The general rule of thumb is: when stored properly, baking soda will last for two to three years sealed in its original container. Once opened, it will keep for at least six months.
You certainly can use old baking soda from the fridge to clean... Baking soda is a good cleaner, and when it breaks down it makes a salt called washing soda, along with carbon dioxide gas and water. This is a slow reaction at room temperature and even slower in the fridge.
In fact, baking soda is considered to be shelf stable for at least 2 years when stored under typical room temperature conditions (25 °C with 60 % humidity). For this reason, baking soda does not expire.
Technically, eating expired baking soda won't hurt you, so you don't have to worry about falling ill from a cake gone wrong. However, if baking soda has gone bad, it won't work very well. Using baking soda that's past its prime could result in baked goods being denser and flatter than expected.
Keep baking soda away from any wood surface, including wood floors, wooden coffee or dining tables, and cutting boards. "Baking soda is slightly abrasive, and if used to clean wood furniture, especially with a polished finish, it can leave scratches," explains Brown.
You can't tell if baking soda has lost its effectiveness by its color or smell, and it's still safe to use for baking well beyond its expiration date. When it "goes bad," that simply means it's lost its effectiveness as a leavening agent in baked goods, helping them rise.
Using Up Old Baking Soda
Though it is no longer useful for baking, you can still use baking soda that has gone bad for myriad cleaning purposes: It's a great refrigerator deodorizer. Use baking soda as a kitchen and bathroom surface cleaner (make a paste of three parts warm water to one part baking soda).
Baking powder won't have an off smell or taste—unless it's been contaminated with something else. And it is safe to use past its expiration date, even if it isn't as effective. You'll just end up with a flatter, denser baked good than you would if you used fresh baking powder.
You should notice a fresher smell within one to three days, but baking soda in the fridge needs to be replaced at least every three months. The box of baking soda may need to be replaced sooner if it begins to absorb too many foul odors. Try dating the package to help you remember when to replace it.
Carbonated soft drinks or sodas are not perishable, and are safe past the date stamped on the container. Eventually flavor and carbonation will decrease. For best quality, consume unopened diet sodas within 3 months after the date expires; regular sodas within 9 months.
The Food Marketing Institute's "The Food Keeper" recommends storing unopened baking soda at room temperature for 18 months. After opening, store at room temperature for 6 months for best quality.
The granulation for baking soda is different than that found in the ordinary, 1lb Yellow Box. The baking soda in Fresh-N-Natural box may not give the same baking results because the granulation size is intended specifically for deodorizing. Fresh-N-Natural is essentially the same as Fridge-N-Freezer.
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.
There are several pantry-friendly ingredients that you can use as baking soda substitutes, including egg whites, self-rising flour and even club soda. Or, you can use baking powder - and even a couple of extremely scientific sounding items that perhaps you just happen to have lying around - baker's ammonia anyone?
Place 1/4 teaspoon baking soda in a cup and add 2 teaspoons vinegar. Just like baking powder, if baking soda doesn't bubble, it's old and should be replaced.
Real Salt never expires.
Food only spoils when fungal, bacterial, yeast, or other microbial growth takes place. All of these require water. Salt doesn't contain water, so it doesn't support microbial growth, meaning it won't spoil. In fact, salt is actually used as a preservative for other foods, like meat.
If stored properly, Brown Sugar should last indefinitely. If your Brown Sugar smells “off” or unusual in some way (it should be sweet and a little earthy smelling, especially Dark Brown and Demerara Style), it has most likely absorbed the smell of something else nearby because it wasn't sealed properly.
Baking soda is a natural deodorizer that can help absorb and neutralize mild odors inside the refrigerator. Adding an open box of baking soda to one of the interior shelves of the refrigerator can minimize unwanted odors. Depending on what's causing the smell, baking soda may take up to three days to remove odors.
The Best: Remodeez Aqua Refrigerator Deodorizer
This means that a single Remodeez will last much longer than anything full of baking soda (though the baking soda models can be refilled). Basically, you only need to replace it every six months—which is about five months and 27 days longer than your oldest leftovers.
The general rule of thumb is: when stored properly, baking soda will last for two to three years sealed in its original container. Once opened, it will keep for at least six months.
Remember also that too much baking soda in a recipe and not enough acid will still result in a soapy, metallic taste in the baked good.