The Effect of Sugar Substitutes
Compared to Sugar on the Growth
of Yeast
By: Darcy Horn
10th Grade Honors Biology
Why I Chose This?
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Home Use
Not Very Time Consuming
Materials Easily Accessible
New Information
Hypothesis and Problem
• Hypothesis: If sugar substitutes are solutions
added to the yeast, then the yeast will have
less growth.
• Problem: To see how sugar is compared to
sugar substitutes in the growth of yeast.
Vocabulary Concepts
• Water displacement- used to measure the volume of a
solid object, occurring when an object is immersed in a
fluid, pushing it out of the way
• Proofing- a way to test whether yeast is good
• Yeast Fermentation- the process where yeast is used to
change sugar into lactic acid
• Lactic Acid- a colorless or yellowish, syrupy, watersoluble liquid, produced during muscle contraction as a
product of anaerobic glucose metabolism, abundant in
sour milk, prepared usually by fermentation of
cornstarch, molasses, potatoes, etc.
Background to Yeast
• Yeast are unicellular, aerobic or anaerobic organisms
• Yeast, like animals, give off CO2 as a byproduct of
respiration
• reproduce through budding in which an adult yeast
cell grows an offspring from its body
• For reproducing yeast cells need energy. Yeast utilizes
the glucose in its environment to make energy
• Sugar acts as a catalyst to yeast growth
Experiment
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Independent Variables
Pure granulated sugar (control)
Aspartame-Equal
Sucralose- Splenda
Acesulfame Potassium- Nutra-Sweet
ADDED TO
• Active yeast
• Water
Experiment (continued)
• Let balloon sit for one hour
• Water displacement method
• Record data
Design Diagram
IV:
Sugar Substitutes
Levels:
Granulated Sucralose
Sugar
(control)
Aspartame Acesulfame
Potassium
Trials:
10
10
10
10
DV: The Growth of Yeast (mL of CO2 produced)
Constants: Amount of each sugar/sugar substitute (12.6g), amount of water added to
each test (30mL), temperature of water (43°C-46°C), amount of yeast in each test (1/4
ounce each), amount of time given to each trial (1 hour), environment of experiment
Photo Documentation
Results with Averages
Sugar Substitutes (IVs)
Growth
of yeast
(mL)
Granulated
Sugar
(control)
60 mL
110 mL
80 mL
100 mL
80 mL
90 mL
110 mL
110 mL
100 mL
93.5 mL
Sucralose
Aspartame Acesulfame
Potassium
112 mL
108 mL
110 mL
115 mL
95 mL
114 mL
110 mL
107 mL
116 mL
109 mL
87 mL
93 mL
90 mL
91 mL
79 mL
85 mL
92 mL
66 mL
84 mL
85.5 mL
84 mL
88 mL
80 mL
82 mL
82 mL
90 mL
89 mL
84 mL
80 mL
84 mL
Averages
• Sucralose- 109 mL
• Granulated Sugar (control)- 93.5 mL
• Aspartame- 85.5 mL
• Acesulfame Potassium- 84 mL
The Effect of Sugar Substitutes
Compared to Sugar on the Growth of
Yeast
Statistical Analysis- ANOVA
x
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(mean)- 93.5, 109, 85.5, 84
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Sx (standard deviation)- 16.338, 6.307, 8.045, 3.741
Total sample size- 40
x (overall average)- 93
x
SSTR= 3935
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SSE=3468.83
SST= 7403.83
MSTR= 1311.667
MSE= 93.752
Fdata=13.99
Critical Value- 2.79
P=.05
ANOVA Table
Source of
Variation
Sum of
Squares
Sugar
3935
Degrees
of
Freedom
3
Mean
Square
Ftest
Statistic
1311.667
13.99
37
93.752
(treatment)
Error
Total
3468.83
7403.83
13.99 > 2.79 (critical value)
REJECT Ho--All sums are equal
Ha- Not all sums are equal
Conclusion- Why?
• Most dextrose (sugar) in Splenda
– All substitutes contained some dextrose
• Reason they caused yeast to grow at all
• Substitutes have no calories- cell organisms
can’t break them down (Can’t feed yeast)
Sources of Error
• Tying balloons- water spillage
– Effect on yeast growth
Improvement: have someone else help tie balloons
• Water displacement
– Each balloon not sunk to same level
– Inaccurate results
Improvement: Be more careful with displacement of balloon
• Time in between water measurement and water inserted in balloon
– Caused temperature to change
• Effect on yeast growth
Improvement: Enter water into balloon immediately after measuring
Real-World Application and Further
Research
• Bread Making
– Do not use Sucralose; undependable
– Use sugar for better results
– Sucralose only worked because contained sugar
• Further research on yeast
– Test temperature of water on yeast growth
– Test concentration of sugar on yeast growth
Acknowledgements
• My parents Karen and Fred Horn
• My biology Teacher Mrs. Pietrangelo
• The librarians at WHS library