Fermentation Pathway

During dough fermentation, the metabolic pathway that results in the formation of CO2 gas is the fermentation pathway. This process is carried out by yeast, such as Saccharomyces cerevisiae, which is commonly used for fermentation in baking.

1. Glycolysis
The first step in the fermentation pathway is glycolysis. During glycolysis, glucose is converted into pyruvate. This process occurs in the cytoplasm of yeast cells and does not require oxygen. Glycolysis produces a small amount of ATP and NADH.

2. Decarboxylation of Pyruvate
After glycolysis, pyruvate is decarboxylated, which means that a carbon dioxide (CO2) molecule is released. This step is catalyzed by the enzyme pyruvate decarboxylase. The decarboxylation of pyruvate generates acetaldehyde.

3. Reduction of Acetaldehyde
The next step in the fermentation pathway is the reduction of acetaldehyde. This reaction is catalyzed by the enzyme alcohol dehydrogenase. NADH, which is produced during glycolysis, is used to reduce acetaldehyde to ethanol. This reaction regenerates NAD+ for glycolysis to continue.

4. Release of CO2 Gas
During the reduction of acetaldehyde, a molecule of CO2 is released. This CO2 gas is what causes dough to rise during fermentation. The gas gets trapped in the dough, creating bubbles and giving the dough a light and airy texture.

Importance of CO2 in Dough Fermentation
The release of CO2 gas during dough fermentation is important for several reasons:

1. Dough Rising: The production of CO2 gas causes the dough to rise, resulting in a lighter and more voluminous texture in baked goods.

2. Flavor Development: The production of CO2 gas enhances the flavor of baked goods. The presence of ethanol produced during fermentation contributes to the aroma and taste of the final product.

3. Gluten Development: The release of CO2 gas during fermentation helps to stretch and develop the gluten network in the dough, improving the structure and texture of the baked goods.

In conclusion, during dough fermentation, the fermentation pathway is responsible for the production of CO2 gas. This pathway involves glycolysis, decarboxylation of pyruvate, reduction of acetaldehyde, and the release of CO2 gas, resulting in dough rising and the development of flavor and texture in baked goods.