Why Does Bread Dough Rise?

It's not magic! Here's the kitchen science behind why bread dough rises.

Breads that use yeast are different from all other baked goods. It takes several steps to bake bread, and one step is to put the dough in a warm place and wait for it to rise. But why is that step so important—and why does bread dough rise, anyway?

What Causes the Dough to Rise?

Yeast! Recipes like our Basic Homemade Bread all call for “active dry yeast.” You may be surprised to know that yeast is a living thing. It needs to eat, like anything that’s alive, and it loves sugar. In a process called fermentation, the yeast feasts on any sugar in the bread dough and then burps! In the bread world, burping isn’t rude—the yeast is creating air bubbles in the bread dough.

To wake up the yeast and get it ready for baking, you “proof” it—here’s how to proof yeast.

What Keeps the Air Bubbles in the Bread

The stretchy part of bread that holds the gas is called gluten. Gluten is formed when the proteins in flour come in contact with water, and as the two ingredients are kneaded, more and more gluten forms. This stretchy molecule traps air bubbles inside the dough.

Why Does Bread Dough Rise?

Bread rises because yeast eats sugar and burps carbon dioxide, which gets trapped by the bread’s gluten. The more sugar your yeast eats, the more gas that gets formed, and the higher the bread rises! (Here are some possible reasons why your bread isn’t rising.)

Most recipes call for the dough to rise at least twice; this gives the yeast extra time to eat sugar and produce gas bubbles. The final rise is known as proofing the bread dough. Curious about how long it takes bread to rise? It depends on factors such as the room’s temperature and the quality of the yeast.

The yeast keeps eating even as the bread is shaped into a pans and put in the hot oven. When it’s done baking, you’re left with a solid, well-risen loaf created by that hard-working yeast. What an amazing (and delicious) process.

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Grace Mannon
Grace learned a ton about the nitty-gritty of food and nutrition while earning her master’s degree in food science. She worked for a well-known baby food company and a company responsible for many favorite snack foods before transitioning to being a stay-at-home mom. She loves writing about complicated food science concepts in an understandable way and as a Taste of Home contributor, Grace covers a little bit of everything, from vintage recipes to must-have holiday foods and treats.