Leftovers—I bet you have some in your refrigerator right now. They’re great to have around for a quick meal, but it’s also easy to get tired of them and leave them in the fridge for too long. Foods don’t necessarily have to look or smell bad in order to be unsafe to eat. The general rule for most leftovers, especially those that contain meat, fish, poultry, or eggs, is four days, and that’s only if you handle them properly.

Most bacteria grow best in a temperature range of 40° to 140°F—the danger zone—so the first thing you should do is make sure your leftovers cool quickly out of the danger zone. Put them in wide, shallow containers to increase surface area and refrigerate them partially covered until they’re chilled, then cover them well. Any perishable food that remains in the danger zone for more than 2 hours (1 hour if the air temperature is above 90°F) should be thrown out. Use a refrigerator thermometer to be sure your refrigerator maintains a temperature below 40°F. And if you don’t think you’ll eat the leftovers within a few days, wrap them well and freeze them at 0°F or below. Frozen leftovers will remain safe to eat for a long time, but quality will begin to suffer within a few months.