How To Boil an Egg: The Science, the Controversy, and the Perfect Yolk

[masterslider id=”5″]

Year after year, the most common how-to questions on Yahoo searches revolve around tying neckties, getting rid of fruit flies, and boiling eggs. Compared to the 177,147 ways to do the first and man’s pitched battle with pests, cooking an egg should be pretty straightforward—after all, we’ve been at it for thousands of years.

Nope. For one thing, there’s the eternal tug-of-war between the cold start versus the simmering boil. For another, how soft you want the yolk defines your very definition of boiled. Trends such as the haute restaurant’s embrace of humble bowls of ramen have made the quest for the perfect yolk akin to a treasure hunt.

Click through as we take a closer look at the confusion —and as we find some answers.

What makes up an egg

Egg whites, also called the albumen, are about 90 percent water and 10 percent protein. In a process called coagulation, simmering heat jostles those tightly furled amino acids that make up the protein, bumping them up against their neighboring water molecules. Simmer the egg just right, and you get a richly textured albumen. Keep that water boiling too long, however, and you’ve just made rubber.

Age makes for a better boil

Crack open a fresh, raw egg and the white comes out opaque, its cloudiness due to carbon dioxide. The older the egg, the more transparent and thinner it gets, as the  acidic carbon dioxide gas has oozed away. When that carbon dioxide dissipates, peeling is easier. The Food Lab columnist J. Kenji López-Alt advocates letting hen-fresh eggs sit for a couple weeks before boiling—or using them for another purpose. There’s a downfall here, though: With time, air space expands in the blunt end of the egg, and it can ruin a boiled egg’s shapely silhouette.


A watched pot

According to the American Egg Board, your pot should be wide enough for the number of eggs you want to cook. “Make sure that eggs are always in a single layer,” says spokesperson Serena Schaffner. “If you stack them or crowd them, some eggs end up closer to the heat source for a longer period of time than others, which can cause them to overcook or not cook at the same rate.”


Safety first

When it comes to boiling eggs, the American Egg Board errs on the side of food safety. “We recommend that all eggs be cooked so the whites and yolks are firm and any dishes containing eggs reach an internal temperature of 160 degrees,” Schaffner writes.


Running hot and cold

Do you start with eggs in “cold” (or room temperature) water, or do you simmer the water first, then gently drop in the eggs? Scientists at the Exploratorium,  a hands-on science museum in San Francisco, run both hot and cold: Cold proponents say the gradual process minimizes rubbery whites. Hot fans say there’s more control over timing. Everyone agrees that too-hot water will make egg whites cook too fast.

For his piece  The Food Lab: The Hard Truth About Boiled Eggs, MIT grad J. Kenji López-Alt subjected dozens upon dozens of egg to both methods. Ultimately, he recommends going straight from the fridge to hot water for a cleaner peel (as seen in this image).


The dangers of boiling

In the same  Food Lab post, López-Alt lines up eggs cooked in boiling water for varying durations of time. It’s a delicate balance, because the white and the yolk cook at different rates: While egg whites need to hit 180 degrees to firm, yolks dry up and crumble at 170 degrees.


Shell shocked

Dimples aren’t cute on everyone. As you recall, air sacs expand with age. When heat is applied, air expands and—without an escape route—pushes back against the egg, changing its shape. Some recommend pricking the fat end of the shell to maintain that egg’s rounded figure. Others think the hole makes cracking more likely, thereby risking the albumen to leak. What everyone agrees on: a cold-water plunge post-boil stops the cooking process. And that, in turn, will help you avoid the dastardly dimple.


Oven boil?

If you care about egg aesthetics, the stove won’t work. “We did try to test hard-boiling eggs in the oven, but couldn’t get a perfect hard-boiled egg using that technique,” says American Board Egg rep Schaffner. “We often ended up with brown spots all over the eggshell and egg whites, once peeled.” And who wants speckled eggs?


Under pressure

In his book Egg: A Culinary Exploration of the World’s Most Versatile Ingredient, Michael Ruhlman recommends pressure cookers as a “fabulous way to cook eggs in the shells.” (He also says the tool will making peeling easier, but Lopez- Alt  insists there’s zero correlation.)

The method: Place eggs in the steamer basket or trivet of the cooker with 1 cup water and turn the setting to low. Place the cooker over high heat until it whistles, then lower to medium-low heat for 7 minutes. Remove the pot, wait for the pressure to drop (run the pot under cold water after 5 minutes if necessary), then soak the eggs in an ice bath for at least 10 minutes.

Gentle steam bath

Steam-boiled eggs? Lopez-Alt’s earlier mission for easy-to-peel eggs led him to this gentle yet ancient method. All you need in an inch of water in a large pot and your steamer insert of choice. Wait for the water to boil before adding eggs to the steamer basket, then cooking for 6 minutes for soft-boiled or twice that long for hard. Keep an ice cube tray handy for an immediate chill-down.


Vacuum-sealed perfection

How do you make a soft-boiled egg have the homogeneous texture of a savory custard? SpiceKit co-founders Will Pacio and Fred Tang, who have worked at The French Laundry and the Ritz-Carlton, use an immersion circulator to cook eggs for 30 minutes in a 147-degree bath. Pro equipment can cost around $800, but these days there are home chef versions for under $200. And while this sounds like sous-vide—or vaccuum-sealed—cooking, there’s no need to put the egg in a bag. “The egg,” Pacio says, “is in its own perfect seal.”


Rush the ramen egg

Now, what about that perfect ramen egg we talked about earlier? No matter how you soft-boil the egg, you have to take into account that broth will be hot—likely 99 degrees, estimates Pacio of SpiceKit—and it’ll cook those eggs further. Don’t be tempted to undercook, though. Make your perfect egg and serve up those noodles fast, Pacio recommends.


Boil up some tea eggs

How about using the boiling liquid to flavor your eggs? Here’s a  Chinese tea egg recipe from Laura Kelley, author of The Silk Road Gourmet:

Chinese tea eggs
6 cups cold water
6-8 chicken or duck eggs
¼ cup light or dark soy sauce
1 tablespoon cane or demerara sugar
1 tablespoon black tea leaves
2-3 pieces star anise (lightly cracked or crushed)
1 small stick cinnamon
1 teaspoon peppercorns (cracked)
Peel from 1 tangerine or mandarin orange

If eggs are not fresh, take them out of the refrigerator for an 1 hour. Heat water in a medium saucepan. As it approaches a boil, place eggs carefully in the water. Water should cover the eggs by at least 1-2 inches. Bring water and eggs to a boil, then lower heat to a medium-to-high simmer for 2 minutes.

With a slotted spoon, remove the eggs from the water. Holding an in one gloved hand, tap each egg with the dull side of a knife or a spoon to slightly crack the shell in several places . Set cracked eggs aside for a few moments.

Add other ingredients to the saucepan and stir well. Let steep for 2-3 minutes and return cracked eggs to the saucepan. Cover and let cook on a low simmer for 30 minutes, adding water if necessary. Turn heat off and let sit for at least 2 hours to overnight. The longer they steep, the more robust the flavor will be. Drain and serve warm or cold.