A Guide to Leavening and Leavening Agents

What do a great joke and a great loaf of bread have in common? They both get a rise. (Ba-dum-ching.)

Leavening is a crucial step in the baking process for breads and other baked goods, including cookies, pie crusts, and pastries. And a leavening agent is what you use to make it happen.

You have various options when it comes to which leavener you choose to work with, and each of them offers something unique. To break it down, we’re covering the essentials, from what a leavening agent does to the differences between baking powder vs. yeast and other common raising agents.

You may be familiar with the term “leavening” or “leavened bread,” but what does it really mean?

Here’s a quick leaven definition: A leavened baked good is one that has gasses trapped inside of it. This creates an expanded dough that’s typically lighter and softer than its unleavened counterpart.

These gases are formed using a chemical reaction, with leavening agents (also known as raising agents) doing the work of making that reaction happen. These agents may be a specific ingredient—such as baking soda or yeast—or they may be introduced through technique, such as creating a dough in such a way as to bring in steam and form air pockets.

Examples of foods that are made with a leavener include many types of breads, as well as cookies, cupcakes, cakes, and brownies. Basically, if it doesn’t come out of the oven as flat as it went in, that’s due to the work of a leavening agent. 

What is leavening as it relates to bread specifically? There’s no difference when it comes to the definition of leavened bread versus other leavened baked goods. Where a distinction might come about is that not all breads are leavened, and that when breads are leavened it’s usually done with yeast.

We’ll get into what those unleavened varieties are in a bit, but for now, know that leavening bread is simply the process of introducing a leavening agent or technique in order to trap gas in the dough and make the bread rise. 

If you want to become a pro baker, you need to know your leavening agents.

There are three broad types of leavening agents: chemical, biological, and vaporous. And within these types, there are more specific ingredients, each with its own function.

So, what are the three types and what are leavening agents within each group? Here’s what to know.

Chemical leavening agents use, well, chemicals to produce a rising reaction. They work very quickly, which is why they’re among the most common leavening agents you’ll find in baking recipes. They include:

Biological leavening agents refer to different types of yeast, a “living” ingredient that eats sugar and produces carbon dioxide gas and ethanol in return. Yeast helps many variations of bread rise, and it’s also used in fermentation, such as when making beer or wine.

You have a couple of options when it comes to yeast, each working in a slightly different way:

Other than the precise leavening process it produces, yeast also varies from other types of leavening agents in that it has a distinct flavor. (So be wary of overdoing it in a recipe.)

Last up is vaporous leaveners—a.k.a. water-based leaveners. And there’s really only one raising agent in this category: steam.

When water turns into steam, it multiplies in volume more than a thousand times, which means a significant expansion (or rise) in your finished product. Examples of this are puff pastry and pâte à choux, two delicate pastry doughs that are created by first making room for water to expand and then introducing the dough to heat in order to turn that water into steam. When the heat is removed and the steam evaporates, pockets of air are left behind—hence the light and fluffy nature of these pastries.

By now you should know the difference between baking powder vs. yeast, as well as the answer to “what is a leavening agent?”. But what we haven’t covered yet is products that are purposefully unleavened.

There are many types of unleavened breads, including varieties you’re probably familiar with—think roti, naan, matzoh, and tortillas.

Unleavened bread is created by omitting a leavening agent like yeast. They’re typically (but not always) flatbreads, and they may be soft or hard in texture. Try your hand at both leavened and unleavened breads to expand your baking repertoire and discover just how many delicious things you can make.