Can Corn Syrup Go Bad?

Corn syrup is the secret ingredient that makes so many baked goods chewy and sweet. But unless you’re using it regularly (e.g., as a maple syrup substitute), chances are it takes quite some time for you to finish a bottle.

One day you reach for the corn syrup and notice that it’s passed the date on the label. The first question you ask yourself then is: can corn syrup go bad?

You don’t want to discard it if it’s still okay to eat, but at the same time, you don’t want to get sick from eating it.

To choose whether or not to use the sweetener, you need to know a few things about it. Those are how to store it, what’s its shelf life, and what are the signs of spoiled corn syrup. Below, we cover all of these. Let’s get going.

Corn Syrup in a Candy Recipe
Image used under Creative Commons from Jessica Merz

Can Corn Syrup Go Bad? How Do You Tell If It Is Bad?

Technically speaking, all foods can go off. But for some of them, the chances of that happening are quite slim. I’m pretty sure you’ve heard that honey lasts forever. Things are similar for other popular sweeteners like maple syrup, molasses, and the subject of this article, corn syrup.

In short, corn syrup most likely won’t go bad unless you leave it open (unsealed) for a prolonged period and other substances along with bacteria will get inside. And that bacteria have enough resources to survive and start multiplying, which isn’t simple in an environment so rich in sugar and scarce with water.

But if that happens, its color will likely change, and the smell will be off too. So if either the appearance, the odor, or the flavor of the syrup has changed, discard it.

One important thing regarding visual changes is that light corn syrup (which is clear [WIKI]) turns yellowish over time, and that’s not an indication of spoilage ([KS]).

The fact that this sweetener pretty much can’t spoil doesn’t mean that it keeps its quality forever. It’s time to talk about its shelf life.

Pancakes with syrup
(credit: Luke Pennystan)

How Long Does Corn Syrup Last?

If you read the website of Karo Syrup ([KS]), you’d learn that it’s safe to eat indefinitely. So unless something bad happens, and the sweetener spoils, it’s fit for use.

But as I already mentioned, it doesn’t retain its flavor forever. That’s where the best-by date on the label comes in.

For sweeteners like corn syrup, the date on the label is only a rough estimate of how long they should be of top quality. It gives you some guidance, but that’s about it.

More often than not, you will find that corn syrup good enough for months and even years past the best-by date. In short, if it looks and smells okay, give it a taste and decide if you continue using it based on that.

Last but not least, please note that opening the bottle for the first time doesn’t alter the shelf life of the syrup ([KS]). It’s not like it lasts indefinitely unopened, but only a couple of months after opening.

As long as you do a decent job at storing it, it will last for years, and you will be able to use all of it without wasting a drop.

Now it’s time to talk about storage practices.

Pancakes with syrup and blueberries
(credit: Calum Lewis)

How To Store Corn Syrup?

Corn syrup doesn’t require much when it comes to storage. A place at room temperature that’s away from sunlight is good enough. That’s mean pretty much any shelf or cabinet in the pantry will do.

If you use it often, the kitchen is perfectly fine, as long as it doesn’t just sit on the counter and isn’t in a place where the temperature fluctuates. Either won’t make the sweetener go off but can negatively affect the flavor.

Once you open the bottle for the first time, the recommendations above stay in place. Besides those, make sure you seal it after every use, and that’s it.

There’s no need refrigerate opened corn syrup; room temp is good enough.

Waffle with syrup
(credit: nabil boukala)

In a Nutshell

  • Corn syrup, unless mishandled in storage, doesn’t go bad. Light corn syrup turns a yellowish hue over time, and that’s not a sign of spoilage.
  • Corn syrup retains quality for years after the date on the package.
  • Keep the bottle at room temperature away from sunlight. Make sure it’s always sealed tight when you store it away.

References