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I would like to know why it is not recommended to put an egg in the microwave. Where does this "legend" comes from ?

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    A whole egg? That would make a mess. Microwaved scrambled eggs are OK in a pinch. – Jolenealaska Dec 16 '15 at 10:35
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    The "legend" comes from everyone who has had to clean the microwave afterwards. It is actually fine to PUT an egg in a microwave, just don't turn it on. – user23614 Dec 16 '15 at 10:48
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    With all due respect, have you actually tried? Why do you think it's a "legend"? What did the "legend" say about what would happen? – Mr Lister Dec 16 '15 at 12:46
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    "Legend"? It's a very documented and easily repeatable procedure. Microwave Eggs cooked in their shells will explode! – MonkeyZeus Dec 16 '15 at 13:57
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    For what it's worth, we make "fried eggs" for egg sandwiches in the microwave by cracking an egg and pouring it onto a small plate with non-stick cooking spray. Then cover with a paper towel and microwave. It does pop and splatter, but the paper towel catches that, and you have a cooked egg very quickly. – JPhi1618 Dec 17 '15 at 14:29
41

This probably refers to whole eggs mostly...

A microwave can boil water very rapidly, and a tight but fragile container like a whole egg will violently rupture if such rapid boiling happens inside it, because the overpressure inside it is already significant when the shell finally breaks.

Here is a video showing an experiment with ca. 180 eggs in a microwave oven, which after a minute or two rupture simultaneously and with enough force to blow the oven open, with debris being propelled several meters.

  • I took a boiled egg out too soon once, and split it in half, discovered my mistake and put the halves into the microwave for a few seconds, a pop, not a big bang, but quite messy – PatFromCanada Dec 16 '15 at 21:31
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    Thanks. My life wouldn't have been complete without seeing that video this morning. – gloomy.penguin Dec 17 '15 at 16:19
23

As someone who tried this out at a young age, I thoroughly DO recommend it! The microwave makes a huge bang and jumps 2 inches off the bench. Good times! (However, you need to do some heavy duty cleaning before mum gets home.)

However, by breaking another rule, you can boil an egg in a microwave.

Steps:

  • 2/3 fill a coffee cup with boiling water.
  • Wrap an egg in aluminium foil.
  • Place wrapped egg in cup. Ensure the water covers all the aluminium foil.
  • Microwave for 4 - 5 minutes.

There may be some overflow from boiled water in the microwave if your coffee cup isn't big enough. A paper towel under the cup will take care of that.

The foil prevents the microwaves exploding the egg, however the water surrounding the foil prevents the arcing that normally happens with metal in the microwave.

A great snack for office workers.

  • 16
    2 wrongs to make a right, brilliant! – CaptainCodeman Dec 16 '15 at 17:55
  • My microwave manual says not to use aluminum foil, so I've done this using plastic wrap, with good results. I do use half power, as others have mentioned. I've also only done it a very few times, so perhaps I just got lucky! – Sue Saddest Farewell TGO GL Dec 16 '15 at 18:30
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    Really? Plastic wrap should be the same as no wrap, ie, the egg should explode - though the explosion may be contained within the wrapping. I did mention that you have to break another (microwave) rule. – mcalex Dec 16 '15 at 18:34
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    I'd bet the egg doesn't explode because the liquid water outside keeps it cooler. – john3103 Dec 16 '15 at 18:53
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    Even if you don't use any foil, the water will still absorb most of the microwaves, and the small fraction that reaches the egg directly probably isn't enough to heat it so rapidly that it would explode. Still, there may be some risk of explosion, especially if you use a small cup and a high-power microwave oven, so the foil method might be slightly safer. – Ilmari Karonen Dec 16 '15 at 21:54
13

A simple undamaged raw egg in a microwave at full power will explode. Unless you have a deep desire to thoroughly scrub your microwave I can not recommend that approach.

The problem is that the egg will be heated to more than 100C, that means the water will start to vaporize and steam has the nasty habit of needing way more room than liquid, and you get a pressurized egg or an "egg-bomb". An egg's shell is a quite robust construction, especially where pressure from the outer side is concerned. Nevertheless, at one point the shell will burst and the egg "explodes".

So how to prevent this?

  1. Method:
    Avoid steam. If you heat the egg very, very gently, i.e. in short bursts witl low energy, you might keep the interior pressure low enough.
    Frankly, if I have a pot and a stove, I'd go that route any time, especially as I can limit the inner temperature better. As boiling water doesn't exceed 100C, the egg will always stay below that, meaning no steam is created.
  2. Method:
    Avoid the build-up of pressure. If you crack the shell and transfer the egg to a bowl, you can easily boil it or make microwave scrambeled eggs etc.
  • 1
    I have had scrambled eggs explode, too. But if you add water, that prevents buildup of high heat - poaching in a microwave works. – Kevin Keane Dec 17 '15 at 4:55
2

Delia Smith recommends using a pin to prick a small hole in the wide end of the egg, where the air bubble is. That way the steam escapes from the shell avoiding a pressure build up. This has always worked for me when water boiling an egg and the shell never cracks.

This might work in the microwave too. It would be an interesting experiment to match the hole size to the rate of steam production, to the power output of the oven. Is that over sciencing the egg making process?

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    I don't think this will work in a microwave. The explosion happens when the egg is hard boiled, not when it is still soft. In fact, I had a hard-boiled egg completely without shell explode, so simply puncturing the shell is not going to do much. – Kevin Keane Dec 17 '15 at 4:52
  • The air bubble doesn't contribute to explosion. It is the water (88% of egg white) which does the job. – user58697 Dec 17 '15 at 22:03
2

In addition to the excellent answers you already got, there are a few more issues:

  • Microwaving cooks inside out. As a result, the yolk will cook first (or at least at the same time as the white).

  • Some late-night-TV gadgets promise to let you cook omlettes in the microwave. In reality, the eggs will still explode, even after scrambling, but the mess is contained in the gadget. The other issue is that you end up with bits of egg superglued to the plastic.

There is a way to cook eggs in a microwave that has worked safely for me: poaching. Fill a bowl with water, and crack a couple eggs into the water. Cook for three to five minutes. Remove with a slotted spoon. The eggs will not be as nice as stove-poached eggs, because the yolk will be hard-boiled, but other than that, the eggs always turn out nice.

The real problem with the egg occurs after it is already hard-boiled.

When you buy a package of hard-boiled eggs from the refrigerated section in some grocery stores, those come with a warning "do not microwave". That is a mstake you only make once...

When you heat a hard-boild egg in the microwave, it will turn out nice and hot - and then explode in your face and burn your lip when you bite into it.

Cutting the egg in half does not help - the yolk will explode and jump right out of the half egg and evenly distribute in the microwave.

I don't know exactly why all this happens. My best guess is that there are two separate processes at work. First, the yolk gets heated faster than the white. It tries to expand, but instead builds up pressure. Secondly, even in a hard-boiled egg, there probably is enough residual water to create quite a bit of steam. Worse: the boiled egg white, as well as the egg yolk are fairly gas tight, so the steam is trapped in lots of pockets in the yolk.

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    Microwaves do not cook inside out. ( todayifoundout.com/index.php/2010/10/… ) What could be happening is, that the yolk, with it's higher fat content, reaches higher temperatures faster. – TheSexyMenhir Dec 17 '15 at 6:50
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    I remember reading that the white of an egg cooks (goes firm) at a lower temperature than the yolk. If I remember rightly, if you can "boil" an egg at a constant temperature of around 70-75 degrees C, the white will cook through and the yolk remains soft, no matter how long you continue to cook for. So if you use alcohol instead of water to boil your eggs in, you don't have to worry about timing. But you do have to worry about setting your kitchen on fire or the house exploding if the alcohol vapours catch light, Might be a tad harder to clean up than egg in microwave. – AdamV Dec 17 '15 at 13:29
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    @AdamV, I think your temperatures are slightly high. When sous viding eggs, people generally go for 65 to 67 ºC. – Peter Taylor Dec 17 '15 at 14:38
  • @AdamV I think the technique you describe is called Sous Vide, and works with water just as well as with alcohol - the trick is to keep it at the exact constant temperature. That's basically what Sous Vide machines do. You can also use it to cook steaks to perfection, for instance. Set the temperature to the one for rare or well done or whatever you need, cook the steak as long as you want. When ready to serve, throw it in a hot pan to sear a very thin layer of the outside crust for the nice brown crisp. – Kevin Keane Dec 25 '15 at 20:34

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