Thermoses to Keep Food Hot or Cold

For those who have favorite foods that need to be kept either hot or cold, there is the vacuum-sealed thermos. Choose a thermos with a stainless steel or glass lining instead of a plastic-lined one. Steel or glass keeps foods hotter or colder than plastic.
 
To maintain a colder temperature, chill the bottle before leaving home.  If it’s hot food to be packed (soup, spaghetti, etc.), fill the thermos with boiling water, let stand a few minutes, empty, then put in the hot food.  (Note: some plastic linings should not be filled with boiling water because have not have been  “approved” by for high temperature exposure.  The FDA tests plastics for migration of various chemicals under specific conditions.   If the plastic isn’t identified as  microwave safe, don’t put boiling water into it.) The thermos bottle should stay closed until lunch. 
 
Experiment at home to see if the food in the thermos stays hot or cold for the amount of time that passes from  your leaving home to eating lunch.  Remember, bacteria grow rapidly in the 40°F-140°F range, so it’s important to keep hot foods hot and cold foods cold.
 
Source(s): 
New Nouveau Brunswick Health

“Hints and Advice for Making Packed Lunches Safe to Eat”
 
United States Department of Agriculture
Food Safety and Inspection Service
“Advice for Packing Safe School Lunches”
 
Susan Brewer, Ph.D.  University of Illinois, Department of Food Science and Human Nutrition