The Effect of Different Levels of pH on the Fermentation of Yeast 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 CO 2.

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 LevelspH of 5pH of 6pH of 7 (control) pH of 8 Trials5555 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 CO 2.

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.

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Data pH 5pH 6pH 7 (control) pH 8 Trial 14.5 cm2 cm4.5 cm3.5 cm Trial 25 cm3 cm4 cm3 cm Trial 35 cm3 cm4 cm3.5 cm Trial 45 cm3.5 cm4.5 cm3 cm Trial 54.5 cm2.5 cm4 cm3 cm Averages4.8 cm2.8 cm4.2 cm3.2 cm

Averages PH 5: 4.8 cm PH 6: 2.8 cm PH 7 (control): 4.2 cm PH 8: 3.2 cm

Graph Level of pH Height of dough in cm. The Effect of Different Levels of pH on the Fermentation of Yeast

Statistical Analysis Source of Variati on Sum of squares Degrees of Freedom Mean Squares F Signifi cance Between Error Total ANOVA

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: o Temperature o Amount of sugar

Acknowledgements Acknowledgements Mrs. P o Preparing solutions o Helping Parents o Bought ingredients

Bibliography