How To Test Baking Soda for Freshness

I always have two boxes of baking soda in my kitchen—one in the pantry and one in the fridge. I know it’s not a big deal if the box in the fridge is old. It still does its job of absorbing orders. But if baking soda for baking isn’t fresh, that can be a disaster.

That’s why it’s key to check the date on the box first. The "use by" or "best by" date is important because baking soda loses its effectiveness over time, says Trung Vu, chef-instructor of pastry and baking arts at the Institute of Culinary Education's New York City campus. 

“Baking soda isn't unsafe to eat after the best-by date,” says Vu. “But if you're using it for baking cookies, for instance, it also won't do as good a job leavening the cake or cookie, so you'll have a much denser, flatter pastry.”

How To Check Baking Soda for Freshness

To test baking soda for freshness:

• Add about 1/4 teaspoon of baking soda to a bowl
• Add a couple of tablespoons of vinegar or lemon juice
• If it bubbles and fizzes, your baking soda is fresh
• If it does nothing, do not use your baking soda for baking

“The reaction of baking soda with an acid creates carbon dioxide gas, which is what causes the fizzing,” says Vu.

Is There a Swap for Baking Soda?

There’s no easy substitution if your baking soda isn’t fresh. “Although there are many other products used to leaven baked goods such as yeast in breads, whipped eggs in sponge cakes, and baking powder in cakes and cookies, there is not a 1:1 swap for baking soda that will create the same texture or desired outcome,” Vu explains.

It might be tempting, but you can’t just swap baking powder for baking soda in your recipe.

“If the situation was reversed and you had baking soda but needed baking powder, you could make a single-acting baking powder by mixing one part baking soda with two parts cream of tartar,” says Vu. “But if what you need is baking soda, there is no way to reverse engineer it from baking powder.”

And don’t try just doubling up on the amount of expired baking soda hoping that will make the difference.

“If you think your baking soda isn't the freshest, adding more to the recipe isn't a great solution,” Vu says. “An excess of baking soda will create a soapy, metallic taste in your baked goods.”

How To Keep Baking Soda Fresh

Proper storage will help you keep your baking soda lasting fresh for a longer period of time.

Once you open baking soda, Vu suggests moving it to an airtight, resealable container and storing it in a cool, dry place like the pantry. Don’t store it in the fridge unless you are using it to absorb odors.

“The refrigerator can also be a moist environment, which can lead to baking soda clumping, something it is already prone to,” says Vu. “Ideally, baking soda is sifted before being used in baking to eliminate any clumps.”