The air bubbles and spongy texture of bread are due to?

Here's how it works:

* Yeast is a single-celled organism that feeds on sugars.

* During fermentation, yeast consumes sugars and produces carbon dioxide gas and alcohol as byproducts.

* The carbon dioxide gas gets trapped within the gluten network created by the flour and water.

* As the dough rises, the trapped gas creates air pockets which give bread its characteristic texture.

The size and distribution of these air pockets, and therefore the texture of the bread, can be influenced by various factors including the type of yeast, the amount of flour used, the kneading process, and the baking temperature.