General information

The structure and composition of chicken eggs


At first glance, an egg, such a familiar food for people, has a very complex structure, which is hard to imagine. Even the most seemingly insignificant element is called upon to perform important functions in the process of giving birth to a chick. The article describes the detailed structure of the eggs laid by the chicken.

The chemical components of chicken eggs

By chemical characteristics, a chicken egg is a valuable set of elements. Enclosed shell space includes all the required substances necessary for the development of a young body. The human body is 97% absorbed by the bird's egg, while it receives many amino acids and vitamins A, B, E.

Protein composition

Generally speaking, the composition of the bird squirrel egg is clearly reflected in its name. In addition to moisture, there are many proteins of animal origin in the protein:

  • Ovoglobulins - about 2%.
  • Ovalbumin (reserve for embryo formation) - approximately 54%.
  • High viscosity glycoproteins - up to 3.5%.
  • Ovotransferrin (has antibacterial effect) - up to 13%.
  • Lysozyme (an enzyme together with ovotransferrin contributes to an increase in antibacterial properties) - at least 3.4%.

The egg white contains ovomucoid, a compound that provokes allergic reactions in the human body. Therefore, one cannot believe the statement that eggs consumed without yolk do not cause individual intolerance.

Due to the fact that the protein has a rich composition, nutritionists actively recommend to consume it in food. It has been proven that proteins are an important building material for all tissues and organs not only of the embryo, but also of the human body.

Protein food is necessary for children, athletes, pregnant women and mothers who are breastfeeding. Chicken eggs are usually the basis of the diet of people suffering from diseases or undergoing rehabilitation after suffering traumas and diseases. Protein is well absorbed. In its raw form, it is recommended to drink protein on an empty stomach. Crude protein is especially beneficial for inflammation of the oral cavity and the gastrointestinal tract.

The composition of the yolk

About 1/3 of the yolk consists of fats, it also contains about 16% of proteins, not more than 50% of moisture. About 2% is allocated to carbohydrates, minerals and vitamins.

Also egg yolk is rich in such components:

  • macro and microelements,
  • essential amino acids for the human body,
  • choline,
  • vitamins of group B, vitamin D, vitamins E, K, F,
  • carotenes
  • lecithin
  • lipids and phospholipids.

On the composition of the egg yolk birds are debated. Chemical analysis has nothing to do with this. Scientists are in conflict with each other regarding cholesterol, which contains up to 140 mg in the yolk. Although the cholesterol in the yolk is “good”, many people still prefer to refrain from eating it for food. If you consume it in large quantities, of course, there will be no benefit from this.

Egg structure

All components in the structure of chicken eggs are very important in the development of a new life. The yolk feeds the embryo, the air chamber facilitates the delivery of oxygen, the shell forms a protective barrier between the future chick and the outside world.

The shell covers the outside of the chicken egg, and also allows it to maintain its physical integrity, and is also a protection against bacteria. Most of the shell consists of a calcium matrix with an organic impurity.

The shell is also rich in such minerals and trace elements:

The shell has such a unique structure: it is permeated with a multitude of pores, forming tunnels between mineral crystals. The tunnels help ensure gas exchange between the inside of the product and the outside atmosphere. The number of pores varies between 7-15 thousand. Most of their concentration is in the lower part of the egg with a blunt end, where there is a gas chamber under the shell.

The shell can be white or brown, it all depends on the breed of bird, on the concentration of pigments (porphyrins), which are located in the calcium matrix of the shell. They have no effect on the nutritional properties of the product and its quality. Also, the color of the shell does not affect the type of food and the technique of growing chickens.

The quality and strength of the shell is directly dependent on the mineral metabolism of the animal and on the diet. No less important factors in the strength of the shell are sanitary.

The shell under the shell and the air chamber

The two-layer shell under the shell consists of organic fibers interwoven. The stage of egg formation depends on the shape given by the shell, only after that the shell begins to form.

At the blunt end of the egg, the layers of the shell are separated, and between them forms a cavity filled with oxygen - this is an air chamber. It is formed when a bird blows an egg. The air chamber contains as much oxygen as the germ will need during the entire incubation period.

Cord is a kind of umbilical cord, fixing the yolk in a certain position - in the center of the protein. The cord is formed from one or more strips of spiral-shaped tissue, and is located on both sides of the yolk. Through the cord, the embryo is fed from the yolk.

Different places have different density of protein. The thinnest layer is enveloped in the yolk, in which the cord is located. Next, the layer of liquid protein thickens - it is necessary for feeding the embryo at the initial stage. Further, the densest layer, feeding the embryo at the second stage, and performing protective functions, does not allow the future chick to contact the shell.

Protein is rich in such components:

  • biotin - 7 mcg,
  • water - 87.9%,
  • Pantothenic acid - 0.30 mg,
  • dry substances - 12.1%,
  • Niacin - 0.43 mg,
  • proteins - 10.57%,
  • Riboflavin - 0.56 mg,
  • fat 0.03%
  • folacin - 1.2 mcg,
  • carbohydrates - 0.9%,
  • vitamin B6 = 0.01 mg,
  • ash (mineral substances) - 0.6%,
  • lysozyme - 3%,
  • ovoalbumin - 69.7%,
  • ovomucins - 1.9%,
  • ovoglobulin - 6.7%,
  • ovomucoid proteins - 12.7,
  • conalbumin - 9.5%.

Yolk Shell

The shell of the yolk is a kind of transparent layer that is necessary for the formation of the egg itself at the stage of its development. In the first 2-3 days of incubation, the yolk shell is the source of nutrients for the embryo.

It contains all the nutrients that accumulate in the egg cell of an animal in the form of plates or grains, which sometimes merge into a single mass. If you look at the raw yolk, it becomes noticeable dark and light layers that alternate. Dark layers are filled mostly with dry substances.

The first few days of embryo development are based on the production of nutrients and oxygen obtained from the yolk. The composition of the yolk contains such components:

  • 1.1% ash (minerals),
  • 48.7% water
  • 1% carbohydrate
  • 51.3% dry matter
  • 32.6% fat
  • 16.6% of proteins.

Germ Disk

Also, the germinal disc is called blastodisc. This is a cluster of cytoplasm, located on the surface of the yolk. This is where the chicken begins to emerge. The clot has a lower density than the entire yolk, due to which it can reside in the upper part.

The entire surface of the shell, including the pores, is covered with a special film - an organic cuticle consisting of 90% of proteins and a small amount of hydrocarbons, lipids. This layer protects the egg from the penetration of infections, gases and moisture.

In order to keep the acquired egg for a long time, you must try not to damage the cuticle..

Each poultry farmer needs to know what an egg is, as well as its structure, chemical composition. This information is reviewed in the video. As for the incubation of eggs, such knowledge is especially useful:

How are eggs formed

They form in birds in the ovary and oviduct. An adult female bird has hundreds of immature germ cells in the ovary. By the time the egg is laid, the germ cells begin to grow, they accumulate nutrients and turn into yolks. About once a day, the mature yolk enters the oviduct.

The yolk moves along the oviduct; in the process, a squirrel is secreted onto it from the glands of the walls. Further, in the designated oviduct department, the prepared egg is covered with the shell splay. At the bottom of the oviduct is the uterus, in which the egg is about 19 hours, the shell is also formed there. After that, through the cloaca it is displayed outside. The formation stage can take different times, depending on the type of bird. For example, in chickens it's about 25 hours. The next demolition process begins no earlier than half an hour or an hour after the previous one.

The chemical composition of chicken eggs

The chemical composition of chicken eggs is slightly different from that of other birds.

The main part of the composition is protein (protein), but the protein and yolk contain various types of proteins.

Egg white - albumin (ovalbumin).

Egg yolk consists of seven different proteins: albumin, ovoglobulin, conalbumin, avidin, ovomucin, ovomucoid, lysozyme.

Contrary to popular belief about the benefits of raw eggs, chicken should be eaten only after processing. It is caused by the fact that the composition of chicken egg protein in its raw form includes trypsin inhibitor - antitripase, due to which up to 50% of protein is not hydrolyzed. Accordingly, the process of digestion for a person will be difficult. In addition, in raw egg yolk, avidin protein irreversibly binds a number of vitamins (biotin and others), contributing to biotin deficiency. In the yolk and the pores of the shell pathogenic microflora may be present (the most dangerous of which is salmonella).

Therefore, chicken eggs are of great benefit and play a significant role in sports and a healthy lifestyle, but always in the form prepared in any way.

Detailed structure of chicken eggs

The shell covers the outside of the egg and is important because it maintains its physical integrity and is a bacteriological barrier. It consists mostly of a calcium matrix with an organic impurity, that is, calcium is the most representative and important element in the shell. It also contains other minerals and trace elements, although with a lower concentration:

The shell structure is as follows: it is permeated with a multitude of pores that form tunnels between the crystals of minerals. These tunnels provide gas exchange between the inside of the egg and the outside atmosphere. The number of pores varies from 7,000 to 15,000. A large concentration of pores is located in the lower blunt-lined part of the product, where the gas chamber is located under the shell.

The color of the shell can be white or brown, depending on the breed of chickens, on the concentration of pigments, called porphyrins, and located in the calcium matrix of the shell. These pigments do not affect the quality and nutritional properties of the product. Different shades of shell color also depend on the individual state of each chicken. The type of food and the bird breeding system do not affect the color of the shell, nor the intensity of this color.

The quality and strength of the shell depends mainly on the mineral metabolism of the chicken and, as a result, on its proper feeding. Other factors affecting the strength of the shell are as follows:

  • genetics,
  • sanitary conditions of poultry,
  • ambient temperature

The entire surface of the shell, including the pores, is covered with a special film - organic cuticlewhich consists mainly of proteins (90%) and a small amount of lipids and hydrocarbons. The main function of the cuticle is to close the pores and thus form a physical barrier against the penetration of microorganisms into them. The cuticle also allows you to avoid a large loss of water during evaporation and gives the product a brilliant look. After the chicken laid an egg, this film is wet, then it dries out and degrades gradually. After 2-4 days, the cuticle completely disappears.if the product is washed, or grind, then the film disappears ahead of this period.

Two membranes cover the shell from the inside, they are called nanticyric inner and outer membranes. Both surround the protein and counteract the penetration of bacteria into it.

When a chicken carries an egg, the membranes in it are firmly connected to each other. Some time after the appearance of the egg, due to the decrease in its internal volume during cooling (the temperature of the chicken’s body is 39 ºC and equal to the temperature of the freshly laid egg), air from the atmosphere penetrates into the thick pole of the product, since it is the bottom of the shell that contains the maximum number of pores. In this lower zone of chicken eggs, the membranes as a result of this process are separated and form gas chamber.

The inner membrane has fine fibrous structureand consists of keratin. In the presence of lysozyme in the protein matrix, the membrane slows down the penetration of some types of microorganisms into the product, and prevents the penetration of others. The outer membrane is more porous than the inner membrane, and serves as the point of attachment of the shell to the rest of the egg. Both membranes form around the edible part of the product the isthmus, which is part of the oviduct, which is located between the egg shell, which, as its name suggests, is the site of shell formation.

As the product loses its freshness, it also loses water evaporating through the pores in the shell, as a result of which the gas chamber at its lower pole increases in volume. Product stored at high temperatures, aging faster. The height of the air chamber in the egg is one of the main signs of its freshness and, as a result, quality, regardless of the number of days elapsed after the appearance of the product. Category A product must have air chamber less than 6 mm high.

The integrity and purity of the shell are factors that determine whether an egg is suitable for human consumption as fresh or unsuitable. When the shell is dirty or damaged, it is possible that the organisms have penetrated into the center of the product.

For this reason, the product, whose shell is dirty, has cracks and other signs of violation of its integrity, cannot be supplied for sale.

It is widely believed that eating crushed shells will allow the use of a large amount of calcium contained in it. Nevertheless, the chemical state in which calcium is in the shell makes it impossible for it to be absorbed by our body.

As mentioned above, the egg protein consists of two distinct parts: viscous and flowing.

The viscous part of the protein surrounds the yolk and is the main source of riboflavin and egg protein. The less viscous or fluid part of the protein is closer to the shell. When you peel a fresh egg from the shell, you can clearly see the difference between these two parts, as the yolk, surrounded by a viscous protein, floats in its center. As the egg loses its freshness, the viscous protein loses its texture and eventually merges with the fluid part.

At its core, the composition of egg protein is as follows: water 88%, proteins 12%. The most important protein (54% of the mass of all other egg proteins) is ovalbumin, whose properties are interesting from nutritional and culinary points of view. The quality of the protein is related to its fluidity and can be estimated by the viscosity of its outer shell.

The richness of essential amino acids of egg protein proteins and their harmonious combination led to the use of egg protein as a standard with which the quality of proteins of other nutrients is compared and assessed. In the kitchen, ovalbumin is interesting in the preparation of many dishes due to its gelatinous structure, which it acquires after heat exposure. Protein contains more than half of all egg proteins, and is also rich in lipids. Vitamin B2 is found in protein in greater quantities than in the yolk.

The protein is transparent, however, in some cases whitish "clouds" may appear in it, which do not imply any problem for its use as a food product and are associated only with the freshness of the egg.

The yolk does not just float freely in the egg whites, it is held on both sides by woven threads of protein, which are connected with its poles by their second ends.

The yolk is the central yellowish part of the egg, which is surrounded by a membrane that separates it from the protein and provides the shape of the yolk itself. When this membrane breaks, the yolk flows out and mixes with the protein.

In the yolk are the main vitamins, lipids and minerals of the egg, so from a nutritional point of view, this is the most valuable part. The water content in the yolk is approximately 50%.

The solid or dry part of the yolk is equally divided between proteins and lipids, leaving a small part of the vitamins, minerals and carotinoids. The latter are responsible for the yellowish color of the yolk, which can have different colors and shades depending on the feeding of the birds, and have antioxidant properties. Note that the color of the yolk is of commercial interest.

Внутри желтка находится зародышевый диск, небольшой прозрачный диск, являющийся местом, где начинается деление эмбриональных клеток в случае оплодотворенного яйца.

В редких случаях можно встретить яйца с двумя желтками. Такая ситуация возможна, когда курица производит две яйцеклетки вместо одной в процессе овуляции. Такая ситуация часто наблюдается в начале кладки, когда курица начинает нестись.

Пятна красноватого или коричневого цвета, которые иногда появляются внутри яйца, не нужно путать с развитием зародыша. These spots are the epithelial cells of the oviduct, which separated from it during egg formation. These cells do not pose any problems in the use of the product in food, and they can be easily removed with the tip of a clean knife. When packing a product, if these spots are visible in the transmitted light of a special camera, then such an egg is no longer considered to belong to quality category A.

Air chamber

The cavity filled with gas, between the two layers of the membrane shell, is the air chamber. It forms when a hen breaks an egg. It contains the amount of oxygen that the germ needs during the entire incubation period.

This is a kind of umbilical cord, which fixes the yolk in a certain position (in the center of the protein). Located on both sides of the yolk. Formed from 1 or 2 spiral strips of tissue. Through the cord, the embryo is fed from the yolk.

Yolk sheath

This is a kind of transparent layer that forms the egg itself at the stage of its development. Serves as a source of nutrients for the embryo in the first 2-3 days of incubation.

It is a set of nutrients that accumulate in the egg cell of an animal in the form of grains or plates, sometimes merging into a single mass. If you carefully examine the raw yolk, then you can see the alternation of dark and light layers. The dark layers contain mostly solids. In the first days of development, the embryo receives not only nutrients from the yolk, but also oxygen.

The yolk contains:

  • water - 48.7%,
  • dry substances - 51.3%,
  • proteins - 16.6%,
  • fats - 32.6%,
  • carbohydrates - 1%,
  • ash (mineral substances) - 1.1%.

Protein density is different in different places. The thinnest layer envelops the yolk. It is a rope. Next comes a thick layer of liquid protein, which is the source of nutrition for the embryo at the initial stage. The next layer is more dense. It feeds the embryo in the second stage and performs protective functions, not allowing the future chick to contact with the shell.

Protein contains:

  • water - 87.9%,
  • dry substances - 12.1%,
  • proteins - 10.57%,
  • fat 0.03%
  • carbohydrates - 0.9%,
  • ash (mineral substances) - 0.6%,
  • ovoalbumin - 69.7%,
  • ovoglobulin - 6.7%,
  • conalbumin - 9.5%,
  • ovomucoid proteins - 12.7%,
  • ovomucins - 1.9%,
  • lysozyme - 3%,
  • Vitamin B6 - 0.01 mg,
  • Folacin - 1.2 mcg
  • Riboflavin - 0.56 mg,
  • Niacin - 0.43 mg,
  • Pantothenic acid - 0.30 mg,
  • Biotin - 7 mcg.

The structure of the chicken product

Any bird's egg consists of the same components, only the percentage ratio can fluctuate. On the basis of chicken eggs, try to deal with their structure and chemical composition. The composition of the egg will always consist of the shell, as a percentage, it accounts for up to 12% of the volume, then protein - up to 61% and the most valuable yolk - 32%. These figures may fluctuate and have smaller numbers, but this will directly depend on the size of the eggs.

But that is not all. Under the egg shell is the shell loop shell. If you take a good look, you can see a speck on the yolk, which can be dark orange or red - this is the germinal disc, the second of which is the hem. After fertilization of eggs, the embryo will develop here. Interesting fact, the hem will always be at the top, thus it gets more heat in the incubator, or under the hen.

If the protein is poured onto a plate, then it will be possible to see that from the yolk upward and downward thin nodules of the cord are pulled, this is halazah. They help the yolk to always be in the center of the eggs. And even when a person turns it in his hands, the yolk itself will rotate around its axis.