Eggs may be boiled following different processes. These options represent different modifications of eggs compounds.

Boiled eggs (soft-boiled, medium-boiled and hard-boiled eggs) are different because of the boiling time. Soft-boiled eggs have to be boiled during 3 minutes, medium-boiled eggs 5 minutes and hard-boiled eggs 12 minutes. Eggs lose water during the boiling process depending on the boiling time: soft-boiled eggs lose 25% of water, and hard-boiled eggs 50% approximately.

Particular characteristics of these preparations are linked to the different coagulation points of white and yolk. The white coagulation starts at 57º C and at 70º C the white solidifies. The yolk coagulation starts at 65º C and it becomes totally solid at 70º C. Coagulation occurs by the denaturation (lost of the three-dimensional structure of the white and yolk proteins) that the heat produces. Albumins coagulate and become more digestible. If the boiling process is too long, it may affect to thermo sensitive vitamins.

Poached eggs are coagulated without shell in simmering water. You have to add some acid product such as vinegar or lemon. You cook them during three minutes and you drain them later.

Fried eggs, in an omelette or scrambled will reduce the amount of evaporation egg water. This process increases the amount of fat because of the oil. This fact makes fried eggs less digestible than boiled eggs. Coagulated albumins remain as most of vitamins do.

Baked eggs lose 58% of water due to evaporation. Baked eggs have less albumins, fat and vitamins than former preparations.

You can also eat raw eggs, the whole raw egg or any of its parts. Raw egg consumption is not advised for hygienic and nutritional reasons. The protein avidin, found in the egg albumen, is linked to the vitamin biotin and prevents its absorption. The heat destroys this link and allows us to take this vitamin.

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