February 14, 2025
3 min read
How Do You Cook a Perfect Egg? Scientists Have Figured It Out
Materials scientists have found a way to perfectly cook an egg white and egg yolk simultaneously
Hard-boiling, soft-boiling or using a trendy sous vide—no matter the approach, cooking a whole egg preserves either the texture of the yolk or the white but rarely both. Now scientists think they have cracked the perfectly cooked egg.
To trigger the optimal denaturation, or breakdown, of proteins in an egg while also keeping key nutrients intact, the ideal temperature to cook an egg yolk is around 65 degrees Celsius (149 degrees Fahrenheit). For the egg white, or albumen, it’s around 85 degrees C (185 degrees F). Hard-boiling makes sure the albumen is fully cooked, but it can yield a chalkier yolk. Soft-boiled eggs have a smoother yolk, but they can be too runny for some people’s taste. A sous vide egg—cooked in 60- to 70-degree-C (140- to 158-degree-F) water for at least an hour—is close to the ideal. The resulting egg is creamy all the way through, but the albumen is only partially set. The appliance is also not a common kitchen feature.
Materials science PhD student Emilia Di Lorenzo and professor Ernesto Di Maio, both at the University of Naples Federico II in Italy, typically work on methods for making polymers with layers of different densities. But for their latest study, they sought a novel method for preparing an egg that would allow the yolk and egg white to cook optimally without separating them. “What we did in the case of eggs was to take this approach and try to get a layer of texture instead of a layer of densities,” Di Lorenzo says. The inspiration was an egg dish that cost €80 (a little more than $80) in which the components were cooked perfectly but separately.
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Di Lorenzo and Di Maio theorized that alternating the raw egg (still in its shell) between hot water and tepid water repeatedly over short periods of time would allow yolk and albumen to reach their perfect form. They used mathematical modeling and computer simulations to establish their alternating temperatures—100 degrees C (212 degrees F) and 30 degrees C (86 degrees F)—and times—32 minutes total, switching every two minutes. Then it was time to cook a lot of eggs to test the methods out.
The team examined their results with Fourier transform infrared (FT-IR) spectroscopy, which uses infrared waves to probe chemical structure, in order to find out how protein breakdown in the egg yolk and white had affected the texture of eggs that were hard-boiled, soft-boiled, or cooked via sous vide or the new method.
The texture of an egg yolk and white when it is raw, hard-boiled, soft-boiled, cooked by sous vide, and cooked with the new “periodic” method.
Source: “Periodic Cooking of Eggs,” by Emilia Di Lorenzo et al., in Nature Communications Engineering, Vol. 4, No. 5. Published online February 6, 2025
Of course, when you’re making eggs, you’re probably not ranking your preparation options based directly on the degree of protein denaturation, so the researchers further probed the texture and taste of the eggs with more qualitative approaches. Texture profile analysis, which involves compressing pieces of egg, determined that the hard-boiled egg’s albumen and yolk were harder and chewier than the other options but that the rest of the preparations were only subtly different. More subjective taste differences were assessed by a panel of sensory experts.
The team went through dozens upon dozens of eggs. There were “160 alone for the sensory analysis—personally cooked by Ernesto Di Maio” in his kitchen, Di Lorenzo says.
The researchers found that if you’re looking to maximize your morning nutrition, their newly proposed “periodic” cooked egg may be the way to go. The periodic eggs preserved the egg’s nutrients better than other preparations. “The most outstanding result was the preservation of polyphenols, but a lot of amino acids are preserved as well,” Di Lorenzo says. Amino acids are useful for building proteins in our body, and polyphenols are antioxidants that show promise as anti-inflammatory compounds.
The project changed Di Maio’s egg routines forever. Though he acknowledges that the preparation takes a bit longer, he’ll be periodic cooking going forward. Di Lorenzo, however, may not change her diet.
“We were really already deep into this egg project,” Di Maio says, when “[Di Lorenzo] told me that she doesn’t like eggs—at all.” Di Lorenzo looks at it more mildly. “Maybe,” she proposes, “this was a quest to try and like eggs.”
