Some Like It Hot, Some Like It Cold—Either Way, Here’s How to Keep Home-made School Lunches Safe and Tasty

Lunch BoxDiane laughs as she recalls carrying a peanut butter and jelly sandwich to school every day for some eight years:  “It was the only meal my mother considered safe to consume after being unrefrigerated all morning.” Today, we know that safety doesn’t require such monotony.  However, the challenge remains—how to pack nutritious, delicious meals that will remain uncontaminated even if they spend all morning on a coatroom floor.


Perishable foods (those that need to be kept hot or cold) must not be left in what food scientists call the “danger zone” (40°-140°F; 4°-60°C)  for more than two hours. Bacteria and other pathogens that can contaminate foods and cause illness grow rapidly in that temperature range.  Children’s lunches, if left unrefrigerated for about four hours, must contain only shelf-stable items, or parents must learn a few techniques for keeping hot food hot and cold food cold. (These tips will also come in handy when adults prepare their own portable lunches.)


Many people are somewhat misinformed about which foods need refrigeration and which don’t. Food scientist Karin Allen warns, “Raw cut-up vegetables and fruit can be some of the most hazardous foods.”  Don’t put them in a lunch that won’t be refrigerated. Instead, pack a whole banana, an apple, or one of those handy individual-portion sealed cups of cut-up fruit in juice.


What about cheeses?  Dr. Allen says, “If the sandwich is made with a semi-hard cheese (such as cheddar, Swiss, or Colby) or a processed cheese [such as American], it doesn’t need to be kept cold.  These cheeses are refrigerated to extend their shelf life, not to prevent contamination.”  On the other hand, Allen explains, “Softer cheeses (such as Mozzarella, Edam, and Monterey Jack) should be chilled, as should fresh cheeses, such as cream cheese, ricotta, and queso fresco.”  Food scientist Joe Regenstein is a bit more lenient when it comes to cream cheese.  He claims it’s acidified enough to tolerate a half day at room temperature.  “My wife takes cream cheese to work every day and doesn’t refrigerate it,” he says but adds this warning: “I would not do the same with cottage cheese; it seems to be a lot more sensitive.” 


You can also pack most deli meats in school lunches that will sit at room temperature all morning, says Dr. Regenstein.  Any cured meat will last unrefrigerated a half day.


Sealed substitute milk beverages--such as soy or rice milk--don’t need refrigeration, and neither do prepackaged condiments such as mustard, mayo, and relish.  Supermarkets also sell shelf-stable puddings in a variety of flavors. Even though these nonperishable foods don’t require refrigeration, a cold pack in the lunchbox will make them taste better. 


Many kids (and adults, too) enjoy the shelf-stable individual packages of Starkist or Bumble Bee tuna and crackers.  Says Dr. Allen, “These don’t need to be refrigerated or kept chilled because the tuna in the foil pouch has gone through the same kind of heat processing that canned tuna does.” However, before packing these in a child’s lunchbox, be sure the child is capable of opening the packaging easily and with reasonable speed.


It’s much easier to keep a perishable portable meal cold than to keep it hot. You may be able to keep solid perishables cool all morning by inserting a cold pack or frozen juice box or by freezing the food itself. You can freeze many types of perishable sandwiches—those made with leftover chicken, beef, and so on--and pack them for lunch right before you or your children leave the house in the morning.  The sandwiches are likely to be defrosted but still cold by lunchtime. Dr. Allen advises against freezing a tuna sandwich, but hard and semi-hard cheeses taste fine after they’ve been frozen and defrosted.


Cheese sticks (a favorite with kids) don’t need to be frozen; they’ll remain safe to eat if packed right near a cold pack or frozen drink.  The goal is to keep these perishables no warmer than 40ºF.  “Frozen gel packs work great,” says Dr. Allen, “but they have a tendency to get worn or punctured over time.  One alternative is freezing a foil-packaged juice or punch drink.  The foil packaging is flexible enough so that it won’t explode like cans or boxes.”


If your children get tired of sandwiches for lunch, consider baking up a batch of  “meal muffins,” muffins with some veggies inside.  Like sandwiches, these can be frozen and then put in lunchboxes in the morning. To find a recipe for meal muffins from The TV show “Good Morning, America,” consult  You can also find many other muffin recipes online.  Dr. Regenstein points out that the muffin is shelf stable and the veggies inside, if fully baked are protected from contamination by the muffin surrounding them.  Therefore, it isn’t necessary to freeze them to keep them cold until lunchtime.


The bigger challenge is keeping food hot for half a day. Soup, chili, stew, or something else liquid or semi-liquid should stay hot (or at least warm) in a good thermos. A thermos with a stainless steel or glass lining will keep foods hotter (or colder) longer than plastic will. Be sure that it’s clean!  Pour in some hot water to warm it up, spill that out, and then add the hot food.  If it’s really hot and is kept closed, it has no source of contamination, says Dr. Regenstein. 


What’s the best type of lunchbox or bag to buy?  Some parents prefer a metal box because it’s easy to clean and more durable.  However, an insulated plastic or cloth model will do a better job of keeping food hot or cold.  But eventually it’s likely to tear. All things considered, including the carelessness of kids, be grateful if it survives the academic year.  Don’t buy a lunch container that’s so bulky and/or heavy that your child won’t want to lug it around, nor one so small that it can’t hold sufficient food and drink plus a cold pack (if you expect to use that). Remember this: the size of the container, the amount of food you insert, and the temperatures that the lunchbox is exposed to will affect how long the edible items will stay hot or cold. 


Oh, happy day, when your child becomes responsible enough to pack his/her own lunch.  When this day comes, supervise the initial venture and offer tips. The first rule should be to wash one’s hands and the lunchbox or bag before handling the food.  Next, be sure that the lunch your child packs does not consist solely of potato chips, five cookies, and a candy bar. Be sure that everything needed is packed—for example, a hand wipe to use before eating, silverware, napkins, and perhaps condiments. Remind your child to discard perishable leftovers after eating.  Finally, nip lunchtime envy in the bud by asking your child to suggest lunch menus. If you give your child your favorite meal, it may wind up getting traded for another kid’s brownie. 


“Lunch is a huge portion of your child’s food intake for the day,” says Rachel West, a registered dietitian and editor of The Ultimate Kid-Approved Cookbook (  If you’re looking for ways to pack kids’ lunches with maximum nutrition and minimum fuss, the Chicago Tribune “Good Eating” section recommends West’s book.  One idea you’ll find there: bake pre-boxed corn bread but throw in additional ingredients--veggies, protein, or both—for example, an extra egg, shredded cooked chicken, black beans, corn, or salsa. Ummm.  Sounds good enough to eat. 




Karin E. Allen, Ph.D., Utah State University Logan, UT, U.S.A.), Dept. of Nutrition, Dietetics,

and Food Sciences


Joe Regenstein, Ph.D. Cornell University (Ithaca, NY, U.S.A.)   Dept. of Food Science


Good Morning America “Muffin Meal”


Chicago Tribune Good Eating section “Packed with inspiration”

August 10, 2011.




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