What is the primary leavening gas produced by yeast in bread?

What is the primary leavening gas produced by yeast in bread?

• A. Oxygen
• B. Hydrogen
• C. Nitrogen
• D. Carbon dioxide

Answer: (D)

The primary leavening gas produced by yeast in bread is carbon dioxide. When yeast ferments sugars present in the dough, it metabolizes them and releases carbon dioxide and alcohol as byproducts. This carbon dioxide gas is what causes the dough to rise, creating the airy structure characteristic of bread.

During the fermentation process, the carbon dioxide bubbles get trapped in the gluten network of the dough. As the dough is baked, the gas expands, which contributes to the leavening effect, leading to the light and fluffy texture of the final product. The presence of alcohol during fermentation also contributes to flavor development, but it is the carbon dioxide that is crucial for the leavening action essential for bread-making.