* Eggs are considered one of the most nutritious foods.  This is because it contains many nutrients necessary for the growth of the body and the regeneration of its cells, so it is found on the tables in abundance, especially breakfast tables, and it is known to quickly spoil it, so you must make sure of its validity before eating.

Eggs consist of three main layers, namely:

 1- The shell: The shell preserves the egg from microorganisms and external influences, and it consists of 8 to 10,000 porous holes to enable oxygen and carbon dioxide to pass into and out of the egg, and the shell constitutes 9.5% of the total weight of the egg, and is composed of calcium carbonate and calcium phosphate  The outer color of the shell depends on the offspring of the poultry, and its thickness and strength depend on the size of the egg, the offspring of the hen and its age, in addition to the type of food.

 2- Whiteness: the white constitutes 63% of the components of the egg, and its role is to prevent bacteria from reaching the yolk, and it is composed of water by 88%, and dry materials, the most important of which is protein by 12%, and the white is composed of three layers;  An inner liquid layer, an outer liquid layer, between them is another layer of denser liquid.

 3-Yolk: The yolk makes up 28% of the egg's volume, but the water content in it is much less than the white percentage.  As it does not exceed 50%, and is mainly composed of triglycerides, cholesterol and phosphorescent lecithin.  The amount of fat and cholesterol in the egg depends on the nutrition of the chicken, which in turn affects the color of the yolk.  Eating food dyed yellow or orange will produce yolks of the same color.

Eggs are rich in protein, and their digestibility in the body reaches a value ranging between 95% and 98%;  An egg weighing 50 grams is equal to the nutritional value of 50 grams of beef thigh meat or 150 grams of milk, which provides the body with seventy-four calories.

 - The eggs are a source of mineral salts such as chlorine, iodine, copper, manganese, and phosphorous, in addition to iron, whose percentage in eggs reaches 6 mg per 100 grams, and it is also an important source of zinc, selenium, and vitamins (A, B, D, E,  K).  The nutritional importance of eggs appears in the fact that they mine protein substances with a value equal to those found in fish, but it surpasses fish by containing balanced proportions of the essential amino acids that the body cannot automatically produce.

 Methods for preserving and buying eggs There are several methods that must be followed to ensure the safety of eggs:

 1- Avoid buying eggs that are not refrigerated.  Put the eggs in the fridge right after you buy them.  Ensure the safety and cleanliness of each egg separately, as well as that there are no fractures, and in the event of broken eggs, they must be discarded.

 2- Keeping eggs in the carton designated for them, and avoid placing them in the refrigerator door.  Because repeatedly opening and closing the door will make the eggs more exposed to the air.  Eggs can be stored in the refrigerator for three weeks.

Expose the egg to a candle-like light;  As the cell space of the egg is at the widest end, that end is placed diagonally towards the light with the rotation of the wrist, which leads to the movement of the contents of the egg and gives a clear idea of ​​its components of white, yolk and cellular space.

 - The air cell depth in fresh eggs is relatively small;  So that it does not exceed 1/8 inch, and as time progresses, the evaporation process increases inside the egg, thus the depth of the air cell increases and the quality of the eggs decreases, and the yolk in fresh eggs is surrounded by a dense layer of albumin or white, which makes it clear to see it from outside the shell.  Hard,

 As for eggs of low quality, and with the decline of albumin due to aging, the ability to see the yolk becomes easy, and finally, the eggs' containment of flesh or blood spots with a diameter of more than 1/8 inch makes them inedible eggs.  Put the egg in a bowl filled with water, and if the egg floats on the surface of the liquid, this means the eggs are spoiled.

 As time progresses, air seeps into the egg, creating a large air space inside it, which leads to its buoyancy.  Make sure that there is no fracture in the shell, which appears in the form of white lines, and as soon as the egg is exposed to the least amount of pressure, this will break it completely, so it must be discarded directly.  Break the egg in a clean bowl, and make sure that there is no unpleasant odor or unwanted color, if the texture of the white is dense and thick and the shape of the yolk is swollen, this is evidence of the quality of the eggs, but if the white is thin and has a watery consistency and the yolk is flat, then this means that the eggs are rotten  It must be disposed of.

Salmonella: It is a disease-causing bacteria that is transmitted to humans by eating raw or undercooked eggs, and the bacteria are transferred to the outer shell due to the presence of the egg in the fecal channel inside the chicken, and it can also be transmitted in the case of the presence of bacteria inside the ovary before the formation of the outer shell and it forms around  White and yolk, in addition to the possibility of transmission through the pores of the outer shell in the event that the egg is found inside the nest with the feces of the hen.

 * As a result of a person being infected with salmonella, he will suffer from high temperatures, cramps, and diarrhea after a period ranging between 12 and 72 hours of eating contaminated food, and symptoms will last for 4 to 7 days, and the patient will often recover without resorting to antibiotics.  Therefore, eggs must be kept in the refrigerator to prevent bacteria proliferation, wash hands, and surfaces with soap and water in case they come into contact with eggs, and be careful to cook eggs well.