STILLWATER, Okla. – Although thousands of Oklahoma students will crowd cafeteria lines this school year, there will be a good number who opt to go their own way and bring food from home. For those who fit in that latter group, even occasionally, it is important to keep safety in mind.

Just what is the big deal about keeping that turkey sandwich cold or that vegetable soup hot?

“Harmful bacteria can rapidly multiply in temperatures between 40 F and 140 F, so perishable foods that are carried without a way of keeping them cool won’t stay safe to eat for very long,” said Barbara Brown, Oklahoma State University Cooperative Extension food safety specialist.

When it comes to brown bagging it, foods such as whole fruits and vegetables, hard cheese, unopened canned meat and fish, chips, breads, crackers, peanut butter, jelly, mustard and pickles are all just fine at room temperature. However, perishables that commonly find their way into lunch sacks and pails such as luncheon or deli meat and yogurt can remain at room temperature for only 2 hours before becoming unsafe to consume. That timeframe shrinks to just 1 hour in temperatures above 90 F.    

Insulated, soft-sided lunch boxes and bags are your best bet for keeping lunchtime fare safely chilled. Metal or plastic lunch pails and paper bags work, too, as long as an ice source, such as a gel pack, is included with perishables. Double-bagging paper sacks also will help insulate food.

“Remember that prepackaged meals with luncheon or deli meats, crackers, cheeses and condiments also needs to be kept cold,” Brown said. “That includes meats and smoked ham that are cured or contain preservatives.”

If you decide to pack something hot, fill an insulated container with boiling water and let it stand for a few minutes before emptying the liquid and pouring in the food already heated until it is steaming hot. Leave the insulated container closed until it is ready to be eaten in order to keep the food at 140 F or above.   

The way a bag lunch is prepared matters, too. Cleanliness is key, so be sure to wash your hands with soap and water for 20 seconds – that is the equivalent of singing the “Happy Birthday” song twice – before assembling your lunch. The same hand-washing guideline applies when you get ready to eat it.

“Any cutting boards, dishes, utensils and countertops should be wiped down with hot, soapy water in between each item you prepare,” Brown said. “Consider using separate cutting boards for raw meat and poultry and for foods that will not be cooked such as bread, lettuce or tomato. If you have only one board, wash it thoroughly in between each use.”

Finally, when it is time to enjoy the midday meal, if you are using the microwave to reheat it, be sure to cover it to keep the moisture and encourage safe and even heating. Also, go ahead and throw away any used food packaging and bags. Reusing packaging could contaminate other food and cause foodborne illness.


Oklahoma State University, U.S. Department of Agriculture, State and Local Governments Cooperating: The Oklahoma Cooperative Extension Service offers its programs to all eligible persons regardless of race, color, national origin, religion, gender, age, disability, or status as a veteran, and is an equal opportunity employer. 

Leilana McKindra
Communications Specialist
Agricultural Communications Services
140 Agriculture North
Oklahoma State University
Stillwater, OK 74078
Phone: 405-744-6792
Fax: 405-744-5739
Email: [email protected]

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