That bag of popcorn is just the beginning. First sold in 1947, the microwave oven wasn’t a common household item until the late 1960’s. Along with the fridge, conventional oven, blender, and coffeemaker, it is now considered an essential appliance in the American kitchen. But while we all use it to warm up coffee and pop our corn, this countertop contraption remains poorly understood and often underestimated. Microwaves don’t cook food from the inside out—a common myth—and despite the term “nuke,” it’s not nuclear radiation that’s reheating last night’s burrito. What’s more, microwaves can outperform conventional techniques when it comes to vegetables, quick soups, and fried snacks. Put aside the Pop Secret—it’s time to take a deeper look at the humble microwave.
Hot Pocket:
The Microwave’s Humble Beginnings
For the microwave’s invention, thank Percy Spencer’s sweet tooth. The Raytheon engineer was lingering in front of an active microwave radar set when the Mr. Goodbar in his pocket began to melt. Ingredients used in Spencer’s early food-heating experiments include popcorn kernels and an egg (which exploded in a colleague’s face).
The first microwave oven weighed in at 750 pounds, and was five feet, six inches tall. At first, it was only used in restaurants and other places where large quantities of food had to be prepared at once.
WHY IT WORKS
Essentially, microwaves cook food by producing electromagnetic waves that force polarized water molecules within it to oscillate. We experience this atomic-scale movement as increasing temperature. Imagine water molecules as antennae, interacting with the waves in the oven much like a radio antenna does with radio waves. The more water in the food, the more effective it is as an antenna. Plant foods have a high water content relative to most foods—making them very effective antennae indeed.
But it’s important, too, to consider the size of your antennae. In conventional ovens, small foods cook faster than larger ones. It tends to be the opposite with microwaves. A microwave (that is, the wave itself, not the oven) is 12.8 centimeters long. To receive the waves properly, food should be at least a quarter of that length—so about 3.2 centimeters (a little larger than one inch). Think about how an individual popcorn kernel can take minutes to pop. And yet, you can pop an entire bag of popcorn kernels in about 60 seconds. Grouped together, all the kernels form a target mass that can couple with the microwaves and absorb them, similar to how a radio antenna picks up radio waves. The lone kernels are so small (relative to the length of the microwaves) that they can’t easily absorb the waves’ energy, and thus take longer to cook.
From an engineering perspective, the microwave oven is a fairly simple machine, but for one complex and fascinating piece: the magnetron. (Watch this awesome video for more on how magnetrons work. )
See the diagram below to better understand how energy flows from the socket in your kitchen into the food itself.
The All-Important Defrost Button
Ever try to defrost food in your microwave on the “cook” setting? You’ve likely wound up with food that’s partly cooked and partly frozen.
Here’s what happening: Because frozen water has a different atomic structure than liquid, ice is invisible to microwaves. Once part of the food melts, however, the liquid water will start to strongly absorb the waves, causing that portion to cook quickly while areas around it remain frozen. To even things out, the microwave’s defrost function works by turning the magnetron on and off, allowing the frozen parts of the food to “catch up” to the already-cooked parts, thereby encouraging more-even heating.
Is it safe? Is it healthy?
Yes, and yes. Contrary to popular myth, microwave radiation is not related to nuclear radiation whatsoever. As described above, microwave ovens use electromagnetic radiation that occurs at frequencies between 300 MHz and 300 GHz—the same kind of electromagnetic radiation (except at a different wavelength) as visible light and radio waves. It doesn’t make your food radioactive, not even a teensy little bit. And it doesn’t have anything to do with radioactivity or nuclear reactors.
Another popular myth says that microwave ovens destroy all the nutrients in the food. In fact, it’s the opposite—microwaving often preserves more nutrients than other cooking methods. The longer and hotter you cook something, the more nutrients you lose, and with boiling and pressure-cooking, you can lose additional nutrients to surrounding water as well. Microwaves work by exciting the water molecules in your food, which then heat up and cook the surrounding material very quickly, protecting the food from the damage that can be done by time, heat, and cooking water.
MICROWAVING VEGETABLES
When cooking vegetables, it’s of paramount importance to preserve their fresh aromas and vivid colors. The best way to do that is to cook them rapidly. That’s where the microwave comes in: You can cook vegetables perfectly in a microwave, in just a few minutes. How many minutes exactly? That depends on the wattage of your machine, along with the amount and size of the food you are cooking. Through trial and error, we found that in our 1,000-watt microwave, we got the best results by cooking one-inch pieces for 30–45 seconds. Experimenting with your microwave will help determine your own optimal cook times and settings.
This simple technique opens up myriad possibilities for delicious vegetable dishes with a much lower risk of failure. No more limp, weepy asparagus or soft, watery carrots. When you prepare vegetables in the microwave, you can focus on the rest of the dish, instead of just the vegetables themselves.
MICROWAVED SOUPS
From elegant amuses bouches to quintessential comfort dishes, puréed soups are an important component of every cook’s repertoire. What with all the simmering and stirring, however, they can be pretty time-consuming. Because microwaves cook vegetables so quickly—preserving flavor and aroma so well—you can use them to whip up excellent soups far faster than traditional cooking methods allow. Here are two recipes to get you going.
OTHER IDEAS
Looking for more cool stuff to do with that countertop oven? Check out our method for microwaved vegetables confits. Super-simple and mess free, they’ll enhance all sorts of preparations and, as in the case of our Confit Squash Salad, can form the basis of a pretty killer dish as well. Ham fans, meanwhile, will love the way we harness the microwave’s dehydrating abilities to transform silky prosciutto into a crunchy garnish.
Microwaved Vegetable Confit
Quick word association: When you hear “confit,” what’s the first thing that comes to mind? If you said “duck,” you’re not alone—duck leg, salt-cured and slowly cooked in its own fat, is the most common form of confit we encounter in restaurants these days.
Confit is also a great way to make the most of flavor-enhancing alliums such as garlic and cipollini onions. We like to place them in canning jars, cover with a fat such as olive oil, then microwave on low until they take on a tender texture. Use them to flavor soups and salad dressings, spread them over crostini, or mix them into dips.
This technique works for just about any firm, starchy, or sugary vegetable—try potatoes, parsnips, turnips, onion, garlic, squash, carrots, or radish. It won’t work well with fresh green vegetables, and although we love tomato confit, we found that the tomato falls apart when cooked in the microwave. Keep in mind that some vegetables may take longer to cook if you are trying to caramelize them (as with garlic or onions).
For a quick vegetarian dish, try ourMicrowaved Squash Confit, dressed with hazelnut crumble and ricotta salata.
Confit Squash Salad
Don’t get us wrong. Grandma’s baked butternut squash—doused in butter, sprinkled with brown sugar—is great. But there are all sorts of winter squashes on offer at the market these days, and no end to the fun things you can do with them. Among our favorites: kabocha, a generic term for several Japanese varieties characterized by their turban shape and sweet, rich yellow flesh. Best of all, kabocha’s deep green skin softens nicely as it cooks, meaning you can often skip the pesky peeling step.
Here, we rest the kabocha in salt and sugar, then confit it in clarified butter to create an almost fudgelike texture. Smooth, but not too smooth, the squash should push back a little as you bite into it. We give it a hit of lemon juice for brightness, and garnish with toasted hazelnuts, chives, and a flurry of ricotta salata before serving. Feel free to sub in other squashes such as butternut (you know, if Grandma’s coming over), but in that case you’ll need to peel the skin off before you cook.
Got leftover hazelnuts? You can always use them in our sexyMicrowaved Radicchio Salad.
Crispy Prosciutto
Delicate, yet full of deep pork flavor, prosciutto is one of the world’s best-loved foods. Wrapped around melon or dates, spread atop a pizza, or mixed into a quiche, the dry-cured ham delivers a hit of salty sophistication to any dish. We love crisping up a few slices in the microwave then using them as a garnish for our Asparagus, Egg, and Ham dish.
LEARN MORE
Click the image below to enlarge, download, and print our Microwave poster, chock-full of weird and wonderful information about your mysterious countertop contraption.
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