What in the world is the difference between baking soda and baking powder? Great question. So great, that I did not know the answer until now.
A few weeks ago my friend Lauren and I were having dinner. What's the difference between baking soda and baking powder she asked her food blogging friend. I have absolutely no idea, I said. If I had just asked you to name every salt one can cook with, you'd know the answer immediately.
She had a point. I don't bake. So, I had a thought: If I didn't know the difference, I bet a lot of our readers don't either. Well here we go.
Baking soda is used in baking to help stuff rise and fluff. When the baking soda reacts with an acid (i.e. cream of tartar, lemon juice, yogurt, buttermilk, vinegar, etc.) carbon dioxide is released. Think of a pancake or a cake. All of those little bubbles that form that make them fluffy is from the carbon dioxide - a product of the baking soda and acid.
Now, baking powder is baking soda with an acid (i.e. cream of tartar) added to it. So if there is already an acid in the recipe (buttermilk, lemon, citrus, etc.), then the additional acid in baking powder will remain unconsumed in the chemical process - leaving an unpleasant taste. Thus, baking powder is most often used with a more neutral ingredient, such as milk.
Why do some recipes call for both? That's a good question. When both ingredients are present, the baking powder does more of the leavening and the baking soda neutralizes any additional, unwanted acidic taste.
What if you need a substitution?
Your recipe calls for 1 tsp of baking powder, but you don't have baking powder. Don't fret. Use 1/4 teaspoon baking soda, 1/2 teaspoon cream of tartar plus 1/4 teaspoon of cornstarch.
Your recipe calls for 1 tsp of baking soda, but you only have baking powder. This isn't ideal, but will do. Triple the amount of baking powder - so use 3 tsps of baking powder instead. This will add additional acidity, but if you're desperate, it'll work.
Alright peeps - that's all I got. Demystifying the crazy world of baking. I'm exhausted.