Eggs are among the most nutritious foods on earth and can be part of a healthy diet. The egg is a wonderful source of protein, unsaturated fatty acids, vitamins and minerals. Nutritionists routinely compare other food proteins to eggs and they consider the egg to be the standard or perfect protein. Eggs are one of the most complete, yet least expensive, protein foods.
An egg weight on average 60g and consists of three parts; the shell (approx. 6g) is made of calcium and magnesium carbonates calcium and magnesium phosphates and other organic substances the albumen also called the white weight approx 20g is made of water and protein and coagulates readily when heated the yolk is positioned and held in the center by elastic band-like structures (a thickening of the albumen) known as the chalaza, and constitutes the most nutritionally valuable part of the egg. It is rich in proteins of high biological value (linked to iron and phosphorous) as well as fats vitamins and minerals.
The white is surrounded by a shell, which in turn is made up of two layers. In the wider portion of the shell these layers tend to come unstuck generating a space full of air called the air space which is important in determining the freshness of the egg.
Proteins have considerable nutritional value they contain amino acids that the human organism has difficulty producing therefore they must be introduced through diet to ensure growth and reconstruction of tissues proteins contained in the white and the yolk of an egg are the best source of protein for man albeit certain proteins in the white can cause allergic reaction in individuals with particular sensitivity.
Eggs contain a modest quantity of fats (compared to 16-47% found in cheese and 35% in salami and sausage products) with various chemical structures; eggs contain triglycerides rich in saturated fat phospholipids and cholesterol Note that eggs now contain one forth less cholesterol than in the past at 371mg/100g. for this reason Indications on weekly consumption of egg given to hypercholesterolemia sufferers are now less restrictive but there is still a ban on packaged products with a high yolk content e.g. mayonnaise custards certain desserts (typically tiramisu) or pasta dishes containing which is also rich in cholesterol.