Warm Lunches Made Easy: How to Get the Most Out of Your Insulated Food Jar

As the weather starts to cool down here in Australia, it’s the perfect time to start thinking about packing warm meals for school lunches! Not only is it a great option for kids who aren’t big on sandwiches, but it’s also a handy way to use up leftovers (win-win!).

If you didn’t already know, our Hot N Cold Hero Box  is the only stainless steel lunchbox in Australia that comes with an insulated food jar. That means you can ditch the plastic alternatives—something we know many of you prefer for both environmental and health reasons.

And if you love our 2 or 5-compartment lunchboxes but still want the flexibility of adding a food jar, we’ve got you covered! The 250ml insulated food jar from the Hero Box is available as a stand-alone product.

Why Our Food Jar is Different

Our petite 250ml food jar is smaller than some others on the market, which means it has a few limitations when it comes to how long it can keep food hot. But there’s a good reason for its size! It’s been designed to fit inside our Hot N Cold Hero Box and be super easy for young kids to eat from—think wide-mouth opening and a simple flip-top lid.

 We’ve put together our top tips to get the most out of your food jar!

Preheat (or Pre-Chill) Your Food Jar

• For hot meals: Fill your jar with boiling water, pop the lid on, and let it sit for 10 minutes before adding your food.
• For cold foods: Stick the jar in the freezer for 10 minutes (lid off) before adding things like yoghurt or custard.

Why does this help? Well, science! Heat always tries to move to a cooler place, so if your jar starts off cold, your food will lose heat straight away. Warming (or cooling) the jar first slows down that process.

2. Stick to Wet Foods

Insulated food jars work best with wet foods like:

• Soup
• Saucy pasta or noodles
• Curries

Liquids retain heat much better than dry foods. Plus, filling the jar completely with food means no air pockets, which can make food cool down faster.

We don’t recommend using food jars for solid foods like sausage rolls, nuggets, or sandwiches. While you *can* do this, just know they won’t stay warm for as long and might end up a bit soggy.

3. Heat Your Food Piping Hot

• Make sure your food is hotter than you’d eat it—ideally at boiling point—before putting it in the jar.
• If you’re using a microwave, stir the food regularly to avoid cold spots. Cold spots will cause heat to escape more quickly once transferred to the jar.
• If you can, heat food on the stove instead—it’s the best way to get an even temperature.

4. Fill the Jar to the Top

A full jar is a warm jar! Fill it as close to the brim as possible to reduce air pockets that speed up heat loss.

5. Use Extra Insulation

•  Keep the food jar inside the Hot N Cold Hero Box to add an extra layer of insulation.
• Avoid opening the jar before lunchtime! Every time the lid is opened, heat escapes, so remind your little one to keep it sealed until they’re ready to eat.
• Store it in an insulated lunch bag to help maintain the temperature even longer.

6. Keep It Out of the Fridge

Cold environments speed up heat loss That means:

• Don’t store the food jar or lunchbox in the fridge before packing hot food.
• Skip the ice pack in your lunch bag when sending a hot meal.

7. So, How Long Will It Stay Warm?

We get asked this a lot, and the answer depends on a few factors—like what you’re packing, how hot it was to begin with, and the outside temperature.

If you follow all of our tips (preheating the jar, using wet foods, keeping it sealed, and storing it inside the Hero Box), you can expect food to stay warm for up to 4 hours —and possibly up to 5 hours if kept in an unopened Hero Box.

8. Timing It Right
Since the food jar keeps food warm for a set period, some kids might prefer to eat their hot meal during their first break and save their other snacks for later.

Our 250ml insulated food jar is designed for easy use, no-fuss eating, and keeping food warm for chilly Winter school days. By following these simple tips, you’ll get the absolute best out of it—and your little one will enjoy warm, comforting meals all autumn and winter long!