Coolers are usually used to keep things iced cold but can you use a cooler to keep food hot and how does that even work?
It turns out that you can. The same insulation that keeps drinks iced cold and traps out that summer heat can actually trap heat IN your cooler. However, there are a few extra steps, precautions to take and things to be aware of.
You can use a cooler to keep food hot as well as cold. The same insulation that keeps out the heat works to trap heat in, keeping your food hot for hours at a time. For best results line the cooler with aluminum foil and pre-heat it with warm water.
You just need to be careful when keeping food hot in a cooler that it doesn't just stay lukewarm and become the perfect breeding ground for bacteria.
Keeping food safe is all about keeping it extra hot. Heating it up extra before putting in your cooler and using extra things like aluminum foil, towel, hot water bottles or hot bricks will keep it at a safe and delicious temperature for hours at a time.
Can A Cooler Keep Things Hot? How Does It Work?
Most of us think of a cooler as something that keeps things cold. Especially with fancy coolers like Yeti which can keep ice for over a week at time. When it comes to coolers, we mostly just think of the cold.
However, coolers don't really care about whether your food and drinks are hot or cold on the inside. All they do is work really well to stop heat transfer.
Coolers are insulated with foam which contains millions of tiny air bubbles. This makes it really difficult for heat to move through the walls of your cooler.
When you've got cold stuff in your cooler this stops the outside heat getting into your cooler and warming up the ice inside.
However, when you've got hot stuff in your cooler these walls work in the same way to stop the heat inside from moving to the outside.
Because the heat can't move through the walls and into the outside world easily it stays trapped inside the cooler keeping your food hot for longer.
Coolers aren't perfect so eventually the food will cool down, but it can stay hot for hours or even days in the right cooler that is prepared properly.
What Are The Best Ways To Keep Food Hot In a Cooler
When putting ice in a cooler you usually just throw the ice and drinks in and you're done. However, if you want to keep hot food for a long time in your cooler (without warping or breaking the cooler) then a few more steps are required.
Here's the best ways to keep food hot in a cooler
Get a Good Cooler
Firstly the quality of your cooler does make a difference. High-end coolers like Yeti will keep food hot for much longer than a cheap $20 cooler you picked up from your local hardware store.
The better the cooler at holding ice, the better the cooler will be at keeping food hot too.
Pre-Heat Your Cooler
At room temperature the walls of your cooler will be cold compared to your food. This can instantly suck a lot of heat out of your food.
So you'll first want to pre-heat the walls of your cooler. To do this simply fill up your cooler with hot water from the tap and leave it to sit anywhere from 30 minutes to 2 hours.
Then discard the water, give your cooler a quick dry down and fill up with your hot food.
Line Your Cooler With Aluminum Foil
Coolers are great at stopping two types of heat transfer – convection and conduction – but they aren't designed to stop heat radiation from escaping your cooler.
Heat radiation can move through a vacuum and move through a cooler, which will lead to your food cooling down.
Luckily, aluminum is an excellent reflector of heat radiation with about 97-98% reflection.
Lining your cooler with aluminum foil will add this extra layer of insulation keeping your food hotter for longer.
Add a Hot Water Bottle, Heat Pack or Hot Bricks
While some food like soups and casseroles are very dense and pack in a lot of thermal energy foods that aren't quite as dense have trouble staying hot for long periods of time.
Often it's important to add some other source of heat to keep your food hot, so you're not just relying on the heat energy in the food itself.
Hot water bottles are a great easy way to do this as they are very dense and pack in a lot of thermal energy and when you fill them up with boiling water they can get very hot.
Wrapping bricks in aluminum foil and putting them in the over is another good way to add a heating element into your cooler. I wrote more about this in my article on how to keep food hot in a cooler.
Use Towels, Cardboard or Paper For Insulation and Filling Up Space
Super hot food containers, hot bricks or even hot water bottles can be so hot that they damage the plastic of your cooler or even melt the insulation. Read more about boiling water in a cooler.
Put a towel on the bottom of your cooler to both insulate your food and protect the cooler from heat damage. Also use towels, cardboard or scrunched up newspaper to fill in any air space in the cooler.
Lots of air space in your cooler will cause your food to cool down quickly. So fill up this space with towels or paper and your food will stay hot for longer.
How Long Can You Keep Food Hot In a Cooler?
If you prepare your cooler properly and follow the steps above, adding in hot bricks or a hot water bottle then it's possible to keep food hot in a cooler up to 24 hours.
However, if you don't prepare your cooler properly for the type and amount of food you have your food might cooler down a lot quicker than that.
High quality coolers with thick walls of insulation are able to retain heat much better and keep food hotter much longer than a cheap cooler. So if you have a Yeti cooler, or something similar then that is going to work better than a cheap alternative.
How Do You Make a Cooler Warmer?
If you want to keep your cooler warmer so food can stay hotter for longer there are some simple steps you can do.
To keep your cooler warmer for longer pre-heat it with hot water. Line the inside of the cooler with aluminum foil and add a hot water bottle or hot bricks for extra heat energy. Then wrap your food in towels and it'll stay hot in your cooler for longer.
Do the above steps and your cooler should stay warmer for a lot longer than it would otherwise.
This means your food will be hot and good to eat for longer, but if your food is staying extra hot (above 165ºF or 74ºC) then it'll also stop bacteria growing making your food safer to eat.
Can You Put Boiling Water In a Cooler?
You might think it's a good idea to put boiling water in a cooler. This might be to cook hot dogs, corn on the cob or to keep items warmer for longer. However, it's definitely not advised.
Putting boiling water in a cooler will likely warp the inside of the cooler potentially cracking the plastic. In expensive coolers like Yeti it can actually melt the insulation causing permanent damage. Stick to temperatures below 180ºF (82ºC).
Can You Use a Soft Cooler Bag For Hot Food?
Soft cooler bags are more lightweight than their hard plastic counterparts and they are easier to take traveling or on-the-go. But can you use a soft cooler bag for hot food?
You can use a soft cooler bag for hot food but there is a bigger chance of the plastic in the cooler melting. To avoid this wrap your food in a towel to both keep the food hotter for longer and to protect the cooler from heats that may melt it.
Soft coolers like Yeti use a thin and flexible inner lining that is durable and waterproof but isn't designed to handle high heats. If your hot food comes into contact with this then it can melt it.
This will damage your cooler and if you melt a hole through the plastic it'll stop being water proof.
However, soft coolers do pack some good insulation and so they are great at keeping food hot. Just wrap the food in a towel so you don't melt the plastic.
For even better results wrap the food in aluminum foil and add a hot water bottle or heat pack to keep food hot even longer.
Hot bricks aren't advised as they give off too much heat and may damage your soft cooler bag.