Does Salt Expire—and How Do You Know if Your Salt Has Gone Bad?

Since time immemorial, humans have used salt as a preservative. In fact, preserving foods with salt goes back further than written records. Our ancestors salted meat, fish, vegetables and even fruits to prevent them from decaying quickly. Considering that, you’ve probably never stopped to wonder, Does salt expire?

The answer might surprise you, but to understand it, you’ll need to know a few facts about salt. It works to preserve foods by drawing water out of the foods and effectively drying them. This is actually a very clever use for salt: See, all living things—including bacteria—require water. By adding salt to food, we deprive bacteria of the water they need to thrive, preventing them from growing and making us sick.

The salt in butter, for instance, draws water out of the butter and leaves only the fat, which is why salted butter has a longer sell-by date than unsalted. Of course, if it makes foods last longer, does salt expire? Read on to learn the answer and find out whether salt ranks among the foods that never expire.

Does salt expire?

The short answer is that salt does not expire. Remember, the microbes that lead to spoilage and food poisoning all need water to grow. But pure salt doesn’t contain water, which means it never goes bad.

But there’s another reason salt doesn’t expire: It’s toxic to most microbes. According to a National Academies Institutes of Medicine report, “adding salt to foods can also cause microbial cells to undergo osmotic shock, resulting in the loss of water from the cell and thereby causing cell death or retarded growth.”

True, your shaker of salt often wears a best-by date on its label, but that’s usually because it’s required by law or because people tend to trust products with a best-by, use-by or sell-by date. According to the U.S. Department of Agriculture, salt lasts indefinitely, as long as you keep it in cool, dry conditions in the pantry.

That said, products that contain salt will eventually go bad. So butter will expire, as will last night’s seasoned leftovers. Even highly processed foods like canned goods expire.

OK, but does salt go bad if the product contains more than just plain salt? Surprisingly, yes. According to Morton Salt, salt products that contain other ingredients—iodine, spices, flavors or colors, for instance—can deteriorate with time.

How long does salt last?

Believe it or not, salt lasts indefinitely. That is, pure salt will last forever.

But many of the salt variants contain compounds and ingredients beyond the sodium chloride in pure salt. Himalayan salt, for example, gets its pink color from mineral impurities. Unrefined sea salt contains trace amounts of algae. Iodized salt contains iodine. And table salt, Kosher salt and other types contain anti-caking agents that can degrade over time, leading to clumping.

Those added compounds don’t stay fresh forever, so the salt won’t either. But it also won’t spoil or cause foodborne illnesses. Consume it after its use-by date, and it may not be top quality, but it won’t harm you.

How do you know if salt is expired?

You don’t! Remember, salt doesn’t expire.

Still, there are times when you’ll probably want to toss your salt in the trash because its quality has declined. Spotting salt that’s past its prime isn’t quite as easy as telling the difference between fresh and expired eggs, but you’ll know it when you see it.

For instance, salt can pick up the scent of other products or absorb scents from foods you’ve cooked. If your salt smells, odd or otherwise, you may want to discard it so you don’t pass that scent on to the foods you season.

People living in humid climates, particularly near bodies of water, will sometimes find that their salt has formed clumps. That’s a result of moisture and age (remember, anti-caking agents will degrade with time). While it won’t harm you, it may make it harder to shake the salt out of the container.

And finally, if you’re cursed with bugs in your pantry and some end up in your salt, chuck it in the trash. Nobody should eat buggy salt.

Can you use expired salt?

Go ahead and shake on some “expired” salt—it’s not one of those foods you have to toss after the expiration date. That’s because the answer to “does salt expire?” is no. Plus, expiration dates aren’t hard-and-fast spoilage dates. In fact, there’s no law in the United States regulating sell-by, best-by or use-by dates (except on baby formula). Think of them more as guidance for eating food when it’s at peak quality.

Just don’t expect to get the benefits of iodized salt—iodine is necessary for thyroid function, according to research in the journal Nutrients—if you’re consuming it past the expiration date. The iodine content in salt generally declines over time. According to an older study published in Food and Nutrition Bulletin, iodine loss is minimal during its first six months of storage but increases in the next six months.

So try not to let your salt sit around for too long if you’re counting on it for iodine. And keep it in the shaker, not a cutesy saltcellar that won’t preserve it as well. Of course, you can get iodine from other sources, like bread, cod, seaweed and yogurt.

Can expired salt make you sick?

Expired salt won’t make you sick. Because salt makes it hard for microbes to thrive, it doesn’t collect the same microorganisms that other foods do—you know, the ones that’ll have you running to the bathroom after devouring some meat stored in the fridge for too long or milk that expired a month ago.

So there you have it: the answer to “does salt expire?” You can safely keep that container of salt you lost at the back of your cupboard three years ago. It’s still good!

Sources:

• National Library of Medicine: “Strategies to Reduce Sodium Intake in the United States”
• FoodSafety.gov: “FoodKeeper App”
• Morton Salt: “Morton Salt Expiration Guide”
• Nutrients: “History of U.S. Iodine Fortification and Supplementation”
• National Institutes of Health: “Iodine”
• U.S. Department of Agriculture: “Food Product Dating”
• Food and Nutrition Bulletin: “Stability of Iodine in Iodized Salt Used for Correction of Iodine-Deficiency Disorders. II”