Corn bread was pancake flat yesterday, which got me to studying the recipe and the ingredients. Then I realized I'd never understood baking powder. What is it? what does it do?
BP acts like yeast, releasing CO2 to make gas bubbles so the batter will be fluffy. Yeast do it by eating sugars and then farting CO2. BP does it by chemical reaction.
It's like those baking soda rockets we made when I was a kid. Fill the rocket with acid (vinegar) wrap a little ball of baking soda (sodium bicarbonate) in a piece of Kleenex to delay the chemical reaction, and stuff the ball of baking soda into the rocket with the vinegar and ram the plug home...and stand back. Eventually the CO2 would propel the rocket off the launch pad, usually landing on a roof somewhere.
Important safety lesson, do not stand over a charged rocket and look down with your remaining eye.
Baking Powder is comprised of a base (usually baking soda--sodium bicarbonate) and an acid (usually Cream of Tartar--potassium hydrogen tartrate, an acid salt) in powder form, which prevents reaction. There is usually a filler, too, like corn starch or potato starch, both to add volume when measuring out and to buffer and slow the reaction. Dry, these items will not react. But any liquid activates the baking powder and causes it to off gas CO2.
Here's the lesson of where I went wrong:
Lesson 1: I put the liquids into the bowl first and then added the dry ingredients. This allowed the BP to cook off before I mixed the batter and trapped the gasses. If BP had been the last item added, I might have gotten away with this, but when it's among the first to get soaked, I was sunk. (This is the reason you're told on the box to mix the dry ingredients first--I failed to follow simple directions).
Lesson 2: I probably made the loss of CO2 all a lot worse by over mixing (again, this caution is on the box, so I failed to follow simple directions). BP, unlike yeast, releases a set amount of gas per reaction. If you mix the batter too much, you release all the gas from the batter and it goes flat. With yeast, they keep digesting sugars and farting CO2 until they die, which is why you can work a yeast batter loner.
We use baking powder instead of yeast because we like biscuits in 20 mins vs 2 hours with yeast. (this also is why they sell "Yeast Rolls" and "Dinner Rolls" side by side. I never thought that there was a difference.)
Lesson 3: there are double activation or double acting baking powders available. These act like single action baking powders when you get them wet, but also have a second reaction that is heat activated by baking, which give you a second chance.
Lesson 4: honey (as well as buttermilk) is slightly acid. So I should have cut back on the baking powder and substituted baking soda because I used ¼ cup honey instead of sugar in the recipe.
Double acting baking powders have the same first acid, Cream of Tartar, but add another acid that is temperature activated as well, giving the pastry a second rise...or in my case, a second chance.
Eric writes about baking powder, pancakes, and the baking powder recipe here.
photo by EmmiP