Egg white

Egg white

Overview
Egg white is the common name for the clear liquid (also called the albumen or the glair/glaire) contained within an egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

. In chicken
Chicken
The chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird...

s it is formed from the layers of secretions of the anterior section of the hen's oviduct
Oviduct
In non-mammalian vertebrates, the passageway from the ovaries to the outside of the body is known as the oviduct. The eggs travel along the oviduct. These eggs will either be fertilized by sperm to become a zygote, or will degenerate in the body...

 during the passage of the egg. It forms around either fertilized or unfertilized egg yolk
Egg yolk
An egg yolk is a part of an egg which feeds the developing embryo. The egg yolk is suspended in the egg white by one or two spiral bands of tissue called the chalazae...

s. The primary natural purpose of egg white is to protect the yolk and provide additional nutrition for the growth of the embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...

 (when fertilized).

Egg white consists primarily of about 10% protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

s (including albumin
Albumin
Albumin refers generally to any protein that is water soluble, which is moderately soluble in concentrated salt solutions, and experiences heat denaturation. They are commonly found in blood plasma, and are unique to other blood proteins in that they are not glycosylated...

s, mucoprotein
Mucoprotein
A mucoprotein is a glycoprotein composed primarily of mucopolysaccharides. It can be found in the synovial fluid of the knees....

s, and globulin
Globulin
Globulin is one of the three types of serum proteins, the others being albumin and fibrinogen. Some globulins are produced in the liver, while others are made by the immune system. The term globulin encompasses a heterogeneous group of proteins with typical high molecular weight, and both...

s) dissolved in water, which makes up the other 90%.
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Encyclopedia
Egg white is the common name for the clear liquid (also called the albumen or the glair/glaire) contained within an egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

. In chicken
Chicken
The chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird...

s it is formed from the layers of secretions of the anterior section of the hen's oviduct
Oviduct
In non-mammalian vertebrates, the passageway from the ovaries to the outside of the body is known as the oviduct. The eggs travel along the oviduct. These eggs will either be fertilized by sperm to become a zygote, or will degenerate in the body...

 during the passage of the egg. It forms around either fertilized or unfertilized egg yolk
Egg yolk
An egg yolk is a part of an egg which feeds the developing embryo. The egg yolk is suspended in the egg white by one or two spiral bands of tissue called the chalazae...

s. The primary natural purpose of egg white is to protect the yolk and provide additional nutrition for the growth of the embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...

 (when fertilized).

Egg white consists primarily of about 10% protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

s (including albumin
Albumin
Albumin refers generally to any protein that is water soluble, which is moderately soluble in concentrated salt solutions, and experiences heat denaturation. They are commonly found in blood plasma, and are unique to other blood proteins in that they are not glycosylated...

s, mucoprotein
Mucoprotein
A mucoprotein is a glycoprotein composed primarily of mucopolysaccharides. It can be found in the synovial fluid of the knees....

s, and globulin
Globulin
Globulin is one of the three types of serum proteins, the others being albumin and fibrinogen. Some globulins are produced in the liver, while others are made by the immune system. The term globulin encompasses a heterogeneous group of proteins with typical high molecular weight, and both...

s) dissolved in water, which makes up the other 90%. Unlike the yolk, which is high in lipid
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...

s (fats), egg white contains almost no fat, and carbohydrate
Carbohydrate
A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...

 content is less than 1%.

Egg white has many uses in food
Egg (food)
Eggs are laid by females of many different species, including birds, reptiles, amphibians, and fish, and have probably been eaten by mankind for millennia. Bird and reptile eggs consist of a protective eggshell, albumen , and vitellus , contained within various thin membranes...

 (e.g. mousse
Mousse
Mousse is derived from the French word mousse which means "lather" or "foam". A mousse is a prepared food that incorporates air bubbles to give it a light and airy texture...

) and also many other uses (e.g. in the preparation of vaccine
Vaccine
A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe or its toxins...

s such as those for influenza).

Composition


The egg white is about two-thirds of the total egg's weight out of its shell, with nearly 92% of that weight coming from water. The remaining weight of the egg white comes from protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

, trace mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...

s, fatty material, vitamin
Vitamin
A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. In other words, an organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on...

s, and glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

. A raw U.S. large egg white weighs 33 grams with 3.6 grams of protein, 0.24 grams of carbohydrate
Carbohydrate
A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...

 and 55 milligrams of sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

. It also contains about 17 kcalories
Calorie
The calorie is a pre-SI metric unit of energy. It was first defined by Nicolas Clément in 1824 as a unit of heat, entering French and English dictionaries between 1841 and 1867. In most fields its use is archaic, having been replaced by the SI unit of energy, the joule...

 and no cholesterol
Cholesterol
Cholesterol is a complex isoprenoid. Specifically, it is a waxy steroid of fat that is produced in the liver or intestines. It is used to produce hormones and cell membranes and is transported in the blood plasma of all mammals. It is an essential structural component of mammalian cell membranes...

. It contains approximately 40 different proteins. Below is a list of the proteins found in egg whites by percentage, along with their natural functions.
  • 54% Ovalbumin
    Ovalbumin
    Ovalbumin is the main protein found in egg white, making up 60-65% of the total protein. Ovalbumin displays sequence and three-dimensional homology to the serpin superfamily, but unlike most serpins it is not a serine protease inhibitor...

     - Nourishment; blocks digestive enzymes
  • 12% Ovotransferrin
    Ovotransferrin
    Ovotransferrin is a glycoprotein of egg white albumen. Transferrins are iron binding proteins and acute phase reactants of animal serum. The sequence of ovotransferrin is similar to that observed for serum transferrin in many species. However, structurally this protein differs from its serum...

     - Binds iron
  • 11% Ovomucoid - Blocks digestive enzymes
  • 4% Ovoglobulin G2
  • 4% Ovoglobulin G3
  • 3.5% Ovomucin
    Ovomucin
    Ovomucin is a trypsin inhibitor found in raw egg white.Ovomucin has nine disulfide bonds....

  • 3.4% Lysozyme
    Lysozyme
    Lysozyme, also known as muramidase or N-acetylmuramide glycanhydrolase, are glycoside hydrolases, enzymes that damage bacterial cell walls by catalyzing hydrolysis of 1,4-beta-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in a peptidoglycan and between...

  • 1.5% Ovoinhibitor
  • 1% Ovoglycoprotein
  • 0.8% Flavoprotein
    Flavoprotein
    Flavoproteins are proteins that contain a nucleic acid derivative of riboflavin: the flavin adenine dinucleotide or flavin mononucleotide ....

  • 0.5% Ovomacroglobulin
  • 0.05% Avidin
    Avidin
    Avidin is a tetrameric biotin-binding protein produced in the oviducts of birds, reptiles and amphibians deposited in the whites of their eggs. In chicken egg white, avidin makes up approximately 0.05% of total protein...

  • 0.05% Cystatin
    Cystatin
    The cystatins are a family of cysteine protease inhibitors with homology to chicken cystatin. Cystatins typically comprise about 115 amino acids, are largely acidic, contain four conserved cysteine residues known to form two disulfide bonds, may be glycosylated and/or phosphorylated, with...



(Total listed 95.8%)

Egg white foam



The physical stress of beating egg white can create a foam. There are two types of physical stress caused by the beating them with a whisk, the first being that the whisk drags the liquid through itself, creating a force that unfolds the protein molecules. This process is called denaturation
Denaturation (biochemistry)
Denaturation is a process in which proteins or nucleic acids lose their tertiary structure and secondary structure by application of some external stress or compound, such as a strong acid or base, a concentrated inorganic salt, an organic solvent , or heat...

. The second stress comes from the mixing of air into the whites, which causes the proteins to come out of their natural state. These denatured proteins gather together where the air and water meet and create multiple bonds with the other unraveled proteins, and thus become a foam, holding the incorporated air in place. This is because the proteins consist of amino acids; some are hydrophilic (attracted to water) and some are hydrophobic (repelled by water). This process is called coagulation
Flocculation
Flocculation, in the field of chemistry, is a process wherein colloids come out of suspension in the form of floc or flakes by the addition of a clarifying agent. The action differs from precipitation in that, prior to flocculation, colloids are merely suspended in a liquid and not actually...

.

When beating egg whites, they are classified in three stages according to the peaks they form when the beater is lifted: soft, firm, and stiff peaks. Overbeaten eggs take on a dry appearance, and will eventually collapse.

Egg whites will not beat up correctly if they are exposed to any form of fat
Fat
Fats consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. Chemically, fats are triglycerides, triesters of glycerol and any of several fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure...

, such as cooking oil
Cooking oil
Cooking oil is purified fat of plant origin, which is usually liquid at room temperature ....

s or the fats contained in egg yolk
Egg yolk
An egg yolk is a part of an egg which feeds the developing embryo. The egg yolk is suspended in the egg white by one or two spiral bands of tissue called the chalazae...

.

Copper bowl


Copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

 bowls have been used in France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 since the 18th century to stabilize egg foams. The copper in the bowl assists in creating a tighter bond in reactive sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

 items such as egg whites. The bond created is so tight that the sulfurs are prevented from reacting with any other material. A silver plated bowl will have the same result as the copper bowl or a pinch of powdered copper supplement from a health store used in a glass bowl will yield the same result as well. Drawbacks of the copper bowl include the expense of the bowl itself, as well as the fact that the bowls are difficult to keep clean. Copper contamination from the bowl is minimal, as a cup of foam will contain a tenth of one's daily normal intake level.

Adding an acid


Cream of tartar (potassium bitartrate) is an acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...

ic salt that can be used to change the pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

 of the egg white to an acidic range. This has the effect of stabilizing the foam, and is therefore an alternative to using a copper bowl. About 1/8 teaspoon or 0.5 g of cream of tartar should be used per one egg white to create this effect. One-half teaspoon (2 ml) of lemon juice can also be used to create the same results.

Health issues


Although egg whites are prized as a source of low-fat, high-protein nutrition, a small number of people cannot eat them. Egg allergy
Egg allergy
Egg allergy is a type of food allergy. It is a hypersensitivity to dietary substances from the yolk or whites of eggs, causing an overreaction of the immune system which may lead to severe physical symptoms for millions of people around the world....

 is more common among infants than adults, and most children will outgrow it by the age of five. Allergic reaction
Food allergy
A food allergy is an adverse immune response to a food protein. They are distinct from other adverse responses to food, such as food intolerance, pharmacological reactions, and toxin-mediated reactions....

s against egg white are more common than reactions against egg yolks. In addition to true allergic reactions, some people experience a food intolerance to egg whites.

Eggs are susceptible to Salmonella
Salmonella
Salmonella is a genus of rod-shaped, Gram-negative, non-spore-forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm, lengths from 2 to 5 µm, and flagella which grade in all directions . They are chemoorganotrophs, obtaining their energy from oxidation and reduction...

contamination. Thorough cooking eliminates the direct threat [i.e., avoid runny fried eggs], but the threat of cross-contamination remains if people handle contaminated eggs and then touch other foods or items in the kitchen, thus spreading the bacteria.

In August 2010, the FDA ordered the recall of 380 million eggs because of possible Salmonella contamination. The Los Angeles Times reported, "With 380 million eggs under recall, consumers may be anxious about eating any egg or food product containing eggs. Here's the upshot: Thoroughly cooked eggs are safe, but cross-contamination could be a problem."

Uses


Egg white is a fining agent
Finings
FiningsThe term is a mass noun rather than a plural. are substances that are usually added at or near the completion of the processing of brewing wine, beer and various nonalcoholic juice beverages. Their purpose is for removal of organic compounds; to either improve clarity or adjust flavor/aroma...

 that can be used in the clarification and stabilization of wine
Clarification and stabilization of wine
The clarification and stabilization of wine in winemaking involves removing insoluble and suspended materials. The insoluble material causes a wine to be cloudy. These processes may include fining, filtration, centrifugation, flotation, refrigeration, barrel maturation, pasteurization and racking...

.

See also



  • Albumen print
    Albumen print
    The albumen print, also called albumen silver print, was invented in 1850 by Louis Désiré Blanquart-Evrard, and was the first commercially exploitable method of producing a photographic print on a paper base from a negative...

  • Haugh unit
    Haugh unit
    The Haugh unit is a measure of egg protein quality based on the height of its egg white . The test was introduced by Raymond Haugh in 1937 and is an important industry measure of egg quality next to other measures such as shell thickness and strength....

    , a unit of measure for egg albumen

Works cited

  • Elmhurst College
    Elmhurst College
    Elmhurst College is a comprehensive private liberal arts college in Elmhurst, Illinois with a tradition of service-oriented learning. It has a rich affiliation with the United Church of Christ.- History :‎...

    , Denaturation Protein
  • Exploratorium
    Exploratorium
    The Exploratorium is a museum in San Francisco with over 475 participatory exhibits, all of them made onsite, that mix science and art. It also aims to promote museums as informal education centers....

    , Anatomy of an Egg
  • Gilbertus. Compendium Medicine Gilberti Anglici Tam Morborum Universalium Quam Particularium Nondum Medicis Sed & Cyrurgicis Utilissimum. Lugduni: Impressum per Jacobum Sacconum, expensis Vincentii de Portonariis, 1510.
  • Good Eats, Let Them Eat Foam. DVD. Television Food Network, June 13, 2001.
  • McGee, Harold. On Food and Cooking: The Science and Lore of the Kitchen. New York: Scribner, 2004, edited by Vinay.

External links