The scientifically proven way to boil eggs perfectly is to alternate between a pot of boiling water and a pot of water for 32 minutes.



Boiled eggs may seem like a simple dish, but there are many different recipes, such as 'boil on high heat for xx minutes, then on low heat for xx minutes,' or 'boil for xx minutes, then turn off the heat and wait xx minutes.' A research team at the University of Naples Federico II in Italy has scientifically determined the optimal way to make boiled eggs. By using the resulting recipe, it is possible to create boiled eggs in a state where the whites are firmly set and the yolks are not too hard. The research team has compiled a paper on how to make boiled eggs, which has been published in the scientific journal Communications Engineering.

Periodic cooking of eggs | Communications Engineering

https://www.nature.com/articles/s44172-024-00334-w

When making boiled eggs, problems such as 'boiled eggs, both the white and yolk are too hard' or 'the yolk is just right, but the white is too soft' tend to occur. The cause of these failures is that the white and yolk solidify at different temperatures.

The white begins to solidify at about 85 degrees, and the yolk at about 65 degrees. To aim for 'a firm white that doesn't become too hard, but the yolk doesn't become too hard,' it is necessary to heat the white to over 85 degrees while keeping the yolk at around 65 degrees, but if you continue to boil it in boiling water at 100 degrees, the yolk's temperature will exceed 65 degrees by a large margin and it will become too hard. Also, if you heat it for a long time in water at around 65 degrees, the white will not reach 85 degrees and will become too soft.

The important point to note here is that when the temperature outside the eggshell changes, the area near the center of the egg is less affected by the change in temperature, while the area close to the shell is more affected. In other words, if the temperature of the water changes when boiling an egg, the temperature of the white will rise and fall according to the temperature of the water, but the temperature of the yolk tends to remain relatively constant. Once the white has solidified, it will remain solid even when the temperature drops, so by alternately transferring the egg between 'hot, boiling water' and 'lukewarm water' at the appropriate times, you can keep the temperature of the yolk at around 65°C while the white solidifies.



The research team used mathematical models and fluid dynamics to calculate the temperature of the boiling water, the temperature of the lukewarm water, and the timing of transferring the egg. As a result, they concluded that the recipe , which involves heating water in two pots, one at 100°C and the other at 30°C, placing the egg in the 100°C pot and transferring it alternately to the 30°C pot every two minutes while boiling for a total of 32 minutes , would keep the yolk at 67°C and produce an ideal boiled egg in which the white is firmly set but the yolk is not too hard.

The images below are, from left to right, 'eggs boiled at 100 degrees for 12 minutes,' 'eggs boiled at 100 degrees for 6 minutes,' 'eggs vacuum-cooked at 65 degrees for 1 hour,' and 'eggs boiled according to this recipe.' You can see that the egg boiled according to this recipe has a firm white while the yolk is not too hard.



If you can't wait 32 minutes and just want to make boiled eggs quickly, we recommend the recipe introduced by the Ministry of Agriculture, Forestry and Fisheries: 'Bring to a boil in a small amount of water, then heat over medium heat for 4 minutes, turn off the heat and wait 3 to 5 minutes.'




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in Science,   Food, Posted by log1o_hf