Quick Answer
Uncooked corn on the cob should not be left out at room temperature for more than 2 hours. After this time, harmful bacteria can multiply quickly and make the corn unsafe to eat. For best quality and food safety, store uncooked corn on the cob in the refrigerator and use within 5-7 days. You can also freeze uncooked corn on the cob for longer storage.
How Long Can Uncooked Corn on the Cob Sit Out?
Freshly picked corn on the cob is best when consumed right away but realistically, the corn will need to be transported from the farm, stored properly, and prepared for eating. Many people ask, “How long can I leave uncooked corn on the cob out before it goes bad?”
Here are some guidelines for how long uncooked corn on the cob lasts at room temperature:
At Room Temperature
– 1-2 hours: Still safe to eat, but corn is losing quality and sweetness. Kernels are drying out.
– Over 2 hours: Increased risk of food poisoning. Harmful bacteria like E. coli and salmonella can multiply quickly on husked corn at room temperature. Discard corn left out longer than 2 hours.
– All day (8+ hours): Unsafe to eat. Toss corn left out overnight.
The 2 hour window is the recommended maximum time uncooked corn should sit at room temperature. The warmer the ambient temperature, the faster the corn will deteriorate. On a hot summer day, the corn could become unsuitable to eat in less than 2 hours.
In the Refrigerator
When stored properly in the refrigerator, the shelf life of uncooked corn on the cob is extended.
– 1-2 days: Best quality. Still fresh and juicy.
– 3-5 days: Edible but losing freshness. Kernels shrivel slightly.
– 5-7 days: Marginal quality. Noticeable drying and toughening of kernels.
– Over 7 days: Discard. Dried out with poor texture and flavor.
For best flavor and texture, cook fresh corn on the cob within 1-2 days of purchasing. With refrigeration after harvest, the sugars start converting to starches quickly, making the corn less sweet and juicy.
Does Husking Help Corn Last Longer?
Corn left in the husk tends to stay fresh a little longer than husked corn. The husk helps retain moisture in the corn kernels. However, keeping the husk on only extends the shelf life by 1-2 days.
Husked or unhusked, corn on the cob should still not be left at room temperature for more than 2 hours. The husk does not prevent bacterial growth.
What Happens If You Eat Bad Corn on the Cob?
Eating corn on the cob that has been left out too long can cause foodborne illness. Potential symptoms include:
– Nausea
– Vomiting
– Stomach cramps
– Diarrhea
– Fever
Some of the bacteria that can grow on corn out too long include E. coli, Salmonella, Bacillus cereus, and Listeria monocytogenes. Listeria is especially concerning for pregnant women, the elderly, and those with compromised immune systems.
In severe cases, food poisoning from bad corn can even lead to hospitalization. Botulism, though rare, is another serious risk if corn is not properly handled and stored.
If you suspect you are sick from eating bad corn, seek medical care. Prevent dehydration from vomiting and diarrhea by drinking fluids.
How to Store Corn on the Cob
To extend the shelf life of uncooked corn on the cob after purchasing:
Refrigeration
Refrigerate corn immediately and keep stored at 40°F or below. Do not wash before refrigerating. Place husked corn in a perforated plastic bag. For corn with the husk on, place in a breathable container or just set on a refrigerator shelf. Properly stored, fresh corn will last 5-7 days.
Freezing
Corn can be frozen on or off the cob. To freeze:
1. Husk corn and remove silk.
2. Blanch corn in boiling water for 2-5 minutes.
3. Cool in ice bath for 2-3 minutes.
4. Drain and pat dry.
5. Place ears in freezer bag and freeze. Or, cut kernels off cob and freeze in airtight container.
6. Frozen corn on the cob will last 8-12 months.
Freezing stops the conversion of sugars to starches, retaining sweetness. Thaw frozen corn in the refrigerator before cooking.
Canning
Proper pressure canning makes corn shelf stable for 1-2 years stored in a cool, dark place. Only can corn that is freshly picked and at peak quality. Follow a tested canning recipe for best results.
How to Tell if Corn on the Cob is Bad
It’s not always obvious when corn has gone bad, but here are some signs to watch out for:
– Dried, wrinkled, or mushy kernels
– Yellow/brown discoloration
– Moldy appearance, especially at ends
– Slimy texture
– Rancid or sour odor
– Corn silk looks dried out
Trust your senses. If the corn smells funky or is clearly past its prime, do not risk eating it. When in doubt, throw it out.
Can You Cook and Eat Bad Corn?
No, you should not attempt to cook and eat corn on the cob that has been left out too long at room temperature. Heat from cooking does not destroy the toxins created by bacteria. Consuming bad corn can still lead to food poisoning or serious illness.
Discard corn that is questionable. It is not worth getting sick over.
Conclusion
For food safety and quality, uncooked corn on the cob can only be left out at room temperature for up to 2 hours before harmful bacteria multiply and the corn starts to dry out. Refrigeration extends the shelf life up to a week. Freezing or pressure canning allows even longer storage. Always inspect corn carefully before eating and discard any that shows signs of spoilage like wrinkled kernels or foul odors. With proper handling, fresh corn on the cob can be enjoyed without worry.
| Storage Method | Shelf Life of Uncooked Corn |
|---|---|
| On countertop (room temperature) | 2 hours max |
| Refrigerator | 5-7 days |
| Freezer | 8-12 months |
| Pressure canned | 1-2 years |
References:
United States Department of Agriculture. “Selecting, Storing and Serving Ohio Sweet Corn.” https://ohioline.osu.edu/factsheet/HYG-5551
North Carolina Cooperative Extension. “Handling Fresh Corn Safely.” https://lee.ces.ncsu.edu/2016/07/handling-fresh-corn-safely/
National Center for Home Food Preservation. “Selecting, Preparing and Canning Corn.” https://nchfp.uga.edu/how/can_04/corn.html
Iowa State University Extension and Outreach. “How to Freeze Corn on the Cob.” https://www.extension.iastate.edu/foodsavings/how-freeze-corn-cob
Clemson Cooperative Extension. “Corn – Food Safety.” https://hgic.clemson.edu/factsheet/corn-food-safety/