Eggs as food
Bird eggs are a common food source. The most commonly used bird eggs are those from the chicken, duck, and goose; but smaller eggs such as quail eggs are occasionally used as a gourmet ingredient, as are the largest bird eggs, from ostriches. The eggs of sea turtles are sometimes used for food also. Eggs are frequently used in both sweet and savoury dishes as a source of protein and/or to bind the other ingredients in a recipe together. Sometimes the egg yolk is used separately from the egg white (or albumen).
The egg yolk is suspended in the egg white by one or two spiral bands of tissue called the chalaza (Greek word from "khalaza" meaning hailstone, or hard lump.)
Nutrition of chicken eggs
Chicken eggs are the most commonly eaten eggs, and are highly nutritious. They supply a large amount of complete protein—according to the Food and Agriculture Organization of the United Nations, egg protein is of a higher quality than all other food proteins—and provide significant amounts of several vitamins and minerals, including vitamin A, riboflavin, folic acid, vitamin B6, vitamin B12, choline, iron, calcium, phosphorous and potassium. They are also one of the least expensive single-food sources of complete protein, which is essential to life, health, and well being.
All of the egg's vitamin A, D and E is in the yolk. The egg is one of the few foods which naturally contain vitamin D (though this nutrient is naturally produced in humans when their skin is exposed to sunlight). A large egg yolk contains approximately 60 calories (250 kilojoules); the egg white contains about 15 calories (60 kilojoules). A large yolk contains more than two-thirds of the recommended daily intake of 300 mg of cholesterol. The yolk makes up about 33% of the liquid weight of the egg. It contains all of the fat in the egg and almost half of the protein.
Recently, chicken eggs that are especially high in Omega 3 fatty acids have come on the market. These eggs are made by feeding laying hens a diet containing polyunsaturated fats and kelp meal. Two brands available in the UK are Columbus Eggs[1] and The Hearty Egg[2]. Nutrition information on the packaging is different for each of the brands.
Health issues of eating chicken eggs
Cholesterol and fat
Chicken egg yolks contain a small amount of fat. People on a low-cholesterol diet may feel the need to cut down on egg consumption, although most of the fat in egg is unsaturated fat and may not be harmful. The egg white consists primarily of water (87%) and protein (13%) and contains no cholesterol and little, if any, fat.
Some people try to avoid eggs in their diet because they are high in cholesterol, which is concentrated in the yolk. This issue is sometimes addressed by removing some or all of the eggs' yolks. People sometimes do this themselves, or may use prepared egg substitutes such as Egg Beaters.
The United States egg industry launched its continuing "Incredible Edible Egg" campaign, which touts eggs as a healthy part of a balanced diet. The American Egg Board publicizes modern research which shows that dietary cholesterol has less effect on blood cholesterol than previously thought.
Contamination
A health issue associated with eggs is contamination by pathogenic bacteria like Salmonella. Eggs exit a female bird via the cloaca, so care must be taken to avoid the eggs being contaminated with fecal matter. In commercial practice, eggs are quickly washed with a sanitizing solution within minutes of being laid.
Most health experts advise people to cook their eggs thoroughly before eating them, as the heat is necessary to kill any infectious micro-organisms that may be present. Raw and undercooked eggs have been associated with salmonella infection. As with meat, ready-to-eat food should not come in contact with containers and surfaces that have been used to process raw eggs.
The risk of infection from raw or undercooked eggs is dependent in part upon the sanitary conditions under which the hens are kept. Some smaller egg producers make a point of keeping their hens in cleaner (and, in their view more humane) conditions, and observe few or no cases of salmonella in the birds themselves.
Cooking and preparation
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The primary cooking techniques for eggs are:
Some common egg dishes are
Eggs, particularly their yolks, are important as binding agents in many preparations in European cooking due to the emulsifying action of lecithin. This property is crucial for sauces such as mayonnaise and Hollandaise; custards such as crème anglaise, crème brûlée, flan, and lemon custard; and meat dishes such as sausages and pâté.
Eggs may also be pickled; hard-boiled and refrigerated; or eaten raw, though the latter is not recommended for people who may be susceptible to salmonella, such as the old, the infirm, or pregnant women.
If an egg is overcooked, a greenish ring sometimes appears around egg yolk. This is a manifestation of the iron and sulfur compounds in the egg. It can also occur when there is much iron in the cooking water. The green ring does not affect the egg's taste; overcooking, however, harms the quality of the egg's protein.
When eggs become rotten, the yolk will turn green, and the egg will emit a pungent sulfurous odor when broken. Although deemed offensive by most Western palates, fermented eggs are considered a delicacy by some in China when prepared using a special method which includes letting them sit for three months to age (or rot, depending on one's interpretation).
Egg substitutes for baking
For those who choose not to or are unable to consume eggs, alternatives used in baking include other rising agents, such as Ener-G egg replacer; or binding materials, such as ground flax seeds. Tofu can also act as a partial binding agent, since it is high in lecithin due to its soy content. Extracted soybean lecithin, in turn, is often used in packaged foods as a cheap substitute for egg-derived lecithin.
Egg characteristics
The shape of an egg is approximately an oblate ellipsoid, but, while keeping cylindrical symmetry, there is typically not quite symmetry in a plane perpendicular to the long axis. See also oval (geometry).
Shell color
Different breeds of chicken can lay eggs with Egg shells varying from whites through to brown and rarer colours such as speckled green. Although there are absolutely no nutritional differences, there is often a cultural preference for one colour over another. For example, in most regions of the United States, eggs are generally white; while in the northeast of that country and in the United Kingdom, eggs are generally light-brown. These habits may be associated with perceptions of greater purity in white-shelled eggs or greater wholesomeness in brown-shelled eggs.
===Yolk color===
Yolk colour depends on the diet of the hen; if the diet contains yellow/orange plant pigments known as xanthophylls, then they are deposited in the yolk, colouring it. A colourless diet can produce an almost colourless yolk. Farmers may add natural pigments to enhance yolk colour, but artificial colours are banned.
Abnormalities
Some hens will lay double-yolked eggs as the result of unsynchronized production cycles, although heredity causes some hens to have a higher propensity to lay double-yolked eggs. Double-yolked eggs only rarely, and even then only with human intervention, lead to the successful development of two embryos [3].
It is also possible for a young hen to produce an egg with no yolk at all.
Ethical issues
Many who practice vegetarianism feel it is acceptable to eat eggs as the bird is not killed and the eggs remain unfertilized. People concerned about animal welfare (especially vegans) are reluctant to eat mass-produced eggs as factory farming is considered cruel. Even free-range eggs are sometimes unacceptable to those who are concerned about animal welfare as it is felt that alleged free-range birds may not be much better off than confined birds. Many vegans believe it is inaccurate that eating eggs does not cause an animal to be killed since most farms (both free-range and factory farms) kill the chickens once their egg production declines. Most farms also buy the chicks from hatcheries where the male chicks are killed at birth. From a religious standpoint, some vegetarians, such as certain practitioners of Buddhism and of Hinduism, feel that eggs are the same as "liquid meat" and thus are unacceptable for consumption.
Trivia
- If a raw egg is spun, abruptly stopped and then quickly released, it will start to spin again as the liquid inside continues to rotate. This technique can be used to reliably determine whether an egg is raw or already boiled – a solid egg will remain stationary once halted. Additionally, if a cooked egg and a raw egg are spun with the same force, the cooked egg will spin much faster.
- It is difficult to break a chicken egg by squeezing it from end-to-end on its long axis.
- An ostrich egg can make omelets for ten people, and takes forty-five minutes of boiling to harden through.
- An egg that floats in water is likely to have been spoiled by bacteria that entered through the pores in the shell and created gas inside it. The increased pressure due to the gas production may push some of the white through the shell, which may also signify a bad egg.
- A popular folk remedy for a leaky car radiator is to crack in a raw egg. This has been known to work, although automotive professionals do not recommend it.
- A popular urban legend holds that an egg can be balanced on its end during equinoxes/soltices, though in reality an egg can just as easily be balanced on any other day.
Pop culture
- A popular Easter tradition in some parts of the world is the decoration of hard-boiled eggs (usually by dyeing). Adults often hide the eggs for children to find, an activity known as an Easter egg hunt. See Egg decorating and Easter eggs.
Egg Attacks
Although a food item, eggs are sometimes thrown at people or things such as houses and cars. This act, "egging," is a minor form of vandalism and therefore usually a criminal offense. On Halloween, for example, trick or treaters have been known to throw eggs (and sometimes flour) at property or people from whom they received nothing. Eggs are also often thrown in protests, as they are cheap, nonlethal, and at the same time, very messy when broken.
See also
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