Find Out Here if Cornstarch Go Bad After a Long While

Does cornstarch go bad after storing it for a long period?

When you clean out your pantry, you likely find old bags of not-often-used food items like cornstarch. And when you find one, you’ll be wondering if it’s okay to cook with. Know that cornstarch is a food. It is not so likely to go bad, but it will after a while.

Now that this is established, you should know how fast cornstarch goes bad, the signs of spoilage to look out for and how you can store it properly. This article contains all the vital information that you should know about the shelf life of this kitchen ingredient.

What Is Cornstarch?

Cornstarch or maize starch is a kitchen ingredient made from the endosperm of corn kernels. This powder has both culinary and non-culinary uses. In the kitchen, maize starch is a thickening agent for soups, gravies, sauces, marinades, glazes, pies, batters, and casseroles.

In addition, maize starch is a gluten-free alternative to wheat flour. It’s a staple any gluten-free family will want in their kitchen. Moreover, it is a better thickener than flour. It gives a transparent, flavorless thick gel, unlike the opaque end product of using flour as a thickener.

Some of the non-culinary uses of maize starch include a DIY remedy for skin irritations, a natural dry shampoo, matte nail polish, making DIY deodorant, detangling agent, for ironing, stain removal, to clean stuffed animals and fabrics.

Does Cornstarch Go Bad?

Cornstarch has a very long and indefinite shelf life. But it will go bad under the wrong storage conditions. Maize starch will only go bad when you expose it to moisture.

SEE: If Almond Flour Go Bad and Discover Ways to Preserve it

Does Cornstarch Go Bad in the Refrigerator?

It is not necessary to keep maize starch in the refrigerator. But, if you find yourself keeping it there, you’ll have to be extra careful.

In the refrigerator, you store many food items which may include watery or moist food items and odorous food items. If you have such foods in the refrigerator, you should keep the flour in an airtight freezer bag to prevent contamination.

Moreover, maize starch is best stored in the pantry away from moisture.

Does Unopened Cornstarch Go Bad?

An unopened bag or container of cornstarch can last indefinitely. It won’t go bad even when it’s past its expiration or best-by date. As long as it remains unopened, it is protected from moisture, insects, or bugs that can contaminate it and trigger spoilage.

What Is the Shelf Life of Cornstarch?

Maize starch has an indefinite shelf life. Whether opened or unopened, under the right storage conditions, cornstarch will last very long.

SEE: Why Can Humans Digest Starch But Not Cellulose?

Can Expired Cornstarch Make You Sick?

If you cook with cornstarch that has mold growth and has been invaded by insects, you may experience signs of food poisoning. However, if your maize starch is past its expiration date but has been under proper storage conditions, it is still safe to cook with.

But if you are unsure about cooking with expired maize starch, you can use it for non-culinary purposes like starching your clothes, cleaning and removing stains, detangling knots, and DIY skin irritations remedy.

SEE: Here’s How to Stop Food Spoilage and Food Poisoning

How to Tell if Cornstarch Is Bad

Check for clumps

When maize starch has come in contact with moisture, it begins to clump. Maize starch is a dehydrated food item, but it absorbs moisture quickly. It makes it easy for clumps to form in the starchy powder. 

However, a clumpy maize starch can be restored. All you need to do is remove the lumps and run the flour through a sifter to remove any more lumps.

Any mold growth or insects?

Check the surface of the maize starch for mold growth. If you notice any grey growth on the surface of the powder, you should throw it away. Cooking with moldy food items can result in respiratory infections and a weak immune system.

Also, check for bugs in the bag of maize starch. There could be a lot of them in the bag, and this is a big deal. Asides from the bugs, their eggs could be in the bag too. If you notice bugs in the bag of maize starch, throw it away and save yourself from sickness.

Smell it

If you found an old bag of maize starch in the pantry, the first thing to do is to smell it. Good maize starch smells like corn, but spoilt maize starch has an unpleasant, sour smell. It also smells nothing like corn.

SEE: You Probably Didn’t Know You Could Freeze Corn on Its Cob to Preserve It

Taste the cornstarch

If you have doubts about the bag of maize starch, you should taste it. Just a little pinch is enough to detect spoilage. If the maize starch has gone off, it’ll have a sour taste. Do not overlook this. If you go ahead to cook with sour cornstarch, it’ll give you a sour dish.

How to Preserve Cornstarch

  • After opening the bag of maize starch, reseal it properly to keep out moisture and insects
  • If you can’t trust the bag enough, transfer the maize starch into an airtight jar
  • In addition, keep bags or jars of maize starch away from sunlight. Keep them in the dark corners of the pantry
  • Also, don’t keep the bag or jar of maize starch close to the stove. High temperatures can ruin the quality of the maize starch
  • Do everything possible to make sure that moisture doesn’t get into the bag

SEE: How to Get Free Food at Pollo Campero


Does cornstarch go bad quickly?

No, it doesn’t. Cornstarch is one of those foods with a very long shelf life. On the off chance that it goes bad quickly, it may have been contaminated by insects.

How long does cornstarch last after opening?

An opened bag of cornstarch can last very long if you reseal it properly. Moreover, keeping it away from moisture can help preserve its shelf life.

Why is your cornstarch not thickening your meals?

If your cornstarch is not thickening your meals, it doesn’t mean it has gone bad. Rather, it means that you’re not using enough of the powder. Moreover, if you’re not cooking at a high temperature, the meal will not thicken.

Can you freeze cornstarch?

Yes, you can freeze cornstarch. This act may not be necessary, but you can keep a bag of maize starch in the freezer to preserve it for longer. However, it won’t freeze. Also, freezing maize starch may expose it to moisture since it is stored alongside moist foods.

If freezing maize starch becomes an option, store it in an airtight freezer bag. You should also keep it far from odorous food items.


Cornstarch is a staple in many kitchens. It has a very long shelf life, but this doesn’t excuse it from spoilage. It may take a very long while before cornstarch goes bad. However, it will eventually go bad if you don’t store it properly.

If you are about to buy bags of cornstarch from a sale at the store, go by the best-by date. Buy cornstarch that has a long time before its printed date. Also, if you have found an old bag of cornstarch in your pantry, examine it for signs of spoilage. If you notice any, trash it and get a new bag.

Thanks for reading.

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