Why you should never microwave boiled eggs

A hard-boiled egg reheated in the microwave can explode so violently it damages your hearing, researchers have found. 

The discovery was made after scientists were asked to serve as expert witnesses for a case involving damage allegedly caused by a hard-boiled egg. 

The shelled hard-boiled egg had been reheated in a microwave and apparently exploded in a restaurant customer’s mouth, causing burns and possibly hearing damage. 

The case was settled out of court but in the meantime 100 eggs were boiled in a microwave to see what damage they could do.

Experts found the explosion can be as loud as listening to a jet plane from 100 feet (30m) away – and it seems superheated water is to blame. 

A hard boiled egg reheated in the microwave can explode so violently it damages your hearing, researchers have found (stock image)

WHAT DID THEY DO?

Because there was little scientific literature on the subject, the investigators initially took an unorthodox approach by reviewing YouTube’s collection of microwave explosions.

Researchers took a more scientific approach and controlled a number of important variables such as sound levels or internal temperatures and the kind and size of egg.

First, selected hard-boiled eggs were placed in a water bath and heated for three minutes. 

Secondly, the temperature of the water bath was then measured both at the middle and end of the heating cycle.

Finally, the eggs were removed from the water bath, placed on the floor and pierced with a fast-acting meat thermometer to induce an explosion.

Potatoes and hard-boiled eggs are among the most common culprits of potentially dangerous explosions.

While both potatoes and eggs might explode, their mechanisms of bursting are different.

Anthony Nash and Lauren von Blohn, sound engineers from San Francisco-based firm Charles M. Salter Associates, explored the mechanism of exploding eggs as part of expert witness testimony.

‘We needed to quantify the peak sound pressures from an exploding egg so we could compare it to hearing damage risk criteria,’ said Dr Nash. 

They found that at one foot away, the peak sound pressure levels from microwaved eggs covered a wide range from 86 up to 133 decibels.

This is about the same as the sound of a motorcycle running 30 feet (9.1 meters) away to the sound of a jet plane 100 feet (30 m) away, respectively, writes Live Science. 

Although this is more noise than you’d want to subject yourself to for a long period of time it has a ‘low probability’ of causing damage, the researchers wrote.

‘On a statistical basis, the likelihood of an egg exploding and damaging someone’s hearing is quite remote. It’s a little bit like playing egg roulette’, said Dr Nash. 

One in three of the tested eggs survived the microwave heating cycle and then exploded when pierced by a sharp object.

Because there was little scientific literature on the subject, the investigators initially took an unorthodox approach by reviewing YouTube’s collection of microwave explosions.  

The case was settled out of court but in the meantime 100 eggs were boiled in a microwave to work out whether the bang really could harm a diner's ears (stock image)

The case was settled out of court but in the meantime 100 eggs were boiled in a microwave to work out whether the bang really could harm a diner’s ears (stock image)

WHY DO EGGS EXPLODE?

Experts believe the egg yolk is more receptive to microwave radiation than is pure water (water constitutes about half the weight of an egg yolk).

The duo hypothesized that the egg’s protein matrix traps small pockets of water within the yolk, causing the pockets to superheat well above the nominal boiling temperature of ordinary tap water.

When these superheated pockets are disturbed by a penetrating device, or if one attempts to bite into the egg yolk, the water pockets all boil in a furious chain reaction leading to an explosion-like phenomenon.

‘Those experiments had been done by non-scientists who were casually detonating eggs in a microwave,’ said Dr Nash.

Dr Nash and Dr von Blohn took a more scientific approach and controlled a number of important variables such as sound levels or internal temperatures and the kind and size of egg.

First, selected hard-boiled eggs were placed in a water bath and heated for three minutes. 

Second, the temperature of the water bath was then measured both at the middle and end of the heating cycle.

Finally, the eggs were removed from the water bath, placed on the floor and pierced with a fast-acting meat thermometer to induce an explosion.

‘For both the exploded eggs and eggs that didn’t explode, we would probe the inside of the yolk with the thermometer,’ said Dr Nash.

‘We discovered that the yolk’s temperature was consistently higher than the surrounding water bath.’

The implication is that the egg yolk is more receptive to microwave radiation than is pure water (water constitutes about half the weight of an egg yolk).

The duo believe the egg’s protein matrix traps small pockets of water within the yolk, causing the pockets to superheat well above the nominal boiling temperature of ordinary tap water.

When these superheated pockets are disturbed by a penetrating device, or if one attempts to bite into the egg yolk, the water pockets all boil in a furious chain reaction leading to an explosion-like phenomenon.

Dr Nash and Dr von Blohn will present their research on the sound pressures generated by exploding eggs at the 174th Meeting of the Acoustical Society of America in New Orleans, Louisiana. 

 



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