How to know eggs are good

   er and baking soda are two staples almost everyone has around that seem to last forever. But a lot of people don't know that they eventually start to lose their potency after enough time on the shelf. If you can't remember when you bought it, it's probably time for a new box.

When baking powder expires, you'll definitely notice the difference after your baked goods all turn out flat. Same thing with baking soda, which is an ingredient in baking powder, though you'll have the added disadvantage of stinkier pets, books, and shoes.

The expiration date on the box isn't always accurate, but there's a quick way to test both baking powder and baking soda to see if they need to be replaced.

How to Tell if Baking Powder Has Expired
Baking powder usually has a shelf life of about 9 to 12 months. Testing it is super easy. Just stir about half a teaspoon of baking powder into a cup of hot water. It will immediately start to fizz and release carbon dioxide gas if it's still fresh enough to use. This trick should work with both single- and double-acting powder.

How to Tell if Baking Soda Has Expired
Baking soda (aka sodium bicarbonate) is said to have an infinite shelf life, but after you've had it for a few years you should test to make sure it hasn't lost all its potency. Unlike baking powder, baking soda only reacts when you add an acid to the solution.

To test it, add half a teaspoon of vinegar to a cup of hot water, then stir in half a teaspoon of baking soda. Like the baking powder, if it produces a lot of carbon dioxide bubbles, it's still good.

Do you test your baking powder and soda for freshness, or just use them and hope for the best? Let us know in the comments.