How to Store Cornmeal Long-Term and Does Cornmeal Go Bad?


Author:
Last Updated: April 22, 2021

Cornmeal is one of the best staples to keep stored.  However, there is a lot of confusion about cornmeal shelf life and whether it’s okay to store it long-term.

Here I will cover everything you need to know about shelf life, which types of cornmeal last longest, storage methods, and more.

Cornmeal Shelf Life

Cornmeal will generally last 6 to 12 months when stored at room temperature in its original packaging.  In an air-tight container stored in a cool, dark, and dry place, cornmeal can last even longer than this.

When stored with oxygen absorbers in Mylar bags, cornmeal can last over 10 years.  However, the shelf life ultimately depends on a lot of factors like the type of cornmeal and storage conditions.

Which Type of Cornmeal Lasts Longest?

By definition, cornmeal is just dried corn kernels that have been ground up.  Cornmeal is then broken down into types based on its fineness and whether it has been bolted or not.  As a general rule, bolted cornflour will last the longest.

Bolted vs. Unbolted Cornmeal

Bolted cornmeal: (aka degerminated cornmeal) means the ground corn kernels went through a sieve.  The sieve removes pieces of the hull and germ, both of which contain oils.

Unbolted cornmeal: (also called water-ground, stone-ground, or old-fashioned) will still contain hull and germ.

Almost all commercially sold corn flour today is bolted.

When nutrition is your primary concern, unbolted cornmeal is healthier.  But the oils in unbolted cornmeal will cause it to go rancid fairly quickly.

Going rancid doesn’t happen overnight: the cornmeal will gradually start tasting bitter and stale.  It might still be safe to eat after 6 months but won’t be pleasant to eat.

Grind Fineness

When a grain is finely ground, more of its surface is exposed to oxygen and will start to go bad faster.  Thus, you’d expect whole corn kernels to last the longest, followed by grits, polenta, and cornflour.

However, this isn’t always true with cornmeal.  The reason is that coarsely-ground cornmeal usually still contains oil-rich pieces of the germ and hull.  Even though it has less surface area, grits will still go bad faster than corn flour because of the extra oils.

Top Tip: When in doubt, look at the nutrition label of the cornmeal.  The lower the fat content, the longer the cornmeal will last.

Best Ways to Store Cornmeal

Freezer

Shelf Life: Indefinitely

The best way to store cornmeal is in the freezer.  It will last indefinitely this way.  However, be cautious when removing cornmeal from the freezer: moisture will start to form in the bag.  The pockets of moisture can cause the cornmeal to get moldy very quickly.

Air-Tight Containers

Shelf Life: 1-2 years

Storing cornmeal in air-tight containers such as mason jars or good plastic containers will help increase shelf life. The container will prevent oxygenation and also help keep pests out (moths particularly love cornmeal).

Cornmeal can even last several years like this so long as the temperature and humidity are low. Be sure to keep the containers away from sources of heat like water heaters or stoves.

Note that pest eggs are sometimes already in the cornmeal when you buy it.  When they hatch in a few weeks or months, you’ll see their larvae crawling around inside the container.  Learn more about how to prevent pantry pests.

Oxygen Absorbers

Shelf Life: 5-10+ years

The oxygen absorbers are little packets of iron that grab onto oxygen molecules.  When you up an OA in a sealed, air-tight container, it creates an oxygen-free storage environment.  The food will last longer because oxidization can’t occur.  Mold, bacteria and pests also won’t be able to survive without oxygen, so the cornmeal stays safe to eat.

You can use oxygen absorbers in mason jars or even some food-grade buckets.  However, Mylar bags are generally considered to be most reliable for long-term food storage.

Read more about how to pack food in Mylar bags and how to use oxygen absorbers here.

Warning: Cornmeal, Botulism and Oxygen Absorbers

Most bacteria cannot survive without oxygen.  Botulism is an exception. It survives in oxygen-free environments.  However, it does require moisture to survive, which is why it’s safe to use oxygen absorbers for dry foods but not wet foods.

I mention this because corn kernels and cornmeal are often very moist. When stored in an air-tight container with oxygen absorbers, it could cause botulism.

A few Primal Survivor readers have even written saying that they saw signs of botulism in their bags of whole corn kernels (though not cornmeal): the bags were puffy and bulging.

Botulism requires a moisture level of 35% to grow.  Because it is such a big deal though, you generally shouldn’t store anything with more than 10% moisture in an oxygen-free environment.

Typical moisture levels of cornmeal are around 14%.  Corn flour tends to have less moisture at around 8-10%.

To play it safe when packaging corn kernels or cornmeal with oxygen absorbers, only package it on low-humidity days. You might even want to dry it out a bit in the oven first (and then let it come to room temperature before packing).

Leave a comment

  1. Hello I have stored cornmeal in mylar bags With oxygen absorbers but the mylar bags have swelled up like a balloon any ideas?

    Thank you

    Reply

Leave a Comment