Ingredient: Eggs
Category: General
Season: All
When we talk about eggs these are usually chicken eggs, but the also those of other birds and turtles, as well as those of fish.
An egg is a round or oval body laid by the female of many animals, consisting of an ovum surrounded by layers of membranes and an outer casing, which acts to nourish and protect a developing embryo and its nutrient reserves.
Most edible eggs, including bird eggs and turtle eggs, consist of a protective, oval eggshell, the albumen (egg white), the vitellus (egg yolk), and various thin membranes.
Every part is edible, although the eggshell is generally discarded. Nutritionally, eggs are considered a good source of protein and choline, they provide nutrients, proteins, fats, vitamins and minerals, nearly everything needed for life.
Culinary use:
Chicken egg sizes
Bird eggs are a common food and one of the most versatile ingredients used in cooking.
They are highly important in many branches of the modern food industry. The most commonly used bird eggs are those from the chicken.
Duck and goose eggs, and smaller eggs such as quail eggs are occasionally used as a gourmet ingredient, as are the largest bird eggs, from ostriches.
Gull eggs are considered a delicacy in England, as well as in Scandinavian countries, particularly in Norway.
In some African countries, guinea fowl eggs are commonly seen in marketplaces, especially in the spring of each year.
Pheasant eggs and Emu eggs are perfectly edible but less widely available. Sometimes they are obtainable from farmers, poultery suppliers, or luxury grocery stores.
Most wild bird's eggs are protected by laws in many countries, which prohibit collecting or selling them, or only permit these during specific periods of the year.
Chicken eggs are widely used in many types of dishes, both sweet and savory.
Eggs can be pickled, hard-boiled, scrambled, fried and refrigerated. They can also be eaten raw, though this is not recommended for people who may be especially susceptible to salmonella, such as the elderly, the infirm, or pregnant women.
In addition, the protein in raw eggs is only 51% bio-available, whereas that of a cooked egg is nearer 91% bio-available, meaning the protein of cooked eggs is nearly twice as absorbable as the protein from raw eggs.
As an ingredient egg yolks are important emulsifier in the kitchen, and the proteins in eggs white makes all kinds of foams and aerated dishes possible.
Quail eggs are considered a delicacy in many countries. They are used raw or cooked as tamago in sushi.
In Colombia, quail eggs are considered less exotic than in other countries, and a single hard-boiled quail egg is a common topping on hot dogs and hamburgers, often fixed into place with a toothpick.
A boiled egg can be distinguished from a raw egg without breaking the shell by spinning it. A hard-boiled egg's contents are solid due to the denaturalising of the protein, allowing it to spin freely, while viscous dissipation in the liquid contents of a raw egg causes it to stop spinning within approximately three rotations.
The albumen, or egg white contains protein but little or no fat. It is used in cooking separately from the yolk, and can be aerated or whipped to a light, fluffy consistency.
The albumen is the healthiest bit of the egg.
Beaten egg whites are used in desserts such as meringues and mousse. Ground egg shells are sometimes used as a food additive to deliver calcium.
Boiled eggs that are difficult to peel are usually too fresh. Fresh eggs have a lower pH, and this does not allow the shell to separate easily from the underlying albumen. When put into vinegar the shell will disintegrate slowly.
Flavour
Although the age of egg and the conditions of its storage have a greater influence, the bird's diet does affect the flavour of egg.
For example, when a brown-egg chicken breed eats rapeseed or soy meals, its intestinal microbes metabolize them into fishy-smelling triethylamine, which ends up in the egg.The unpredictable diet of free-range hens will produce unpredictable eggs.
Problems with cooking
If a boiled egg is overcooked, a greenish ring sometimes appears around egg yolk. This is a manifestation of the iron and sulphur compounds in the egg. It can also occur when there is an abundance of iron in the cooking water.
The green ring does not affect the egg's taste; overcooking, however, harms the quality of the protein (chilling the egg for a few minutes in cold water until the egg is completely cooled prevents the greenish "ring” from forming on the surface of the yolk).
Cooking also increases the risk of atherosclerosis due to increased oxidization of the cholesterol contained in the egg yolk.
Substitutes
For those who do not consume eggs, alternatives used in baking include other rising agents or binding materials, such as ground flax seeds or potato flour. Tofu can also act as a partial binding agent, since it is high in lecithin due to its soy content.
Applesauce can be used as well as arrowroot.
Extracted soybean lecithin, in turn, is often used in packaged foods as an inexpensive substitute for egg-derived lecithin.
Other egg substitutes are made from just the white of the egg for those who worry about the high cholesterol and fat content in eggs. These products usually have added vitamins and minerals as well as vegetable-based emulsifiers and thickeners such as xantham gum or guar gum. These allow the product to maintain the nutrition found in an egg as well as several culinary properties of real eggs.
This makes it possible for food like Hollandaise sauce, custard, mayonnaise, as well as most baked goods to be prepared using these substitutes.
Preservation
The simplest method to preserve egg is treating it with salt. Salt draws water out of bacteria and molds, which prevents their growth. The Chinese salted duck egg is made by immersing duck eggs in brine, or coating them individually with a paste of salt and mud or clay. The eggs stop absorbing salt after about a month, having reached chemical equilibrium. Their yolks become an orange-red coloured solid, but the white remains liquid. They are boiled before consumption, and usually served with rice congee.
Another method is to make pickled eggs, by boiling them first and immersing them in a mixture of vinegar, salt, and spices like ginger or allspice.
Frequently, beetroot juice is added to impart a red colour to the eggs.
If the eggs are immersed in it for a few hours, the distinct red, white, and yellow colours can be seen when the eggs are sliced. If marinated for several days or more, the red colour will reach to the yolk.
If the eggs are marinated in the mixture for several weeks or more, vinegar's acetic acid will dissolve much of the shell's calcium carbonate and penetrate the egg, making it acidic enough to inhibit the growth of bacteria and moulds.
Pickled eggs made this way will generally keep for a year or more without refrigeration.
A Century egg or thousand-year-old egg is preserved by fermenting an egg in a mixture of clay, wood ash, salt, lime, and rice straw for several weeks to several months, depending on the method of processing.
After the process is completed, the yolk becomes a dark green, cream-like substance with a strong odour of sulphur and ammonia, while the white becomes a dark brown, transparent jelly with little flavour or taste.
The transforming agent in century egg is it's alkaline material, which gradually raises the pH of egg from around 9 to 12 or more.
This chemical process causes an "inorganic version" of fermentation, which breaks down some of the complex, flavourless proteins and fats of the yolk into simpler, flavourful ones
Each egg has an air pocket, nature included this air pocket so that the tiny, developing chick could breathe. However, when eggs are for consumption rather than hatching, they are cooled and stored and their water content starts to evaporate, and the air pocket gets bigger.
It follows, therefore that, generally speaking, the larger the air pocket the staler the egg. (I say generally because sometimes a hairline crack, invisible to the human eye, can let air into a very fresh egg: but this is distinctly rare.)
The freshness of an egg is very important in cooking.
Stale eggs, with their flat yolks and watery whites, spread themselves miserably to all corners of the frying pan. Not to mention the ones whose yolks in poaching water completely part company with their whites – while the whites in turn are reducing the water to a mass of foaming bubbles.
Size:
We are now back to size descriptions, which are descibed in the following link Chicken egg sizes
The eggs now available are:
Organic
Produced in the same way as free-range but, in this case, the hens’ habitat is land that has been certified as free from herbicides and pesticides (as is the land on which their feed has been grown)
Free-range
Means the hens have continuous daytime access to open-air runs that contain Vegetation
Barn or Perchery
Means the hens are enclosed but have floor space covered in straw, or other materials;
Finally, the remaining eggs are all produced in battery units
These eggs have paler yolks and are very cheap to buy
In commercial intensive farming:
Hens of special laying breeds may produce as many as 300 eggs a year. After 12 months, the hen's egg-laying ability starts to decline, and commercial laying hens are then slaughtered and used in baby foods, pet foods, pies and other processed foods.
Shell Colour:
Egg shell colour is caused by pigment deposition during egg formation in the oviduct and can vary according to species and breed, from the more common white or brown to pink or speckled blue-green.
In general, chicken breeds with white ear lobes lay white eggs, whereas chickens with red ear lobes lay brown eggs.
Although there is no significant link between shell colour and nutritional value, there is often a cultural preference for one colour over another.
For example, in most regions of the United States, chicken eggs are generally white; while in the northeast of that country and in the United Kingdom, they are generally light-brown.
In Brazil and Poland, white chicken eggs are generally regarded as industrial, and brown or reddish ones are preferred.
Yolk
The yolk in a newly laid egg is round and firm. As the yolk ages it absorbs water from the albumen which increases its size and causes it to stretch and weaken the vitelline membrane (the clear casing enclosing the yolk). The resulting effect is a flattened and enlarged yolk shape.
Yolk colour is dependent 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 (like those produced in battery farmed eggs). Farmers may enhance yolk colour with artificial pigments, or with natural supplements rich in lutein (marigold petals are a popular choice), but in most locations, this activity is forbidden.
Air cell (inside egg at the large end)
The larger end of the egg contains the air cell that forms when the contents of the egg cool down and contract after it is laid.
Chicken eggs are graded according to the size of this air cell, measured during candling. A very fresh egg has a small air cell and receives a grade of AA.
As the size of the air cell increases, and the quality of the egg decreases, the grade moves from AA to A to B.
This provides a way of testing the age of an egg: as the air cell increases in size, the egg becomes less dense and the larger end of the egg will rise to increasingly shallower depths when the egg is placed in a bowl of water.
A very old egg will actually float in the water and should not be eaten
Abnormalities
Some hens will lay double-yoked eggs as the result of unsynchronised production cycles. Although heredity causes some hens to have a higher propensity to lay double-yoked eggs, these occur more frequently as occasional abnormalities in young hens beginning to lay.
Usually a double-yoked egg will be longer and thinner than an ordinary single-yolk egg.
Double-yoked eggs occur rarely, only leading to observed successful hatching under human intervention, as the unborn chickens would otherwise fight each other and die.
It is also possible for a young hen to produce an egg with no yolk at all. Yolk less eggs are usually formed about a bit of tissue that is sloughed off the ovary or oviduct. This tissue stimulates the secreting glands of the oviduct and a yolk less egg results
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