Onion
Encyclopedia : O : ON : ONI : Onion
- For the parody newspaper, see The Onion. For the technique of anonymous computer messaging see Onion Routing.
Onion in the general sense can be used for any plant in the Genus Allium but used without qualifiers usually means Allium cepa, also called the garden onion. Onions (usually but not exclusively the bulbs) are edible with a distinctive strong flavor and pungent odor which is mellowed and sweetened by cooking. They generally have a papery outer skin over a fleshy, layered inner core. Used worldwide for culinary purposes, they come in a wide variety of forms and colors.
Onions may be grown from seed or very commonly from "sets". Onion sets are produced by sowing seed very thickly one year, resulting in stunted plants which produce very small bulbs. These bulbs are very easy to set out and grow into mature bulbs the following year, but they have the reputation of producing a less durable bulb than onions grown directly from seed and thinned.
Either planting method may be used to produce spring onions or green onions, which are just onions harvested while immature, although "green onion" is also a common name for the Welsh onion, Allium fistulosum which never produces dry bulbs.
Onions are frequently used in school science laboratories because they have particularly large cells which are easily visible even through rather low-end optical microscopes.
History
It is thought that bulbs from the onion family have been utilised as a food source for millennia. In Palestinian Bronze Age settlements, traces of onion remains were found alongside fig and date stones dating back to 5000 BC. It would be pure conjecture to suggest these were cultivated onions. The archaeological and literary evidence suggests cultivation probably took place around two thousand years later in ancient Egypt. This happened alongside the cultivation of leeks and garlic and it is thought that workers who built the pyramids were fed radishes and onions.
The onion is easily grown, transportable, and has good storage qualities. Egyptians worshipped it, believing that its spherical shape and concentric rings symbolized eternal life. Onions were even used in Egyptian burials as evidenced by onion traces being found in the eye sockets of Ramesses IV. They believed that if buried with the dead, the strong scent of onions would bring breath back to the dead. The onion then made its way to Greece where athletes ate large quantities of onion because it would lighten the balance of blood. Roman gladiators were also rubbed down with onion to firm up their muscles. In the Middle Ages onions were such an important food that people would pay for their rent with onions and even give onions as gifts. Doctors were also known to prescribe onions to end headaches, snakebites and hair loss. The onion was introduced to North America by Christopher Columbus on his 1493 expedition to Haiti.
Onions are one of the earliest crops mentioned in written text, in the Bible's Book of Numbers (11:5) as part of the Egyptian diet of that time. Six types of onions were known at the time of Pliny the Elder's Natural History.
Onions in India
Onions are a staple food in India, both due to its use as a common base for curries and as the cheapest and most widely available vegetable for the poor. In modern democratic India, "onion crises", (where food prices, but especially onion prices, rise significantly) have been a frequent and contentious political topic . The onion issue has been regarded as decisive in some key political events - the Indian general elections of 1980 were labelled "The Onion Election" by Indira Gandhi, who led her party to a landslide victory attributed in large part to high onion prices. The Indian general elections of 1998 were also given this label in the media. [link] [link][link][link][link][link].Culinary and medicinal uses
Onions are available in fresh, frozen, canned, and dehydrated forms. Onions can be used, usually chopped or sliced, in almost every type of food, including cooked foods and fresh salads, and as a spicy garnish; they are rarely eaten on their own but usually act as accompaniment to the main course.
- Depending on the variety, an onion can be sharp and pungent or mild and even sweet.
- Chopped, it is one of the three vegetables considered the holy trinity of Louisiana Creole and Cajun cuisine.
- Cocktail onions, or pickled pearl onions, are used to garnish drinks such as Gibsons.
In many parts of the undeveloped world, onions are used to heal blisters and boils. In the United States, products that contain onion extract (such as "Mederma") are used in the treatment of topical scars.
Onions and crying
As onions are sliced, cells are broken open. Onion cells have two sections, one with enzymes called alliinases, the other with sulfides (amino acid sulfoxides). The enzymes break down the sulfides and generate sulfenic acids. Sulfenic acids are unstable and decompose into a volatile gas called syn-propanethial-S-oxide. The gas then dissipates through the air and eventually reaches one's eye, where it will react with the water to form a mild solution of sulfuric acid. The sulfuric acid irritates the nerve endings in the eyes, making them sting. The tear glands then produce tears in response to this irritation, to dilute and flush out the irritant.The release of gas can thus best be prevented by cutting the onions under running tap water or completely under water, though this may not be very practical. Wetting the onions and your hands before slicing will lessen the effect, as some of the gas will react with the moisture on the onions and on your skin (instead of the moisture on your eyes). This reaction may result as an odor which may be removed with lemon. It also helps to breathe exclusively through the mouth during the preparation. Using a sharp knife will rupture fewer cells and cause less eye irritation. For more tips and information, please check links in External links section. Chilled onions (onions kept in the fridge for a while) will make you 'cry' less than onions kept at room temperature because lower temperature inhibits the enzymes and gas diffusion. Also, some people 'freeze' the knife (leave it in the freezer for around 2 minutes) before cutting the onions to prevent the tears.
Different species of onions will release different amounts of sulfenic acids, thus some will cause more tear formation and irritation than others.
Types of onion (Allium cepa)
- Bulb onions - Grown from seed (or onion sets), bulb onions range from the pungent varieties used for dried soups and onion powder to the mild and hearty Sweet onions, such as the Vidalia from Georgia or Walla Walla from Washington that can be sliced and eaten on a sandwich instead of meat.
- Multiplier onions - Raised from bulbs which produce multiple shoots, each of which forms a bulb.
- *Shallot (most of the types in the markets are Allium cepa)
- *Potato onion
- Tree onions or Egyptian onions - These produce bulblets in the flower head, and are the result of hybridisation between Allium cepa and welsh onions.
Related species
The genus Allium is a large one, and most of the species are considered to be "onions" in the looser sense. Commonly raised vegetable alliums include the leeks, garlic, elephant garlic, chives, shallots, Welsh onions and Chinese chives. There are also species, such as Allium moly, grown for ornament.Several species of Allium, including A. canadense and A. diabolense, can be collected in the wild and their leaves and bulbs used as food.
External links
Eye Irritation Information
- [How stuff works article on eye irritation by onions]
- [Library of Congress article] (more details on eye irritation)
Eclectic Herbal Information
- [King's American Dispensatory] @ Henriette's Herbal
- [Mrs. Grieve's] "A Modern Herbal" @ Botanical.com
- [Potato Onion (Allium cepa, var. aggregatum)] Mrs. Grieve's "A Modern Herbal" @ Botanical.com
- [Tree Onion (Allium cepa, var. proliferum)] Mrs. Grieve's "A Modern Herbal" @ Botanical.com
Homeopathic Information
- [Allium cepa (all-cep.)] "Kent's Lectures on Homeopathic Materia Medica" by Dr Robert Séror
- [Allium cepa] "A Primer of Materia Medica for practitioners of Homœopathy" by Timothy Allen
See also
References
From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.