Yeast and Bread Fermentation

Students explore the role of yeast in bread making by preparing dough in a bag, observing changes over time, and investigating how yeast fermentation produces carbon dioxide that causes dough to rise.

1. Prepare bread dough ingredients in a sealed plastic bag and knead until combined.
2. Allow the dough to sit and observe how its volume increases during proofing as yeast ferments sugars.
3. Store the dough in the refrigerator if the experiment continues to another day.
4. Bake the dough in an oven.
5. Record observations of dough before and after, noting changes in texture, size, and structure.

20-Minute Mini Lab: Explore Yeast, Bread and Fermentation - Bite Scized Education:

• Compare dough proofed at room temperature versus refrigerated dough.
• Test different types of flour or sugar sources.
• Allow dough to rise for different lengths of time and compare results.
• Substitute yeast with baking powder or baking soda to compare leavening methods.

• Wash hands before and after handling dough.
• Clean surfaces and utensils to avoid contamination.
• Use oven mitts and caution when handling hot baking trays.
• Ensure students do not consume raw dough.

• Why does the dough expand in volume as it sits? (Yeast ferments sugars, producing carbon dioxide gas that gets trapped in the dough structure.)
• What environmental factors might change the rate of fermentation? (Temperature, sugar type/amount, oxygen availability.)
• How is yeast similar to and different from other living organisms? (It is a microbe that respires and consumes nutrients but is a single-celled fungus rather than a multicellular organism.)