Does Cornstarch Go Bad? How Long Does It Last?

logo by Editorial Staff | Updated on August 3rd, 2022

Quick answer: Cornstarch may be used in recipes for an extended period. It does not lose its power over time, unlike baking powder.

The only “natural” reason to toss it out is if water or vermin get into the packaging. Aside from that, everything will be good. So, if you open the packaging and find mold or other organic growth within, throw it away. Water is most likely to blame for this growth.

Starch and corn cob on the table

If the powder appears to be fine, it most likely is. It’s fine if there are some little clumps. Before usage, you may always sift the powder.

What exactly is cornstarch?

Cornstarch, also known as corn flour, is derived from corn and used in various industrial, culinary, and cleaning purposes. This staple, invented in 1844, is widely used in corn-growing areas throughout the United States and other nations.

Cornstarch is frequently thought to be interchangeable with wheat flour. It does not, however, contain gluten, making it ideal for gluten-free diets. Furthermore, because it is transparent rather than opaque, it is an excellent choice for meals where the final aesthetic is important.

What is the purpose of cornstarch?

Cornstarch is most commonly used as a thickening agent in recipes. I use it in beef and broccoli soup and egg drop soup. To use cornstarch as a thickening, combine it with cold water to create a “slurry.” The proportion of cold water to cornstarch is 1:1.

Cornstarch, derived from maize rather than flour, may be an excellent gluten-free option for the roux. Cornstarch is an excellent thickening for gravy, and it may be added at the end to make the gravy thicker or thinner.

What Is the Difference Between Cornstarch, Corn Flour, and Cornmeal?

Several goods have the word “corn” in their name. And, if you’re anything like me, you’re perplexed. This brief primer should give you the necessary knowledge to determine which.

Corn flour and cornmeal are both made from ground maize. Cornmeal is coarsely ground, whereas corn flour is finely ground. Corn flour can be made from cornmeal, but not the other way around. Both have a maize taste to them.

Cornstarch is a product manufactured from maize starch. So it’s not the complete grain that’s in the endosperm, but merely the starch. It has no flavor and is mostly used as a thickening ingredient in soups, sauces, and gravies.

How Long Does Cornstarch Last?

Let’s get to the topic now. Do you want to know if you can utilize the cornstarch that has been sitting in your pantry for months? So, go ahead and utilize it! In other words, cornstarch has an infinite shelf life! But does this imply that you store your cornstarch container incorrectly? Certainly not!

Cornstarch, like any other powdered food, contains little to no moisture. As a result, there is no free water for bacterial and fungal development. Molds, on the other hand, may find your cornstarch delicious if it is not stored properly.

And don’t be shocked if you find ants munching on your cornstarch jar or container if you leave it open and unsealed. Furthermore, ants can die if they consume too much cornstarch. What could be worse than finding ants in your cornstarch jar? Ants that have died!

As a result, cornstarch is not susceptible to spoiling. It also doesn’t diminish in quality substantially. Even if you believe it has, adds some warm water and check for yourself! On the other hand, cornstarch must be kept in the proper conditions.

At pantry
Cornstarch (Opened or unopened)Indefinite

How Long Does Cornstarch Last in the Outdoors?

Cornstarch should be kept in the pantry or a cupboard to keep it fresh for as long as possible. The coldness of the pantry prevents moisture from forming, and so prevents bacteria development.

Cornstarch should be stored in a container with a firmly fitting cover. Moisture will have a lower probability of entering the container. This will help it stay fresh for as long as possible.

If there is moisture on the box or if the box has been exposed to heat, discard the cornstarch. Cornstarch in touch with these substances will not be preserved forever. Cornstarch may be kept in the pantry or cupboard for years if properly handled.

How Long Will Cornstarch Last in the Fridge?

It is not required to keep cornstarch in the refrigerator. The fridge will not affect the shelf life of the cornstarch. Cornstarch has an unlimited shelf life if stored in a properly sealed container in the refrigerator.

The cornstarch will stay cool and useable in the fridge. The only issue with the refrigerator is that moisture is more likely to infiltrate the product due to other goods in the fridge or the refrigerator’s temperature creating moisture.

When storing cornstarch in the refrigerator, it is critical to pay attention to the cornstarch and check it for moisture before using it.

How Long Can Cornstarch Be Stored in the Freezer?

Cornstarch, like the fridge, does not need to be stored in the freezer. The freezer’s temperature does not affect the cornstarch’s shelf life. Freezing cornstarch might promote moisture and organic development in your product.

When storing cornstarch in the freezer, ensure the lid is securely fastened to the product. Moisture might easily accumulate due to the cold if it is not airtight.

Cornstarch may be kept in the freezer forever if stored in an airtight container. Moisture will be kept out, preventing the goods from rotting.

How Can You Tell If Cornstarch Is Bad?

If you don’t use your wet cornstarch immediately, it should go in the garbage.

Your cornstarch might become bad, but what are the warning signs?

It’s not difficult to tell whether your cornstarch has gone bad. Because this component contains a white powder, you can quickly determine whether or not it has been spoiled.

If there is any discoloration on your cornstarch, it is most likely that it has gone bad. So, here are five warning indicators to look for before eating tainted cornstarch.


The bugs are the first indicator that your cornstarch is contaminated. These organisms are tiny, yet they are generally black or dark brown. So you won’t be surprised to see them in your cornstarch bag.

You may believe these small bugs are insignificant, and there is no reason to throw away your cornstarch. Yes, these bugs are just OK. However, remember that these bugs may harbor hazardous germs or parasites.

Furthermore, even if you remove the bugs, their larvae or eggs may remain in your cornstarch because of their small size. Having stated that, your health may be jeopardized. As a result, it is preferable to throw away your bug-infested cornstarch.


It is self-evident that you must discard all moldy foods in your home. According to billions of research, mold is one of the leading causes of major health issues such as immune weakness, lung illness, and even death.

As a result, the next time you observe gray mold, you must get rid of those cornstarch sacks. This is especially important if you are allergic to mold. (1)

Bad smell

The fragrance of your cornstarch is another indicator that it has gone bad. You should smell the cornstarch before using it if it has been kept for a long period.

Cornstarch often has a very pleasant maize fragrance. It occasionally transports me back to my hometown’s corn harvest when I was a small child. And if you’re a big lover of cornstarch-based goods, I’m sure you’ll notice the difference.

So, what does rotten cornstarch smell like?

A sour odor is a good sign of ruined cornstarch. In addition, ruined cornstarch has a strong and disagreeable odor.

Is it true that your cornstarch stinks? It’s time to say goodbye.

sour flavor

My cornstarch is free of bugs, mold, and nasty odors. Is it safe to consume?

Yes. But… hold on! Don’t worry. You still have one more thing to double-check!

Have you ever tried tasting your cornstarch before using it in a recipe? No? Okay. You must gradually develop this habit. This will be beneficial to you.

Take 1/4 teaspoon cornstarch and taste it before adding it to your soup or sauce. If the sourness overpowers the natural flavor of your cornstarch, you can no longer use it in soups. Throw it out and get a new one!

When You Discover Lumpy Cornstarch

Your clumpy cornstarch does not go in the garbage. Clumsiness, on the other hand, indicates that your cornstarch has become moist. And the moisture has now made its way into your cornstarch.

In other words, when your cornstarch absorbs moisture, it’s not long until mold grows in your cornstarch bag. Cook it if you still think it’s a waste to toss away your cornstarch. However, before cooking, remember to smell and taste it.

Is it OK to eat cornstarch that has gone bad?

As previously stated, as long as it is kept dry and properly maintained, cornstarch has an endless shelf life and will not harm you if consumed beyond the best date.

Is it possible for cornstarch to lose its effectiveness?

Unlike baking powder and spices, cornstarch does not lose its potency over time. Cornstarch, in reality, remains practically constant over time if properly preserved.

What happens if you consume contaminated cornstarch?

If you consume terrible cornstarch, nothing will happen. The only exception is if the starch contains mold or insects. Nonetheless, you are unlikely to suffer any negative consequences (at the very worst, you might have some digestive upsets).

The only exception is if you consume uncooked cornstarch. You should avoid eating raw cornstarch; there’s no logical reason you would because it doesn’t taste good.

Although it is edible in little amounts and is used in various medical procedures, swallowing raw cornstarch might induce bloating and stomach troubles since it is tough for your body to digest.

What Is the Best Way to Store Cornstarch?

If you frequently use wheat flour, you already know how to keep cornstarch useful. Because there is no need to worry about temperature, it does not need to be refrigerated to extend its life. The optimal temperature is room temperature.

If you live in a humid region, keep cornstarch in a dryer and cooler, and store it in a resealable baggie. The container it comes in should be adequate, but the baggie will assist guarantee that no moisture enters.

Cornstarch, like baking soda, may absorb unpleasant aromas, which will undoubtedly change the flavor. Because common household pests may get into cornstarch, it’s best to store it in a resealable, airtight container.

Can Cornstarch Be Freeze?

Have you ever wondered if you could keep the packet of cornstarch in your refrigerator or freezer? Though freezing is a wonderful solution for many foods, it should not be your first choice if you want to keep cornstarch for a long time.

To begin with, cornstarch has a very long shelf life. You may relax and utilize cornstarch that has been sitting in your pantry for months or even years if you choose. As a result, you don’t need to freeze it at all.

Second, one of the primary functions of a freezer in food preservation is to freeze the moisture content of food products, rendering them inaccessible to microbes.

However, because cornstarch is in powder form, we don’t understand why freezing would improve long-term preservation. Finally, freezing your cornstarch may expose it to too much moisture, which you may prevent by just putting it in your pantry cabinet.

However, if freezing is your preference, you may store your cornstarch powder in the freezer if you wish, although, as we previously stated, this doesn’t assist much.

Also, if you’ve kept your powder in the freezer, be in mind that your container is airtight. Otherwise, your cornstarch powder would absorb moisture from the freezer, resulting in the spoiling of cornstarch powder.


The good news is that cornstarch will last practically indefinitely if stored properly. As a result, you may safely store cornstarch in your cupboard for an extended period. However, you should check in on your cornstarch now and again to ensure it is still intact.

Moisture is cornstarch’s primary adversary, and it is this fact component that will cause it to deteriorate. Proper storage is essential for extending the life of cornstarch and other foods. Cornstarch can be safely used several months or even years after the expiration date if properly preserved.


Editorial Staff

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