Whether you want to eat last night's leftovers or have a warm soup on the road there are some simple and easy ways you can keep your food hot on the go.
I personally love having hot leftover pasta for lunch while I sit in my van at the beach working on my websites or coming in after a surf session.
You might want to keep food hot when you're at work. It can be a great way to save money and it's also often way tastier than eating cold sandwiches or something else for lunch. Not to mention the fact it's usually much healthier than take away options too.
Prepping Food So It's Hot On The Go
Correctly prepping your food and the containers you're going to keep it warm in is an extremely important step so you have hot safe food on the go.
If you don't prep properly you're food can becomes lukewarm, cold and may even spoil and go off and you'll leave yourself hungry.
I've done a full article on how to keep food hot but are a few key tips that make the majority of the difference.
Heat Your Food Up Extra Hot
Whatever method you use to keep your food hot your food will cool down somewhat over the course of the day. So remember to heat up your food hotter than you want to eat it.
This will both work to kill off any harmful bacteria as well as ensure your food stays hot (and safe) on the go for longer.
Make it as hot as you can right before packing it to go.
Pre-Heat Your Container
Whether you're using a thermos or glass tupperware it's important to preheat the container so it doesn't steal heat from your food.
Fill your container with boiling water and leave to sit for 2-5 minutes then discard and dry before adding your food. Don't do this for plastic as boiling water and plastic aren't friends.
Pre-heating your cooler if you're planning on using it to keep food warm is also a good idea. Do this by filling your cooler with warm water from the tap and leaving for 30 minutes to 2 hours to heat up the insulation.
Stop The 3 Types of Heat Transfer
Whenever trying to keep food hot on the go you want to do what you can to stop the 3 different types of heat transfer:
Convection – This is heat moving away from your food, usually in the form of evaporation/steam. Use an airtight container or foil/wrap to trap in steam and its heat.
Conduction – This is heat moving through objects. Insulating your food with anything from a vacuum insulation to a towel or paper can stop heat escaping your food as quickly.
Radiation – Hot items give off infrared or heat radiation. To stop this use a reflective substance that bounces the radiation back. Copper and aluminum are perfect for this with aluminum foil being the easiest way to trap this kind of heat.
Keeping Food Hot and Safe To Eat On The Go
I want to quickly talk about keeping warm food safe on the go. Because if you aren't careful your leftovers that you want to eat for lunch can become a breeding ground for bacteria.
You need to be aware of what temperatures bacteria can grow.
Keeping things cold below 40ºF (4.4ºC) stops most bacteria from growing. This is the temperature your fridge is usually set up.
But keeping food hot above 140ºF (60ºC) or above 165ºF (74ºC) for meats and leftovers also stops most bacteria from growing and kills off a lot of bacteria.
But keeping food in what's called the “danger zone” between 40-140ºF (4.4-60ºC) makes your hot food perfect conditions for bacteria to grow. So it's important to try to keep your hot food out of the danger zone and eat it within 1-2 hours after it cools down to this temperature range.
So make your food hot enough that it is above the danger zone and eat it as soon as possible once it enters the danger zone temperature range.
How To Keep Food Hot On The Go
Below I've got 8 simple ways to keep food hot on the go. A lot of these methods can be used in combination to give you a better result.
So don't just do one of the things listed below but do multiple in combination and find out which one words best for you given what containers your have, what kind of food you're trying to keep hot and for how long as well as your budget.
1. Use a Vacuum Insulated Thermos
A vacuum insulated thermos is THE BEST way to keep food hot on the go. No other insulator is able to keep for hot for as long as a thermos or insulated flask does.
These can keep for hot for 6-7+ hours meaning you can make hot soup in the morning and still have warm soup at dinner time.
Thermos flasks (or any brand) have two walls of stainless steel with a vacuum in between.
Heat really struggles to move through a vacuum and it's the best known insulator according to wikipedia.
To use simply pre-heat the inside of your flask with boiling water then tip out and dry before adding your hot food. Quickly close the lid and you're good to go.
For extra heat retention and to keep food hot on the go for that little bit longer wrap your flask in aluminum foil and a towel and keep it out of the cold as much as possible. Only open it when you're ready to eat.
2. Wrap Your Food In Aluminum Foil
Wrapping food in aluminum foil is a great way to keep many types of food hot on the go.
Aluminum foil keeps food hot in two ways.
Firstly, it reflects back heat radiation at about 97-98% making it hard to escape your food so your food stays hot longer.
Secondly, it stops steam and water evaporating from your hot food because it can't pass through the aluminum foil. Steam and water evaporation actually takes a lot of heat with it away from your food cooling it down super quickly. So stopping this from happening keeps your food hotter much longer.
Aluminum however is not great at stopping heat transfer through conduction which is why you'll often use aluminum foil with something like an airtight container or even a cooler.
3. Use a Cooler To Keep Food Hot
While most of us think of coolers as a way to keep things cold, the very same insulation that stops your ice from melting can actually stop your food from losing it's heat.
You can use a cooler to keep things hot, often for the entire day especially if you prepare it correctly.
The better your cooler is at keeping ice the better it will be at keeping things warm. High-end coolers like Yeti will keep food hot much longer than cheaper coolers with less insulation.
To keep food hot on the go in a cooler you need to take a few extra steps.
Pre-heat the cooler – Pre-heat the cooler by filling it with hot water from the tap and leaving for 30 minutes to 2 hours. This will warm up the insulation.
Line with aluminum foil – Coolers are great at stoping heat conduction but aren't designed to stop heat radiation. So lining them will aluminum foil will reflect back more heat and keep your food hot on the go for longer.
Use towels or paper to fill gaps – Towels are great for both insulating and keeping food hot but also protecting your plastic cooler from the extreme heat of your food. So always wrap food in towels. Also add towels or scrunched up paper to fill in empty air space.
Add thermal mass – This is a fancy way of saying add extra hot things to your cooler so your food stays hot longer. Hot water bottles, heat packs or hot bricks are a great way to add a lot of thermal mass to your cooler and your food will stay hot way longer.
I've also done a full article on how to keep food hot in a cooler for more helpful tips.
4. Use Towels
Towels are actually pretty good insulators and stop heat escaping from your food.
So wrapping your food container in a towel will trap in the heat and keep your food hot on the go for longer.
If you don't have a cooler then I find an airtight container wrapped in alfoil and a towel can be a great quick option.
5. Use Cardboard or Paper
Have you ever noticed that pizza comes in a cardboard box?
While this is likely because cardboard is rigid and cheap it also serves the added benefit that cardboard is a good insulator and keeps food hot for longer. So is paper.
This is also why some places wrap fish and chips in paper or newspaper, it's both cheap and it keeps the food hot for longer.
So wrapping your food in paper or putting it in a small cardboard box can help to keep it hot on the go longer.
If you don't have a cooler then a cardboard box with some aluminum foil and some towels can easily become a makeshift cooler.
I don't advise putting hot food directly in cardboard as when I looked into whether or not you can microwave cardboard I found out cardboard can leech harmful chemicals into your food when heated.
6. Use a Hot Water Bottle or Heat Pack
Rather than just relying on your food to keep itself hot you can add an external heat element to your food to keep your food hot on the go for longer.
A hot water bottle filled with boiling water or a heat pack made extra hot can actually help to warm up your food on the go.
If you're not using a cooler then taking your food container, putting a hot water bottle right next to it and wrapping it all in a towel can be a good quick solution.
If you have a cooler then you can also make hot bricks in the oven which can keep food hot when you're out and about for hours and hours.
7. Pre-Heat Your Container
An important step to keep food hot for longer is to not let the container steal all the heat of your food.
A container kept at room temperature can quickly cool down your food as heat is used to warm up the container.
To make your food stay hot for longer pre-heat your container by filling it with hot or boiling water and leaving it to sit for a couple of minutes before discarding the water.
This works great with glass, ceramic and stainless steel containers but isn't advised with plastic as boiling water can deteriorate the plastic and leech chemicals.
8. Keep It Airtight
When food is hot it will often let off steam. This evaporating water takes a lot of heat with it as it leaves your food.
When this happens your food will cool down much quicker because it's losing so much heat energy.
Using an airtight container is a great way to trap this heat energy and to stop it escaping from your food.
I like to use an airtight thermos flask or a glass tupperware container so the steam won't escape and my food won't spill in my bag.
Use These Methods In Combination With Each Other
I've listed 8 different ways to keep food hot when you're on the move and out and about but you don't just have to pick one idea and just do that.
These methods are most effective when used in combination with each other.
Pre-heat your containers, wrap them in alfoil and towels and add them into a cooler with a hot water bottle or hot bricks and use paper or cardboard to fill up the air space.
Using them in combination will get you the best results so choose which combination works best for you and your food will stay hot for hours at a time when you're on the go.