The answer depends entirely on the sort of leftover to be reheated. Leftover Pizza would be reheated quite differently than leftover pot roast or soup.
Leftovers should always be reheated to an internal temperature of 145 degrees. This helps to prevent any bacteria and avoid getting sick.
165
Take the temperature of it! Fish and seafood should be cooked to a minimum internal temperature of 145 degrees Fahrenheit, ground meats should be cooked to 155 degrees Fahrenheit, whole meats such as beef roast or pork should be cooked to 145 degrees Fahrenheit, and poultry should be cooked to 165 degrees Fahrenheit. Anything you are trying to reheat should also be reheated to an internal temperature of 165 degrees Fahrenheit.
Three days is the longest you should keep Egg Foo Young leftovers, as the eggs and other ingredients are the perfect breeding ground for bacteria, which can cause foodborne illness. As with other leftovers, when you DO reheat them, make sure it's reheated to 165 Degrees F, to kill any bacteria that may have started to form.
As long as you have fully cooked the meat it is safe to reheat a curry that you made with the meat. You can reheat cooked meat as long as you have cooked it correctly and stored it properly.
As long as the food was cooked properly the first time and proper storage precautions were observed, then there is no set temperature that must be reached in order to safely reheat it. Warm to whichever temperature you desire in order to enjoy it.
Reheating frozen roasted chickens by cutting them up first is easier than reheating a whole chicken. If you reheat a whole chicken, it may dry out from being in the oven for so long. You can reheat cut up pieces at a high temperature for a short period of time which prevents them from drying out.
Absolutely. Otherwise there would be no need for the word "leftovers." Generally, your senses help prevent you from eating anything unsafe. Keep your food prep and storage areas clean, promptly refrigerate leftovers, and you'll be fine. If something is left in the fridge too long, you won't need a PhD to identify it.
The best way to reheat lasagna is to use a microwave oven. You should heat for about 2 minutes at max power per serving, covered in plastic film to avoid it from getting dry. If you reheat it in a traditional oven, do it at a low temperature (140ºC), covered in aluminum foil for about 20 to 25 minutes. You can use a knife to poke it trough the center to check the core temperature.
2 weeks
Internal temperature of pork needs to reach 145° to kill bacteria, so I would cook it to 140° and let it rest 15 minutes to reach an internal temperature of 145°
a couple days