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Soft-Boiled Science: Egg-cellently Cooked Eggs

A cooking challenge from Science Buddies



George Resteck

Key concepts
Food science
Proteins
Heat
Eggs

Introduction
Have you ever been in such a rush in the morning that you barely had time for breakfast? Eggs can be a good breakfast choice because they can be cooked quickly and in many different ways. Eggs have been eaten for thousands of years, all over the world. Hard-boiled eggs are commonly used for dying Easter eggs, but a soft-boiled egg can make a yummy breakfast or snack. How does different exposure to heat at different times change the way an egg cooks? In this activity you'll determine the best recipe for producing consistent, soft-boiled eggs that will get your day off to a great start no matter what time of year!

Background
The typical egg packs a big punch in a small package. One large egg has about 75 calories, many essential nutrients, lots of high-quality protein, various vitamins, multiple minerals, choline, folate and riboflavin. Eggs can help you maintain muscle strength as well as promote a healthy brain and eye function. The yolk contains the fat of the egg, most of the vitamins and minerals, and about half of the protein. The albumen (egg white) is mostly water (about 90 percent) and protein (about 10 percent).

There are several methods for preparing eggs. They can be scrambled, poached, fried, pickled, hard-boiled and soft-boiled. In a raw egg the proteins in the egg are folded and curled up tight. But when you cook an egg, the heat causes its proteins to uncurl so that they interact with one another, forming a network of connected proteins. In a soft-boiled egg the white is firm but the yolk is between runny and solid—in other words, the yolk should be viscous, or thickened and sticky. 

Materials
• Three raw eggs
• Pot with lid
• Ice cubes
• Water
• Large bowl
• Stove top (adult supervision is recommended while using the stove and handling any hot items)
• Slotted spoon
• Timer
• Plates

Preparation
• If the eggs are being stored in the refrigerator, take them out and let them warm to room temperature. This may take about an hour.
• Remember to always wash your hands with soap and warm water after handling uncooked eggs because they can carry salmonella. For this same reason, it is not recommended that you eat any uncooked eggs you prepare in this activity.
• Gently place an egg in a pot and add water. Fill the pot so that the egg is covered by about an inch of water.
• Put several ice cubes in a large bowl and fill it with enough water to cover an egg. This will be your ice water bath. If many of the ice cubes melt during the activity, add new ones to the bowl.

Procedure
• Place the pot of water with the egg in it on the stove top, put the lid on the pot and bring the water to a boil. (Please have adult supervision when operating the stove and handling hot items.)
• Once the water is vigorously boiling, let the egg cook for five minutes. Keep the lid on the pot during this time.
• After boiling for five minutes, carefully remove the egg using the slotted spoon and place it into the ice water bath.
• Let the egg sit in the bath for one minute, then remove the egg, peel it and place it on a plate.
• Observe the egg. Is the white firm or watery? How thick is the solid white? Is the yolk slimy, viscous or hard? Overall, does it seem like the egg is soft-boiled?
• Bring the water in the pot back up to a vigorous boil and use the slotted spoon to carefully place a new raw egg into the boiling water. Let the egg boil for five minutes (with the lid on the pot).
• After five minutes, carefully remove the egg and place it into the ice water bath. Let the egg sit there for one minute, then remove it, peel it and place it on a plate.
• Observe the egg. Is the white firm or watery? How thick is the solid white? Is the yolk slimy, viscous or hard? Overall, does it seem like the egg is soft-boiled?
• Bring the water in the pot back up to a vigorous boil and carefully place a new raw egg into the boiling water. Once the egg is submerged, turn off the stove and move the pot to a cool burner. Let the egg steep in the just-boiled water for five minutes. Leave the lid off the pot while the egg steeps.
• After five minutes, carefully remove the egg and place it into the ice water bath. Let the egg sit for one minute, then remove it, peel it and place it on a plate.
• Observe the egg. Is the white firm or watery? How thick is the solid white? Is the yolk slimy, viscous or hard? Overall, does it seem like the egg is soft-boiled?
Which cooking method seemed to lead to the best soft-boiled egg: bringing the egg and water up to a boil together, just cooking the egg in already boiling water or steeping the egg in just-boiled water? If they showed similar results, which method seemed to use less energy?
Extra: Eggs come in different sizes. You could try three different sizes of eggs with the method that worked best for you in this activity. Does the size of the egg affect how well the best soft-boiling recipe works?
Extra: You could try this activity again but increase or decrease the amount of time that the egg is in hot water. Can you perfect the soft-boiling recipe?

Observations and results
Was the egg that was brought to a boil along with the water overcooked, being more similar to a hard-boiled egg than a soft-boiled one? Were the other eggs much closer to being soft-boiled?

When the egg and water were brought up to a boil together, the egg was probably fairly hard-boiled, with a completely firm, thick white and a hard yolk (although it may have had a slightly less cooked, more orange area in the very center). The egg that was steeped in the just-boiled water should have been much more watery, with a much less firm white that was mostly white (but maybe clear in places) and a slimy yolk. Depending on the exact conditions used, however, this egg may have been slightly more cooked and appeared soft-boiled. The recipe that probably resulted in the most soft-boiled-like egg was just cooking the egg in the already boiling water, which cooked the egg more than did steeping it in the just-boiled water, but less than bringing the egg and water up to a boil together. Another common approach to soft-boiling eggs is using simmering, instead of boiling water. What other commonly made foods can you use science to help perfect the recipe?

Cleanup
Always wash your hands with soap and warm water after handling uncooked eggs because they can carry salmonella. Be sure to also wash objects, such as plates, that came into contact with the uncooked eggs. For this same reason, it is not recommended that you eat any uncooked or partially cooked eggs you prepared in this activity.

More to explore
Anatomy of an Egg , from the Exploratorium
Science of Eggs , from the Exploratorium
How to Get Perfect Soft-Boiled Eggs Every Time , from Brigid Ashwood at Wired
Egg-cellently Cooked Eggs: The Process of Soft-Boiling an Egg , from Science Buddies

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