When it comes to baking powder and baking soda, you can't have one (powder) without the other (soda.) But that doesn't mean the ingredients are interchangeable. Here's how they're different.
What is Baking Soda?
Baking soda is another name for sodium bicarbonate. It's a base that reacts when it comes into contact with lemon juice, vinegar, or buttermilk, sometimes in such spectacular fashion that it's the basis for science fair projects. Reacting in this case means releasing gas bubbles, which is what helps cakes and cookies rise. When baking soda doesn't react, it has a distinctive metallic taste: In other words, measure carefully.
The other problem with baking soda is how quickly it reacts. That's good if you're assembling a model volcano, but less advantageous if you're trying to pull off a birthday cake. In that case, you want the rising to occur gradually over a longer period. That's where baking powder comes in.
What is Baking Powder?
Baking powder includes baking soda, and also monocalcium phosphate and either sodium acid pyrophosphate or sodium aluminum sulfate. Those acids react with sodium bicarbonate (baking soda), but not until they're hot and wet. So the process of creating air bubbles doesn't begin until the batter's mixed and heated in the oven.
Sometimes a recipe will call for both baking soda and baking powder. That's because after baking soda neutralizes the available acid, the pastry still needs a little more lift.
It's important to remember that if you're out of baking powder, you can't use baking soda instead. But you can make your own baking powder, and some cooks believe the mix tastes better than what's commercially available.
How to Test If Your Baking Powder or Baking Soda Is Still Good?
Has your baking powder or baking soda been hanging around the cupboard for quite some time? Luckily there’s a simple test to determine if it's still active. To test if baking powder is still good, drop half a teaspoon of it into hot water. If it fizzes and forms bubbles, it’s still good. To test baking soda, drop half a teaspoon of it into a small amount of vinegar. Once again, if it fizzes it’s still active. If you don’t get any sort of reaction, it’s time to toss that box and buy some new baking powder or baking soda.
Here's how to make your own baking powder.
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