How does the Leavening process work?
For fermentation to occur, it requires a base, and a strain.
The base is a carbohydrate, or the flour, salt and the strain is usually a type of bacteria or fungus or the yeast.
Yeast is considered a living organism — the ability to use energy (eat)!
When yeast, humans, and other living organisms use energy (eat), they break down high-energy molecules like sugar to get the energy they need and give off a gas called carbon dioxide as a by-product of this reaction
As soon as yeast (living organism) comes into contact with flour and water, the fermentation process starts. This reaction produces carbon dioxide gas which gets retained by the dough in the small pockets of the gluten structure. As more gas is produced, the gluten stretches and the bread rises.