ACarbon dioxide
BNitrogen
COxygen
DHelium
Answer:
A. Carbon dioxide
Read Explanation:
Yeast Fermentation and Bread Leavening
The Chemical Process:
Yeast, a single-celled fungus, consumes sugars present in bread dough.
Through a process called anaerobic respiration (fermentation), yeast converts these sugars into ethanol (alcohol) and carbon dioxide (CO2).
The chemical equation for this fermentation process is: C6H12O6 (sugar) → 2 C2H5OH (ethanol) + 2 CO2 (carbon dioxide) + Energy.
The Leavening Effect:
The carbon dioxide gas produced is trapped within the gluten network of the dough.
As more CO2 is generated, it forms small bubbles, causing the dough to expand and rise.
This expansion is known as leavening, which gives bread its light and airy texture.
Factors Influencing Fermentation:
Temperature: Yeast activity is optimal between 75-80°F (24-27°C). Higher temperatures can kill yeast, while lower temperatures slow down fermentation.
Sugar Availability: Yeast requires sugars to ferment. The type and amount of sugar in the dough affect fermentation speed.
Yeast Strain: Different strains of yeast have varying fermentation rates and produce different flavor profiles.