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

1. The Effect of Sugar Substitutes Compared to Sugar on the Growth of Yeast By: Darcy Horn 10th Grade Honors Biology

2. Why I Chose This? • Home Use • Not Very Time Consuming • Materials Easily Accessible • New Information

3. 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.

4. 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.

5. 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

6. Experiment Independent Variables • Pure granulated sugar (control) • Aspartame-Equal • Sucralose- Splenda • Acesulfame Potassium- Nutra-Sweet ADDED TO • Active yeast • Water

7. Experiment (continued) • Let balloon sit for one hour • Water displacement method • Record data

8. Design Diagram 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

9. Photo Documentation

10. Results with Averages Sugar Substitutes (IVs) Growth of yeast (mL)

11. Averages • Sucralose- 109 mL • Granulated Sugar (control)- 93.5 mL • Aspartame- 85.5 mL • Acesulfame Potassium- 84 mL

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

13. 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

14. ANOVA Table 13.99 > 2.79 (critical value) REJECT Ho--All sums are equal Ha- Not all sums are equal

15. 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)

16. 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

17. 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

18. Acknowledgements • My parents Karen and Fred Horn • My biology Teacher Mrs. Pietrangelo • The librarians at WHS library