How Bread Works

By: Marshall Brain

Bread Basics

If you pick up a slice of bread and examine it closely, you can see that it is full of air holes. This makes it spongy and soft. You will also see that bread is moist. If you let a slice of bread sit out on the counter for a day, you will realize just how moist fresh bread is!

Bakers use two simple facts of life to create soft, spongy, moist bread:


  • First, they use the fact that yeast (a single-cell fungi) will eat sugar, and from the sugar create alcohol and carbon dioxide gas as waste products. The carbon dioxide gas created by yeast is what gives bread its airy texture, and the alcohol, which burns off during baking, leaves behind an important component of bread's flavor.
  • Second, wheat flour, if mixed with water and kneaded, becomes very elastic. The flour-and-water mixture in bread becomes stretchy like a balloon because of a protein in wheat known as gluten. Gluten gives bread dough the ability to capture the carbon dioxide produced by yeast in tiny flour balloons.

You can perform a few experiments to better understand how bread works.