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Chicken egg is the content of the hard-shelled reproductive body produced by a chicken, Gallus gallus domesticus Brisson, belonging to the Phasianidae family, considered as food.
While the primary role of the egg obviously is to reproduce the species, most eggs laid by domestic chicken, except those specifically set aside for hatching, are not fertilized but are sold mainly for human consumption.
The structural components of the egg include the shell and shell membranes (10 percent); the albumen or white (60 percent), including the thick albumen, the outer thin albumen, the inner thin albumen, and the chalazae; and the yolk (30 percent).
An egg is designed by nature to provide protein, vitamins and minerals for the developing chick. In a fertilized egg the yolk supplies the nutrients and the albumen supplies the water necessary for the development of the embryo. In addition, the layers of albumen act as a cushion to protect the embryo from jarring movements, while the chalazae help to maintain the orientation of the embryo within the egg.
Chicken eggs represent the bulk of egg production in the United States and Europe.
Fresh eggs are gathered on automatic collection belts at the farm and stored in a cooler at about 7¢X C. The eggs are then delivered to a central processing plant, where they are washed, sanitized, and graded. Grading involves the sorting of eggs into size and quality categories using automated machines.
Flash candling (passing the eggs over a strong light source) detects any abnormalities such as cracked eggs and eggs containing bloodspots or other defects. Higher-grade eggs have a thick, upstanding white, an oval yolk, and a clean, smooth, unbroken shell.
In the United States eggs are sized on the basis of a minimum weight per dozen in ounces. One dozen extra large eggs weigh 27 ounces; large eggs, 24 ounces; medium eggs, 21 ounces. Weight standards in other countries vary, but most are measured in metric units. For example, eggs might be sold in cartons of 10 eggs each.
Most eggs sold in modern supermarkets are approximately four to five days old. If kept refrigerated by the consumer, they will maintain good quality and flavor for about four weeks.
The shell color of the egg comes in white or brown. They are nutritionally identical. The shell color merely indicates the variety of chicken which laid the egg. Yolk color may be more intense from a free-range chicken than from a battery chicken, depending on what it has eaten. The color of yolk is due to carotenoids in the chicken's diet.
Also known as Hen's Egg.
See also Food, Animals, Birds and Meat, Chicken. |
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| Properties: |
Chicken egg: sweet in flavor, mild in nature, it is related to the channel of the lung;
egg white: sweet in flavor, cool in nature;
egg yolk: sweet in flavor, warm in nature. |
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| Functions: |
Chicken egg as a whole is a very strong tonic. It nourishes the blood and yin (body fluids), protects the foetus, and calms wind. For those cases at the convalescent stage of diseases, such as febrile (hot) disease, anemia (too few red blood cells in the bloodstream), yin deficiency, wounds and consumption disorders, chicken's egg is the most ideal nutrient due not only to its high nutritious contents, but also to its digestibility. In Chinese concept, eggs are believed to be "warming," and are given to nourish the elderly and the weak.
Key benefits of eggs are that they provide vitamin D to help the body to absorb calcium; eggs may improve male fertility, and may prevent damage to blood vessels. Eggs also help to keep nerves in working order.
Egg shell, when used in powder form, is good at stopping abdominal pain, rickets (caused by deficiency of vitamin D) in children and osteomalacia (painful softening of the bones, due to deficiency of vitamin D and calcium) in adults. The inner membranous layer (called "phoenix cloth" in traditional pharmacology) nourishes yin and benefits the lung, and is applied in chronic coughing and hoarseness. |
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| Applications: |
Chicken egg is used for febrile disease, depression, dry cough, hoarseness, pink eyes, sore throat, insecure foetus, thirst after childbirth, diarrhea, malaria, burns, skin diseases.
1. For malaria:
Boil appropriate amount of bittern water (12-15 ml for adult, 3-5 ml for children younger than 5 years old, 5-8 ml for 5-9 years old, 9-11 ml for 10-18 years old). Crush 2 egg shells and put into the boiling bittern. Stir thoroughly until it becomes a pie. Administer immediately. It is reported in 'Eating Your Way to Health' that out of 66 cases thus treated, 44 were cured for escaping the coming malarial episode. Fifty-six cases were examined for follow-up. All but 3 cases revealed no relapsing.
2. For eczema and psoriasis (chronic, scaly skin disease):
First sterilize 2 eggs with ethyl alcohol. Place in a jar only slightly larger than the eggs. Add vinegar until the eggs are totally covered. Seal the jar and let stand for a week. Then break the shell and pour the egg white and egg yolk into another sterilized jar and seal. Now, rub the skin lesion with a cotton ball dipped in the prepared egg, several times a day. It is advisable not to discontinue the therapy. According to 'Eating Your Way for Health', nine cases out of 12 with eczema were cured, with the other 3 cases improved. Two out of 5 cases with psoriasis were also cured. |
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| Dosage and Administration: |
Boil, poach, bake, stir fry, stew, scramble or pickle.
Make into omelettes, souffles and pancakes.
In cooking, make use of an eggs's ability to thicken sauces, bind ingredients, coat foods, and glaze baked foods.
A fresh chicken egg is hard-boiled and pickled in a mixture of vinegar and salt. Raw onion rings may be added for extra flavor. Serve as a snack or as an accompaniment to cold meats.
When buying eggs, look for well-shaped eggs free from blemishes and cracks.
Store eggs in the refrigerator with the pointed ends facing down. |
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| Cautions on Use: |
More than 90 percent of all eggs are free of contamination at the time they are laid.
Contamination with Salmonella bacteria and with certain spoilage organisms occurs essentially afterward. Only one egg in every 7,000 harbors Salmonella bacteria that are passed on by the hen. Proper washing and sanitizing of eggs eliminates most Salmonella and spoilage organisms deposited on the shell. The organism Salmonella enteritidis, a common cause of gastroenteritis (a form of food poisoning), has been found to be transferred through the hen ovary in fewer than 1 percent of all eggs produced. Ovarian-transferred Salmonella enteritidis can be controlled by thorough cooking of eggs (i.e., until there are no runny whites or yolk). People who may be particularly at risk, such as pregnant women, the elderly, and young children, should eat only well-cooked eggs.
Certain spoilage organisms (e.g., Alcaligenes, Proteus, Pseudomonas, and some molds) may produce green, pink, black, colorless, and other rots in eggs after long periods of storage. So, avoid eating eggs that are stored for some time. |
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Chicken egg contains high-quality protein (i.e., proteins that contain all the amino acids needed in the human diet), fat, vitamins A, B1, B2, B6, B12, D and E, and nicotinic acid, minerals, including calcium, phosphorus, iron, folate, selenium. It also contains ovalbumin, ovomucoid, ovomucin, and conalbumin.
One egg supplies more than an adult's daily requirement of vitamin B12.
Chicken eggs are one of the few dietary sources of vitamin D, which the body needs to absorb calcium to create and maintain strong bones. Most of the body's vitamin D is made under the skin through the action of sunlight. The body can store it, and most people make enough during the summer to last the winter. Children up to three years old, who have not built up reserves, need an extra 7 mcg a day, people over 65 need 10 mcg, and pregnant women need 10 mcg in the last three months of gestation. People who do not get enough exposure to the sun also need extra vitamin D. The intakes can be improved by including more eggs in the diet.
Eggs have traditionally been a symbol of fertility in many cultures, and modern science has confirmed the rationale of such belief. Research has revealed that men require a good intake of selenium to ensure high sperm quality and quantity. Intakes in Western Europe are falling, partly due to the use in bread of European soft flours, which are low in selenium, rather than American hard flours, which are relatively rich in this mineral. One egg supplies 10 percent of an adult's recommended daily intake of selenium, and can contribute significantly to overall intakes when eaten regularly as part of a healthy, balanced diet.
Eggs contain both selenium and vitamin E, two nutrients that are known to have antioxidant properties that may reduce the risk of damage to blood-vessel walls and therefore the likelihood of heart disease developing.
Eggs are useful sources of vitamin B12, which is needed for the correct formation of the protective coating around nerves. A lack of B12 can lead to irreversible nerve damage. Pragnant women who have a low intake of vitamin B12 risk damaging their child's nervous system. Eggs also contain vitamin B6 and folate, which are both necessary for healthy nerves.
All the fats, or lipids, as well as the cholesterol are found in the egg yolk. Yolk lipids are high in unsaturated fatty acids, with the ratio of unsaturated to saturated fatty acids commonly being 2 to 1 lecithin, fatty acids and lutein.
By influencing the diet of the hen, some processors are able to market shell eggs with yet a higher ratio of unsaturated to saturated fatty acids. Particular emphasis is being given to increasing the highly unsaturated long-chain omega-3 fatty acids by adding fish oil to the hen feed. Omega-3 fatty acids have been shown to play a role both in normal growth and development and in the prevention of many diseases.
A large egg contains 6-8 g of protein and 5-7 g of fat, of which less than 2 g is saturated. The cholesterol content of a whole large egg is approximately 216 milligrams--a substantially lower figure than that reported before the late 1980s, when improved analytical techniques were instituted. Moreover, the egg industry has probably made some progress in lowering cholesterol content through genetic selection and improved diets.
The concern that eggs raise blood cholesterol is in most cases unfounded, because cholesterol in foods does not have a significant effect on the level of cholesterol in the blood. In fact, the greater health concern is not dietary cholesterol but excessive blood cholesterol manufactured by the liver from saturated fats. Consequently, the relatively high cholesterol content of eggs is only of concern to people who already have raised blood cholesterol levels.
Eating three to four eggs a week, especially in the winter months, may help improve calcium absorption and possibly reduce the risk of osteoporosis (a condition that affects especially older women and is characterized by decrease in bone mass with decreased density and enlargement of bone spaces producing porosity and fragility).
Egg shell contains mainly calcium carbonate, calcium phosphate, magnesium phosphate, with some porphyrin. |
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