Insulated lunch bags, unlike the traditional brown or plastic lunch bags, can keep food warm or cold longer and prevent it from becoming stale. Because of their embedded insulation, insulated lunch bags retain heat and preserve freshness better than traditional lunchboxes. How do they work? Layers are the short answer.
How Do Insulated Lunch Bags Work?
Most Custom Insulated Bags have multilayered insulation. The insulation is usually composed of an outer layer, a liner, and a middle layer. The middle layer must be at the top of your lunch bag, as it will make it more durable than an ordinary lunch box.
The vacuum between the outer and inner layers of thermoses and insulated lunch boxes is what prevents energy dissipation. Insulated lunch bags, on the other hand, keep food and drinks warm and cold due to a dense foam core layer. The insulation is more effective than the thicker and denser foam.
The outer layer is protected from heat seepage through the foam layer. This keeps heat and cold from reaching the contents of the bag. Insulated lunch bags don’t heat up when they are filled with heated items. This is because the heat in the surrounding environment is not dissipating. Most lunch bags’ outer layer is made from non-woven, vinyl or heavy fabrics.
Many insulated lunch bags have an inner layer, or lining, that provides extra protection. It can be made from foil, heavy vinyl or plastic that is heat reflective and waterproof.
Heat reflective simply means the bag’s inner foil-like layer reflects heat to the food rather than absorbing it and allowing it to escape. The bag’s foil-like inner layer reflects heat to the food, allowing it to retain its original temperature, flavour and moisture longer than a normal bag.
An insulated lunch bag can also protect food from becoming stale, just as tin foil does, but to a greater extent.
How Long Can An Insulated Lunch Bag Keep My Food Warm/Cold?
This question is not easy to answer. Many factors affect the time it takes to store food in an insulated lunch bag.
- Type of bag
- What gel packs are included in the insulated bags?
- Temperature outside
If food is hot, it should remain warm for two to three hours and cold for four to five hours, without adding gel packs. You can get up to four hours more by purchasing a heated or frozen gel pack.
Boost Insulated Lunch Bags’ Performance
These are some tips to help you keep your food cold or warm for longer with an insulated lunch bag.
- Add a cold/warm source to the bag. For example, heated gels pack/water bottle if food is warm; or a frozen gel packet/water bottle/juice box if food must be kept chilled.
- Heat the food before packing, or transfer the chilled food directly from the freezer to the lunch bag.
- Wrap food in aluminum foil to add insulation. To further protect heat from escaping, wrap the food in a tea towel.
- Do not open the lunch bag until you are ready to eat the food. This will prevent any thermal energy from being released.
- Keep the lunch bag in places that have air conditioning. If you need to keep it chilled, your car trunk is not the best place for it.
- Use the right-sized lunch bag to suit your needs. An empty insulated container is more efficient than jam-packed one.
- Separate hot and cold items even if certain items are in the bag but others are out.
