Scientists Crack the Mystery of an Exploding Egg

By Charles Choi | December 6, 2017 12:40 pm

(Credit: Shutterstock)

Scientists had an explosive mystery on their hands. A man suing a restaurant claimed an egg he bit into detonated loudly enough to damage his hearing. Was this a legit complaint, or an attempt to capitalize in a litigation-happy culture?

Well, after a scientific investigation, the man’s story is legit. Although microwave ovens have become a staple appliance in many kitchens, they come with oft-unheeded warnings that certain foods pose risks to people when reheated. Potatoes and eggs are among the most common culprits of potentially dangerous microwaving mishaps.

The research team’s investigation revealed that tiny pockets of water can super-heat inside microwaved eggs, bursting with potentially dire consequences.

When potatoes get heated in microwaves, pressure from steam can build up under potato skins. This can lead potatoes to rupture in sudden, unpredictable ways, said researchers at acoustical consulting firm Charles M. Salter Associates in San Francisco.

The attorney of the insurers of the restaurant that got sued hired the acoustical consultants as expert witnesses to find out more about how eggs behave when microwaved. The man who sued the restaurant claimed he suffered severe burns and hearing damage after a microwaved hard-boiled egg exploded in his mouth. (Many other details of the event, such as the restaurant, city, date and time, remain confidential.)

Since there was little scientific research into whether exploding eggs were loud enough to generate hearing damage, the scientists initially took the unorthodox approach of reviewing YouTube videos where people casually detonated eggs in microwaves. However, because these videos seemed to be more for personal entertainment than for scientific exploration, they did not account for a number of important factors, such as sound levels, internal temperatures, or the various kinds and sizes of eggs.

In experiments, the scientists reheated nearly 100 hard-boiled eggs in carefully controlled conditions. First, the eggs were placed in a water bath and microwaved for three minutes, and the temperature of the water bath was measured both at the middle and end of the heating cycle. The eggs were then removed from the water bath, placed on the floor and pierced with a fast-acting meat thermometer to induce an explosion.

About a third of the reheated eggs exploded outside the oven. For those eggs that did explode, their peak sound pressure levels ranged from 86 to 133 decibels at a distance of 12 inches.

“I would guess that the sound pressure level at the ear of an individual would be 10 decibels higher. A single event such as this would not cause hearing damage, in my opinion,” said acoustical consultant Tony Nash at Charles M. Salter Associates. He noted the U.S. Defense Department had data as to what levels of sound pressure “can lead to hearing damage risk.”

The scientists found the yolks were consistently hotter than the surrounding water baths. This likely means that yolks absorb more microwave radiation than pure water.

The researchers suggested that microwaved egg yolks can develop many small pockets of superheated water much hotter than water’s normal boiling temperature. When this unstable water gets disturbed — say, when the egg is bitten into — it can boil very rapidly. “The release of steam can be explosive,” Nash said. Nash and his colleague Lauren von Blohn detailed their findings Dec. 6 at the annual meeting of the Acoustical Society of America in New Orleans, Louisiana.

The case was ultimately settled out of court. The researchers suggested their restaurant acoustics experiments should underscore the fact that “heating certain foods in a microwave oven can be dangerous,” Nash said.

Perhaps even eggs-tremely dangerous.

CATEGORIZED UNDER: Space & Physics, top posts
MORE ABOUT: physics
  • Uncle Al

    Boiling and freezing require a nucleation center, a flaw in the continuum from which the phase transition initiates. Bottled water is particle-free in an exceptionally smooth blown container. Gently put it in the freezer and wait. It supercools to metastable -10 °C and lower. Carefully remove it, then tap on a table. Given water’s large enthalpy of fusion, 79.72 cal/g, does it overshoot 0 °C? Youtubev=Fot3m7kyLn4

    Viscous and jelled systems are often reluctant to iniitate.

  • darryl

    I would be eggstremely upset if there was no egg related pun in this article.


    • jamaicajoe


  • HaroldT

    Were these eggs with or without shells?

  • DaveK

    I’d call BS on this. The only conceivable way an egg could “explode” when bitten into would be if it was still in its unbroken shell.

    Who on earth bites into an egg with the shell still on it? Sheesh!

    • MadMac

      You would lose. Neither the shell nor the membrane, between the shell and the white, need be intact.

      Many years ago, I decided I wanted to use a microwave to make a hard boiled egg to chop up for a tuna salad sandwich. “Rationalizing” if I put it in water, I should be able to do it without the egg exploding, since the water should serve as a sort of heat sink by boiling before the egg got too hot inside.
      i cooked the egg, using a less than maximum level as an extra precaution, for about 5 or so minutes with no boom, but halfway expecting one at any second.

      Pleased with myself that nothing went wrong, I did a quick (very quick) quench under running water to make pealing it easier and pealed the egg, did another quick rinse to be sure no shell bits remained, then opened my chopper jar and dropped the egg in. BOOM! Instant egg on the ceiling and a VERY surprised me!

      Yeah, even after being handled during a couple of quick rinses, cracked and pealed, the egg ended up exploding when I dropped it about 4-5 inches into a jar with a plastic disk in the bottom…….when I thought there was no longer any possible way for it to explode.

      Source of the explosion had to be the yolk, the shell and the membrane had been fully removed.

      • David Sigetich

        You mean “peeled.” When large bells are rung they peal.

        • nik

          Ding Dong!

      • jamaicajoe

        What happens is so that the heated liquid inside stays superheated and just below boiling point while the outer part of the egg is intact. As soon as it is opened to the lower ambient pressure outside it superheats and expands violently. This is why you never remove a radiator cap from a hot engine, the pressure inside lowers the boiling point. The devil is in the details.

        • JR

          raises the boiling point I think !

    • Jakejd

      Madmac is right. The most common circumstance in which eggs explode coming out of the microwave is when they’ve been reheated. This is dangerous with or without the shell. Try it for yourself – book an egg, let it cool, then peel it and put it in the microwave. Time how long it takes for it to explode. But be prepared for a mess. (Maybe do it at a friend’s house, when they aren’t home).

      The sound is awesome. A little egg packs a series pow.

  • Jenny H

    Why would you flipping microwave an egg?

    • (((chimera: #resist#persist)))

      The guy (who sued the restaurant) probably asked for his boiled egg to be hot. The place most likely already had boiled eggs cooked and kept in the fridge. So they got one out and did what any self-respecting yet unthinking 21st-Century dweller would do — popped it in the microwave for a minute rather than a hot water bath for 5.

  • StanChaz

    So when are “we” weaponizing them?
    They used to be dreaded Halloween projectiles…

  • nik

    I microwave raw eggs in a small open pot, rather like poaching, but, BIG but, its necessary to use minimum power, and time it very carefully, which can be difficult as it depends on the size of the yolk, which can vary, even in eggs of the same nominal size.
    Get it wrong, and BANG!
    Then I have to spend 10-20 mins cleaning scrambled egg plastered around the whole of the inside of the microwave.
    Another way to get an eruption, is to boil water or milk in a mug, with a microwave, take it out, and pop in a teaspoon of instant coffee powder, but only if you enjoy cleaning up the resultant mess, that will erupt out of the mug!

  • bwana

    Last line… Boo!


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