Science, Tech, Math › Science How to Test Baking Powder and Baking Soda for Freshness Share Flipboard Email Print Diana Rattray Science Chemistry Chemistry In Everyday Life Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated August 14, 2019 Baking powder and baking soda lose their effectiveness over time, which can ruin your baking. Here's how to test baking powder and baking soda to make sure they are still good. Key Takeaways: Baking Powder and Baking Soda Freshness Baking powder and baking soda have a shelf life. Over time, these kitchen chemical lose their ability to make baked goods rise.You can test baking powder by mixing a small amount with a bit of hot water. Bubbles should be produced.You can test baking soda by mixing it with a few drops of lemon juice or vinegar. It should produce bubbles.Store baking powder and baking soda in a sealed container. Exposure to humidity eventually deactivates them. How to Test Baking Powder Baking powder is activated by a combination of heat and moisture. Test baking powder by mixing 1 teaspoon of baking powder with 1/3 cup hot water. If the baking powder is fresh, the mixture should produce lots of bubbles. Be sure to use warm or hot water; cold water will not work for this test. How to Test Baking Soda Baking soda is meant to produce bubbles when mixed with an acidic ingredient. Check baking soda by dripping a few drops of vinegar or lemon juice onto a small amount (1/4 teaspoon) of baking soda. The baking soda should bubble vigorously. If you don't see a lot of bubbles, it's time to replace your baking soda. Baking Powder & Baking Soda Shelf Life Depending on the humidity and how well the container is sealed, you can expect an opened box of baking powder or baking soda to retain its activity for a year to 18 months. Both products last longest if they are stored in cool, dry locations. High humidity can lessen the effectiveness of these leavening agents much more quickly. It's a good idea to test baking powder and soda before using them, just to be sure they are still good. The test is quick and simple and can save your recipe!