Tips on Reheating for Safe, Yummy Leftovers

leftover pizzaRemember "srevotfel"?  You ate it, but perhaps you didn't love it. No, this isn't an exotic imported dish; it's just "leftovers" spelled backwards to avoid calling a re-warmed meal by an unappealing name. You'll probably have leftovers in your not-too-distant future. After all, you don't want your holiday spread to look skimpy; you know that, when the pickings seem lean, guests take less. But, when you cook too much for the size of the crowd you're entertaining, leftovers are inevitable.  So what, of all this stuff they didn't eat, can be safely reheated, and how can we make srevotfel taste good enough to be devoured with enthusiasm?  In the following Q/As, we have expert answers from our Board scientists and the U.S. government.  Let's begin with safety.


What's the safe way to reheat food?


According to the FDA food code, the goal is to get all parts of potentially hazardous food to at least 165°F and held at that temperature for at least 15 seconds. While it's cooking, the food should be stirred (if possible) or rotated for uniform heating.


To be sure you've gotten food to the required temperature, you need to check it with a food thermometer.  A large amount of food (a whole roast or a turkey) should be poked with the thermometer in 2-3 places. After cooking, allow the product to stand for two minutes. 


What about ready-to-eat commercially processed food in a sealed container?  Follow the directions given on the package.  If there are none, heat or reheat to 165°F.


It is a good idea, food scientist Dr. Joe Regenstein advises, to be sure that your thermometer is actually measuring the correct temperature.  Check your thermometer in boiling (or just-boiled) water and then in an ice bath. At sea level, water boils at 212oF, so that's what your thermometer should read. (Check the “correct boiling point” if you are at a higher elevation.) Inserted in an ice/water bath, your thermometer should register 32oF.


What about foods that, originally, required heating only to 145°F to be safe, for example beef or fish?  These should also be reheated to 165°F.  (Sorry about that.  They may wind up pretty dry. To avoid that, you might want to reheat in a sauce.)  The reason for reheating at a higher temperature than the original cooking temperature is that, having been cooled and then heated again, these foods have gone through the "danger zone" (40°F - 140°F) twice, and that is the time when bacteria multiply quickly. The goal in reheating is to kill pathogens that grew in the food during that time.


How many days can I keep refrigerated leftovers before reheating and serving?  


The general advice from scientists is 3-4 days, but some types of foods can be kept a little longer.

For the specifics on this question, see the Shelf Life Advice article "How long can I keep refrigerated leftovers?" This article deals with edibles eaten warm and with foods served cold.


Dr. Regenstein points out that some foods actually taste better the second day.  But, after that, for consuming leftovers, the sooner the better is a good general rule to follow.


What are some tips on properly handling leftovers being saved for reheating?


Food scientist Dr. Catherine Cutter offers these safety tips:


  • Keep perishable food out at room temperature as short a time as possible, not longer than 2 hours.
  • After the meal, get leftovers cooled down as fast as possible. Once refrigerated, they'll cool faster if placed in shallow pans or smaller containers. Another trick for rapid cooling is to put leftovers in the freezer if you have the room and can remember to then take the items out after about an hour, before they freeze, assuming you want to eat them within the next few days. 
  • Another technique for speeding up cooling is to give hot food an ice bath by setting the bowl containing hot food into a larger bowl containing water and ice cubes.  Cool the food down to about 40°F before refrigerating.  Add more ice cubes if necessary to keep the water cold.
  • Here's the safest way to serve leftovers:  Don't reheat all of them (because you don't want to reheat leftovers twice).  Instead, take out the platter(s) and bowls of cold leftovers and invite diners to help themselves and then microwave their individual plates.  Refrigerate the food that remains.  Later, you can bring the food out again if diners want more. This is informal, but it's a way to keep pathogens to a minimum.  You're probably serving them to your family, so impressive presentation is not so important.


Of my Thanksgiving leftovers, what could I have frozen for later use?


It's too late now.  If you've still got turkey or stuffing in your fridge, throw it out.  But keep in mind next year that many of the traditional Thanksgiving items can be frozen and used during the winter holiday season. We don't recommend them for next Thanksgiving for quality, not safety, reasons.


Dr. Regenstein says that turkey, if wrapped tightly in a freezer-wrap plastic bag, will "keep for a few months. Stuffing that has been frozen probably won't retain it's original texture, but it is perfectly safe to eat, and the end product can be tasty although texture is off. I would pan fry the stuffing to help drive off the moisture that comes out after defrosting. 


"Cranberry sauce can be frozen, though it might not be as gelled after freezing. Gravy freezes well. If it's in the refrigerator long enough for the fat to rise to the top, remove the fat before freezing. Before reheating, look for molds as a sign of the end of shelf life. After reheating, use the smell test. If it smells okay and looks okay (no mold), taste a very tiny bit to decide if you want to serve it."


Can I reheat leftover beef?


Food process engineer Dr. Timothy Bowser gives reheated beef a qualified yes: "If the food is well-prepared and not thermally abused (left to cool on a counter in an exposed dish), it should be safe to reheat later.


"Reheated meats are susceptible to acquiring a warmed-over flavor (WOF) that is caused by oxidation of fats. Meat with WOF has been described as tasting like cardboard or paint. Preservatives are used to prevent this in processed meats. There are two methods that can be used at home to minimize exposure of cooked meat to oxygen and therefore reduce WOF flavors:  (1) cover meat with gravy or sauce, and/or (2) place the product in vacuum packaging. Spices that contain natural antioxidants (e.g. rosemary, marjoram, sage, thyme, mace, allspice and clove) may also help to reduce WOF in meats."


Dr. Regenstein also expresses concern about WOF: If the WOF is strong, he advises, don't eat it. If it's mild, covering meat with gravy may help to mask the WOF.


Will the remains of shrimp dishes taste okay when reheated?


Dr. Regenstein recommends storing leftover shrimps and shrimp dishes in the bottom back of the fridge to keep them as cold as possible.  Also, handling them with clean hands will help to extend shelf life.  To decide if the dish is worth serving, once again, Dr. Regenstein suggests 3 tests--looking, smelling, and, (if the food  passes the first two tests) tasting a tiny amount. 


What about ethnic carry-out foods such as Chinese, Thai, or Indian--are they safe and tasty to reheat?


Yes, says Dr. Regenstein. "Just be sure the food is fully heated and perhaps refresh the taste with a little soy sauce or other appropriate seasoning."


Food process engineer Dr. Timothy Bowser agrees. "We often save leftovers from carryout Asian food shops to eat at the following meal or the next day. If the food is well-prepared, consumed hot, and the leftovers are immediately refrigerated in a secure package, it should remain good to eat for at least a day or two."


Can I reheat frozen pizza or quiche? 


"You can," says Dr. Regenstein, "but it may dry out. Think in terms of adding extra sauce, some extra seasoning, etc. [Extra cheese wouldn't hurt either.] And be sure to heat it to the recommended temperature, 165°F."


Dr. Bowser is fairly optimistic about reheated pizza even if it's not doctored: "A lot depends on how the product is treated. If it is cooked properly and the leftovers are well packaged and immediately chilled, it should be fine for reheating within a few days. The flavor may not be as good, but it should be safe to consume. My teenage boys (three of them) frequently eat leftover pizza, and the taste doesn’t seem to matter to them." [Teen-age boys are a cook's delight.  If it's food, they'll happily eat it.]  


Can coffee that sits in the coffeemaker overnight be reheated the next morning? Will it taste decent and be safe to drink?


Dr. Regenstein says, "Safe yes. Taste--okay but not great."


Dr. Bowser says, "If it is black, coffee is a poor growth medium for microorganisms. It should be okay to drink when left overnight. If mold is visible, throw it out. Some people prefer the flavor of leftover coffee, but, in my opinion, it is always best to brew a fresh pot."


NOTE: For more information about reheating leftovers, go to this Shelf Life Advice article: "FAQs on Reheating Food: Pizza, Chicken and Everything Else."




Timothy J. Bowser, Ph.D. , Oklahoma State University, Dept. of Biosystems and Agricultural Engineering


Catherine N. Cutter, Ph.D., Pennsylvania State University, Dept. of Food Science


Joe Regenstein, Ph.D., Cornell University, Dept. of Food Science "Food Safety Fact Sheet: Reheating Foods"



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