Mayonnaise
Mayonnaise (often abbreviated mayo) is a thick condiment made primarily from vegetable oil and egg yolks.  Whitish-yellow in color, it is a stable emulsion formed from the oil and the yolks and is generally flavored with lemon juice and/or vinegar, salt, and sometimes mustard. Numerous other sauces can be created from it by adding additional seasonings (see below).

# History and etymology
One explanation of the origin of the name is that the idea was brought back to France from Mahon, Spain, after Louis-Francois-Armand du Plessis de Richelieu's victory over the British at the city's port in 1756. Later, Marie-Antoine Careme made it lighter by blending the vegetable oil and egg yolks into an emulsion; his recipe then became famous throughout Europe. If this history is correct, allioli (the Balearic version of aioli) would seem to have been the inspiration. 
The name mayonnaise is generally said to have been derived either from Mahon (giving mahonnaise), or from the French word manier (meaning to stir or to blend, giving magnonnaise).
The Larousse Gastronomique 1961 suggests another explanation: "However logical Careme's justification for the exclusive use of the term magnonaise may seem, we are not by any means convinced that it should take the place of the usual form, mayonnaise. Mayonnaise, in our view, is a popular corruption of moyeunaise, derived from the very old French word moyeu, which means yolk of egg. For, when all is said, this sauce is nothing but an emulsion of egg yolks and oil."
Since the name's real origin is unknown, several other explanations exist:
- The sauce may have been christened mayennaise after Charles de Lorraine, duke of Mayenne, because he took the time to finish his meal of chicken with cold sauce before being defeated in the Battle of Arques. Though, this suggestion was first made by the nineteenth-century culinary writer Pierre Lacam.
According to the Oxford English Dictionary, mayonnaise made its English language debut in a cookbook of 1841.
Ambrose Bierce said in his Devil's Dictionary that mayonnaise is "One of the sauces which serve the French in place of a state religion."

# Making mayonnaise
Mayonnaise can be made with an electric mixer, an electric blender, or a food processor, or by hand with a whisk or fork. Mayonnaise is made by slowly adding oil to an egg yolk, while whisking vigorously to disperse the oil. The oil and the water in yolks form a base of the emulsion, while the lecithin from the yolks acts as the emulsifier that stabilizes it. Additionally, a bit of a mustard may also be added to further stabilize the emulsion. Small particles of the mustard serve as nucleation sites for the droplets forming the mayonnaise.

## Traditional recipe
The traditional French recipe is essentially the same as the basic one described above, but it uses top-quality olive oil and sometimes vinegar or lemon juice. Some nouvelle cuisine recipes specify safflower oil. It is considered essential to constantly beat the mayonnaise using a whisk while adding the olive oil a drop at a time, fully incorporating the oil before adding the next tablespoon.  Experienced cooks can judge when the mayonnaise is done by the emulsion's resistance to the beating action.  Mayonnaise made this way may taste too strong or sharp to people accustomed to commercial products.
Overworking the olive oil can make mayonaisse bitter.   Therefore, it is common to use safflower oil to create the initial emulsion, then add olive oil, working it in with a wooden spoon rather than a whisk.

## Vegan mayonnaise
Several brands of soy-based vegan mayonnaises are available, such as Nayonaise and Vegenaise. Vegan mayonnaise can also safely be made at home.

## Composition
Homemade mayonnaise can approach 85% fat before the emulsion breaks down; commercial mayonnaises are more typically 70-80% fat. "Low fat" mayonnaise products contain starches, cellulose gel, or other ingredients to simulate the texture of real mayonnaise.
Some homemade recipes use the whole egg, including the white.  It can also be made using solely egg whites, with no yolks at all, if it is done at high speed in a food processor.  The resulting texture appears to be the same, andif seasoned, for example, with salt, pepper, mustard, lemon juice, vinegar, and a little paprikathe taste is similar to traditional mayonnaise made with egg yolks.
Commercial producers either pasteurize the yolks, freeze them and substitute water for most of their liquid, or use other emulsifiers.  For homemade mayonnaise it is recommended using the freshest eggs possible.  Some stores sell pasteurized eggs for home use.  The eggs can also be coddled in 170F (77C) water, after which the hot yolks, now slightly cooked, are removed from the whites.  Homemade mayonnaise will generally only keep under refrigeration for three to four days.
Mayonnaise has a pH between 3.8 and 4.6, making it an acidic food.  There is a misconception that foods like potato salad can make a person sick if left out in the sun, due to the mayonnaise spoiling.  This is false; the pH of mayonnaise prevents harmful bacteria from growing in it.  Left out of refrigeration, mayonnaise will develop an unappetizing taste and smell, due to other types of bacteria and molds that can spoil it; but will not make one sick. 

# Use of mayonnaise
Worldwide, mayonnaise is most commonly served in a sandwich, or with salad such as potato salad or canned tuna  ("tuna mayo" or tuna salad).  Regional uses are listed below:

## In the United States
Commercial mayonnaise sold in jars originated in New York City, in Manhattan's Upper West Side. In 1905, the first ready-made mayonnaise was sold at Richard Hellmann's delicatessen on Columbus Avenue, between 83rd and 84th Streets. In 1912, Mrs. Hellmann's mayonnaise was mass marketed and called Hellmann's Blue Ribbon Mayonnaise.
At about the same time that Hellmann's Mayonnaise was thriving on the East Coast of the United States, a California company, Best Foods, introduced their own mayonnaise, which turned out to be very popular in the western United States.  Head-to-head competition between the two brands was averted when, in 1932, Best Foods bought out the Hellmann's brand.  By then both mayonnaises had such commanding market shares in their own half of the country that it was decided that both brands be preserved.
In the Southeastern part of the United States, Mrs. Eugenia Duke of Greenville, South Carolina, founded the Duke Sandwich Company in 1917 to sell sandwiches to soldiers training at nearby Fort Sevier. Her homemade mayonnaise became so popular that her company began to focus exclusively on producing and selling the mayonnaise, eventually selling out to the C.F. Sauer Company of Richmond, Virginia, in 1929.  Duke's Mayonnaise, still made to the original recipe, remains a popular brand of mayonnaise in the Southeast, although it is not generally available in other markets.
Reily Foods Company of New Orleans, LA, produces Blue Plate Mayonnaise, an extremely popular mayonnaise in the Southern United States. Formerly owned by Hunt-Wesson and manufactured in New Orleans, LA, Blue Plate Mayonnaise is now produced in Knoxville, TN.
Professional athletes have used mayonnaise as a home remedy for aching joints and an ache blocker. When applied direct to the aching joint it acts as a natural lubricator for overly tense muscle areas.

## Europe
In northern Europe, mayonnaise is often served with French fries, especially in the The Netherlands, Belgium and Germany, as well as increasingly in the United Kingdom, France and Spain.  It is also served with cold chicken or hard-boiled eggs in The Netherlands, France, Poland, Ukraine and the UK.
Guidelines issued in September 1991 by Europe's Federation of the Condiment Sauce Industries recommend that oil and liquid egg yolk levels in mayonnaise should be at least 70% and 5% respectively, although this is not legislated. Most available brands easily exceed this target. 

## Japan
Japanese mayonnaise is typically made with apple cider vinegar or rice vinegar and a small amount of MSG, which gives it a different flavor profile from mayonnaise made from distilled vinegar. It is most often sold in soft plastic squeeze bottles. Its texture is thinner than most Western commercial mayonnaises.  A variety containing karashi (Japanese mustard) is also common.
Apart from salads, it is popular with dishes such as okonomiyaki, takoyaki and yakisoba. It is sometimes served with cooked vegetables, or mixed with soy sauce or wasabi and used as dips. In the Tokai region, it is a frequent condiment on hiyashi chuka (cold noodle salad).
Kewpie (Q.P.) is the most popular brand of Japanese mayonnaise, advertised with a Kewpie doll logo.
People who are known to like mayonnaise are commonly called mayoler () by their friends.

## Russia
Mayonnaise is very popular in Russia where it is made with sunflower seed oil which gives it a very distinctive flavor. A 2004 study showed that Russia is the only market in Europe where more mayonnaise is sold than ketchup by volume. Leading brands are Calve (marketed by Unilever) and Sloboda (marketed by Efko).
Furthermore, in many Russian speaking countries, one can find different commercial flavors of mayonnaise, such as olive, quail-egg, and lemon.

## Chile
Chile is the world's third major per capita consumer of mayonnaise and first in Latin America.  Since mayonnaise became widely accessible in the 1980s Chileans have used it on locos, hot dogs, French fries, and on boiled potatoes.

## As a base for other sauces
Mayonnaise is the base for many other chilled sauces and salad dressings. For example:
- Aioli is often made as an olive-oil mayonnaise with garlic.
- Rouille is aioli with added red pepper or paprika.
- Tartar sauce is mayonnaise spiced with pickled cucumbers and onion.  Capers, olives, and crushed hardboiled eggs are sometimes included. A simpler recipe calls for sweet pickle relish and more lemon juice.
- Some types of Russian dressing (also known as Marie Rose sauce in Europe) combine mayonnaise with tomato sauce or ketchup  and yoghurt  or heavy cream.  In North America, however, most homemade varieties and all commercial brands of Russian dressing use little or no mayonnaise as a base.  They are very dark red and sweet dressings made with vegetable oil, tomato paste, vinegar, sugar, and a variety of herbs and spices (often including mustard).
- Thousand Island dressing is a salmon-pink dressing that combines tomato sauce and/or tomato ketchup or ketchup-based chili sauce, minced sweet pickles or sweet pickle relish, assorted herbs and spices (usually including mustard), and sometimes including chopped hard-boiled eggall thoroughly blended into a mayonnaise base.
- Fry sauce is a mixture of mayonnaise, ketchup or another red sauce (e.g., Tabasco sauce, Buffalo wing sauce, or one of many smokey barbecue sauces popular in the Northwest states), spices, and sometimes a strong tasting salty liquid (such as worchestershire or soy sauce) is added to balance out the sweeter red sauces. Commonly eaten on french fries in Utah,  Idaho, eastern Washington and rural Oregon.
- Mayonesa is a lime-flavored mayonnaise, usually found in Mexican or Spanish grocers in North America.
- Sauce remoulade, in classic French cuisine is mayonnaise to which has been added mustard, gherkins, capers, parsley, chervil, tarragon, and possibly anchovy essence. An industrially made variety is popular in Denmark with french fries and fried fish. It is quite different from most of the remoulade sauces that are frequently found in Louisiana and generally do not have a mayonnaise base.
- Ranch dressing is made of buttermilk or sour cream, mayonnaise, and minced green onion, along with other seasonings.

# Notes
-  "Mayonnaise is an emulsion of oil droplets suspended in a base composed of egg yolk, lemon juice or vinegar, water, and often mustard, which provide both flavor and stabilizing particles and carbohydrates." On Food and Cooking, Harold McGee, Scribner, New York, 2004.
-  David, E. (1960). "French Provincial Cooking" (1999 edition) p.120
-  A more usual definition of moyeu, from Mallarme.net: "Partie centrale de la roue ou semboitent les rais, et par ou passe lessieu. "Mais de ce que les moyeux des roues de votre carrosse auront pris feu, sensuit-il que votre carrosse nait pas ete fait expressement pour vous porter dun lieu a un autre?" Voltaire, Dictionnaire Philosophique, "Causes finales."  Translation: "Central part of the wheel, where the spokes are housed, through which the axle passes." A fourteenthth-century surgeon, Guy de Chauliac, did use moyeu to mean yolk of the egg: "Oeufs sont temperez : toutes fois l'aulbin tire a froideur, et le moyeu   a la chaleur, avec sedation." ("Eggs are tempered, for albumen tends to "cooling" and the yolk tends to "heating", in the Four humours theory. The word moyeu would have been pronounced quite close to "mayo".
-  The page reference has not been identified; the passage appeared either in Lacam's Memorial historique et geographie de la patisserie (privately printed, Paris 1908), in  his Nouveau patissier glacier francais et etranger (1865) or his Glacier classique et artistique en France et en Italie, (1893).
-  Egg-Free Vegan Mayonnaise Recipe
-  Happy Birthday, Dear Mayo - We Hold You Dear : NPR
-  See, for example, Larousse Gastronomique, 2003, ISBN 0 600 60863 8, page 1054.