Ice packs are filled with a gel that freezes solid, and they’ll usually keep food safe and cold for around 6 hours. Bacteria grows on perishable food once it warms up to 40 °F (4 °C), so use plenty of ice packs to keep the temperature down in your entire lunch box. [2] X Research source
You can reuse the sponge by rewetting it and sticking it back in your freezer.
If you normally pack a soda or canned drink for lunch, avoid putting it in the freezer since the can could burst open as ice forms.
Alternatively, you can try making a sandwich and freezing it ahead of time. Just avoid freezing any sandwiches if they have mayonnaise, lettuce, or tomatoes since it will ruin their texture. [6] X Research source
Invest in a freezable lunch box that has built-in ice packs so you don’t have to add any extra. [8] X Research source You can also sew your own lunch box with insulation fleece fabric.
If you can’t find an insulated bento box, you can just put a standard one inside of an insulated lunch bag instead.
Paper bags are better for food that’s safe to eat at room temperature, such as peanut butter sandwiches, fresh uncut fruit, nuts, and canned meat. Keep your lunch refrigerated as long as you can before you have to leave so there’s less time for it to heat up.
Thermoses are great for drinks, but you can also put pasta, salad, yogurt, or even sushi inside of them. Let your Thermos chill overnight so it’s cold when you pack your lunch in the morning. [11] X Trustworthy Source US Department of Agriculture U. S. agency responsible for promoting good agricultural practices and protecting consumers Go to source
