As I’ve mentioned many times before, baking is one big chemistry experiment, and a very integral part of each experiment is the leavening agent you use. By definition, a leavening agent is a substance that causes dough and batter to expand and rise by releasing gas within the mixture.
There are several different types of leaveners, some chemical and some biological, so let’s break them down:
First, baking soda. Baking soda (chemically known as Sodium Bicarbonate) is a pure leavener that is alkaline and needs to be mixed with liquid and an acid to be activated. It’s most commonly used in cookies, muffins, and cakes. When activated, carbon dioxide is produced, allowing the baked good to rise and become fluffier.
Next, baking powder. This is a complete leavener, meaning that it contains the sodium bicarbonate and the acid needed to create the rise. Baking Powder also typically contains cornstarch to create a buffer between the two while being stored, but there are varieties available that do not.
The last leavening agent I want to talk about is yeast. While baking soda and baking powder are chemical leavening agents, Yeast is a biological agent. Yeast is activated when combined with warm water. As yeast grows, fermentation begins, and it converts sugar into carbon dioxide and alcohol. As with all leavening agents, that gas is what gives rise to your products. When preparing to use yeast, take note of which kind your recipe calls for: Active Dry Yeast or Instant Dry Yeast. The difference in name is small, but it’s huge in practice. Active Dry Yeast has to be activated before adding to your dough, which you do by combining it with warm water. Instant Dry Yeast can be added straight to your flour. They are both sold in small packets at the grocery store, so just be sure you’re paying attention when purchasing.