The Difference Between the White and Yellow Parts of an Egg

The white part of an egg is known as the albumen, and the yellow part is called the yolk. Both the yolk and the albumen have different roles to play in the growth of a new life inside the egg and have different nutritional qualities when consumed.

Roles of the Yolk and the Albumen

• The eggs that we eat have not been fertilized, so there is no chick growing inside them. If an egg has been fertilized, the embryo grows inside the yolk. The yolk is designed to be the primary source of food for the embryo as it grows. The white of the egg works as protection for the embryo in the early stages of growth and provides an additional source of nutrition in the late incubation stages.

The Yellow of the Egg

• Because the white and the yellow parts of the egg have different natural functions, they have different qualities. The yolk contains more protein than the other parts of the egg in order to aid the growth of the embryo. It also contains some fat and most of the egg's vitamins and minerals, such as iron, vitamin A, vitamin D and calcium.

The White of the Egg

• The white of the egg is made up of four layers of thick and thin albumen. This part of the egg contains primarily water, which protects the embryo. It also contains around 40 different types of protein to offer the embryo additional nourishment in the latter stages of incubation.

Nutrition of The White and Yellow of the Egg

• Because 99 percent, around 4.5g, of the egg's fat content is held in the yolk, the yellow part of the egg is high in cholesterol with one egg yolk containing around 184mg of the recommended daily 300mg. However, the yolk contains the majority of the egg's nutrients, particularly essential fatty acids and fat-soluble vitamins. The egg white contains little more than protein, so it lacks nutritional value and variety if eaten in isolation from the yolk. Nutritionists recommend that individuals with low to normal cholesterol levels can safely eat whole eggs in moderation.

Uses for the White and Yellow Parts of the Egg

• Egg whites are used in a number of recipes, notably meringue. It can also be used as an ingredient in batter for chicken, fish or vegetables. Egg yolks are used to make custard and are frequently used as an emulsifier.