Cornstarch Shelf Life: Can It Go Bad?

Cornstarch, whether you use it for cleaning or for cooking, there’s no doubt you’ve wondered how long you can keep this pantry staple in your cupboard. 

Simply a product made out of fine starch from the kernels of corn, cornstarch is easy to store and lasts for an incredibly long period of time.

How long, you might ask? Keep reading to learn more about whether cornstarch goes bad and how you’ll be able to tell if it does.

What is Cornstarch?

Sometimes referred to as corn flour, cornstarch is extracted from corn and is used in a  variety of industrial, culinary, and cleaning applications. Originally created in 1844, this staple is common in corn-growing places in the United States and other countries. 

It is often used as a thickening agent for some of the following dishes: 

  • Marinades
  • Gravy 
  • Sauces
  • Casseroles
  • Pies
  • Desserts
  • Soups
  • Glazes 
  • Batters

Cornstarch is often viewed as being interchangeable with wheat flour. However, it contains no gluten, so it’s great for people who are following gluten-free diets. Plus, since it is transparent instead of opaque, it’s a good option for dishes where the final appearance matters. 

What is the Shelf Life of Cornstarch?

Cornstarch has a surprisingly long shelf life. It is made out of corn syrup, a byproduct of corn, so it has a mostly indefinite shelf life.

You really don’t need to worry about your cornstarch going bad unless moisture or bugs make their way inside a container.

Unlike other thickening agents, like baking powder, that do not go bad but lose their potency over time, cornstarch experiences no loss in effectiveness even after long term storage.

That’s great to know, as cornstarch is often used as a thickening agent in sauces or gravies. 

How Long Does Cornstarch Last?

Most flour products including cornstarch often come with a sell-by or best-by date, but these dates are really intended more for manufacturers and wholesalers than they are for consumers.

You can ignore this date as long as you are storing your cornstarch properly. It will be safe to use in pies, sauces, and gravies for years on end. 

How to Tell if Cornstarch Has Gone Bad

Cornstarch really doesn’t go bad, so there’s no way to tell if it has spoiled already. Plus, it doesn’t lose its potency over time, either, so you don’t have to worry about it not passing muster when it comes to using it in your favorite recipes. 

The exception to this is when it comes to bugs and moisture. Cornstarch can occasionally experience a loss in quality when bugs and water get inside the packaging. You’ll probably know when this has happened, though, as the cornstarch may appear clumpy. If the problem has to do with an insect infestation, chances are, you’re going to notice the bugs or their eggs, too.

If water gets inside your cornstarch container, you may find mold or other nasty growths developing inside the package. If you see these, get rid of the cornstarch immediately. In some cases, you might be able to pick the mold out, but it’s usually too difficult to determine if the water damage has extended to the entire package. 

When you inspect your cornstarch after you know it has been accidentally exposed to water, you might not see any signs of problems. Usually, that means it’s still okay to use. There will be occasional clumps, but as long as there’s no mold, it’s safe to use. Simply stir it up or sift it before you use it. 

How to Store Cornstarch Properly

Cornstarch can be stored in the same way you would store any other type of flour. That’s easy to remember, as the two are usually used in similar ways and so you’ll want them kept close by each other.

In other words, keep your cornstarch in a cool, dry location. You don’t need to keep it in the refrigerator, where it will likely take up unnecessary space. In fact, there’s really no added benefit to storing cornstarch in the fridge.

Cornstarch is designed to absorb moisture, so it’s important that you store it in an airtight container in which it will not be exposed to any ambient humidity in the air. It should also be kept out of extreme heat – so keeping it right next to your stove is probably not a great idea. 

You can keep your cornstarch in a pantry or even in an isolated cupboard. Some people even keep cornstarch in dry areas of their basements or root cellars.

The main thing to remember is that cornstarch should be kept tightly sealed when not in use. Cornstarch is sometimes sold in bags and other times sold in plastic tubs. If you can purchase it in a rigid plastic container, that’s better, as it will be easier for you to reseal your container after you have used it. 

If you don’t have the luxury to purchase your cornstarch in this way, an easy tip to overcome this is to transfer your unused cornstarch into a resealable container for later use. Repackaging your cornstarch might seem like a cumbersome extra step, but it will protect the powder from moisture and any potential odors that might affect its smell and taste.

Resealing and packing up your cornstarch will also help to keep it protected from pests, like insects, that might want to get inside and lay their eggs. That sounds unpleasant, but unfortunately, it happens all the time – even in clean pantries!

Uses for Expired Cornstarch

Cornstarch does not have a shelf life, so it never truly expires. However, if you have a ton of cornstarch in your cupboard that needs to be used up, you might want to consider some of these alternative uses:

  • Add to eggs to make them more fluffy
  • Soothe skin irritation
  • Use as a makeshift deodorant
  • Get rid of oil stains 
  • Use in a bleach pen
  • Untangle knots
  • Make your own paint or nail polish 
  • Clean stuffed animals
  • Use as a dry shampoo
  • Use to starch your clothes
  • Make a DIY face powder 


Can I use cornstarch past the expiration date?

Cornstarch is not usually sold with expiration dates, but is instead sold with sell-by or best-by dates. These dates are not a good indicator of how long cornstarch can be used, because it is really fine to use it indefinitely.

That being said, if you notice a date on your cornstarch package – and that date has already passed by – don’t worry about using it up. As long as it looks normal (or even has a few clumps that can be broken up and stirred in) it’s perfectly safe to use.

What happens if you eat bad cornstarch?

Nothing will likely happen if you eat bad cornstarch. The exception to this is if there is mold or insects in the starch. Still, you are unlikely to experience any adverse effects (you might have some digestive upsets, at the very worst).

The exception to this is if you eat raw cornstarch. You should avoid eating raw cornstarch, and really, there’s no logical reason as to why you would want to, as it doesn’t taste the best. It’s edible in small quantities and is used in various medical interventions, but consuming raw cornstarch can cause bloating and stomach upsets as it’s difficult for your body to digest.

Does corn flour go bad?

Corn flour is the same thing as cornstarch. It does not go bad unless exposed to water or insects.

Does cornstarch lose its thickening power over time?

Unlike other baking agents, like baking powder, cornstarch does not lose its potency over time, nor does it lose its thickening ability.

Does cornstarch lose its effectiveness?

Cornstarch does not lose its effectiveness over time as long as it is stored properly. Refrigeration is not necessary.

Does cornstarch get bugs?

Unfortunately, all kinds of dry goods can attract pantry pests, and cornstarch is no exception. Usually, the culprit to be aware of is the weevil. Weevils are small brown bugs that look like grains of rice, except that they move. Weevils are usually harmless, but there’s no reason why you would want to eat them. Discard your cornstarch if you notice these pests inside.

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