Have you ever found a can of baking powder hiding in the back of your cabinet and wondered if it was still good? There's a simple way to test if it's still got the lift your baked goods need.
Put a teaspoon of baking powder in a cup of hot water. If it bubbles, the baking powder still has what it takes to make those baked goods rise. If it doesn't bubble, it's time to make your own with only 2 ingredients. If you want it to make a bigger batchto keep on hand for the next time you're going to bake and have it last a while, then you will need 3 ingredients.
To make your own baking powder: You will need 1 teaspoon baking soda and 2 teaspoons cream of tartar. I don't usually stock cream of tartar except when I'm making meringues, which is about once a year, so this is an ingredient you need to put on your grocery list. I usually have plenty of baking soda around for cleaning and other uses because it's so versatile.
Mix the baking soda and cream of tartar together until combined. Then use it immediately. If you want to make a larger batch and store it for a period of time, it's recommended to add 1 teaspoon of corn starch with the other ingredients.
For that larger batch, the basic recipe is 1 part baking soda, 2 parts cream of tartar and 1 part corn starch. Corn starch is that handy ingredient that absorbs moisture so it's been known to be used on baby butts and sweaty feet, but it also works great preserving the active agents in your homemade baking powder.
Since I don't like any ingredients in my food that might be unhealthy, making your own baking powder gives you the added confidence that there isn't any aluminum in it, which is a common ingredient in baking powder.