Baking soda and baking powder both look the same and smell the same… and they react very similarly within your baked good, but they are not the same and cannot be used interchangeably in your recipe.
Baking soda aka sodium bicarbonate is a base (Pause: okay, so remember in science class we learned about bases and acids and pH levels. Bases are one one end and include baking soda and soap, the other end are acids and right in the middle is water which is neutral?)
It reacts when combined with water and acidic ingredients such as sour cream, buttermilk, or brown sugar. It neutralizes the acidity a bit and also creates carbon dioxide which lifts up your batter by creating tiny bubbles. This reaction begins the moment baking soda touches your liquid ingredients, which is why you cannot leave your mixed batter sitting around. You must bake immediately or else you won’t get as much rise. It also promotes browning
You can use roughly 1/4 teaspoon of baking soda per 1 cup of all-purpose flour.
Baking powder does contain baking soda, but it also has an acidic element – usually cream of tartar. Often, it also contains cornstarch to keep the powder dry. Since baking powder contains sodium bicarbonate/baking soda, plus an acid or two, it is mostly used with recipes with little to no natural acidity such as those that use whole milk or Dutch-processed cocoa powder.
You will need roughly 3/4 – 1 teaspoon of baking powder per 1 cup of all-purpose flour.
There are two types of baking powder: single acting and double acting. Since double acting baking powder is what you typically find in grocery stores (and is what most recipes call for), this is the type I am refering to within this post. Double acting baking powder has two types of acids that react within your baked good. The first reacts the moment you combine the baking powder with your liquid ingredients. The second only reacts when heated to above 120 degrees F. Most baking powders use aluminum sulfate as its second acid. I highly recommend using an aluminum-free baking powder as it can leave a slightly metallic taste to your baked goods. Just look at the labels. (Two of my favorite brands are Trader Joe’s and Clabber Girl – no I’m not being paid to say that!)
Can I substitute Baking Powder for Baking Soda and Vice Versa?
Short answer: yes. Accurate (longer) answer: ehhh…. it depends.
Using Baking Powder Instead Of Baking Soda
You need 2 – 3 times more baking powder than baking soda to get the same rise. So if your recipe calls for 1 teaspoon of baking soda, you will need 2 (ideally 3) teaspoons of baking powder. But by doing this, you will affect the taste of the final product.
Using Baking Soda Instead of Baking Powder
If you remember the ingredients I said were in baking powder, you should already know that you can create a fairly good replica of baking powder at home. Simply mix baking soda with cream of tartar. You will need 2 teaspoons of cream of tartar for every 1 teaspoon of baking soda for a ratio of 2:1. With this homemade baking powder mix, you do not need to make any adjustments to the amount of baking powder called for in the recipe. So if the recipe calls for 1 teaspoon of baking powder, use 1 teaspoon of your baking powder mix.
Why Do Some Recipes Use Both?
Basically: because there isn’t enough acid to react to the baking soda to create the bubbles you need for good lift in your finished product.
How Do I Know If My Baking Soda/Powder Is Still Good?
Both baking soda and baking powder are best used within six months (ignore what the packaging says, trust me). After that, it loses its potency and will not provide you with much rise. To make sure you observe these time limits, I recommend buying the smaller containers of baking powder and baking soda and writing the date you open each onto the container.
You can do a quick test to see if your baking powder and baking soda are still good.
Mix 1 teaspoon of baking powder with 1/3 cup hot water. You should see lots of bubbles. If not, replace it.
Mix 1/4 teaspoon of baking soda with a few drops of vinegar. It should bubble a ton (to the point where it looks white/froth-like). If it doesn’t, replace it.