Key Concepts
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 perfect breakfast choice because they can be cooked quickly and in many different ways.  Not only do eggs have a spotlight right now because of Easter approaching, but eggs have been commonly eaten for thousands of years, all year round and all over the world.  A soft-boiled egg is a choice that many people make.  They like the way the thickened tasty yolk coats their hash browns or toast.  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!

This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,200 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.

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 pregnancy, brain function, and eye health.  The yolk contains all of the fat of the egg, most of the vitamins and minerals, and about half of the protein.  The albumen (or egg white) is mostly water (about 90%) and protein (about 10%).  People who are limiting their fat intake can eat egg whites, since the egg whites contain no fat.

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 by heating it, the heat causes the proteins in the egg to uncurl so that they interact with each other, forming a network of connected proteins.  In a soft-boiled egg, the white is firm but the yolk is in 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
  • Slotted spoon
  • Timer
  • Plates

Preparation

  1. If the eggs are being stored in the refrigerator, take them out and let them warm up to room temperature.  This may take about an hour.  
  2. Remember to always wash your hands with soap and warm water after handling uncooked eggs since they can carry Salmonella.  For this same reason, it is not recommended that you eat any uncooked eggs you prepare in this activity.
  3. Gently place an egg in a pot and add water.  Fill the pot with enough water so that the egg is covered with about an inch of water. 
  4. Put several ice cubes in a large bowl and fill it with enough water that it will 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

  1. Place the pot of water with the egg on the stove top, put the lid on the pot, and bring the water to a boil.  
  2. Once the water is vigorously boiling, let the egg boil for 5 minutes.  Keep the lid on the pot while the egg boils.
  3. After boiling for 5 minutes, carefully remove the egg using the slotted spoon and place it into the ice-water bath.  
  4. Let the egg sit in the ice-water bath for 1 minute, then remove the egg, peel it, and place it on a plate.  
  5. 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?
  6. 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 5 minutes (with the lid on the pot).
  7. After boiling for 5 minutes, carefully remove the egg and place it into the ice-water bath. Let the egg sit in the ice-water bath for 1 minute, then remove the egg, peel it, and place it on a plate.
  8. 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?
  9. 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 5 minutes.  Leave the lid off the pot while the egg steeps.
  10. After steeping for 5 minutes, carefully remove the egg and place it into the ice-water bath.  Let the egg sit in the ice-water bath for 1 minute, then remove the egg, peel it, and place it on a plate.
  11. 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?
  12. 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 boiling water, or steeping the egg in just-boiled water? If they gave similar results, which method seemed to use less energy?

Extra: You could use an infrared thermometer (which can be purchased online) to measure the temperature of the egg white and yolk after boiling.  How hot do the eggs get when using the different cooking methods?  

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 it works in the best soft-boiling recipe? 

Extra: You could try this activity again but increase or decrease the amount of time that the egg is in the hot water.  Can you perfect the soft-boiling recipe? 

Observations and Results

Was the egg that was brought up to a boil 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 resultant egg was probably fairly hard-boiled, with a completely firm, thick white and a hard yolk (though it may have had a slightly less cooked, more orange area in the 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 may be clear in places) and a slimy yolk.  However, depending on the exact conditions used, 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 boiling water, which cooked the egg more than 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 water, instead of boiling water. 

Cleanup

  1. Always wash your hands with soap and warm water after handling uncooked eggs since 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 eggs you prepared in this activity.

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Credits

Teisha Rowland, PhD, Science Buddies

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Key Concepts
Proteins, heat, eggs
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