How to Boil an Egg

Medically Reviewed by Jabeen Begum, MD on November 04, 2022
5 min read

Do you like eggs? How do you like them prepared? Scrambled, poached, or maybe hard-boiled? Hard-boiled eggs are popular, both during certain holidays and on the fitness scene. But is there a certain way to prepare a perfectly hard-boiled egg? Do you just need a pot, water, and an egg? Do you need to know how long to boil eggs? Well, there actually may be a science to it. 

Boiled egg nutrition is about the same as any other preparation, with extra ingredients pending. A serving of two eggs usually contains:

  • Over 80% of your daily recommended amount of Vitamin D
  • Over 50% of your daily recommended amount of folate
  • Over 40% of your daily recommended amount of selenium
  • Over 20% of your daily recommended amount of Vitamin B2

Eggs are a valuable source of protein, which is essential for muscle and tissue strength and repair. One egg contains about 6.3 grams of protein. Eggs increase levels of HDL, or good cholesterol, in the body. This is why it poses no risk factors for heart disease. Eggs also have variable amounts of vitamins A, E, B5, B12, iodine, iron, and phosphorus. 

The whites of the egg are what make a boiled egg solidify. It is about 90% water and 10% protein. The egg whites are amino acids. When the egg is raw, the proteins form a tight ball. When the egg is heated, the ball of protein unfolds and coagulates. The proteins are then exposed and form into a digestible, protein-rich gel, and eventually your healthy hardboiled egg.

You may put your eggs in cold water or wait for the water to boil before dropping in the egg. There are advantages and disadvantages to both. If you choose to drop the egg in boiling water it will heat up quickly. If you choose to place it in cold water and then boil, it will heat slowly. The heating difference will affect the cooked egg white. When the heat is up too high or you cook it too long, the egg white proteins form extra bonds, squeezing out some of the water content and making the egg rubbery. If you start with cold and heat the eggs slowly it helps with the rubbery effect, but you have no control over cooking time and it takes longer. 

Ideally, you should follow these steps to boil the ideal egg:

  • Place your eggs in your pot
  • Add water until there is at least an inch covering the eggs
  • Allow your water to heat until just before boiling
  • Take your pot off the heat and place a cover on top
  • Let your eggs remain in the hot water for about 25 minutes
  • Lastly, plunge them in ice water

In hot, salty water, an egg white will solidify more quickly than in fresh water. A dash of salt in your water will help with the mess if the egg cracks and spills with water. The egg spillage will solidify when it hits the salt and seal the crack. 

If you do not plunge your eggs into cold water after you take them off the heat, they will keep cooking. The longer that goes on, the more likely you are to end up with a green yolk and rubbery white egg. Speaking of green-gray yolks, why does that happen? It comes from the egg yolk iron content reacting with the sulfur in egg whites. In the heat, they mix to make the colored sulfide. To avoid it, only cook eggs to the desired doneness then plunge them in cold water. 

Some people choose to put a pinhole in the large end of their egg before placing it in water. There is a small space of air there and when heated, the air expands and sets the egg white, leaving a flattened end. Pricking allows the air to escape and provides a rounded edge. 

How old your egg is will affect how it turns out. Extremely fresh eggs are harder to peel because it is more acidic. As the egg gets older, carbon dioxide leaks out of the shell and it will be less acidic.

The USDA has many guidelines when it comes to storing and eating eggs. You should always buy uncracked and clean eggs from a refrigerated case. They should be purchased by the expiration date. Take your eggs home to refrigerate them. The carton protects them, so do not take them out until you are ready to use them. Try to store them in the coldest part of your refrigerator. 

Eggs in their shells can remain in the carton, in your refrigerator for up to five weeks, even if passed the sell-by date. Make sure to wash your hands before and after using raw eggs. You should also wash countertops and utensils. Raw eggs should not be out of the refrigerator for more than two hours. Once you boil your eggs and they cool, you should peel them and eat them. You may also choose to slice them in a salad. If you decide to make deviled eggs or cold egg salad, all should be eaten or thrown away within four days.

Pretty low in calories and a rich source of protein, eggs are a good option when trying to lose weight. Eggs are filling, so eating them helps with the satisfaction of less hunger and less of a need to snack during the day. Eggs are part of a well-balanced diet. A good diet aids in stress reduction and impacts symptoms of optimism with performance. The B12 and iron in eggs are associated with reducing anxiety, and depression, and help naturally with sleep. 

Eggs are also very versatile. Once you master boiling, they are very simple to make. They also keep long. You can refrigerate them in their shells up to a week after boiling. Eggs are also popular with kids. They look like a ball and are fun to decorate as easter eggs during the holiday season.