Popcorn kernels might seem like a great food to stockpile for emergencies. However, popcorn is surprisingly one of the hardest foods to store long-term. Because of its moisture content, you can’t store it like you would with other dry staples.
Here’s what you need to know about popcorn shelf life and the best way to store it.
Do Popcorn Kernels Go Bad?
Popcorn kernels generally don’t go bad in the sense that they will become unsafe to eat. However, it is very easy for popcorn kernels to get too dried out in storage. Even slight changes in moisture content can cause the kernels not to pop.
Why Long-term Popcorn Kernel Storage Is So Difficult
To understand why popcorn kernel storage is so difficult, you first need to understand what makes popcorn pop.
Popcorn kernels consist of a very hard hull with a moist starchy interior. When you heat the kernel, the moisture starts turning into steam. This creates a lot of pressure which causes the hull to pop open. When it does, the inflated starchy interior goes to the outside.
Changes to the Popcorn Kernel Moisture Mean It Won’t Pop
Researchers have established that the perfect moisture level for popcorn is approximately 14%. If the popcorn kernel gets too dry inside, there won’t be enough moisture to create that pressure buildup.
Likewise, any damage to the hull means the pressure won’t build up in the popcorn kernel. The hull can easily get cracks when it becomes too dry or experiences changes in moisture levels. (1, 2)
Fat Content Is Also a Problem
Another issue with popcorn kernel storage is its high-fat content. Unpopped corn kernels have a fat composition of approximately 3.2-4.6%. By comparison, uncooked whole grain rice has a fat content of 4.7%.
When exposed to oxygen, fats start to oxidize and go rancid. Rancid foods aren’t necessarily unsafe to eat in the sense that you will get food poisoning. However, they develop a nasty sour taste. (3, 4, 5)
Oxygen Absorbers Are Not an Option!
With dry foods like rice, you can use oxygen absorbers to prevent fats from oxidizing. However, oxygen absorbers are not safe to use with popcorn kernels. Botulism can grow in oxygen-free environments, but only if there is enough moisture.
Guess what has enough moisture? Yes, the 14% moisture content of popcorn kernels could provide the perfect breeding ground for botulism if stored with oxygen absorbers!
Read: Oxygen absorbers for food storage
Because popcorn is so sensitive to moisture changes, it is best to use popcorn kernels within 6-12 months. Stored in an airtight container in a cool place, the shelf life can be pushed to 2-3 years, but you still may end up with a large number of unpopped kernels.
How to Store Popcorn Kernels Long Term
1. Never use oxygen absorbers to store popcorn kernels
While oxygen absorbers are used with most other dry foods for long-term storage, they should never be used with popcorn kernels. The high moisture content of popcorn kernels means botulism could grow.
2. Also don’t vacuum seal popcorn kernels
Likewise, you shouldn’t store popcorn kernels in vacuum-sealed bags or containers. While vacuum sealing usually doesn’t remove all of the oxygen in the container, it still may create an environment where botulism can grow. Botulism is deadly, so it is better to play it safe! (6, 7)
Read: Vacuum sealing vs. mylar bags
3. Use airtight containers
You must use containers that are truly airtight to store popcorn kernels. This will prevent moisture from escaping the kernels. (8)
Some good options are:
- Mylar bags (without oxygen absorbers)
- Mason jars
- Plastic containers with airtight seals
4. Keep cool
Fats go rancid faster in high temperatures. Because popcorn kernels have a lot of fats in them, you must keep them cool. Ideally, keep them below 70 degrees F.
You can freeze popcorn kernels. Some studies even found that popcorn kernels stored in the freezer popped better than those stored at room temperature. However, moisture levels can easily fluctuate in frozen foods. Unless you live somewhere very warm, it’s probably better not to freeze popcorn kernels. (9, 10)
5. Rotate Regularly
To keep the popcorn kernels fresh and ensure they pop well, you’ll need to rotate through them regularly. Don’t stockpile more than you can rotate through in 1 year.
What to Do with Old Popcorn Kernels?
Old popcorn kernels might not pop well, but they can still be used. You can grind them into polenta or grits with a heavy-duty manual grain mill.
If the popcorn kernels are really old and the oils have gone rancid, they may taste bad. Also, be on the lookout for signs of spoilage like mold, bad smells, or weird tastes.
Is Popcorn a Good Food to Store?
The bottom line is that popcorn is not a great food for long-term storage. It is simply too difficult to store because of its high moisture and fat content.
Unless you really love to eat popcorn and rotate through your supply regularly, you are better off storing other snack foods.
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I had a 4 pound bag of popcorn in the refrigerator and decided to package it in a mylar bag. I didn’t add a oxygen absorber but I’m worried because the mylar bag was cold after I sealed it and later on, I noticed a few tiny droplets of water on the bag. Could botulism grow inside since the popcorn kernels were packed directly from the refrigerator?
Since you didn’t use oxygen absorbers, then you don’t have to worry about botulism. However, MOLD is a concern because of the moisture. I’d open the bag (close to the seal), check the popcorn for mold or bad smells (maybe pop a bit), spread it out and let it air out a bit, and then reseal in the same bag.
I got one of the 20 pound bags from Sam’s Club a while back, and have kept the lot inside one of those 5 gallon plastic drums with an airtight lid. I open and smell them periodically, and have never noted anything ‘rancid’ about them, but I have had a lot of it that I haven’t used for 2 years because I’ve been using braces, and can’t eat popcorn at all (alas, I love the stuff).
If you don’t care about whether some kernels don’t pop, can you just take the ones that do? Better to use some of it than throw it all away, right?
I can do you one better. I bought a 25 lb bag sometime in the late 1990’s and still haven’t finished it. Yes, it still pops fine, although I get a higher percentage of small, harder popped kernels, I assume it’s due to some moisture loss in these 25 or so years. I stored it for the first 5-10 years in the sack it came in inside a closet, and later separated it into smaller airtight containers. No mold, nothing really wrong except the kernels probably don’t pop as fluffy as they did when fresh.
I am seeing so many different things on long-term popcorn storage. I have some that I vacuum sealed in mason jars, no oxygen absorbers but after reading this article, am going to throw it out and start over just to be safe. I know my dad popped some that was stored for many years in a glass jar and it popped just fine. Is there any way to detect botulism?
If the popcorn was stored without O2 absorbers, you don’t have to worry about botulism. It’s only when O2 absorbers were used that you need to worry about botulism. Vacuum sealiing does NOT remove all oxygen, so it will be safe to consume.
I sealed popcorn in mylar bags with oxogen absorbers about a month ago. Is it too late to just repackage them without OA??
Definitely don’t risk it. If there is botulism already growing, you won’t know. :/