The perfect boiled egg is a matter of taste. For most people, it’s probably some variation of soft-boiled: not very runny, but not hard either. So how do you make your eggs? Do you just eyeball a 5-6 minute boil? Do you do longer? Well, how about a 30-minute on-and-off periodic technique where you alternate between hot and cold water to address the different physical phases inside the egg?

Confusing? Yes. Time-consuming? Oh yeah. But the results are worth it, researchers say.

Egg physics

Cooking eggs is a tricky physics problem. The yolk and the albumen (egg white) require different temperatures to reach their ideal textures. While yolks set optimally at around 65°C, albumen needs a higher temperature—around 85°C—to firm up properly.

Traditional methods force a compromise. Hard-boiled eggs cook both parts at high heat, leaving the yolk dry and crumbly. Soft-boiled eggs preserve the yolk’s creaminess but often leave the albumen undercooked. The sous vide technique, a favorite among chefs, maintains a uniform temperature between 60-70°C, creating a creamy consistency throughout but failing to fully set the albumen.

Researchers led by Emilia Di Lorenzo and Ernesto Di Maio at the University of Naples, Italy, believe there’s a better way. They took inspiration from physics, particularly energy transport and heat diffusion.

The researchers started with a mathematical model borrowed from engineering. The model uses time-varying boundary conditions and is used in material sciences to create layers with different densities.

The team used two equations to describe the process and found that the best way to cook the egg evenly was to alternate between two temperatures. In practice, this meant placing raw, shell-on eggs alternatively in hot water and cold water for short intervals. This cycling of heat allowed the albumen to reach its necessary 85°C while keeping the yolk at a steady 65°C—which would have been impossible using conventional cooking techniques.

They compared their new method against three traditional techniques:

• Hard-boiling (100°C for 12 minutes);
• Soft-boiling (100°C for 6 minutes);
• Sous vide (65°C for 1 hour).

Tasty and healthy

After cooking the egg thusly, the researchers first studied it using spectrometry and an MR-like scanner. They confirmed that both phases (yolk and white) were cooked perfectly. They also found that the eggs had more healthy antioxidants (polyphenols) than boiled eggs, though it’s not clear why.

Then, the team conducted a taste test, analyzing the taste, texture, and overall quality of the eggs. They looked at parameters such as texture, umami, softness, and overall flavor. The results showed that periodic cooking produced a unique balance, with the albumen closely resembling that of a soft-boiled egg (firm but not rubbery) and the yolk similar to that of a sous vide egg (creamy and smooth).

Compared to hard-boiled eggs, periodic cooking resulted in a less dry, more palatable texture, while also enhancing sweetness and umami flavors. This confirmed that the method not only improved texture but also influenced taste perception, making it a promising alternative for culinary applications.

This suggests that periodic cooking both enhances texture and preserves more of the egg’s nutritional value.

Want to try it yourself?

Cooking is an art, but it’s also a science — and as this study shows, by understanding heat transfer and material properties, we can put a spin on even the simplest culinary techniques. If you want to try out the periodic cooking technique, here’s how you can do it:

1. Heat a pot of water to 100°C (boiling).
2. Place an egg in boiling water for 2 minutes.
3. Transfer the egg to 30°C water for 2 minutes.
4. Repeat this cycle 8 times (total cooking time: 32 minutes).
5. Crack open the egg and enjoy the perfect balance of creamy yolk and firm albumen.

The study “Periodic cooking of eggs” was published in Nature Communications Engineering. https://doi.org/10.1038/s44172-024-00334-w