The eggs

See also: eggs and cholesterol and fresh eggs

Some consider them the most nutritious food in the world, others fear them for their cholesterol content, still others appreciate their versatility in the kitchen ... it may be for the richness in proteins, good fats, iron, zinc and vitamins, but whatever the ratio bind us to them, we certainly cannot deny their universal importance in human nutrition.
With an average weight of about 50 grams, the hen's egg can be roughly divided into three parts: the outer shell, consisting mainly of calcium, is thin, fragile and porous, therefore capable of allowing gaseous exchanges with the environment; the "albumen or egg white, more internal, is separated from the shell by a double membrane, one of which adheres perfectly to it while the second is more adherent to the albumen; finally, more internally, we find the yolk, separated from the" albumen from another membrane which forms two kinds of cords at the ends, called chalazae, which allow it to remain perfectly in the center of the egg.

These cords then connect to the innermost membrane that separates the egg white from the shell.

After laying, with the lowering of the temperature (which passes from the body temperature of the hen to the ambient temperature), the volume of the egg white decreases; this causes the two membranes that separate it from the shell to detach at the bottom, giving rise to a small dividing cavity which is called the air chamber. Due to water losses, the width of this space, which it is generally 3mm, it increases in size with the passing of the days and is therefore a very used index to evaluate the freshness of the egg.

Nutritional values

Whole egg Waterfall Proteins Lipids Carbohydrates Minerals Kcal Shell 8,5-10,5 1 4 - - 95 - Egg white 60-66 87-89 10,7 - 0,4-0,5 0,5-0,7 43 Yolk 24-30 46,5-48,5 15,8 29,1 0,15-0,25 1,1-1,6 325 Egg white + yolk 90-92 74-76 12,4 8,7 0,3-0,4 0,8-1 128

Insights

The egg yolk

The yolk can be considered as a dispersion of lipoprotein globules in an aqueous mass or plasma; it is therefore rich in proteins, lipids, but also in lecithins; its composition is not homogeneous but consists of more or less dense layers.
Proteins: α and Β lipovitellins (they are the most abundant lipoproteins in the egg), fosvitin (it is the protein that binds iron) and livetine (soluble proteins present in the plasma fraction of the yolk).
Lipids: unlike most foods, only 65% of the lipids of the egg is represented by triglycerides (compared to 98% of other foods). The egg is in fact very rich in lecithins and in general in phospholipids (30%). , which give it noteworthy health and functional properties (the emulsifying power allows, for example, the preparation of mayonnaise). Another characteristic of eggs is that their fats, although of animal origin, are mainly made up of monounsaturated and polyunsaturated ones (those considered beneficial for the body).
Cholesterol: 5% (about 200 mg / egg): it is certainly a high quantity, just think that the daily requirement is estimated at 300 mg and that two eggs would be enough to exceed this limit. However, it must be said that the high lecithin content favors the reverse transport of cholesterol (from the arteries to the liver) by enhancing the activity of HDL (the so-called good cholesterol). The lecithins, which as we have said allow an excellent emulsification of lipids, also favor the brain performance and the digestive processes of the food: two soft-boiled eggs leave the stomach in two hours, against the three necessary for a portion of meat; digestion are in fact proportional to the quantity of fats used and increase, even more so, if the condiments are brought to high temperatures (as in the case of fried eggs). Eggnog and omelettes are also not recommended for those suffering from gallstones (the so-called calculi to the liver), since the large amount of lipids stimulates the contraction of the gallbladder and could therefore cause painful colic.Finally, it should be noted that eggs now contain less cholesterol than in the past, thanks to a constant selection of laying breeds.