Eggs are a symbol of birth, new life, spring, and Easters. Especially at this time in Czech Republic and other Slavonic countries, after Easter, is in most of the households this food a surplus. However, do you know what impact have eggs on the health? What myths are circulating around them? What kinds of eggs are available? Or how surely know that the egg is fresh? We will explain everything in the following article.
The size, shape, and structure of eggs
Eggs of birds tend to have an oval shape on one side of the oval it has slightly sharper edge. Eggs of birds that live in tree cavities are more spherical eggs, but the birds living in extreme conditions (for example on the reefs) have relatively eggs with a relatively sharper oval shape, which is more resembling the shape of a cone. This is so that the egg will not fall down of the cliff, but it will only turn and stay on the spot.
The smallest eggs lay hummingbird, the largest eggs lay ostrich. The basic structural components are egg yolk, egg white, and eggshell. The shell is hard, calcareous egg packaging. The colour of the shells varies according to the environment in which the bird is living and it is strong enough just to carry an adult bird sitting on the eggs, but must also be thin enough so the bird emerging from the egg it able to brake the shell. On the outside each bird eggs varied from others, whether colour, size itself, the size of the pores in the shell etc. The internal structure of birds' eggs is almost identical, differences are in the size of the egg yolk. Another part of the internal structure of the egg is egg white. Inside it, there is an air chamber.
Structure of chicken eggs
Each egg consists of shell, egg white, and egg yolk. 10% of the total weight consists of a shell egg, egg white is about up to 60% by weight, and egg yolk weights the remaining 30%. Egg white is compounded primarily from proteins, it is about 10% of its weight, and the remaining 90% is water. Yolk is about half of the water and the remaining half are mainly fats, from less than twenty percent it is compounded from proteins, and one percent are minerals and saccharides.
For the colour of egg yolks are responsible carotenoids, which are natural pigments that have antioxidant effects. These colourings receive layers in the food. If laying hens consume green plants, then their egg yolks have a distinctive yellow-orange colour. Chicken eggs contain a lot of water; most water is contained in the egg white, the dry matter is mainly from proteins and fats. Proteins are mainly contained in the egg white and egg yolk, fats are concentrated only in the egg yolk. Sugars contained in eggs are minimal. Minerals are contained mainly in the shell.
Egg whites are two kinds of so-called thick egg white, which is 80%, and 20% is thin egg white. In the thick egg white are milky coloured hangers, called chalaza that holds the egg yolk in the middle of the egg white. The quality of egg white is main indicator of quality of the egg. Whites should be clean, transparent, and clear, in high-quality eggs it is almost shimmering.
Hen eggs and cholesterol
Hen eggs contain a lot of cholesterol. Precisely because of the fear of cholesterol has consumption off the hen eggs decreased in most of the developed countries, and even in our country, in the Czech Republic. Previously, it had been frequently recommended to exclude all foods high in cholesterol from your diet, including eggs. They contain about 180 mg of (S egg size) and 250 mg (XL size egg) cholesterol in one egg.
Based on other studies were many of these positions reviewed and cholesterol ingested in the food is today considered in a mild manner. Many experts believe that adequate eating of eggs has for healthy individual minimal risk. If their intake of the eggs or of saturated fats from other sources is not excessive, then there is no significant health risk. It is also because eggs contain lecithin, which acts very favourably against depositing of the cholesterol. Eating eggs is limited up to of 300 mg of cholesterol per day, which should not be exceeded (i.e. 1.5 of average size egg).
Hen eggs have a high nutritional value; it is possible to enrich it with many health beneficial ingredients.
Limited egg consumption is suitable for people with elevated cholesterol level in the blood, it is also recommended to prefer egg whites, which contain no fat or cholesterol.
Buying and storing eggs
Never do not buy eggs in places where there is no respect for their proper storage, or where they are exposed to direct sunlight. If you immersing the fresh eggs in salted water, it should naturally fall to the bottom, but if it swims on the surface, then we can unfortunately doubt about its freshness. Places meant for egg storage, the usual holders on the door of the refrigerator are, in fact, not suitable for storing eggs at all. It is the hottest place in the refrigerator, it is much better to store eggs in the lower or middle shelves, which are much cooler. Never wash the eggshells when you do not plan their immediate consumption. The shell is a protective covering of the eggs, and its washing will damage it, make it easier for microorganisms to enter the egg.
Labelling of the eggs and their meaning
On eggs and packaging, you will find information on how the hens were bred.
- 0 - hens from organic farming
- 1 - hens from free range
- 2 - hens bred in barns
- 3 - hen bred cages
Eggs are graded according to quality into two classes - A and B. For retail sales are intended only fresh eggs Class A. Class B eggs are intended for industrial processing. Grade a eggs are further sorted into groups by weight:
- XL- weight of 73 g and more, very large eggs
- L - weight of 63-73 grams, large eggs
- M - weight 53-73 g, medium egg
- S – weight u to 53 g, small eggs
On each egg should be given information on the way of breeding, the registration country code, and the last four digits of the registration number of the farmstead.
On the consumers packaging of eggs, is in addition to data about the company, name and number of pieces also - class, the number of the packing hall, or sorting facility. It should also has printed on it the sign of the State, the weight and size, the date of minimum durability, the method of breeding the laying hens, producer code (may even be on the inside of the container).
Besides the discussed cholesterol, egg contains many beneficial and protective substances, which are also in a very easily digestible form. Eggs contain proteins and peptides, which are valuable for humans than the protein in meat and milk. Some of the egg protein is even added to medicines. Egg proteins contain all the essential amino acids, some of them prove a significant biological effects.
Egg lipids or fats are found only in the egg yolk. The main components of the lipids are unsaturated and saturated fats, which create 2/3 of fat in the yolk and the remaining third are additives, such as lecithin. Of fat in the egg yolk predominate those so called good – unsaturated over the so called bad ones - saturated fats. From the nutritional point of view, this is physically reasonable and adequate according to the nutritional recommendations.
Eggs contain almost all of the vitamins except vitamin C. The egg yolk contained vitamins A, D, E, B2 and pantothenic acid. In egg white are vitamins of B group. Minerals contained in the eggs mostly are iron, potassium, zinc, and phosphorus. Important trace element contained in egg too is selenium.
How many eggs to eat?
Eggs have a natural nutritional value thanks to beneficial substances that they contain. Excessive fear of cholesterol, are, according to current knowledge, superfluous. However, consumption of eggs should, be limited to 300 mg a day, which should not be exceeded. It is recommended for people with elevated cholesterol levels in the blood to eat only egg whites and avoid the egg yolks. Egg whites contain no fat or cholesterol.
Although quail eggs are five times smaller than the hen eggs, it contains 5x more phosphorus, potassium and iron. Phosphorus is very useful, because it contributes to the intellectual development of individuals. Quail eggs also contain a lot of cobalt, copper, niacin, and essential acids. One of these essential acids is tyrosine. Tyrosine is responsible for healthy colour of skin and complexion. Quail eggs have a high content of lecithin and so their consumption contributes to reducing of cholesterol levels in blood. Quail eggs are in addition allegedly supporting the potency.
Quail eggs are suitable for people who suffer from anaemia, asthma, or from inflammation of the stomach mucosa. Their regular consumption has antibacterial and immune-modulatory effects. It normalizes blood pressure and it also improves digestion. Quail eggs should eat children and pregnant women and it is also recommended for individuals with weakened immune systems. Eggs are a natural source of Omega-3 and Omega-6 fatty acids, which have positive effect on the cardiovascular system.
We can cook quail eggs in the same way as a chicken egg. WE can also eat raw quail eggs. Just simply break up the egg with a knife and eat it.
Ostrich eggs are the largest eggs of all living birds. Ostrich egg weight is between 750 - 1600 g, it can weigh as about 25 chicken eggs. Eggs are creamy white to shiny, and their shell is very strong and tough.
You can buy ostrich eggs on the farm, where are ostriches breaded, especially for their meat, but also for other ostrich products. Price of ostrich eggs is around CZK 300 (prox.£ 7,5) per one egg. Ostrich eggs have compare to hen egg much lighter egg yolk. Ostrich eggs are somewhat healthier, because they have cholesterol level, than is contained in hen eggs.