Someone considers 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 their richness in proteins , good fats, iron , zinc and vitamins , but whatever 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 roughly be divided into three parts: the outer shell, mainly made up of calcium , is thin, fragile and porous, therefore capable of allowing gaseous exchanges with the environment; L’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 by another membrane which forms two species 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 albumen from the shell.
After the deposition, with the lowering of the temperature (which passes from the body temperature of the hen to the ambient one), 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 gap which is defined as an air chamber. Due to water leaks, the width of this space, which is generally 3mm, increases in size as the days go by and is therefore a widely used index to evaluate the freshness of the egg .
Nutritional values
| Whole egg | Waterfall | Protein | 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 |
| Albumen + 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 is made up of more or less dense layers.
Proteins: α and Β lipovitellins (they are the most abundant lipoproteins in the egg), phosvitin (it is the protein that binds iron) and livetins (soluble proteins present in the plasma fraction of the yolk).
Lipids : unlike most foods, only 65% of egg lipids are triglycerides(against 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, despite being of animal origin, are mainly made up of monounsaturated and polyunsaturated fats (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 therefore two eggs would be enough to go beyond this limit. However, it must be said that the high lecithin content favors thereverse transport of cholesterol (from the arteries to the liver ) enhancing the activity of HDL (the so-called good cholesterol ). Lecithins, which as we have said allow an excellent emulsification of lipids, also favor cerebral performance and the digestive processes of food: two soft-boiled eggs leave the stomach in two hours, against the three necessary for a portion of meat ; digestion times are in fact proportional to the quantity of fat used and increase, even more so, if the condiments are brought to high temperatures (as in the case of fried eggs).Eggnogs and omelettes are also not recommended for those suffering from gallstones (the so-called liver stones ), since the large quantity of lipids stimulates the contraction of the gallbladder and could therefore cause painful colic . Finally, it should be noted that eggs today contain less cholesterol than in the past, thanks to a constant selection of laying breeds.
How to cook Eggs
Hard-boiled eggs
Poached eggs
Marinated egg
Scrambled eggs with alcohol
Soft-boiled egg cooked in the dishwasher
Clever omelette with egg whites
Sunny Side Up Eggs
More egg recipes
Vegetable alternatives to eggs
Other articles on ‘Eggs and health’
- egg properties
- eggs: storage and label
