Visual Differences Between a Raw Egg & a Hard Boiled Egg
- Albumen is the egg white. It is milky and viscous due to carbon dioxide. It only becomes white after whipping or cooking. Egg whites have four "alternating layers of thick and thin consistencies," according to EdibleEgg. Starting with the yolk as a baseline, "they are designated as the inner thick or chalaziferous white, the inner thin white, the outer thick white and the outer thin white." The yolk is various shades of yellow. This is determined by the hen's diet.
- The actual term for hard boiled is "hard cooked," says EdibleEgg. After peeling, the egg white has solidified and is indeed white. The exact color of the yolk will remain consistent after boiling; it will just be solid. When an egg is laid by the hen, it is around 105 degrees Fahrenheit. As it cools to a normal temperature, an "air cell" forms because, "the liquid contents contract more than the shell and the inner shell membrane separates from the outer shell membrane to form the air cell," according to EdibleEgg. This is visible after peeling a hard cooked egg because the bigger end is usually flat from the air cell. Sometimes the yolk will have a greenish color on the outside because "of sulfur and iron compounds in the egg reacting at the surface of the yolk," too much iron in the water or overcooking.
- A raw egg will be cool to the touch because of the need for refrigeration to stay fresh. Visually the egg, if left out for any amount time, will begin to sweat as condensation forms. The shell, depending on color --- white or brown --- will be brighter. After boiling, the shell, if white, turns a little darker, almost grey. Likewise, it will be warm and it will not sweat because it has been cooked.
- Dropping a raw egg will produce a visible mess of viscous liquid depending on the force of the impact. A hard cooked egg, no matter the impact, will simply have a cracked shell, which still adheres to the egg itself.
