I wanted to start a new “Science of Cooking” category on the blog to answer all the questions you guys have emailed me! One of the questions I get the most often (especially from my Swiss/French readers) is about the difference between baking soda and baking powder. Why do we use them? How are they different? Can I use them interchangeably? How do I know which one to use? I spent some time researching the subject to bring you all the answers to your questions, because believe it or not, I didn’t know most of the answers myself!
Why are baking soda and baking powder used in baking?
Baking soda and baking powder are both leavening agents, but the difference lies in the chemistry of both powders. Baking soda (also known as pure sodium bicarbonate) reacts to acidic ingredients, such as lemon juice, buttermilk, yoghurt, cocoa and cider vinegar among others. When baking soda is mixed together with acidic ingredients, it produces carbon dioxide bubbles that allow the dough to rise when baked. These bubbles are created as soon as the baking soda touches an acidic ingredient and can quickly disappear, which is why it is always recommended to bake the batter as soon as you finish incorporating all the ingredients.
Baking powder, on the other hand, already contains an acidic ingredient (usually cream of tartar), as well as a dry ingredient to help absorb moisture (like flour) and baking soda. Due to their different components, baking soda and baking powder don’t react quite equally. Baking soda depends on other acidic ingredients to react, whereas baking powder doesn’t need another acidic ingredient in the batter to produce carbon dioxide bubbles. Things get even more complicated when you realize that there are two different types of baking powders; (1) a single-acting version, in which carbon dioxide bubbles are created as soon as you mix the powder together with wet ingredients, meaning that you can’t let the batter sit prior to baking or if not it will fall, and (2) a double-acting version, in which most of the carbon dioxide bubbles are released when the batter is baking in the oven.
Baking powder contains baking soda. So can I replace baking soda with baking powder?
You unfortunately cannot use baking soda instead of baking powder, as baking soda relies on other acidic ingredients to make the batter rise. You can generally use baking powder instead of baking soda, however you may need to add much more of it and it might affect the taste of your dessert.
How do I know when to use baking soda or baking powder?
Remember, baking soda needs to interact with an acidic ingredient to help the batter rise. Baking soda is always favored in recipes containing one or more acidic ingredients, such as in these mini red velvet cupcakes that call for yoghurt, cider vinegar and cocoa powder. Baking powder tends to be included in recipes with more neutral wet ingredients, such as milk, as seen in the recipe for these blueberry muffins.
Can I make my own baking powder?
Of course you can, as long as you have some baking soda available! Just mix two parts creme of tartar with one part baking soda.
For how long can I keep baking soda and baking powder?
It is best to not use them for longer than the expiration date stated on the box, because their leavening properties tend to wear off over time.
Do you have more cooking/baking questions to ask? Email them to me savormania (at) gmail (dot) com and I will answer them in a future Science of Cooking post!