Handle Leftovers with Care
By Dr. Jennifer Cleveland McEntire, Senior Staff Scientist and Director, Science and Technology Projects, Institute of Food Technologists (IFT)
Being a busy mom I rely heavily on two things: leftovers and the microwave. How else would I heat up a quick lunch at work as I rush to get back to a conference call? How would I re-heat the dinner my husband missed due to our mismatched schedules?
Still, despite feeling crunched for time, I do take care to treat my food in a way that protects my family from foodborne illness. There’s much more to the safe handling of leftovers than most people realize, and following a few simple tips can save you—and your loved ones—from illness.
Put leftovers in shallow containers to cool quickly
The center of that big pot of chili you stick in the fridge isn’t going to cool down within 2 hours, and that warm spot in the middle can allow bacteria to grow. The smaller the portion size, the faster it will cool in the refrigerator. And when you go to heat it up in the microwave, it will heat much more quickly and evenly too. [USDA recommends packing leftovers so that they are less than 2 inches deep.]
Refrigerate within 2 hours
Bacteria grow rapidly at warm temperatures, and after just a few hours can reach levels that can cause illness. Refrigeration slows the growth of bacteria. The recommended temperature for your fridge is 40 °F or below (use an appliance thermometer to see how cold it is).
Foods should be refrigerated within 2 hours of preparation. Even though it may seem energy efficient to let foods cool down on the counter before sticking them in the fridge, there can be a risk if they are left out too long.
It’s important to remember that the clock starts ticking the moment your food is done cooking—so when dining out, consider the time the food is at the restaurant and the time you travel home. For more details, see Safe Handling of Take-Out Foods.
The microwave is just another way to heat food. The microwaves bounce around and literally “excite” the food. However, the microwaves may not hit every part of the food evenly. In foods with multiple ingredients (like a casserole) some ingredients may get more “heated” than others.
It’s really important that all parts of reheated food reach 165 °F before they are eaten. There are a few ways to ensure this happens:
- Stir the food in the middle of heating;
- Let the food sit for a few minutes after it finishes in the microwave to ensure the food cooks evenly. During this “standing time,” the cold parts of the food will absorb some heat from the hotter portions. Many microwave meals recommend this, so pay attention to microwave instructions.
- After the “standing time,” check the food with a food thermometer.
For more info on reheating in a microwave, see the video How to Properly Cook Foods in the Microwave.