alcohol

3. Hypothesis and Predictions
● The real sugars will be fermented by yeast because they are simple
carbohydrates.
● The artificial sugars will not be fermented by yeast because they do not
contain carbohydrates.
● Predictions:
○ White sugar and brown sugar will ferment.
○ Sweet ‘N Low, Truvia and Splenda will not ferment.

4. Methods
1. Prepared Yeast Solution: 1.25 g of yeast dissolved in 100 mL of water
a. Cultured at 30 degree celsius
2. Prepared different sugars: 0.3 grams of each type of sugar dissolved in 20 mL of
water
3. Labeled 50 mL beakers and Khune fermentation tubes
4. In the 50 mL beakers we mixed together the sugars and yeast: 8 mL of sugar
solutions into yeast
5. Poured mixers into the Khune Fermentation Tubes
a. Filled the tube completely ( 25mL total)

5. Methods
6. Covered the opening of the Khune tubes with parafilm
7. Placed khune tubes in 30°C water bath
- Time ZERO
8. At 30, 50 and 70 minutes we measured the displacement of liquid by gas
● Experiment was performed 3 times

6. Results

7. Results
Trial 1 Control White
Sugar
Brown
Sugar
Sweet ‘n
Low
Truvia Splenda
30
Minutes
0 0.10 0.08 0 0 0
50
Minutes
0 0.50 0.30 bubbles 0 0
70
Minutes
0 1.00 0.70 bubbles 0 bubbles
Measure of CO2 (in mm)

8. Results
Trial 2 Control White
Sugar
Brown
Sugar
Sweet ‘n
Low
Truvia Splenda
30
Minutes
0 0.30 0.20 0 0 0
50
Minutes
0 0.80 0.50 bubbles 0 0
70
Minutes
0 1.20 0.80 bubbles 0 0
Measure of CO2 (in mm)

9. Results
Trial 3 Control White
Sugar
Brown
Sugar
Sweet ‘n
Low
Truvia Splenda
30
Minutes
0 0.50 0.10 0 0 0
50
Minutes
0 0.80 0.60 bubbles 0 0
70
Minutes
0 1.30 1.00 bubbles 0 bubbles
Measure of CO2 (in mm)

10. Results

11. Analysis
● Results after trials support our hypothesis and our predictions.
● As expected real sugars did ferment and the artificial sugars did not.
● Analysis:
○ Real sugars contain carbohydrates which are metabolized by yeast during fermentation.
○ Artificial sugars do not contain carbohydrate groups and cannot be metabolized by yeast.
❖ Conclusion: If you plan on brewing your own beer or wine we recommend
using real sugars.