Compared to liquid water, microwave heating is less efficient on fats and sugars (which have a smaller molecular dipole moment).[31] Sugars and triglycerides (fats and oils) absorb microwaves due to the dipole moments of their hydroxyl groups or ester groups. However, due to the lower specific heat capacity of fats and oils and their higher vaporization temperature, they often attain much higher temperatures inside microwave ovens.[30] This can induce temperatures in oil or very fatty foods like bacon far above the boiling point of water, and high enough to induce some browning reactions, much in the manner of conventional broiling (UK: grilling), braising, or deep fat frying. Foods high in water content and with little oil rarely exceed the boiling temperature of water.
In 1945, the heating effect of a high-power microwave beam was accidentally discovered by Percy Spencer, an American self-taught engineer from Howland, Maine. Employed by Raytheon at the time, he noticed that microwaves from an active radar set he was working on started to melt a chocolate bar he had in his pocket. The first food deliberately cooked with Spencer's microwave was popcorn, and the second was an egg, which exploded in the face of one of the experimenters.[10][11] To verify his finding, Spencer created a high density electromagnetic field by feeding microwave power from a magnetron into a metal box from which it had no way to escape. When food was placed in the box with the microwave energy, the temperature of the food rose rapidly. On 8 October 1945, Raytheon filed a United States patent application for Spencer's microwave cooking process, and an oven that heated food using microwave energy from a magnetron was soon placed in a Boston restaurant for testing.[12]
This is a great microwave for power users who want complete control over their cooking — those often frustrated with overcooked leftovers or constantly sticking their finger in to check for cold spots. We didn’t mind spending a little extra time learning the features and extras we came to value, but it could be overkill for the average user looking for a familiar design.

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Microwave ovens are frequently used for reheating leftover food, and bacterial contamination may not be repressed if the safe temperature is not reached, resulting in foodborne illness, as with all inadequate reheating methods. While microwaves can destroy bacteria as well as conventional ovens, they do not cook as evenly, leading to an increased risk that parts of the food will not reach recommended temperatures.[72]
Microwave heating can be deliberately uneven by design. Some microwavable packages (notably pies) may include materials that contain ceramic or aluminium flakes, which are designed to absorb microwaves and heat up, which aids in baking or crust preparation by depositing more energy shallowly in these areas. Such ceramic patches affixed to cardboard are positioned next to the food, and are typically smokey blue or gray in colour, usually making them easily identifiable; the cardboard sleeves included with Hot Pockets, which have a silver surface on the inside, are a good example of such packaging. Microwavable cardboard packaging may also contain overhead ceramic patches which function in the same way. The technical term for such a microwave-absorbing patch is a susceptor.[43]
The second problem is due to food composition and geometry, and must be addressed by the cook, by arranging the food so that it absorbs energy evenly, and periodically testing and shielding any parts of the food that overheat. In some materials with low thermal conductivity, where dielectric constant increases with temperature, microwave heating can cause localized thermal runaway. Under certain conditions, glass can exhibit thermal runaway in a microwave to the point of melting.[41]
Microwave ovens don’t actually deliver heat to a food item the way a conventional oven does (via heated air); they work by using microwave energy to cause the water and other simple molecules in food to rapidly vibrate, which generates internal friction at the molecular level, heating the food from within. That’s why microwave ovens can heat things so quickly, and why they’re so good at steaming vegetables in their own juices—they don’t rely on the slow and uneven process of transferring heat energy from the air, the way a conventional oven does. But the microwaves aren’t delivered evenly, the way heated air in a conventional oven is. That’s why microwave trays rotate: so that, ideally, every section of the food item gets equal treatment. But the world doesn’t operate on ideals, and neither do microwave ovens. Almost inevitably, you’ll get hotter spots near the center of the oven, which may or may not matter depending on the size of the thing you’re microwaving.
The most shocking revelation in all of our research was the fact that among the hundreds of microwaves for sale today, many have completely identical hardware. Like, exactly the same—except for slightly different keypads and brand-name badges. This is because most of the microwaves in the world are produced by only a handful of manufacturers. But we also learned that even if the housing looks exactly the same, the way the models are programmed can still make a big difference in performance between seemingly identical microwaves.

The GE JES2051SNSS was one of the best models we tested at defrosting frozen meat. But at 19.25 by 13.63 by 23.88 inches, we felt it was just too large for most kitchens. Our own experience and user feedback taught us that a smaller microwave is preferable. However, we think this is an excellent choice for someone who has ample counter space and prefers a larger microwave.
If your primary concern is cooking speed, you need a microwave with higher wattage. The unit has to be large enough for your family's needs but not too large to fit in your kitchen. It is desirable to have quick keys, multi-stage cooking, and true variable power. Easy cleaning is a must because, at some point, you will need to wipe up after a cooking job.

A great microwave oven can cook food and heat food. Think: Not just popcorn and leftovers, but steamed veggies, like spaghetti squash, “baked” potatoes, and crispy bacon that’ll rival the cooking results you get from your range — not to mention it’ll do it two to five times faster. Plus, once you learn how to poach eggs in the microwave, you might also finally stop trying to learn how to the old-fashioned way.


This GE microwave oven with a 16-inch turntable proves you don't need to spend a bundle to get perfectly "baked" potatoes, steamed broccoli, or evenly heated mac 'n cheese. Thanks to a smooth control panel with lettering that contrasts well with the background, it's super easy to read the display and wipe it clean. If stainless steel isn't your style, this model also comes in black and white. 
The Toshiba EM131A5C-BS handles all your basic tasks and balances counter space with a roomy capacity. Available in either black or silver stainless steel, this countertop microwave has an interior capacity of 1.2 cubic feet while measuring just over 20 inches wide and 17 inches long. Its 1,100 watts of power can be adjusted with 10 power settings, and customers agree that it cooks food evenly and quickly. The unit also is equipped with sensor cooking and two defrost settings, though some people found that not all of the pre-set cook modes worked as expected and the microwave defrosted too aggressively for some meats. Still, this Toshiba countertop microwave has a solid reputation for being easy to use and reliable.

The defrost options (varying by type or weight) are ideal if you want to warm something up with the microwave before cooking with the convection setting. If you have a busy kitchen and want multiple ways to cook foods (instead of just nuking the occasional popcorn bag), Cuisinart delivers. About the only thing that it’s missing is the ability to set power levels, but with all these other features, that’s a minor quibble to be had.
Microwave ovens come in a variety of styles to fit all your home decor needs. It doesn’t matter if we are talking about otr microwaves or countertop microwaves. Some are black stainless steel, others are shiny stainless steel finish for the modern kitchen. If you have retro decor, there is also a retro microwave for you. Many people prefer a stainless steel exterior. It is easy to find the right model that blends right into your kitchen and matches your, espresso machines, food processors, coffee makers, air fryers and other appliances. Many of today’s models can even work with other smart home devices if your home is a smart home.
The cooking chamber is similar to a Faraday cage to prevent the waves from coming out of the oven. Even though there is no continuous metal-to-metal contact around the rim of the door, choke connections on the door edges act like metal-to-metal contact, at the frequency of the microwaves, to prevent leakage. The oven door usually has a window for easy viewing, with a layer of conductive mesh some distance from the outer panel to maintain the shielding. Because the size of the perforations in the mesh is much less than the microwaves' wavelength (12.2 cm for the usual 2.45 GHz), microwave radiation cannot pass through the door, while visible light (with its much shorter wavelength) can.
You may be a bit limited in your choice of OTR microwaves because you’ll need a model that fits snugly above your stove. Most people also want an appliance that matches their range. And, unfortunately, OTR microwaves are more complicated to install, especially if you haven’t had one before. In these instances, you may need to hire an electrician, which can drive up the overall cost of your new microwave. 
If you really want microwave power levels that function accurately, look for a microwave with an inverter. What is an inverter microwave? Essentially, it uses a different type of microwave production that actually does change the power levels and heating. Set power to 5, and the inverter will make sure heating is at 50%. Other types of microwaves will use a cycling method, where the power is always set to 100% but at level 5 it cycles half as much as at level 10. Inverter technology tends to make power levels much more effective and sensible, but either way it’s important to know what you’re getting into.

The Toshiba EM131A5C-BS handles all your basic tasks and balances counter space with a roomy capacity. Available in either black or silver stainless steel, this countertop microwave has an interior capacity of 1.2 cubic feet while measuring just over 20 inches wide and 17 inches long. Its 1,100 watts of power can be adjusted with 10 power settings, and customers agree that it cooks food evenly and quickly. The unit also is equipped with sensor cooking and two defrost settings, though some people found that not all of the pre-set cook modes worked as expected and the microwave defrosted too aggressively for some meats. Still, this Toshiba countertop microwave has a solid reputation for being easy to use and reliable.
In our experience, sensors and other smart features make microwaves more useful than they’ve been in the past. Technology that can detect the moisture in your food or note the size of what you’re cooking – and making cooking decisions for you based on that data – is almost always worthwhile. Just remember to give those sensor cooking features a try instead of ignoring them! It might make your baked potatoes perfect.
This microwave tells you exactly how long your food is cooking — a feature that seems like a given, but isn’t. When we cooked potatoes in testing, some of the microwaves with moisture sensors would cook for as long as five minutes with a few dots circling around the display, no indication of time. If you’re trying to follow a recipe or keep an eye out for overheating, these displays make it difficult to keep track of time.
Microwaves generated in microwave ovens cease to exist once the electrical power is turned off. They do not remain in the food when the power is turned off, any more than light from an electric lamp remains in the walls and furnishings of a room when the lamp is turned off. They do not make the food or the oven radioactive. Compared to conventional cooking, the nutritional content of some foods may be altered differently, but generally in a positive way by preserving more micronutrients - see above. There is no indication of detrimental health issues associated with microwaved food.[66]
If your primary concern is cooking speed, you need a microwave with higher wattage. The unit has to be large enough for your family's needs but not too large to fit in your kitchen. It is desirable to have quick keys, multi-stage cooking, and true variable power. Easy cleaning is a must because, at some point, you will need to wipe up after a cooking job.
Sir Henry Tizard travelled to the U.S. in late September 1940 to offer the magnetron in exchange for their financial and industrial help (see Tizard Mission).[7] An early 6 kW version, built in England by the General Electric Company Research Laboratories, Wembley, London, was given to the U.S. government in September 1940. The magnetron was later described by American historian James Phinney Baxter III as "[t]he most valuable cargo ever brought to our shores".[9] Contracts were awarded to Raytheon and other companies for mass production of the magnetron.
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