Reheating refrigerated food properly is crucial for food safety. When food is not stored at safe temperatures, bacteria can multiply quickly and cause foodborne illness. However, there are steps you can take to safely reheat leftovers and other refrigerated foods.
Why is proper reheating important?
Proper reheating is important to kill any harmful bacteria that may have grown while food was cooling and being refrigerated. Bacteria multiply fastest between 40°F and 140°F. Simply taking food out of the refrigerator and eating it ‘cold’ does not make the food safe. Cold food needs to be reheated thoroughly to 165°F to kill bacteria.
Some common bacteria that can be present in food include:
- Salmonella – Can cause diarrhea, fever, and cramps
- E. coli – Can cause diarrhea, urinary tract infections, respiratory illness, and other illnesses
- Listeria monocytogenes – Can cause fever, muscle aches, nausea, and diarrhea
- Staphylococcus aureus – Can cause nausea, vomiting, and diarrhea
- Clostridium perfringens – Causes diarrhea and cramps
These bacteria can grow undetected in food during storage. Proper reheating will kill the bacteria and make the food safe to eat again. Insufficient reheating may allow bacteria to survive.
What are the best ways to reheat refrigerated food safely?
Here are some tips for safely reheating refrigerated food:
Use the stove, oven, or microwave
The best ways to reheat food are on the stove, in the oven, or in the microwave. These methods allow direct heat to be applied and temperatures high enough to kill bacteria can be reached.
On the stove: Heat sauces, soups, and gravies over medium-high heat, stirring frequently until steaming hot (165°F). Bring larger items like meat slices up to a boil.
In the oven: Use the oven to reheat items like pizza, baked potatoes, and casseroles. Preheat oven to 350°F and reheat until internal temperature reaches 165°F. Use a meat thermometer to check the temperature of thicker foods.
Microwave: Microwave leftovers using a microwave-safe container for 1-2 minutes until heated through. Stir occasionally and allow standing time. Rotate food for even heating.
Avoid slow or indirect heat methods
Slow heating methods like low oven temperatures may not heat foods quickly enough to kill bacteria. Methods that apply indirect heat, like the crockpot or steamer, may also not effectively reheat refrigerated foods.
Do not:
- Use crockpots or slow cookers
- Use steamers
- Use warming trays
- Heat in low oven (under 250°F)
With these methods, temperatures might not get hot enough throughout the food to destroy bacteria.
Heat thoroughly until steaming hot
It is important that all parts of refrigerated foods are reheated until steaming hot. Bacteria can survive in cold spots. Use a food thermometer to check that leftovers reach an internal temperature of 165°F. Soups, sauces and gravy should be bubbling hot.
Bring sauces and gravies to a boil
When reheating sauces, soups, and gravies, it is important to bring them to a boil to ensure any bacteria present are destroyed. Just reheating until warm is not sufficient.
Stir while reheating
Stir foods occasionally to distribute heat evenly and avoid cold spots where bacteria can survive. Make sure to stir casseroles and dishes with layers like lasagna.
Allow standing time
Allow cooked foods to stand for a couple minutes after reheating. This allows the temperature to distribute thoroughly and continue killing bacteria. The center of thick foods may still be colder than the outer portions immediately after reheating.
How long can refrigerated leftovers keep for?
Refrigerated leftovers that have been handled safely should be reheated and eaten within 3-4 days. Here are approximate storage times for refrigerated foods:
| Food Type | Refrigerator Life |
|---|---|
| Cooked meats and meat dishes | 3-4 days |
| Cooked fish and seafood | 3-4 days |
| Cooked egg dishes | 3-4 days |
| Cooked vegetable dishes | 3-5 days |
| Soups and stews | 3-4 days |
Discard any leftovers that are older than these time limits. Do not taste old leftovers to determine if they are spoiled – bacteria that cause illness can grow without changing the taste or look. When in doubt, throw it out.
Can you reheat refrigerated food more than once?
It is not recommended to reheat leftovers more than once. Each time food is allowed to cool to refrigerator temperatures, more bacteria can grow. Reheating the food will kill most but not necessarily all bacteria present. Then as the food cools again after reheating, the bacteria survivors can multiply.
The safest approach is to discard any refrigerated leftovers after reheating once. Cook a fresh batch if you want that particular meal again. Never reheat the same leftovers more than once.
Should some foods not be reheated?
There are some foods that are not safe to reheat or do not reheat well. Avoid reheating these foods:
- Raw meat, poultry, fish, and eggs
- Deli meats
- Creamy sauces
- Casseroles containing eggs, cream, or mayonnaise
- Cooked rice
- Cooked pasta
- Salads containing mayonnaise
- Lettuce and greens
These items either will not reach safe temperatures during reheating or may undergo texture changes. It is better to cook fresh instead of trying to reheat them.
Tips for safely storing and handling leftovers
In addition to proper reheating, be sure to:
- Refrigerate leftovers within 2 hours
- Store leftovers in shallow airtight containers
- Label containers with date and contents
- Use oldest leftovers first
- Avoid cross-contamination from raw foods
- Follow suggested refrigerator storage times
Proper food handling practices during initial cooking, cooling, and storage are key to preventing bacterial growth in leftovers.
Ready-to-eat leftovers
Some fully cooked foods can be safely eaten cold without reheating. These include items like:
- Hard cheeses
- Opened canned fruits and vegetables
- Opened jars of condiments like ketchup and mustard
- Desserts like cakes and cookies
- Bread
As long as these were handled properly during initial cooking and cooling, they can be eaten straight from the fridge. But take note of recommended storage times.
Conclusion
Proper reheating of refrigerated leftovers and foods is important for preventing foodborne illness. Use direct heat methods like the stove, oven, or microwave to reheat to 165°F. Do not use slow, indirect heat methods. Allow foods to stand for a few minutes after reheating so the heat can distribute evenly. Avoid reheating any food more than once. With safe food handling practices, leftovers can be safely enjoyed for several days after initial cooking.
