In the Addison Community Garden, these are onions. The onions we eat are in the ground, and those are onion flowers or about-to-be flowers on top. I never knew onions had flowers. It is amazing the things you can learn in a community garden. I have used white, yellow and red onions in cooking plus shallots and green onions. The one thing I don’t like is the tears onions cause when you are peeling or cutting them. But I solved that problem by purchasing onion goggles. They fit over your eyes just like swimming goggles and keep your eyes from watering! Wonderful invention. There really is nothing better to flavor a dish, whether it is meat or vegetables. I would not use onions in a dessert though. They are more for savory recipes. Onions are versatile. They can be eaten raw, boiled, sautéed, grilled, roasted, baked, broiled, etc. I last used red onion chopped up in a mango and black bean salsa. Chopped white or yellow onions are in my green beans almondine. I even made a baked onion casserole once that was quite tasty. Let’s find out more about this versatile vegetable.
According to Wikipedia, the onion, also known as the bulb onion or common onion, is a vegetable that is the most widely cultivated species of the genus Allium. The shallot is a botanical variety of the onion. Until 2010, the shallot was classified as a separate species.
Its close relatives include garlic, scallion, leek, chive and Chinese onion.
This genus also contains several other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion (Allium fistulosum), the tree onion (A. ×proliferum) and the Canada onion (Allium canadense). The name "wild onion" is applied to many Allium species, but A. cepa is exclusively known from cultivation. Its ancestral wild original form is not known, although escapes from cultivation have become established in some regions. The onion is most frequently a biennial or a perennial plant, but is usually treated as an annual and harvested in its first growing season.
The onion plant has a fan of hollow, bluish-green leaves, and its bulb at the base of the plant begins to swell when a certain day-length is reached. The bulbs are composed of shortened, compressed, underground stems surrounded by fleshy modified scale — leaves — that envelop a central bud at the tip of the stem. In the autumn — or in spring, in the case of overwintering onions — the foliage dies down and the outer layers of the bulb become dry and brittle. The crop is harvested and dried and the onions are ready for use or storage. The crop is prone to attack by a number of pests and diseases, particularly the onion fly, the onion eelworm and various fungi which can cause rotting. Some varieties of A. cepa, such as shallots and potato onions, produce multiple bulbs.
Onions are cultivated and used around the world. As a food item, they are usually served cooked, as a vegetable or part of a prepared savory dish but can also be eaten raw or used to make pickles or chutneys. They are pungent when chopped and contain certain chemical substances which irritate the eyes.
Description
The onion plant has been grown and selectively bred in cultivation for at least 7,000 years. It is a biennial plant but is usually grown as an annual. Modern varieties typically grow to a height of 6 to 18 inches. The leaves are yellowish- to bluish-green and grow alternately in a flattened, fan-shaped swathe. They are fleshy, hollow and cylindrical, with one flattened side. They are at their broadest about a quarter of the way up, beyond which they taper towards a blunt tip. The base of each leaf is a flattened, usually white sheath that grows out of the basal plate of a bulb. From the underside of the plate, a bundle of fibrous roots extends for a short way into the soil. As the onion matures, food reserves begin to accumulate in the leaf bases and the bulb of the onion swells.
In the autumn, the leaves die back and the outer scales of the bulb become dry and brittle, so the crop is then normally harvested. If left in the soil over winter, the growing point in the middle of the bulb begins to develop in the spring. New leaves appear and a long, stout, hollow stem expands, topped by a bract protecting a developing inflorescence. The inflorescence takes the form of a globular umbel of white flowers with parts in sixes. The seeds are glossy black and triangular in cross-section. The average pH of an onion is around 5.5.
History
Because the wild onion is extinct and ancient records of using onions span western and eastern Asia, the geographic origin of the onion is uncertain, although domestication likely took place in Southwest or Central Asia. Onions have been variously described as having originated in Iran, western Pakistan and Central Asia.
Traces of onions recovered from Bronze Age settlements in China suggest that onions were used as far back as 5000 BC, not only for their flavor, but the bulb's durability in storage and transport. Ancient Egyptians revered the onion bulb, viewing its spherical shape and concentric rings as symbols of eternal life. Onions were used in Egyptian burials, as evidenced by onion traces found in the eye sockets of Ramesses IV.
Pliny the Elder of the first century AD wrote about the use of onions and cabbage in Pompeii. He documented Roman beliefs about the onion's ability to improve ocular ailments, aid in sleep and heal everything from oral sores and toothaches to dog bites, lumbago and even dysentery. Archaeologists unearthing Pompeii long after its 79 AD volcanic burial have found gardens resembling those in Pliny's detailed narratives. According to texts collected in the 5th/6th century AD under the authorial aegis of "Apicius" — said to have been a gourmet — onions were used in many Roman recipes.
In the Age of Discovery, onions were taken to North America by the first European settlers, only to discover the plant readily available and in wide use in Native American gastronomy. According to diaries kept by certain of the first English colonists, the bulb onion was one of the first crops planted by the Pilgrim fathers.
Onion types and products
Common onions are normally available in three color varieties:
Yellow or brown onions — called "red" in some European countries — are sweeter and the onions of choice for everyday use in European cuisine, with many cultivars bred specifically to demonstrate this sweetness (Vidalia, Walla Walla, Cévennes, "Bermuda," etc.). Yellow onions turn a rich, dark brown when caramelized and give French onion soup its sweet flavor.
Red or purple onions — "purple" is used in some European countries — are known for their sharp pungent flavor and are the onions of choice for everyday use in Asian cuisine. They are also used raw and in grilling.
White onions are traditional in classic Mexican cuisine and are milder in flavor; they have a golden color when cooked and a particularly sweet flavor when sautéed.
While the large, mature onion bulb is most often eaten, onions can be eaten at immature stages. Young plants may be harvested before bulbing occurs and used whole as spring onions or scallions. When an onion is harvested after bulbing has begun, but the onion is not yet mature, the plants are sometimes referred to as "summer" onions.
Additionally, onions may be bred and grown to mature at smaller sizes. Depending on the mature size and the purpose for which the onion is used, these may be referred to as pearl, boiler or pickler onions, but differ from true pearl onions which are a different species. Pearl and boiler onions may be cooked as a vegetable rather than as an ingredient and pickler onions are often preserved in vinegar as a long-lasting relish.
Onions are available in fresh, frozen, canned, caramelized, pickled and chopped forms. The dehydrated product is available as kibbled, sliced, ring, minced, chopped, granulated and powder forms.
Onion powder is a seasoning widely used when the fresh ingredient is not available. It is made from finely ground, dehydrated onions — mainly the pungent varieties of bulb onions, and has a strong odor. Being dehydrated, it has a long shelf life and is available in several varieties: yellow, red and white.
Culinary uses
Onions are commonly chopped and used as an ingredient in various hearty warm dishes and may also be used as a main ingredient in their own right e.g., in French onion soup, creamed onions, and onion chutney. They are versatile and can be baked, boiled, braised, grilled, fried, roasted, sautéed or eaten raw in salads. Their layered nature makes them easy to hollow out once cooked, facilitating stuffing them, as in Turkish sogan-dolma.
Onions pickled in vinegar are eaten as a snack around the world and as a side serving in pubs and fish and chip shops throughout the United Kingdom and the Commonwealth. They are part of a traditional British pub's ploughman’s lunch, usually served with crusty bread, English cheese and ale.
Similar to garlic, onions can show an additional color – pink-red – after cutting, an effect caused by reactions of amino acids with sulfur compounds.
A blooming onion, onion bloom, onion blossom, onion flower, bloomin' onion or onion mum is a dish consisting of one large onion which is battered, deep-fried and cut to resemble a flower. It is served as an appetizer at some restaurants.
Cebolada is a Portuguese onion stew, onion sauce or paste that is prepared with onion as a primary ingredient. Versions prepared as a paste may be slow-cooked.
Liver and onions is a dish consisting of slices of liver — usually pork, beef or, in the United Kingdom, lamb — and bulb onions; onion is favored as an accompaniment to liver as the sharp flavor of onion "cuts" the somewhat metallic flavor of liver, which can be off-putting to some eaters. The liver and the onions are usually fried or otherwise cooked together, but sometimes they may be fried separately and mixed together afterwards. The liver is often cut in fine slices, but it also may be diced.
Cong you bing, also known as scallion pancake or "green onion pancake," is a Chinese savory unleavened flatbread folded with oil and minced scallions or green onions. Unlike Western pancakes, it is made from dough instead of batter. It is pan-fried which gives it crisp edges yet also a chewy texture. A unique characteristic of scallion pancakes is the many layers that make up the interior, which help contribute to its chewy texture. Variations exist on the basic method of preparation that incorporate other flavors and fillings. Scallion pancakes are served both as a street food item and as a restaurant dish. They are also sold commercially, either fresh or frozen in plastic packages — often in Asian supermarkets.
Zwiebelkuchen — German for "onion cake" — is a savory German one-crust onion cake made of steamed onions, diced bacon, cream and caraway seeds on either a yeast dough or a leavened dough.
Non-culinary uses
Onions have particularly large cells that are readily observed under low magnification. Forming a single layer of cells, the bulb epidermis is easy to separate for educational, experimental and breeding purposes. Onions are therefore commonly used in science education to teach the use of a microscope for observing cell structure.
Onions are toxic to dogs, cats, guinea pigs and many other animals.
Onion skins can be boiled to make an orange-brown dye.
Phytochemicals
Considerable differences exist between onion varieties in phytochemical content, particularly for polyphenols, with shallots having the highest level — six times the amount found in Vidalia onions. Yellow onions have the highest total flavonoid content, an amount 11 times higher than in white onions. Red onions have considerable content of anthocyanin pigments, with at least 25 different compounds identified representing 10% of total flavonoid content.
Onion polyphenols are under basic research to determine their possible biological properties in humans.
Some people suffer from allergic reactions after handling onions. Symptoms can include contact dermatitis, intense itching, rhinoconjunctivitis, blurred vision, bronchial asthma, sweating and anaphylaxis. Allergic reactions may not occur when eating cooked onions, possibly due to the denaturing of the proteins from cooking.
Eye irritation
Freshly cut onions often cause a stinging sensation in the eyes of people nearby and often uncontrollable tears. This is caused by the release of a volatile liquid, syn-propanethial-S-oxide and its aerosol, which stimulates nerves in the eye. This gas is produced by a chain of reactions which serve as a defense mechanism: chopping an onion causes damage to cells which releases enzymes called alliinases. These break down amino acid sulfoxides and generate sulfenic acids. A specific sulfenic acid, 1-propenesulfenic acid, is rapidly acted on by a second enzyme, the lacrimatory factor synthase, producing the syn-propanethial-S-oxide. This gas diffuses through the air and soon reaches the eyes, where it activates sensory neurons. Lacrimal glands produce tears to dilute and flush out the irritant.
Eye irritation can be avoided by cutting onions under running water or submerged in a basin of water. Leaving the root end intact also reduces irritation as the onion base has a higher concentration of sulfur compounds than the rest of the bulb. Refrigerating the onions before use reduces the enzyme reaction rate and using a fan can blow the gas away from the eyes. The more often one chops onions, the less one experiences eye irritation.
The amount of sulfenic acids and lacrimal factor released and the irritation effect differs among Allium species. In 2008, the New Zealand Institute for Crop and Food Research created "no tears" onions by genetic modification to prevent the synthesis of lachrymatory factor synthase or LFS in onions. One study suggests that consumers prefer the flavor of onions with lower LFS content. However, since the LFS-silencing process involves reducing sulfur ingestion by the plant, it has also been suggested that LFS− onions are inferior in flavor.
A method for efficiently differentiating LFS− and LFS+ onions has been developed based on mass spectrometry, with potential application in high-volume production; gas chromatography is also used to measure lachrymatory factor in onions. In early 2018, Bayer released the first crop yield of commercially available LFS-silenced onions under the name "Sunions." They were the product of 30 years of cross-breeding; genetic modification was not employed.
Guinea hen weed and honey garlic contain a similar lachrymatory factor. Synthetic onion lachrymatory factor has been used in a study related to tear production and has been proposed as a nonlethal deterrent against thieves and intruders.
Cultivation
Onions are best cultivated in fertile soils that are well-drained. Sandy loams are good as they are low in sulfur, while clay soils usually have a high sulfur content and produce pungent bulbs. Onions require a high level of nutrients in the soil. Phosphorus is often present in sufficient quantities but may be applied before planting because of its low level of availability in cold soils. Nitrogen and potash can be applied at regular intervals during the growing season, the last application of nitrogen being at least four weeks before harvesting.
Bulbing onions are day-length sensitive; their bulbs begin growing only after the number of daylight hours has surpassed some minimal quantity. Most traditional European onions are referred to as "long-day" onions, producing bulbs only after 14 hours or more of daylight occurs. Southern European and North African varieties are often known as "intermediate-day" types, requiring only 12–13 hours of daylight to stimulate bulb formation. "Short-day" onions, which have been developed in more recent times, are planted in mild-winter areas in the autumn and form bulbs in the early spring and require only 11–12 hours of daylight to stimulate bulb formation. Onions are a cool-weather crop and can be grown in USDA zones 3 to 9. Hot temperatures or other stressful conditions cause them to "bolt," meaning that a flower stem begins to grow.
Onions may be grown from seeds or from partially grown bulbs called “sets.” Because onion seeds are short-lived, fresh seeds germinate more effectively when sown in shallow rows, or "drills," with each drill 12" to 18" apart. As the seedlings emerge and crowd each other, they are progressively thinned until the proper distance — usually 4" to 6" — between each plant is attained. In suitable climates, certain cultivars can be sown in late summer and autumn to overwinter in the ground and produce early crops the following year.
Onion bulbs are produced by sowing seeds in a dense pattern in early summer, then harvested in the autumn when the bulbs are still small, followed by drying and storage. These bulbs planted the following spring grow into mature bulbs later in the growing season. Certain cultivars used for growing and storing bulbs may not have such good storage characteristics as those grown directly from seed.
Routine care during the growing season involves keeping the rows free of competing weeds, especially when the plants are young. The plants are shallow-rooted and do not need much water when established. Bulbing usually takes place after 12 to 18 weeks. The bulbs can be gathered when needed to eat fresh, but if they will be stored, they are harvested after the leaves have died back naturally. In dry weather, they can be left on the surface of the soil for a few days for drying, then placed in nets, roped into strings or laid in layers in shallow boxes. They are stored effectively in a well-ventilated, cool place.
Pests and diseases
Onions suffer from many plant disorders. The most serious for the home gardener are likely to be the onion fly, stem and bulb eelworm, white rot and neck rot. Diseases affecting the foliage include rust and smut, downy mildew and white tip disease. The bulbs may be affected by splitting, white rot and neck rot. Shanking is a condition in which the central leaves turn yellow and the inner part of the bulb collapses into an unpleasant-smelling slime. Most of these disorders are best treated by removing and burning affected plants. The larvae of the onion leaf miner or leek moth sometimes attack the foliage and may burrow down into the bulb.
The onion fly lays eggs on the leaves and stems and on the ground close to onion, shallot, leek and garlic plants. The fly is attracted to the crop by the smell of damaged tissue and is liable to occur after thinning. Plants grown from sets are less prone to attack. The larvae tunnel into the bulbs and the foliage wilts and turns yellow. The bulbs are disfigured and rot, especially in wet weather. Control measures may include crop rotation, the use of seed dressings, early sowing or planting and the removal of infested plants.
The onion eelworm, a tiny parasitic soil-living nematode, causes swollen, distorted foliage. Young plants are killed, and older ones produce soft bulbs. No cure is known, and affected plants should be uprooted and burned. The site should not be used for growing onions again for several years and should also be avoided for growing carrots, parsnips and beans, which are also susceptible to the eelworm.
White rot of onions, leeks and garlic is caused by the soil-borne fungus Sclerotium cepivorum. As the roots rot, the foliage turns yellow and wilts. The bases of the bulbs are attacked and become covered by a fluffy white mass of mycelia, which later produces small, globular black structures called sclerotia. These resting structures remain in the soil to reinfect a future crop. No cure for this fungal disease exists, so affected plants should be removed and destroyed, and the ground
used for unrelated crops in subsequent years.
Neck rot is a fungal disease affecting onions in storage. It is caused by Botrytis allii, which attacks the neck and upper parts of the bulb, causing a grey mold to develop. The symptoms often first occur where the bulb has been damaged and spread downwards in the affected scales. Large quantities of spores are produced and crust-like sclerotia may also develop. In time, a dry rot sets in, and the bulb becomes a dry, mummified structure. This disease may be present throughout the growing period, but only manifests itself when the bulb is in storage. Antifungal seed dressings are available, and the disease can be minimized by preventing physical damage to the bulbs at harvesting, careful drying and curing of the mature onions and correct storage in a cool, dry place with plenty of circulating air.
Storage
Cooking onions and sweet onions are better stored at room temperature, optimally in a single layer, in large mesh bags in a dry, cool, dark, well-ventilated location. In this environment, cooking onions have a shelf life of three to four weeks and sweet onions one to two weeks. Cooking onions will absorb odors from apples and pears. Also, they draw moisture from vegetables with which they are stored which may cause them to decay.
Sweet onions have a greater water and sugar content than cooking onions. This makes them sweeter and milder tasting but reduces their shelf life. Sweet onions can be stored refrigerated; they have a shelf life of around one month. Irrespective of type, any cut pieces of onion are best tightly wrapped, stored away from other produce and used within two to three days.
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