Book 26, Question 137
How can you design a lunch box that keeps food safe for a few hours?
Cold foods need to stay cold.
Germs grow quickly when food sits between about 40 and 140 degrees Fahrenheit for more than two hours. An insulated lunch bag slows the heat coming in. Pack a frozen gel pack or a frozen juice box next to the food, and keep the bag out of the sun. Warm foods can go in a thermos that has been warmed with hot water first.