Question

Which metabolic pathway takes place in dough that results in the formation of carbon dioxide? Where do bacteria for these fermentations come from?

Answer 1

Part 1: Metabolic pathway
The dough rises due to fermentation or anaerobic respiration.There are two fermentation pathways that can take place:

• Alcoholic pathway:

Yeast in the dough acts on glucose converting it into pyruvate. Pyruvate then gets converted to ethanol and carbon dioxide with the help of alcohol dehydrogenase (the enzyme present in yeast).

• Lactic acid fermentation:

Lactic acid bacteria act on glucose converting it into pyruvate. Pyruvate gets converted into lactic acid and carbon dioxide.

Part 2: Source of microbes
The microbes that ferment are usually added to food as starter cultures. Some bacteria and yeast can also be present in food grains that are used in the preparation of the final product.