Baking Soda – Does it expire? And how to test if it still works!

If your favorite recipes are falling flat, there is a good chance your baking soda or baking powder are no longer performing at their best! Unless you are a busy baker, there is a good chance the open box of baking soda in your cupboard has overstayed its welcome.

We will be referring to baking soda in this article. But the same rules apply to baking powder. You can read about baking soda and baking powder here. Okay. Let’s continue.

How long does baking soda last?

Unopened, baking soda will remain shelf stable until the best-by date on the box, generally 2 years. Once opened, a box of baking soda or baking powder should be used within six months. Not because it becomes stale or moldy, but because it loses its potency and power.

Baking soda is used as a leavening agent to make food fluffy. When baking soda is combined with acidic foods it creates a chemical reaction. Think about science class: baking soda(base) + vinegar(acid) = epic volcano! This same reaction gives a lift to food when baking, resulting in fluffy pancakes, cookies, cupcakes, muffins, cakes, biscuits, etc. Over time, the amount of lift that it can provide decreases. Once a box is opened, baking soda begins to slowly absorb moisture. Over time, this added moisture reduces the power of the reaction. Exposure to extreme temperatures – cold or heat – can also reduce its efficacy.

Baking Soda Test

To prove this theory, we conducted a baking test. Using the same recipe and preparation method, we baked two batches of double-chocolate muffins. Using freshly opened baking soda and baking powder in the first batch and old leavening agents in the second batch. Even before tasting, you can see a visible difference between the muffins.

The fresh baking soda and baking powder produced a full muffin with a fluffy interior. The old products fell flat, resulting in a dense and dry muffin. These findings have confirmed the importance for fresh baking soda when making cakes, cupcakes, and muffins.

We also tested cookies, because cookies tend to be less affected by old leavening agents. The differences were less obvious, essentially unnoticeable. Do you see a difference in the cookies above? The top three cookies used old baking powder. The bottom three cookies were made with new baking powder. Both batches baked beautifully. Therefore, ultimate freshness is less important for cookies, but still suggested, especially if the cookies have a cake-like texture.

How should baking soda be stored?

First, only buy the amount of baking soda that you can use in a 6 month period of time. If you can’t use five pounds, don’t buy five pounds. Next, write the date on baking soda box when you open it! This will eliminate any mystery boxes in your cupboard.

Now, store your leavening agents in a cool, dry place. Keep them away from moisture and out of the fridge or freezer, unless you are intentionally using the baking soda to eliminate odors. (In that situation, the baking soda should be replaced once a month and that soda should not be used for baking as it has absorbed all the fridge smells).

Also, keep baking soda away from your stove and oven. Heat and moisture rise from your range, so don’t store in a cupboard directly above. A spice cupboard or pantry is perfect, keeping it protected from heat, moisture, and sunlight.

You can further protect your baking soda by placing it in an airtight container after opening. This will protect from contamination by moisture or other odors in your cupboard. Remember to keep track of the date it was opened!

How do I know if my baking soda is still good?

Baking soda will react to acid. The fresher the soda, the larger the reaction. So, place a few tablespoons of vinegar in a bowl and sprinkle in a teaspoon of baking soda. If it immediately hisses and forms fizzy bubbles, you’re good to go. If the reaction is just a small fizz, your baking soda should not be used for baking.

Should I throw away old baking soda?

Baking Soda does not “go bad.” It just loses its efficacy! So, there are other uses for baking soda, even when the potency has diminished. Rub your next chicken or turkey with baking soda for crispier skin. Use it for cleaning. Use it as a deodorizer. And more. No need to throw out old baking soda!