Baking Powder

My friend, Russ, after reading my comments about biscotti, pointed out that I should know a little more about baking powder, and he kindly forwarded on some information about what, exactly, baking powder does.

Here's what he sent me:

Baking powder is normally made of three different parts:

An acid
A base
A filler of some sort

All three need to be dry powders that can be mixed together. For example, baking soda (a base), cream of tartar (an acid) and corn starch (the filler) are three common ingredients.

In school, you may have done the experiment where you mix baking soda (a base) and vinegar (an acid) and get a bubbling reaction. Baking powder works the same way. When you add water to baking powder, the dry acid and base go into solution and start reacting to produce carbon dioxide bubbles.

Single-acting baking powder produces all of its bubbles when it gets wet.
Double-acting baking powder produces bubbles again when it gets hot.

If you want to prove to yourself that this is how baking powder works, simply try mixing a teaspoon of baking powder into a cup of hot water. As long as the baking powder is fresh, you will definitely see the reaction!

Thanks, Russ.