Does Cornstarch Go Bad? Long Term Storage Options and Shelf Life

Cornstarch is one of those wonderful staples which can be used in many different recipes or even to make glue.  Because of its long shelf life, it is also one of the best foods to stockpile for emergencies.  If you want to store cornstarch long-term, here’s what you need to know about its shelf life and storage methods.

Does Cornstarch Go Bad?

If stored properly, cornstarch will never go bad. In fact, cornstarch is often added to other foods to increase shelf life.  However, cornstarch can get ruined by microbial growth, insect infestation, and bad odors from the environment.

Cornstarch Can Get Moldy

Cornstarch absorbs moisture from the air around it. If the cornstarch gets too wet, it can start to grow fungus.  One study found that, at 77 degrees F, mold started to grow on cornstarch when it reached moisture levels of 10.7%.  Other microbes can also grow on cornstarch when it gets too moist.

Do Moths and Weevils Eat Cornstarch?

Pantry pests don’t like cornstarch much.  They prefer to eat the fiber-rich exterior of corn and not the pure starch.  I can attest to this personally.  I’ve had Indian meal moths infest my entire pantry.  They managed to chew through plastic bags to get at rice, flour, and other grains but didn’t touch the cornstarch – even though the cornstarch admittedly wasn’t packaged well.

However, I have heard of insects getting into cornstarch.  While it is safe to eat pantry moths and weevils, you might still want to protect your cornstarch from these pests.

Also read: How to Keep Pantry Pests Out of Your Food Stockpile

Starch Will Absorb Bad Smells

Another issue with cornstarch storage is that it can absorb bad smells from the environment.  It is important that you keep it away from cleaning products, chemicals, and anything with strong odors.

How to Store Cornstarch Long-Term

The best way to store cornstarch long-term is to repackage it into airtight containers.  While it isn’t recommended, you can even keep cornstarch in its original packaging.  In that case, it’s important that you keep the cornstarch somewhere dry, away from odors, and protect it from pests.

Best Containers for Storing Cornstarch

  • Sealed Mylar bags: These are the best option for storing cornstarch as they don’t let any air or moisture through.
  • Mason jars: If the ring is not compromised, mason jars will be airtight.

Read: How to Store Food in Mylar Bags

Should I Vacuum-Seal Cornstarch?

Vacuum sealer bags are not a good option for storing cornstarch long-term.  The bags are slightly porous and will eventually allow moisture from the air to get into the cornstarch.   If you only need to store a small amount of cornstarch, vacuum sealer jars are a good option. Read about vacuum sealing vs mylar bags.

Do I Need to Use Oxygen Absorbers with Cornstarch?

You generally do not need to use oxygen absorbers when storing cornstarch.  Because cornstarch has virtually no fat or vitamins, OAs won’t help the cornstarch last longer.  However, oxygen absorbers can protect your cornstarch from insects.

Insects sometimes get into cornstarch and lay eggs. The eggs might even already be in the cornstarch before you bring it home. They then hatch and infest your food. Insects eggs can’t survive without oxygen, so adding oxygen absorbers ensures you won’t get pests in your food.

Read: How to Use Oxygen Absorbers with Food

Should I Use a Desiccant when Storing Cornstarch?

You probably don’t need a desiccant when storing cornstarch.  Cornstarch itself is often used as a desiccant!  So, it’s possible that any other desiccant you add won’t remove moisture from the container.  A better solution is to invest in some airtight containers for the cornstarch and keep them sealed.

Protecting Cornstarch during Natural Disasters

Don’t forget that your emergency foods also need to be protected from physical damage, such as falling debris and floodwater.  Most preppers agree that the best way to protect food is by sealing it in Mylar bags with oxygen absorbers and then putting it into a food-grade bucket.

Packaged this way, your cornstarch could survive almost anything!

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  1. I just found a #10 can of cornstarch. It says it was packaged on 10/98. So it is 26 years old. It has been properly stored in a basement dark room. Could this cornstarch still act as a thickening agent or should I throw it away?

    • It’s best to take it out of the box. You’ll be able to fit more in the bag that way. Also, if using OAs, you’ll want to make sure there is nothing blocking the OA from the food and there is as little extra air around the food as possible. If you aren’t using OAs though,you could leave it in the box.

  2. If I store my organic corn starch in mylar with OA how long will it store.
    I have read that if stored properly it will store for ever is this correct.

    Simon from NZ

    • Yes, it can last forever! Just make sure the Mylar bag doesn’t get damaged or the cornstarch will absorb bad smells and moisture.


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