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Food - Drink
What Happens To Baking Powder When It Expires?
Baking powder is sodium bicarbonate with monocalcium phosphate and sodium acid pyrophosphate, and only lets baked goods rise until the powder is heated up in the oven. While it's easy to tell if you've used too much or too little baking powder in a recipe, it’s not as easy to tell if your baking powder has expired.
The shelf life of baking powder is only six months if it’s kept in a cool, dry place. If you end up using expired baking powder, your baked goods will still be edible, but won't rise and will turn dense, since cakes, cookies, and cupcakes need the leavener's full power to cause a chemical reaction that makes them fluffy.
The best thing to do with baking powder you're not sure about is to test it before adding it to a recipe. Put a ½ teaspoon of baking powder in a bowl, then pour ¼ cup of boiling water on top of it; if your baking powder is still active, the mixture will start bubbling, but if it doesn't, you should throw away your box and buy a new one.