I was getting ready to make Alton Brown’s vanilla wafer cookies (I’m thinking about making rum balls) when I noticed it called for this ingredient:
3/4 teaspoon aluminum-free baking powder
A quick check of my go-to baking powder, Clabber Girl, reveals aluminum (emphasis added):
Ingredients: Cornstarch, Bicarbonate of Soda, Sodium Aluminum Sulfate, Monocalcium Phosphate
So in addition to making my vanilla wafers from scratch, I have to make my baking powder from scratch, too?
Turns out that making baking powder from scratch is is a piece of cake. So to speak!
Why aluminum-free baking powder?
The primary reason: taste. According to David leBotivz:
One of the least expensive, and most effective, things you can do to improve the taste of your cakes, quick breads, cookies, and muffins is to switch to aluminum-free baking powder right away.
If you do make your own baking powder, be sure to pop whatever you’re making right in the oven after it’s mixed as it’ll start to react once you’ve added the liquid to your muffin or quick bread recipe.
Recipe for aluminum-free baking powder
There are many recipes for aluminum-free baking powder, but they all come down to the same thing: three ingredients with a common set of proportions.
Mix two parts cream of tartar with one part baking soda and one part cornstarch
You’ll want to make this is small batches and store in an air-tight container in a dark, cool spot. Not the fridge!
Baking powder versus baking soda
In case you’re wondering about the difference between baking powder and baking soda …
Both are leavening agents. That is, they both cause what we are baking to rise. (Trust me, biscuits made without leavening are Hard. And flat!)
Baking soda, which is pure sodium bicarbonate (alkaline), needs an acid and a liquid to create the carbon dioxide bubbles that cause our baked goods to have lift. Typical acidic ingredients: buttermilk, yogurt, vinegar, honey.
The reaction starts immediately when you mix baking soda, acid and liquid, so get thee to an oven quickly! Products that rely solely on baking soda are called quick breads.
Baking powder combines sodium bicarbonate with an acid (cream of tartar) and a drying agent (a starch) that keeps the other two separate. This means that our recipe does not need to include an acidic ingredient.
A single-acting powder begins reacting when it gets wet; put this batter into the oven quickly. A double-acting powder reacts in two phases, when wet and when hot (it contains two acids); this batter can sit around longer before entering the oven. Finished goods will also be lighter.
Whether a recipe calls for baking soda or baking powder depends on the other ingredients. Buttermilk means you can use baking soda. If a recipe lists milk, you’ll probably need baking powder.
Cookies usually use baking soda; cakes and breads, baking powder. Sometimes, a recipe will require both. In addition, baking soda boosts browning (the Maillard reaction).
Baking soda is the more long-lived of the two leavening agents. Once opened, baking powder shelf-life is usually measured in months; most cooks recommend writing the purchase and open dates on the can.
To determine if your baking powder still has oomph, put a small amount in a bowl. Add a little vinegar (acid). Got bubbles? Good to go.
To test baking soda, put a small amount in a bowl. Add a little water (neutral liquid). Got foam? Good to go.
Learn more at Chemistry @ About.com, Physics.org, SeriousEats and SimplyRecipes
Type used on photo of baking soda and baking powder is Gunny Rewritten.