What happens when an egg is boiled for 6 hours?
I am a boiled egg fanatic. Achieving a perfectly boiled egg is an exact science, and precise timing is essential. I hover over the egg as it boils like a vigilante armed with a timer in hand.
If making the “perfect boiled egg” takes so much precision, I wondered, “what if I just let the egg boil forever?” Would the eggshell disintegrate? How hard would the egg become? Would it become putrid? Curiosity got the best of me.
From 10:15 AM to 3:00 PM, my boiling egg looked as ordinary and unassuming as any other boiled egg.
Egg at 11:44 AM
However, tragedy struck in the 6th hour! Bored by the monotony of boiling an egg for the last 5 hours, I left the kitchen to exercise. Big mistake. When I checked back at 4:00 PM, here is what I saw.
4:00 PM. Ah! All the water had boiled away and the egg had exploded while I was gone!
Despite this premature end to the experiment caused by the complete evaporation of water, I moved straight to the analysis phase.
The egg exploded. When all the water in the pot evaporated, heat conducted directly from the metal pot to the egg rather than from the water to the egg. Metal can get much hotter than boiling water, which is stunted at its boiling point, 100 C. Because of the high dry heat, pressure building inside the egg overcame the fragile shell. Thus, an explosion!
The egg whites were rubbery.
As the egg is cooked, heat disrupts the chemical bonds holding the clumped egg white proteins together. This process is called denaturation, and the unraveling strings of proteins become tangled with each other. The proteins continue to denature and tangle more tightly, creating a rubbery texture.
The egg whites were tan in color.
This is the result of the Maillard reaction, which is responsible for the browning of food. In other words, the heat encourages the breakdown and reaction of proteins and sugars to create brown-colored flavor compounds. This reaction is responsible for meat turning brown when cooked, for example.
The yolk was green on the edges.
Boiling for too long causes the iron in the egg yolk to react with the hydrogen sulfide in the egg whites, creating a layer of green ferrous sulfide between the two parts.
Taste Test Results:
Since the egg whites were brownish due the Maillard reaction, I expected it would taste different than a regular boiled egg. Surprisingly, it tasted the same. Perhaps the new compounds caused by the Maillard reaction thus far had imperceptible flavors. Similarly, the yolk, while chalky and dry, taste surprisingly normal. Lesson learned? The 6 hours did not change the egg’s taste. Instead, it changed the texture and appearance for the worse.
*According to the University of Minnesota, over-cooked eggs with green yolk are safe to eat.
Perhaps if the egg had continued to boil in water versus roast in dry heat, there may have been more astonishing results. However, the exciting results of an exploded egg was still enough to satiate my curiosity!
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