When Does Corn Flour Go Bad? 

Corn flour (also called maize flour) is a staple in making things like tortillas, breads, pancake mixes, and much more. It’s gluten-free, which makes it a popular additive as a binder in foods as well.

If you have a bag of corn flour on hand, you might wonder at some point – when does corn flour go bad?

Corn flour will generally last 9-12 months past its printed use-by/best-by date. It’s slow to go bad, but you should err on the conservative side and not use it that long past its printed date if there are any signs that it’s gone bad.

What are the signs corn flour has gone bad, you might ask? And how should you best store it to prolong its shelf life? We have the answer below!

What is the shelf life of corn flour?

Corn flour is milled from dried whole corn kernels. Like other types of flour, packages of corn flour come with a printed “best if used by” date, which can help remind you of how old the package is if it’s been sitting in your pantry for a bit.

These “best by” dates aren’t necessarily expiration dates, and they usually come with some wiggle room. Most types of flour will last beyond the printed date and are slow to “go bad”.

While there are no exact guidelines in terms of how long corn flour lasts, it’s generally thought to be around 9-12 months after its printed date. Of course, if there are any signs that the corn flour isn’t as fresh as it should be (more on that soon), then you should err on the conservative side and toss it.

How long does corn flour last after opening?

We did our research, and there doesn’t seem to be any difference in the shelf life of corn flour whether it’s open or sealed, or if it’s stored anywhere other than the pantry.

In general, flour should last a bit longer when it’s sealed, but if you practice good storage techniques (again, more on that soon!) then there’s really no difference if it’s sealed or open.

	Pantry	Fridge	Freezer
Corn flour – sealed or open	9-12 months past the printed date	9-12 months past the printed date	9-12 months past the printed date

Can you use corn flour after its expiration date?

As we mentioned earlier, the best-by date isn’t a hard-and-fast expiration date. Flour tends to have a generous shelf life compared to many other types of food, and usually, there isn’t any issue in using it after its best-by date, even if it’s several weeks or months past.

The only time there’d be a concern about using flour past its expiration date is if there are any signs that it’s gone bad, which is more likely if the flour has been improperly stored.

How to tell if corn flour went bad

While flour isn’t as likely to go bad as foods like milk or meat, there will be some clear signs if your corn flour is past its prime.

Some signs to watch out for that corn flour has gone bad:

• It gives off a musty, sour, or other odor other than neutral
• Any signs of moisture in the flour, such as mold or hard clumps
• It tastes “off”, such as being bitter, stale, or having an unpleasant taste

What’s the danger in using corn flour after it’s gone bad?

There isn’t a serious risk that comes with using corn flour after it’s gone bad. First, you’d be likely to tell that the flour had gone bad before you ate enough of it. Even if you didn’t notice the flour had gone bad before you ate it, flour isn’t a typical host of foodborne illnesses like fresh produce and undercooked meat.

The most likely scenario is that you’d get an upset stomach from eating corn flour after it had gone bad.

Best storage practices for corn flour

• Store opened corn flour tightly, such as in an airtight container or the original bag closed securely. Exposing corn flour to air will cause a loss of freshness.
• Keep corn flour away from direct heat or sunlight, which could cause the flour to dry out faster.
• If you don’t use corn flour very often, pop it in the freezer, which won’t impact its texture (unlike cornstarch, which you shouldn’t freeze).

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