The Effect of Different Levels of pH on the Fermentation of Yeast By Rachel Koch Hypothesis and Problem Statement Problem: How do different levels of pH in the environment around yeast effect its fermentation? Hypothesis: If the environment around the yeast has a higher pH, then the yeast will create more CO2. Background Research Yeast: microorganism, Eukaryotic domain and the Fungi kingdom Baker’s yeast: digests sugar Fermentation: release carbon dioxide Energy and warmth for fermentation Dough rising is result of fermentation Design Diagram Title: The Effect of Different Levels of PH on the Fermentation of Yeast Hypothesis: If the environment around the yeast has a higher pH, then the yeast will create more CO2. Levels pH of 5 pH of 6 pH of 7 (control) pH of 8 Trials 5 5 5 5 Design Diagram cont. IV: pH level DV: Height of dough(cm) Constants: Ingredients in dough (besides IV), the measurements of each ingredient, temperature at which the dough is placed to ferment and the amount of time the yeast ferments. Materials Flour Sugar Instant yeast Warm water/solution Oil Salt Ruler HCl NaOH Oven Procedure • Prepare pH solutions in lab with the instructor using NaOH for basic solutions and HCl for acidic solutions. 1. Heat water/solution to 35 degrees C. 2. Add flour, sugar, oil, yeast and salt to the warmed water/solution. Procedure cont. 3. Knead dough for about 8 minutes. 4. Measure the height of the dough. 5. Store dough in a warm place for 45 minutes to allow yeast to ferment. Procedure cont. 2 Put dough in the oven set to 54 degrees C and turn the oven off 6. Measure the final height that the dough raises with a ruler. Photodocumentation Data Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Averages pH 5 pH 6 4.5 cm 5 cm 5 cm 5 cm 4.5 cm 4.8 cm 2 cm 3 cm 3 cm 3.5 cm 2.5 cm 2.8 cm pH 7 (control) 4.5 cm 4 cm 4 cm 4.5 cm 4 cm 4.2 cm pH 8 3.5 cm 3 cm 3.5 cm 3 cm 3 cm 3.2 cm Averages PH 5: 4.8 cm PH 6: 2.8 cm PH 7 (control): 4.2 cm PH 8: 3.2 cm Graph Height of dough in cm. 6 The Effect of Different Levels of pH on the Fermentation of Yeast 5 4 3 2 1 0 pH 5 pH 6 Level of pH pH 7 pH 8 Statistical Analysis ANOVA Source Sum of of squares Variati on Between 13.14 Degrees Mean F of Squares Freedom Signifi cance 3 4.379 0.000 Error 2.1 16 0.1313 Total 15.24 19 33.37 Conclusions Hypothesis did not support data Ideal environment is pH 4-6 Yeast ferments better in acidic substances Data is inaccurate Possible Errors Oven temp. wasn’t exactly the same every time Measurements might not have been exact Measured every half centimeter Improvements Could buy an alternative heating devise Measure ingredients more carefully Measure the height to a tenth of a cm Reasoning Like to bake Thought it was interesting that yeast makes dough rise Extensions Test other factors that effect yeast fermentation, like: oTemperature oAmount of sugar Acknowledgements Mrs. P o Preparing solutions o Helping Parents o Bought ingredients Bibliography "Basic Bread." PrismNet : Austin TX VOIP, Broadband Colocation, Web Hosting. Web. 05 Oct. 2010. <http://www.io.com/~sjohn/bread.htm>. "Fermentation." Utah State University: Intermountain Herbarium. Web. 04 Oct. 2010. <http://herbarium.usu.edu/fungi/funfacts/Fermentation.htm>. "What Are Yeasts?" Saccharomyces Genome Database. Web. 05 Oct. 2010. <http://www.yeastgenome.org/VL-what_are_yeast.html>. Campbell, Neil A., Jane B. Reece, Lawrence G. Mitchell, and Martha R. Taylor. Biology Concepts & Connections. San Francisco: Benjamin Cummings, 2003. Print. "Factors Effecting Fermentation." Web. 19 Dec. 2010. <http://home.earthlink.net/~ggda/factors_effecting_fermentation.htm>. "Yeast Fermentation in Baked Goods." Dakota Yeast. Web. 20 Dec. 2010. <http://www.dakotayeast.com/help-fermentation.html>.