Review: Panasonic Japanese Microwave

I am a mistrustful user of microwaves. I worry they will overcook my food to rubber—and so I continually set my cook times too short and have to start over. I hover protectively, waiting for popcorn to burn, or eggs and butter to explode. I turn convenience into anxiety.

And so it is no small thing when I say that Panasonic's month-old Japanese Microwave (officially denoted by the less endearing moniker of NN-SF57RM) is the first microwave I'm willing to trust enough to walk away from. Rather than add “smart features” like other new-gen microwaves, this microwave is actually kinda smart. Without Wi-Fi, no less.

What distinguishes this oven is simple: I don't have to enter a cook time at all. Rather than leave me to guess, this wee 1-cubic-foot Panasonic uses a multi-point “Genius 2.0” temperature sensor to directly measure the surface temperature of my food every tenth of a second. A mobile antenna underneath the cooking chamber directs energy to where it's needed, which means no rotating turntable is needed. The microwave stops when your food's hot enough to eat.

Without a turntable taking up space and limiting the dish's width, a cubic foot ends up being quite spacious without a large countertop footprint. And its pull-down door, in its way, is a bit cute. But the actual innovation comes in how the oven cooks.

Panasonic's advanced cooking recipes for spaghetti Bolognese are less than intuitive and frankly unnecessary. And the sensor has to be able to “see” your food to measure temperature, which means layered bowls may not heat as evenly.

But for the all-important microwave trinity of reheating leftovers, melting butter, and popping popcorn? This might be the best microwave I've used. I've thrown in frozen TV dinners, yesterday's chicken soup or bowl of rice, goat curry leftovers, and a single pork dumpling. Each cooks to about 180 degrees Fahrenheit, piping but not painfully hot.

Real Genius?

The Japanese Oven has a distinct look, in part because it eschews the usual keypad. There are a few separate buttons for popcorn, defrost, and “beverage.” But for probably 90 percent of the cooks you're likely to do in this microwave, the only thing you need to do is press a single button. Namely, the glowing button-dial on the right-hand side of the microwave labeled Sensor Reheat.

Press the dial and the microwave's display, instead of a timer, will show the equivalent of a loading bar. As the food nears its final temperature, the loading bar will fill up until the food is done—with surprisingly successful results using frozen ready-to-heat dinners and the usual battery of leftovers, whether spaghetti and meatballs or plates of Indonesian rice.

Sensor-controlled cooking is hardly new to microwaves, of course. Any number of microwaves in recent decades, from Breville to Maytag to the previous-generation Panasonic Genius ovens, use humidity sensors to monitor the amount of steam released from food, then adjust power and cook time accordingly.

The most obvious shortcoming with steam sensors is, of course, portion size. If you're nuking small portions of food, it might take a long time to release enough steam to trigger the microwave cutoff. Steam sensors also won't detect if food is heating unevenly.

But this oven's Genius 2.0 sensor works in a fundamentally different manner. An infrared sensor at the top right of the microwave's interior scans for food temperature at 64 locations across the oven. If your pork chop is hot but your green beans are cold, according to Panasonic's engineers, a hidden microwave antenna underneath the microwave will move to direct more heat to the green beans.

Even Flow

The microwave's hidden mobile antenna has the welcome side effect that the usual clattering microwave turntable is unnecessary. In most microwaves, your food must rotate through hot spots and cold spots to heat evenly. In this one, the antenna moves so the food doesn't have to, and so the interior of the microwave is clean and open for business.

Photograph: Matthew Korfhage

According to Panasonic, this also ensures an even cook all the way across the oven, from edge to center. So of course I tested this claim a little more precisely. I laid out an even, single layer of marshmallows and noted the pattern of marshmallow melt—then used an infrared thermometer to verify surface temperature. I then used damp thermal paper, which changes color when it reaches a prescribed temperature, to register how heat moved across the oven.

The results were better than I expected. For cooks longer than a minute, the temperature across the surface of the marshmallows evened out to within about 5 degrees Fahrenheit across the microwave's central cooking area.

Only the front of the oven nearest the door, and about an inch from each side wall, cooked a little cooler—about 20 degrees cooler. This is still an impressive result, especially compared to turntable models that don't even let you use most of the space in your microwave.

Just note that with the sensor cook, you can't cover your food and get the same results. It will interfere with how the microwave senses temperature; i.e., resist the temptation to cover your food unless you're using the basic timed-cook functions, which also exist. I did in fact manage to nuke an egg this way without it exploding all over the oven, but the cautious might still cover their egg and cook in controlled time increments.

The other Achilles heel for the oven's temperature sensors is a multi-layered bowl of food. When I reheated a Korean rice bowl layering short ribs atop cabbage and rice, the cabbage did not cook as hot as the meat or the rice, and I had to mix it in a little and reheat. This is, of course, what I'd expect to happen in nearly every other microwave. But it's worth noting that this oven only feels magical on flat platters.

Functions and More Functions

Simplicity is the key to this microwave, and it's why I like it: I don't have to watch it or worry about it. With few exceptions, the oven's main sensor reheat function will heat my food reliably and evenly to 180 degrees Fahrenheit (or less if I set the heat to any of five lower settings). I am willing to cede this as genius.

But the other main functions also mostly work pretty well. The Beverage button will heat a mug of whatever liquid to about 170 degrees Fahrenheit, the hottest I'd want my coffee or tea. Defrost was able to de-ice a frozen chicken breast in 10 minutes, while barely warming any part of the meat beyond room temperature. (I also needed to rest the chicken breast five minutes, per instructions, to let the heat even out.)

The popcorn setting is essentially a timer, since the infrared sensors can't see through a popcorn bag: Set the weight of your microwave popcorn bag, then let it go. With a bag from Kroger, my results were perfectly acceptable: no burnt popcorn, and a few dozen unpopped kernels at the bottom of the bag. Trying to follow the popcorn maker's instructions, waiting till there were multiple seconds between pops on a high-powered microwave, was dang near a fire hazard. I'll take the Popcorn button.

Classic timed microwave cooks are available, and so is upping or lowering the microwave's power manually. Somewhat idiosyncratically for the American market, Panasonic also added a battery of preprogrammed microwave scratch-cooking recipes, whether one-bowl chicken noodle soup or spaghetti Bolognese with the meat cooked from raw. Scratch microwave cooking is more common in Japan, where kitchens are small—and ostensibly, these functions also showcase the microwave's ability to modulate its power settings for precise cooks. But the microwave recipes still felt like a time capsule from the 1980s.

Photograph: Matthew Korfhage

And yet? The mac and cheese was far better than expected, with a decent velvety roux and only a few dry macaroni. Chicken noodle soup was perfectly fine, as well. But the spaghetti Bolognese was an unholy mess: The meat was rubbery and unseasoned, and the microwaved garlic took on overpowering acridity. Somehow it managed to be bland and still burn my sinuses. None of the programmed recipes were easier to cook than on a stovetop, with a pot.

But while the culinary ambitions might be foolhardy, they're not a major flaw—just something to ignore. I never wanted to make scratch Bolognese in a microwave, and I won't start now. The only recipe functions you'll use are numbers 10 and 11: melt butter, and melt chocolate. I wish they were 1 and 2.

Here, again, the sensor is your friend. The butter heated to meltiness but stopped short of the temp at which it would explode all over the oven. (My editor sent me the messy results of trying the same on her home microwave from KitchenAid.) I did have to mix the butter a bit with a spoon afterward, according to Panasonic's instructions, since a little unmelted mass was left over.

Weird scratch-cooking attempts aside, this Panasonic does everything I want a microwave to do, looks somewhat personable while doing it, and requires almost no thought from me to use. Its durability has yet to be proven. But until further notice, it's my new favorite microwave.

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