Gone are the days when you bought a thermos just to keep your coffee hot. Also known as the soup thermos or food jar, the newer generation of stainless steel extra wide necked vacuum flasks are ideal for keeping hot lunches hot or cold lunches cold for all members of the family.Although a soup thermos can keep food at a suitable temperature for some time, there can be big differences between manufacturers and styles of soup thermos. How the thermos and your food is prepared can also make a difference as to how well it will keep warm or cold. In this article we take a look at some of the best soup thermos and food jars available, as well as how to prepare them properly and clean them thoroughly after use.
Able to keep hot for seven hours, the Thermos Stainless King 16 oz food jar with folding spoon (army green) is our best pick with its serving bowl and five year warranty.
Ideal for kids of all ages, the Thermos FUNtainer 10 oz food jar (blue) is BPA-free and made from durable stainless steel.
Table of Contents
- Quick Comparison: Top 8 Best Soup Thermos
- Things to Consider Before Buying a Soup Thermos
Quick Comparison: Top 8 Best Soup Thermos
1. Thermos Stainless King 16 Oz Food Jar with Folding Spoon
The Thermos Stainless King 16 oz food jar with folding spoon (army green) is able to keep hot for seven hours, or cold for nine. Its outer lid is a stainless steel serving bowl and it has a folding spoon inside the lid, or you can eat directly from the wide Thermos mouth.Its exterior remains cool touch with hot food and condensation-free with cold foods. Although this Thermos is top rack dishwasher safe, hand washing is recommended to ensure any food or liquid debris trapped within components is removed. There is a chance that the exterior coating on the body can start to peel off with regular use, although this Thermos is covered with a five year limited warranty.
2. Thermos FUNtainer 10 Oz Food Jar
With a durable stainless steel construction, the Thermos FUNtainer 10 oz food jar (blue) is able to keep hot for five hours or cold for seven. This Thermos is free from BPA and has an extra wide mouth for easy filling and eating from, although some consider this Thermos a little large for smaller family members.
A number of owners have also complained that this does not keep food hot for as long as expected, which may cause problems for school lunches. This comes with a five year limited warranty from the manufacturer, and although dishwasher safe, handwashing is recommended.
3. Zojirushi SW-EAE50PS 16.9 Oz Food Jar
Made from 18/8 stainless steel, the Zojirushi SW-EAE50PS 16.9 oz food jar (pink) also has a non-stick BPA-free inner coating which is neutral to smell and taste. The lid includes a vent so that you can release the pressure inside the jar before opening and its wide 2.5" neck makes it easy to fill and eat straight out of. The lid also contains dimples for easier opening.This food jar may not keep food hot for as long as expected in all cases and even with careful washing, water may leak into the vacuum space between the two flasks. This jar should also always be kept upright to prevent food from leaking.
4. Stanley Classic 17 Oz Food Jar
Coming with a lifetime warranty, the Stanley Classic 17 oz food jar (hammertone green) can keep hot or cold for 12 hours. Designed to be fully packable and leakproof, its outer lid also doubles as a serving bowl. Made from 18/8 stainless steel, it is free from BPA.There are some concerns around pressure being too high in this food jar and as a result, food can spill out when the inner plastic lid is opened. There can also be occasional problems with screwing the inner lid back on without cross-threading it in the process. However, this food jar also comes with a lifetime limited warranty.
5. MIRA Lunch Jar
Able to keep hot for five hours, or cold for ten, the MIRA lunch jar has MiraGuard Technology, which includes a triple walled vacuum system and a copper coating for better insulation. This leak-proof jar is made from food grade stainless steel and it is free from BPA and phthalates.The 13.5 oz jar has a matte finish for an anti-slip grip and the exterior is condensation free. Its lid is an easy twist design and the flask is hand wash only. Some owners have commented that food is not staying as hot as it should be and like any type of thermos, there can be a risk of leakage even when the lid is fastened properly. Some younger family members may also struggle to remove the lid.
6. Thermos FUNTainer 16 Oz Food Jar
The Thermos FUNtainer 16 oz food jar (charcoal) can keep cold for ten hours or hot for five. Made from durable stainless steel, it has an extra wide mouth for easier eating, filling and cleaning. Hand washing is recommended for cleaning this Thermos, although it is actually dishwasher safe. There is a five year limited warranty on this product.
7. Hydro Flask 12 Oz Food Jar
This blue Hydro Flask 12 oz food jar (pacific) uses TempShield insulation to keep hot or cold for up to three hours. Made from food grade stainless steel it has a wide opening and a durable powder coat exterior finish that will stay condensation free. It also comes with a lifetime warranty from the manufacturer.
8. AKS 16 Oz Food Jar
Able to keep hot for eight hours or cold for 12, the AKS 16 oz food jar (grass green) is made from food grade stainless steel and is free from BPA. This has a wide mouth and leakproof o-rings to prevent leakage. The exterior will stay free from condensation and it also has a non-slip base and scald proof rim for comfortable drinking.
Things to Consider Before Buying a Soup Thermos
Perhaps one of the most important things to consider is how long a thermos or vacuum flask can keep hot or cold - usually measured in hours. It is also worth checking exactly what the duration means as most manufacturers set times based on how long their product will keep liquids hot or cold rather than semi-liquid foods.
When looking at thermos capacity, consider it should always be filled almost to the top for maximum insulation, so you should be looking to buy one that is the right capacity for your needs. Some manufacturers may give specific advice on how far you should fill it, but usually an inch from the top is enough to allow the inner lid to fasten securely yet keep it out of contact with the contents, as heat can be conducted through the lid.
If you have bought some new vacuum flasks, it can be worth taking the time to test them out first before packing your kids off to school with them, as this will give you an idea of how long their soups or mac and cheese will stay hot for.
Preparing a Thermos for Hot Food
Semi-liquid or liquid foods such as stews, soups, chilis and pasta are ideal in a thermos - as long as they have plenty of sauce in them because a thermos can only work properly and insulate with liquids.
It’s always best to prepare a thermos just before you, or your family members leave for work or school so that the food is in it for the least amount of time.
You should fill your clean thermos with boiling water and let it sit for a few minutes to heat up. You can then heat your food to at least 165°F to ensure that it will be safe in the thermos. Depending on the food, if you can heat to boiling (around 212°F) then even better. You may find it easier to heat on the stovetop than in the microwave.
You can then pour out the boiling water from the thermos and add your food. If you have made the thermos up for kids going to school, then make sure they know to ask for help from an adult to open the thermos.
Once the thermos comes home, always pour away any leftovers even if they are still warm.
If your hot food is cool or your cold food is warm when you open a thermos, then dispose of it, do not eat it. When the temperature in a thermos has dropped below 140°F for more than two hours, the food starts to become unsafe as bacteria have begun to form. Likewise, if cold food is too warm, then it will also be unsafe.
Using a Thermos for Cold Foods
If you want to use your flask for cold drinks or foods, then you can chill the thermos overnight; the freezer is ideal. Otherwise, for faster chilling, place some cold water and ice in it and leave it to stand for five minutes or so before pouring out and adding your food which has been stored at or below 40°F.
When you put your cold thermos in your lunch bag you can also pop a freezer pack in for extra food safety.
Invention of the Vacuum Flask/Thermos
In 1892, the Scottish physicist and chemist Sir James Dewar created a vessel with a vacuum jacket to safely store experimental gases. Known as the Dewar flask, these are still used across the globe today.
As Sir Dewar did not patent his design, in 1904, a Germany company called Thermos GmbH utilized his concept and began to develop and make their own Dewar flasks under the name Thermos. Dewar lost a court case with Thermos over the patent, although Dewar was recognized as the inventor of the vacuum flask.
How a Thermos or Vacuum Flask Works
A vacuum flask contains two flasks, one inside the other. Between these flasks, most of the air has been removed to create a vacuum. This vacuum means there are less molecules able to move heat (either from the contents or from outside the flask) from one flask wall to the other.
Because the flasks are also reflective or silvered, this stops even more heat from transferring; instead, it gets reflected away from the flask walls, and the airtight seal at the top stops heat and air from moving in or out of the thermos, although the lid or stopper can conduct some heat if the thermos is overfilled.
Cleaning a Vacuum Flask
You should never submerge any type of thermos, vacuum flask or food jar in water as this can allow water to leak into the vacuum between the two flasks.
If you have a stainless steel thermos, do not clean with chlorine bleach as this may damage the welding on the steel.
After most uses, warm water and some detergent will be enough to get it clean and depending on the width of the neck, you may be able to get a bottle cleaning brush into it to reach the bottom. If the neck is narrower you can add uncooked rice in water and vinegar, replace the lid and shake it until the inner is clean.
Even when you wash your soup flask regularly after use, over time it will usually begin to stain. It may also develop a slightly unpleasant odor. At this point a more vigorous clean becomes necessary. A tablespoon of baking soda for every two cups of capacity in your thermos with some warm water is often enough to remove residue. You can also add some cider vinegar. Leave this solution to stand for a while then scrub and rinse thoroughly.
For a more energetic cleaning session, try filling the thermos to about a quarter of the way up with small ice pieces/cubes and adding a couple of tablespoons of salt. You can then replace the lid and shake until the ice melts. Hopefully after a good rinsing, the residue will be gone.
A denture cleaning tablet in some warm to hot water (one tablet for every two cups of capacity) can remove stubborn mineral stains if you leave it the thermos to stand for a while or even overnight. Stand it in the sink when you do this as it will foam up, and make sure you rinse well afterwards. If this method does not remove all of the stains, you can repeat the process.
If you put your soup thermos away during the summer months, then add a teaspoon of salt to it or even a whole clove to keep it smelling fresher.
We hope you have enjoyed reading our article on food jars, and that you have found some useful information such as what foods are suitable for jars, how far you should fill a thermos, or even how to remove some of those stubborn stains and strange odors which build up in any type of vacuum flask.The soup thermos is perfect for nutritious food on the go and is compact enough for school lunch bags, daypacks or even an office tote, and we hope our reviews of some of the best soup thermos available will help you to decide which will be the most suitable for hot foods or cold.