Editor’s note: These suggestions come from a tip sheet written by Marianne Gravely, technical information specialist for the USDA’s Food Safety and Inspection Service, and published Aug. 16, 2016. Additional information isfrom USDA’s “Keep Lunches Safe” page. There’s a certain week when you know the summer is over. It’s when you start seeing the school supply section take over your grocery and department stores. Parents and children, clutching supply lists, cautiously circle the stacks of paper, notebooks, markers and backpacks as they make their selections.

For many children, the highlight of school supply shopping is buying their lunch box. As you guide them in their choice, make sure that it will keep their lunch safe: • Look for an insulated lunch box or bag. Be sure there is enough room for two cold sources to keep the food safe inside. • Make sure it is easy to clean both inside and out. You’ll want to wash all reusable food storage containers that go in the lunch box or bag with hot, soapy water after each use. • If it comes with a thermos, test it when you get home to make sure it will keep foods piping hot — above 140 degrees — until lunch time. While you’re at the store, pick up some extra ice packs or cold sources. Buy enough to keep extras in the freezer.  Talk to school administration to be sure they are allowing time for students to wash hands with soap and water before and after eating. To use the USDA’s colorful poster on lunch food safety to help children understand why and how to keep their lunches properly stored, click here. Additional tips and tidbits Harmful bacteria multiply rapidly in the Danger Zone — the temperatures between 40 degrees and 140 degrees. So, perishable food transported without an ice source won’t stay safe long. Food should not be left at room temperature more than two hours — one hour if the temperature is above 90 degrees. It’s fine to prepare the food the night before, but pack lunch bags right before leaving home. Freezing sandwiches helps them stay cold. However, for best quality, freeze sandwiches before adding mayonnaise, lettuce or tomatoes. Add these just before leaving home. Prepare cooked food, such as turkey, ham, chicken, and vegetable or pasta salads, ahead of time to allow for thorough chilling in the refrigerator to 40 degrees or below. Divide large amounts of food into shallow containers for fast chilling.

To keep lunches cold away from home, include at least two cold sources. You can use two frozen gel packs that are at least 5-by-3 inches each, or combine a frozen gel pack with a frozen juice box or frozen bottle of water. Freeze gel packs and other cold sources overnight. When packing your bag lunch, place a cold source on top and bottom of the perishable food items. Of course, if there’s a refrigerator available at work or school, store perishable items there upon arrival. If you place your insulated bag in the refrigerator, leave the lid or bag open so that cold air can keep the food cold. Some food is safe without a cold source. Items that don’t require refrigeration include whole fruits and vegetables, hard cheese, canned meat and fish, chips, breads, crackers, peanut butter, jelly, mustard and pickles. Prepackaged combos are sometimes packed for lunch. These combos often contain perishable foods such as luncheon meats, cheese and cut fruit that must be kept refrigerated, even though they may be cured or contain preservatives. When packing hot foods, use an insulated container to keep food like soup, chili, and stew hot. Before adding food, pre-warm the container by filling it with boiling water and letting it stand for a few minutes. Then empty the water and put in the hot food. Keep the insulated container closed until lunchtime to keep the food hot. Pack only the amount of perishable food that can be eaten at lunchtime. That way, there won’t be a problem about the storage or safety of lunch leftovers. After lunch, discard all leftover food, used food packaging, and paper bags. Do not reuse packaging because it could contaminate other food and cause foodborne illness. If you have additional food safety questions, call the USDA’s Meat & Poultry Hotline at 888-MPHotline (1-888-674-6854) or chat live with a food safety specialist at AskKaren.gov, available from 10 a.m. to 4 p.m. Eastern time, Mondays through Fridays in English or Spanish. (To sign up for a free subscription to Food Safety News, click here.)