Is “Cooler Corn” Safe?

by Samantha Kennedy | Aug 19, 2020

A friend of mine recently shared with me a few recipes for what is known as “cooler corn.” As the name implies, it’s a way of cooking a large amount of corn on the cob all at once inside a cooler, thereby saving time and grill and/or stove space.

At first I was intrigued. I had never heard of this cooking method before and my own personal curiosity was piqued. However, as a certified food safety instructor, I was also immediately horrified. As I reviewed several recipes for this “perfect way to make corn for a crowd,” I became increasingly alarmed. There were so many proper food safety practices violated, it nearly turned my stomach.

Cooking food in a cooler is an unsafe cooking method. Coolers are not designed to withstand the high temperatures required for cooking and cannot adequately hold foods at safe temperatures for prolonged periods of time.

For the record: Cooking corn in a cooler is UNSAFE. The safest ways to cook corn are in a stockpot on the stove, in the oven, or on a grill.

Here are the top four reasons this cooking method is not a good food safety practice:

Cooking food in a cooler is an unsafe cooking method. Coolers are not designed to withstand the high temperatures required for cooking and cannot adequately hold foods at safe temperatures for prolonged periods of time. (Photo source: Samantha Kennedy, UF/IFAS Extension)

1. Coolers are not designed to be used for cooking. The plastic used in coolers is not meant to withstand continued exposure to boiling water and will start to degrade over time. The plastic can also be easily scratched or gouged, providing the perfect place for foodborne pathogens such as Salmonella and E.coli to hide and grow. Think of the other things coolers are used for: storing fish or game after fishing or hunting, keeping drinks cold, storing raw meat or poultry for a picnic, etc. There are so many other opportunities to contaminate the cooler before it is used for cooking corn, even thorough cleaning and sanitation may not be enough to eliminate pathogens. Always keep cooking utensils and tools CLEAN to reduce your risk of foodborne illness.

But what about the boiling water? Won’t that kill any pathogens? Well, yes and no. See #4 below.

And NO, having a cooler dedicated only to cooking corn will not solve all the problems stated above. The bottom line is COOLERS ARE NOT SAFE TO COOK FOOD IN.

2. One of the conveniences of this method, as celebrated in the various recipes, is that people can just reach into the cooler and grab a perfectly cooked ear or two whenever the mood strikes. Allowing people to reach in and grab food like this – especially with their bare hands – is a very unsafe practice. People may forget to wash their hands properly before reaching in, thereby adding dirt and bacteria to the water and thus the food. This type of “germ-sharing” is called cross-contamination and is one of the leading causes of foodborne illness. Always keep things SEPARATE. This includes keeping raw food separate from cooked food, using separate utensils for each food, and reducing or eliminating bare hand contact with food.

3. Stacking dozens of ears of corn in a container and submerging them in boiling water does not ensure that all of the corn will be cooked evenly. The ones in the middle may not be cooked all the way through and there may also be temperature fluctuations in different areas of the cooler because of the way the food is stacked. There may be hot, warm, and cool spots, which can lower the overall temperature to an unsafe level and promote the growth of pathogens. Always COOK foods to the proper minimum internal temperature. In the case of corn, this is 135 degrees F. This can be measured by inserting a properly calibrated food thermometer between two cooked ears of corn and waiting until the needle stops moving.

4. One blog post about the wonders of Cooler Corn stated, “You can leave the corn in there for quite a while after it’s done cooking to keep the ears warm. Since the temperature naturally drops over time, the corn doesn’t get mushy.” When I read this, my mind screamed, “DANGER!” in flashing red letters.

Boiling water is a good sanitizer. However, a lot of what makes it effective for killing pathogens has to do with proper contact time with surfaces AT THE APPROPRIATE TEMPERATURE. Most coolers are not designed to keep boiling water that hot (212 degrees F) for any significant period of time. Even quality coolers will not hold the temperature long enough to ensure proper sanitation and elimination of pathogens.

One of the most important food safety principles is keeping cold foods cold and hot foods hot. To ensure the safety of food, it is important to keep cold foods below 41 degrees F and hot foods above 135 degrees F.

Now think about ears of corn submerged in water for a prolonged period of time, as the water slowly cools. After a while, that water will no longer be able to keep those ears of corn above 135 degrees F. They will basically be sitting in a soup of tepid water at the most favorable temperature for pathogens to grow. The longer the corn sits in that water, the higher the risk of foodborne illness. Always properly CHILL foods to keep them at a safe temperature, below 41 degrees F. The flip side of this coin is to also ensure hot food stays hot, above 135 degrees F.

Cooking for large groups can be a challenge, especially when kitchen space is limited. (Check out the UF/IFAS Extension fact sheet “Food Safety at Tailgating” for more food safety tips when cooking out.) However, it is never a good idea to sacrifice food safety for convenience. Always follow proper food safety practices, no matter the situation, and remember the 4 principles of safe food: CLEAN. SEPARATE. COOK. CHILL.

UF/IFAS in an Equal Opportunity Institution.