Baking Soda and Baking Powder: What's the Difference?If you've ever tried to use baking powder in place of baking soda, or vice-versa, you've discovered that the two don't work the same. But what's the difference between baking soda and baking powder?
Both substances are leavening agents, which are used in baking to cause doughs to rise. In the case of baking powder or baking soda, they do this via a chemical reaction that releases carbon dioxide gas. This gas then forms bubbles in the dough, causing it to rise. While the dough is cooking, these bubbles harden as the bread is baked.
There are other types of leavening agents. Yeast is made up of tiny micro-organisms. When they consume sugar, they release gas. Steam can also be used as a leavening agent. This technique is used in making puff pastry, where the dough is folded over again and again, forming many thin layers. The steam that is released during cooking puffs up the layers, causing the dough to rise. Air can also be beaten into to doughs and batters through the creaming method, which is commonly used in making cookies.
Quick Breads: Baking Powder or Baking SodaBut baking soda and baking powder work differently from these other leavening agents because the release of gas is caused by a chemical reaction. The reaction happens quickly, which is why banana bread, zucchini bread and so on, which are made with baking soda and/or baking powder, are known as "quick breads." Other members of the quick bread family include muffins, biscuits and scones, which are also produced using baking powder, baking soda or a combination of both.
Interestingly, pancakes are also a member of the quickbread family. Consider for example, the similarities between this recipe for blueberry muffins and this recipe for blueberry pancakes. It's basically the same ingredients, but the pancake batter is a little bit wetter.
How Do Baking Soda and Baking Powder Work?So, how do baking soda and baking powder actually work? Basically, baking soda is an alkaline, and when you mix in something acidic, like vinegar, it will release gas. The key here is that baking soda needs some sort of acid to activate the reaction. So it will work in recipes that include acidic ingredients like buttermilk, sour cream, lemon juice, yogurt and so on. Molasses is also acidic, and so, believe it or not, is honey. So any of these ingredients would activate the baking soda. But if you were to try to substitute baking soda for baking powder in a recipe where no acidic ingredient is present, there will be no release of gas and the dough won't rise.
Baking powder, on the other hand, is nothing more than baking soda with some sort of acidic compound (different brands of baking powder use different compounds) already included. The baking soda and the acidic compound won't react together until they are moistened, which causes the two chemicals to mix. So-called "double-acting" baking powder is also activated by the heat of the oven or griddle, and thus has greater leavening powers.
Using Baking Powder Instead of Baking SodaSo now let's say you were to use baking powder instead of baking soda. This should create some leavening, because a recipe that calls for baking soda should already include some sort of acidic ingredient as described above. But here's where the problem lies: Baking powder is about one-third baking soda, and about two thirds other ingredients. So while you will indeed get some rise, you won't get enough, because you would essentially only be using one-third the amount of baking soda as the recipe actually requires.
If you were determined to do this, you could triple the amount of baking powder, but because of the additional ingredients in the baking powder, you'd probably notice a bitter flavor. There's also a chance that because of the extra acids in the recipe, the batter would quickly rise and then fall before the bubbles had a chance to bake in. Either way, the results are not good.
Make Your Own Baking PowderYou can, however, make a batch of baking powder yourself. All you need to do is combine one teaspoon of baking soda with two teaspoons of cream of tartar. This will yield one tablespoon of baking powder. You should use it right away, however — don't make up a batch in advance. And if you don't have cream of tartar, you're going to have to go to the store anyway, so you might as well just buy yourself some baking powder.
One last note: Chemical leavening agents like baking powder and baking soda will lose their potency after a while, especially if they are stored in a warm place (like a kitchen!) or if the containers are not sealed tightly. The good news is that both are pretty cheap, so for best results, replace them every six months or so.