We’ve all had it happen: you work so hard on a batch of cupcakes, cookies, or all the layers of a show-stopping cake only to peek into the oven and panic, “Oh no! They didn’t rise!”
Most of the time baked goods that come out flat as a pancake happen because of a failure of leavening action.
The most basic explanation of leavening is air or gas that causes confections to rise as it escapes. This leavening is created by “leaveners” aka the thing that makes that gas!
The basic categories of leaveners are chemical leaveners, organic leaveners, or natural leaveners.
These leaveners work by causing a chemical reaction that releases Carbon Dioxide (CO2). Baking soda and baking powder are the most common chemical leaveners.
Baking soda has a high pH making it “basic” (just like me! Jk, jk) so when an acidic ingredient comes into contact with it, a reaction occurs and CO2 is produced immediately. (Think of that baking soda and vinegar volcano you made back in elementary school science...instant foaming!) Baking soda is considered “quick rising” because of this speedy reaction so it’s best for treats that bake relatively quickly like cookies or pancakes.
Baking powder is “self activating” because it contains a combination of both an acid and a base. This means as soon as baking powder is wet it will begin to produce CO2. However, unlike baking soda, baking powder is “double acting” meaning it produced CO2 both from that first reaction and from a reaction that occurs when it is heated.
This second reaction gives baking powder the lifting power needed for things like cakes that are larger and need to bake longer. Sometimes recipes will have both baking soda and baking powder to take advantage of a quick rise creating a crust and that second heat-activated rise for some extra lifting power.
Remember you can not substitute baking soda for baking powder or vice versa! It’s also a good idea to replace your chemical leaveners every year because they lose potency. Make it the easiest New Year’s resolution ever!
Yeast is the organic leavener all bakers have a love-hate relationship with! These little living microorganisms feed on sugar and produce CO2 (as well as a tiny amount of alcohol). Since they’re little living creatures they produce CO2 at a slower and less consistent rate than a chemical reaction.
All yeast are a little different but the most uniform bakes come from dry yeast (which we use in a few recipes in our new cookbook: Hello, Cookie Dough!) This yeast is bred and grown and then stopped at the height of CO2 production essentially by drying it out. When you activate it by adding it to a little sugar water it is ready to keep eating and producing CO2!
Yeast will continuously produce CO2 until they are denatured (the kind way to say killed off) by high temperatures in the oven. When dough slowly rises on a countertop that’s yeast working at a natural pace. As soon as you pop dough into the oven the yeast basically freak out and produce CO2 very quickly, causing one last leavening explosion, until their eventual demise.
This last super charge of CO2 is what causes the unique holes and patterns in artisan bread.
This group is any ingredient (including air itself) that already contains CO2.
The simple action of whipping a lot of air into a batter can cause leavening. Souffles rise because a ton of air is trapped in the delicate egg whites folded into the batter. When the batter hits the oven heat the souffles will rise and then fall a bit because air adds no structure and is not very powerful (like baking powder above).
Ingredients like soda water, ginger beer, or just regular old beer are also used as a natural leavening agents because of the CO2 already in them. This is where soda bread comes from!
Natural leavening is part of most baked goods even if a chemical leavener is being used, that’s why we “cream” butter and sugar together at the beginning of a dough recipe. The sugar creates little air pockets in the butter and the air stays trapped there until it is released in the oven! Instant fluff!