Leftovers are one of the best parts of eating well, but bacteria grow quickly in the wrong conditions. The U.S. Department of Agriculture and other food safety agencies recommend a handful of simple rules.
The two-hour rule
Refrigerate leftovers within two hours of cooking or of the food coming off the heat. On a hot day above 90°F, such as a picnic or a long summer barbecue, that window drops to one hour.
Keep the fridge cold
Your refrigerator should stay at 40°F or below and your freezer at 0°F. An inexpensive appliance thermometer takes the guesswork out. Divide large batches into shallow containers so they cool quickly.
Use them within a few days
Most cooked leftovers are best eaten within three to four days. If you will not get to them in time, freeze them; frozen food stays safe indefinitely, though quality slowly declines over months.
Reheat thoroughly
Reheat leftovers until they are steaming hot, to an internal temperature of 165°F. Stir food in the microwave partway through so it heats evenly, and bring sauces, soups and gravies to a rolling boil.
When in doubt
You cannot always see, smell or taste the bacteria that cause food poisoning. If you are not sure how long something has been in the fridge, it is safest to throw it out.