What Makes Bread Dough Rise?
My children and I love to bake bread. Many mornings we have mixed the dough and then waited for it to rise, so that we can throw it in the oven and have a freshly baked loaf of bread for lunch. But what is really happening chemically when that bread dough is rising?
The Secret is in the Yeast
Ethanol fermentation causes the bread dough to rise. Yeast organisms consume sugars in the bread dough. Ethanol and carbon dioxide are created as waste products. This all happens in the absence of oxygen so it is considered an anaerobic chemical reaction.
Bread dough rising
Yeast and Carbon Dioxide Bubbles
Chemistry at Work!
The carbon dioxide forms bubbles in the dough causing it to rise. Most of the ethanol is evaporated during baking. To be more precise in a process called glycolysis two pyruvate molecules are produced per one glucose molecule.
Fermentation in action!
The Chemical Reaction
C6H12O6 + 2 ADP + 2 Pi + 2 NAD+ → 2 CH3COCOO− + 2 ATP + 2 NADH + 2 H2O + 2H+
Next the sucrose is fermented. One mole of sucrose is converted into four moles of ethanol and four moles of carbon dioxide. These carbon dioxide bubbles are what really cause the bread dough to rise!
C12H22O11 +H2O + invertase →2 C6H12O6 C6H12O6 + Zymase → 2C2H5OH + 2CO2
So this is the chemical secret of what is really happening when we make a loaf of bread.
Cobb C., Fetterolf M., (2005). The Joy of Chemistry. New York: Prometheus Books
Light Brown, C. (2008). Amazing Kitchen Chemistry Projects You Can Build Yourself. Chicago:
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About the Author
My name is Karen Shiley. I live in the beautiful evergreen Washington state. I have an adventurous spirit and love to share what I learn with everyone. I like science, gardening, cooking, reading, day-trips and above all else my amazing family who supply me with endless amusement and happiness. I originally wrote this article on September, 9th 2012.