Just in case: The best way to reheat pizza

Take a good look at it. It won’t look half as good in the morning.
Brent Hofacker via Depositphotos

Order pizza, and there’s a good chance it’s gone within hours. Something about that round wheel of dough, melted cheese, warm tomato sauce, and seemingly countless topping possibilities is simply irresistible. If only pizza would stay that way forever.

Still, it’s hard to resist the temptation of a leftover slice as you rummage through the fridge for food the next day. Maybe you like cold pizza—there’s no shame in that—but if you’re looking to restore some of that fresh-pizza magic by reheating that ‘za, you’ll need to know what you’re doing.

So, Popular Science’s DIY team tracked down the most popular strategies, bought a whole lot of pizza, and put them to the test. We sought the ultimate method—The Way.

But first—decay, staling, and death

The very moment pizza is born out of the oven, it’s too hot to eat and might not even be done cooking. But right around 140 degrees Fahrenheit—the temperature experts recommend you dig in so you don’t burn your mouth—it begins its inevitable march toward complete decay, just like everything else on Earth.

If you can’t (or won’t) eat your pizza when it’s fresh, all you’ll be able to do later is damage control. You see, cheese only likes to be melted once, because when it does, it loses its integrity. When exposed to high temperatures, cheese loses fat and water, and there’s just no way to get it back.

“That water isn’t going up,” says bread and pizza expert Francisco Migoya, head chef at Modernist Cuisine. “The dough is like a sponge, so it’s just going to absorb it all, making it soggier and gummier as time goes by.”

At this point, the moisture from the sauce and water, plus the fat from the cheese (and any meat), starts seeping into the crust, creating what pizza connoisseurs know as “the gum line”—that layer between the sauce and crust that looks like raw dough. The thicker the pizza, the more pronounced the gum line will be, and the longer it sits there uneaten, the thicker it will get. This, Migoya says, changes the crust permanently.

You should never leave pizza out on the counter or in the oven overnight (because of bacteria), but putting it in the fridge doesn’t do it any favors. Low temperatures congeal everything the dough has absorbed and accelerate the staling process, or retrogradation. In short: The starch in the crust recrystallizes, and all that fresh-pizza chewiness goes out the window.

How we did it

PopSci is based in New York City, so we tested each method with the thin-crust style of pizza the Big Apple is famous for. If you’re reheating Chicago-style deep-dish pizza or another variety, your results may vary.

The slices we used (both plain cheese and topped with pepperoni) spent 12 to 48 hours in the fridge. Reheating frozen pizza is a whole other ballgame, and we can’t speak to that here.

Let the games begin.The official reheating method of the /r/pizza subreddit, this calls for placing your cold pizza on a non-stick pan and cooking it for two minutes over medium-low heat (or until the bottom of the slice is crispy). Then, pour two drops of water (less than a teaspoon) into the pan as far from the pizza as you can get. Cover the pan with a lid and turn the heat to low. Cook it for another minute.

The results

You may be tempted to try this with a cast-iron pan, but we found a standard non-stick pan worked best. The crust was crispy, the cheese (thanks to the steam from the water circulating under the lid) melted perfectly, and the slice was the perfect temperature to be eaten immediately.

Using a cast-iron pan, however, amplifies a number of factors you may not want to deal with while heating up a quick bite. Depending on your stove, it may take what feels like forever to warm the thick metal pan. And if it’s not properly seasoned, tossing a cold slice onto hot, dry iron is a recipe for burned crust (more on that later). Even if you get the pan hot with a thin sheen of oil, the crust will become extremely crispy before the cheese has much of a chance to melt.

Hot tray in a hot oven

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