Baking powder and baking soda are pantry ingredients that don’t always have a high turnover. If you bake irregularly, chances are good that you’ll have that box of baking soda on the shelf for a very long time. Even if you bake regularly, it takes a while for a container of baking powder to get used up – not to mention that it is easy to lose a partially used container in the back of a crowded pantry.
Chemical leaveners, like baking powder and baking soda, can lose their potency over time. This is especially true when they are not stored in airtight containers. Impotent baking powder or baking soda can be the cause the cause of flat cakes, dense cookies and baked goods that simply don’t rise as much as they should. Fortunately, there is a very simple test that you can do to see if that nearly-forgotten box of baking soda is still good enough to bake with. In fact, try this test with fresh baking powder and baking soda so you’ll know what to look for in the future:
To test Baking Soda:
Put a few tablespoons of white vinegar into a small bowl and add a teaspoon of baking soda. It should bubble up furiously, and the foaming should take several moments to subside. The more bubbles, the more potent the baking soda. If there is no reaction, or you only end up with a handful of small bubbles, you need to replace your baking soda.
To test Baking Powder:
Put a few tablespoons of warm water (warm tap water is fine, but cold water is not) into a small bowl and add a teaspoon of baking powder. The mixture should make a fizzing noise and, after a moment, the baking powder will begin to fizz and the water will become very cloudy with tiny bubbles. The more bubbles, the fresher the baking powder. Baking powder reacts with liquids and heat, but does not react as well with cold water (even fresh powder won’t fizz much in ice water), so do not use it for this test.