The Effect of Sugar Substitutes Compared to Sugar on the Growth of Yeast

By: Darcy Horn10th Grade Honors Biology

Why I Chose This?

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, water-

soluble 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

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 DiagramIV: Sugar Substitutes

Levels: Granulated Sugar (control)

Sucralose 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

Granulated Sugar (control)

Sucralose Aspartame Acesulfame Potassium

60 mL 112 mL 87 mL 84 mL110 mL 108 mL 93 mL 88 mL80 mL 110 mL 90 mL 80 mL100 mL 115 mL 91 mL 82 mL80 mL 95 mL 79 mL 82 mL90 mL 114 mL 85 mL 90 mL110 mL 110 mL 92 mL 89 mL110 mL 107 mL 66 mL 84 mL100 mL 116 mL 84 mL 80 mL93.5 mL 109 mL 85.5 mL 84 mL

Sugar Substitutes (IVs)

Growth of yeast (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

• (mean)- 93.5, 109, 85.5, 84• Sx (standard deviation)- 16.338, 6.307, 8.045, 3.741• Total sample size- 40• (overall average)- 93• SSTR= 3935• SSE=3468.83• SST= 7403.83• MSTR= 1311.667• MSE= 93.752• Fdata=13.99• Critical Value- 2.79 • P=.05

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ANOVA TableSource of Variation

Sum of Squares

Degrees of Freedom

Mean Square

Ftest

Statistic

Sugar (treatment)

3935 3 1311.667 13.99

Error 3468.83 37 93.752Total 7403.83

13.99 > 2.79 (critical value)REJECT Ho--All sums are equalHa- 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