File this one under: live and learn. It was Thanksgiving afternoon and time to bust out a batch of biscuits. All went well as I cut the fat into the flour and rolled out the dough (taking care to do the trifold that ensures high-rise biscuits).
But when I pulled them out of the oven, I couldn't help noticing they hadn't risen as high as they have in the past. The culprit, I suspected, was past-its-prime baking powder. So I did what I should have done before the holiday and tested its effectiveness. The verdict: dead leavener.
Baking powder and baking soda are leaveners that help give baked goods height. And they tend to hang out for a long time in your pantry, but they don't last forever, even if you store them correctly–in a cool, dry place. According to the website Joy of Baking (a great reference to bookmark), baking powder only lasts 6-12 months. (Mine had been around, oh, going on two years and, when I checked, was two months past its “best by” date. Oops.) Baking soda lasts longer, but it, too, can lose its leavening power.
Here's how to test 'em:
Baking powder: Combine 1 teaspoon baking powder with 1/3 cup hot water. If it starts bubbling immediately, you're good to go. If not, time to replace it. And be sure to double-check the “best by” date on the new can.
Baking soda: Mix 1/4 teaspoon soda with 2 teaspoons vinegar. It, too, should start foaming right away. Mine did.