Due to safety issues, yes, but mostly because they just taste terrible reheated.

By Zee Krstic
Updated February 19, 2019
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Some things are just not meant to be saved and reheated, which is a lesson I unfortunately learned first hand.

I was vacationing in New England when I decided to put a plate of linguini and freshly steamed mussels (in a heavy cream sauce, no less) into a doggie bag for lunch the next day. If you're anything like me, throwing out a plate of food really hurts your soul.

But when I reheated it in one of my plastic lunch containers the next day, I immediately noticed the taste profile had been thrown way out of whack—unwilling to give up, I powered through rubbery bites… only to run for the bathroom throughout the rest of the afternoon.

My bad experience aside, it turns out there are a few reasons why you should never save certain dishes, whether it's something you've ordered at a restaurant, or (even worse) something you've made at home.

First and foremost, there are a few safety issues with keeping some kinds of leftover food for a prolonged period of time—especially if they're one of the perishable item on this "danger" list provided by the Centers for Disease Control and Prevention. But any leftovers can turn dangerous if they're left in your fridge for too long or if your fridge isn't kept below 40°F.

Donald W. Schaffner, PhD, is a specialist in food science and a distinguished professor at Rutgers University's School of Environmental and Biological Sciences. He says there are a few things you can do to prevent food spoilage—including keeping your car cool in the hot summer months—but his first tip for handling delicate leftovers has to do with a common household gadget you may already own.

"My tip is to purchase a home fridge thermometer and check your fridge temperature in several spots regularly," Dr. Schaffner told Cooking Light. "For best safety and quality, the fridge temp should be as cold as possible without freezing delicate items."

There are two main concerns for highly perishable foods that are kept in the fridge for too long, Schaffner said—Yersinia enterocolitica, which is rare, and Listeria monocytogenes, which is the most common. Listeria can be found in many common items, including cold smoked fish, deli meats, and soft cheeses, especially if they've been made with raw milk. This also applies to dishes that have been made with these ingredients as well.

More food safety tips:

But Dr. Schaffner made one thing clear—when it comes to health and safety concerns, there isn't a "valid food safety reason to avoid reheating and re-serving."

"As long as the food was promptly refrigerated, and its time in the refrigerator was not excessive, and the food was properly reheated, any food would be safe to consume," Schaffner said.

The issue, he says, is with quality—there are foods that taste delicious when first served, but become truly inedible when reheated (especially in the microwave).

I consulted two of our Cooking Light test kitchen experts, Julia Levy and Robin Bashinsky, to see which foods they wouldn't want to give a second pass at the dinner table. Here are the 8 foods you should never reheat—and why:

1) Risotto

Jennifer Causey

Levy says any kind of cream-based sauce can quickly sour in the fridge, and the consistency of risotto becomes "glue like" after sitting in a refrigerator for days. This is especially true for seafood-based risotto dishes, which can also become a breeding ground for risky bacteria.

2) Fried Foods

Victor Protasio

Bashinsky calls french fries the "cosmic void" of leftover potatoes, because spuds usually hold up well as leftovers. But nearly any food that's been battered and deep-fried take on a new texture after sitting in your fridge—and become super dry when reheated, as well.

3) Clams

Getty: Jay's photo

Most shellfish should really be eaten immediately after being cooked, Levy says (with one exception: shrimp, which can definitely be repurposed successfully). But like fresh mussels, clams are simply "horrifically inedible" after being nuked in the microwave. Levy says they can also introduce an off-putting scent into of whatever they've been cooked in—like a casserole, for example.

4) White Fish

Jennifer Causey

If you've cooked a white fish filet all the way through (which you should), then Levy says it'll become increasingly tough to repurpose afterwards. A microwave will bring a rubbery element to something that was once flaky and delicate.

5) Cremé Brulee

Jennifer Causey

This is a classic example of a baked dessert that actually really doesn't hold up well in the fridge, Bashinsky says. Anything with a "crunchy" or "textured" top—think Baked Alaska or any meringue—will not be the same after days of sitting in cool, moist air. Try one of these make-ahead desserts instead.

6) Eggs

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While eggs can certainly be made in advance, reheating them in the microwave is risky because they need to reach an internal temperature of 165 degrees before being served, according to the Food and Drug Administration. If you must save leftover eggs, you're better off reheating them via the stovetop—but don't reheat eggs that have been left out on the counter for more than two hours, the FDA says. That's because listeria can develop quickly at warm temperatures, and pose a critical risk at anything above 90° F.

7) Mushrooms

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Bashinsky says mushrooms can quickly turn from delightful to straight gross in a matter of 24 hours, and that's because the proteins in this delicate veggie can deteriorate rather quickly.

8) Spinach, Beets, and Celery

Adobe: Christine Han Photography/Stocksy

This trio of ingredients are some of the healthiest on this list—but also the most dangerous. According to the CDC, heat can cause these veggies to actually release carcinogens when they're being reheated for a second time. Bashinsky says it's best to prepare these again fresh and then re-introduce them into leftovers for the second time around, if you must.

For more tips and expertise on how to keep leftovers safe, Dr. Schaffner recommends downloading the USDA FoodKeeper app, which is free to anyone right here.