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Does Corn Syrup Expire?

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Corn syrup is a popular liquid sweetener, and it has quite a wide range of uses. Kept at home, you can use corn syrup as a sweetener in both cooking and baking.

However, it can also be one of those ingredients that sit in the cupboard for quite some time before you need it.

Does corn syrup expire? Technically, corn syrup can expire if left for a long time and if bacteria begins to grow. However, corn syrup is very resistant to this, and while the corn syrup you have sitting in the cupboard might have a best-by date, it often lasts for an exceptionally long time.

Keep reading to find out all you need to know about whether or not corn syrup expires, how to tell if it has gone bad, and the best way to store it at home.

What Is Corn Syrup?

Corn syrup is made from corn starch. Using an enzyme, the glucose in the corn starch is changed to fructose, which gives the syrup its sweetness.

You will find both light corn syrup and dark corn syrup on the market. The light corn syrup has a mild sweetness, whereas the dark corn syrup has additives of caramel and molasses, which gives it a very sweet, rich taste, and darker color.

Corn syrup can be used as both a sweetener and thickener and is commonly used to make sweets. It is also used as a humectant, helping to maintain moisture in foods.

Does Corn Syrup Go Bad?

Corn syrup is one of those food items that can sit in the pantry for a long time, and never go bad. It is a very long-lasting ingredient that is fairly resistant to bacteria growth.

Food goes bad over time because of bacteria growth, and these bacteria then become harmful to human health. With corn syrup, the bacteria battles to multiply in the sugar-rich formula without much water present. This is one of the main factors which help it have such a long shelf-life.

If corn syrup ever does expire, it was more than likely caused by incorrect storage. Storing corn syrup is fairly easy, but done incorrectly, it can lead to the corn syrup changing in texture and appearance, and possibly even going bad.

So while corn syrup does not usually spoil, and it can be left in the pantry for a long time, there are some cases where improper storage might lead to it going bad.

It is also a good idea to follow the best-by date on the bottle. While this does not necessarily give an indication of when the corn syrup will go bad, it does offer a date range of when the corn syrup will be at its best quality.

However, it should still be fine to use the corn syrup once it has passed its best-by date. Some will have an expiry date, but this is usually quite far in the future.

Is It Safe To Use Expired Corn Syrup?

It is considered to be safe to use expired corn syrup, as long as it has been stored properly, and as long as the corn syrup does not show any signs of being off.

Most corn syrup bottles will have a best-by date, rather than an expiry date, as corn syrup very rarely goes bad.

This best-by date offers the date range of when the corn syrup is at its best, but it is just a guide and the corn syrup will still be fine to use after this.

Corn syrup is fine to use for years after purchase, but only if stored correctly.

It is a food that is resistant to bacteria growth and therefore spoiling, but there is still a chance of this happening if the bottle is left open, or if it is not stored in the correct environment.

As a rule of thumb, it is safe to use expired corn syrup, but if it is well past the best-by or expiry date, just make sure to check for any signs of spoiling, and discard of it if there is an off odor or smell. It is not worth the risk!

How To Tell If Corn Syrup Has Gone Bad

It does help to know how to tell whether or not corn syrup has gone bad so that you can do an extra check when using corn syrup that has been sitting in the pantry for some time.

While it is rare for corn syrup to go bad, it is always best to look for signs of spoiling, just in case. Here is what to look for:


If the corn syrup bottle appears cloudy, then it could be a sign that mold is starting to grow in the corn syrup bottle. This often happens if the cap has not been closed properly, and moisture has got into the bottle.

If you notice a haze or cloudiness, throw the corn syrup out.

Bad Smell

Corn syrup should not have a bad odor. If you notice a bad smell or odor when opening the bottle, it is a good sign that it has gone bad.

Do not use this corn syrup, and instead throw it straight into the garbage.

An off-odor will usually be bitter, or have a fermented alcohol smell to it.


Corn syrup that has been left open, or which has been exposed to bacteria, might begin to ferment. If fermenting, the corn syrup will have a foam layer on the top or have more bubbles in the syrup than usual.

There is no way to save corn syrup that has begun to ferment, and it should be thrown away. Corn syrup that has begun to ferment will also have a bad odor.

How To Store Corn Syrup

Corn syrup is very easy to store and does not need anything fancy to last for quite some time. It can be stored at room temperature, in a dark environment.

A kitchen pantry cupboard is perfect for this, as it is not warm and it is away from direct sunlight.

You do not need to refrigerate corn syrup once it is open, but you do need to make sure that the cap of the corn syrup is closed properly.

If it is not, moisture and bacteria can get into the corn syrup, and this is when the corn syrup can spoil.

It is recommended to use corn syrup within six months of opening, but if you have stored it correctly, it should be fine to use for quite some time after this.

Can High Fructose Corn Syrup Go Bad?

High fructose corn syrup has a long shelf life, and will not spoil if left in the right conditions over time. Unopened, it can last for years in the cupboard.

Once opened, it can last for just as long, as long as it is stored correctly and no other contaminants are allowed to enter the bottle.

It is all about storage when it comes to corn syrup and high fructose corn syrup spoiling, as this is the main reason it would spoil.

Does Corn Syrup Harden?

Corn syrup does not harden if left to sit. In fact, older corn syrup actually becomes runnier than newer corn syrup.

Corn syrup will only harden if heated to a certain temperature, where the water evaporates and the main component of sugar is left.

Left sitting in the pantry, corn syrup will not harden.

Does Corn Syrup Expire?

In conclusion, it is unlikely that you will ever have corn syrup expire in your kitchen. It is very resistant to bacteria growth, and because of this, does not go bad or spoil.

You do need to make sure that you store the corn syrup correctly, which is not too difficult.

It should be stored in a cupboard at room temperature, away from sunlight, and with the cap closed completely so that no moisture or bacteria can get into the bottle.

This way, your corn syrup will last for years!

Related Questions

Can expired corn syrup make you sick?

Corn syrup does not really expire, but if bacteria get into the corn syrup, mold can grow. Mold can make you sick, and it really is not advised to eat corn syrup that has mold growth.

There are those that say you can remove the mold and then use the corn syrup, but this really isn’t a good idea, and there is a good chance it could make you sick.

Should maple syrup be refrigerated once opened?

Yes, maple syrup should be kept in the refrigerator once opened. This helps to protect it from moisture and bacteria that could cause mold growth, which could cause the syrup to spoil.

What does corn syrup smell like?

Corn syrup does not have too much of a smell, other than being sweet. Dark corn syrup has a richer caramel and molasses smell.

If you notice an oversweet, bitter, or alcohol-like smell when opening a bottle of corn syrup, then it is a good sign that the corn syrup has gone bad, and it should be thrown away.

Up Next: How Long Does Simple Syrup Last?

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