Content of egg
Most eggs sold to consumers are white-shelled eggs that have not been fertilized. The type of hen bred determines the color of shell.
A popular food, non-fertile chicken eggs are mass-produced, inexpensive, readily available and easily prepared.
Although they contain74 percent of water, they are such a rich source of high quality proteins.
Chemically, egg yolk contains proteins, lipids, cholesterol, pigments and a variety of minor organic and inorganic substances. The yellow color is due to the plant pigment xanthophylls – lutein.
The egg yolk is also rich in lecithin, a phospholipid used to emulsify other lipid.
In contrast, the albumin, or egg white, is described as almost pure aqueous protein, consisting of about 40 proteins.
Lipids, the main components of egg yolk, comprise about 69% of an egg yolk based on dry weight.
In fresh egg, the lipids are combined noncovalently with protein, largely in particles of lipoprotein and to a very small extent with carbohydrate.
Eggs are an important source of unsaturated fatty acids – mainly oleic, iron, phosphorus, trace minerals, fat soluble vitamin A, E and K and B vitamins.
