both are leaveners. meaning, they cause your baked goods to rise.
both are white-ish powders.
and that’s where their similarities end.
these two white powders cannot be substituted for one another in a recipe. both work in completely different ways and rely on something else in the recipe in order to cause the reaction that releases gas (which forms bubbles, which causes baked goods to rise.)
let’s break it down, shall we?
baking soda
baking soda is baking soda. it should be used when your recipe also calls for something acidic (lemon juice, buttermilk, vinegar.) why? because in order to do rising at all, baking soda needs to be mixed with an acid. mixed with, say, vinegar, baking soda releases carbon dioxide gas which creates bubbles which - wait for it - causes your baked goods to rise. magic!
baking powder
baking powder is baking powder. it is entirely different than baking soda. it needs no acid. it only needs liquid. which is also quite magical. the thing about baking powder is that if you add it to your recipe and you’re using a fast-acting version, you need to get your batter (or whatever) into the oven or onto the griddle immediately. thankfully, science has helped out with baking powder and slow-acting baking powder has also been developed…this makes it so that the baking powder doesn’t start its reaction with the liquid until it’s reached a certain temperature in the oven.
and, of course, we can’t leave out double acting baking powder - it basically works in two phases: one immediate reaction at room temperature, and another reaction after the baked good has reached a certain temperature in the oven.
together at last: baking soda + baking powder
now, what about recipes using both baking soda and baking powder?
let’s take, for example, buttermilk biscuits. part of the allure of buttermilk biscuits is the tang left behind by the buttermilk, right? if you relied only on baking soda for the rise, you’d have to add so much of it that all of the tangy buttermilk goodness would turn into gas and float right out of your biscuits (please, please use your imagination. thank you.) with the addition of baking powder, you get enough lift - AND you get the tangy taste you’re after. in this situation, baking soda and baking powder work as a team delivering fluffy biscuits that actually taste like buttermilk. now, that IS magic.
now, prepare yourselves because i’m about to blow your minds:
you can actually make your own baking powder. no, really, you can.
here’s how you do it:
mix 2 tablespoons of cream of tartar with 1 tablespoon of baking soda and 1 tablespoon of cornstarch. mix and mix and mix. store in a cool, dry place.
why would you make your own? freshness, of course! and, it’s fun! and you can tell all your friends that you make your own baking powder. in these times of people being all foodie-this and foodie-that, you’ll certainly impress!
tomorrow i plan to explain how you can test the freshness of the baking soda and baking powder that has been sitting in your cupboard for three years. it’s going to be magic. AND fun. magical, impressive fun.