Encyclopedia Of Foods

Vegetables 247OnionThe onion is a round or oval bulb that grows in multiplelayers underground and is covered by a dry, papery skinat maturity. Its flavor can range from mildand sweet to sharp and pungent.Family AmaryllidaceaeScientific name Allium cepaCommon name onion♥ Contains phytochemicals thatpromote healthVarietiesThe two main varieties of onion are freshonions and dry onions. Scallions (alsocalled green onions), the most commontype of fresh onion, are pulled up beforethe bulb forms. Sweet onions, anothertype of fresh onion, grown in warmerclimates, are harvested and sold duringthe spring and summer. They are characterizedby a light-colored, thin skin anda high water and sugar content, whichgives them a mild, sweet flavor. The mostpopular sweet onions are the mild Mauifrom Hawaii, the juicy Vidalia fromGeorgia, and the round, golden Walla-Walla from Washington State.Dry onions, also called storage onions,are grown in cooler northern states andare available year-round. They have adarker, thicker skin, a firmer texture, anda stronger, more pungent flavor. Theyrange from white to yellow and red.Smaller varieties of dry onions includethe marble-sized pearl onions and theslightly larger boiling onions. Althoughred onions tend to be sweeter than yellowor white onions, the flavor of dry onionsis influenced more by variety and originthan by color.Origin & botanical factsOnions were grown by the ancientEgyptians, who regarded them as sacred.From Egypt, onions were brought toRome, where they acquired their currentname, derived from the Latin unio, meaning“large pearl.” Christopher Columbusbrought the onion from Europe to theAmericas. Today, onions are among theworld’s leading vegetable crops.Onion plants are propagated fromseeds or from seedlings and are plantedon raised beds, in fertile, well-balancedsoil. They are hardy plants, able towithstand temperatures as low as 20°Fahrenheit, and are generally planted inearly spring, 4 to 6 weeks before the lastspring freeze. When first planted, youngonions concentrate their growth on newroots and green leaves or tops. Bulb formationdoes not begin until the rightcombination of daylight, darkness, andtemperature is achieved.UsesFresh onions should be refrigerated andused soon after purchase, but dry (storage)onions can be kept in a cool, dry placefor weeks, or even months, without losingtheir nutrients. The onion’s flavor andodor result primarily from sulfuric compounds.When the onion is peeled andsliced, these are released as vapors, causingthe eyes to tear. Chilling the onion beforeuse or peeling it under cold water canalleviate this problem. Onions can beserved raw or cooked and can be added tonumerous other foods as a flavoring.Cooking onions tends to soften them andremoves any sharpness from the flavor.However, because heat makes onionsbitter, they should be cooked over low tomedium heat. Onions can be boiled,steamed, baked, sautéed, scalloped, orgrilled.Nutrient CompositionRaw onions contain phytochemicals thatinclude antioxidants, which promotehealth.Nutrient Content1/2 cup raw,chopped, or 1medium (80 g)Energy (kilocalories) 30Water (%) 90Dietary fiber (grams) 1Fat (grams) 0Carbohydrate (grams) 7Protein (grams) 1Minerals (mg)Calcium 16Iron 0Zinc 0Manganese 0Potassium 126Magnesium 8Phosphorus 26Vitamins (mg)Vitamin A0 REVitamin C 5Thiamin 0Riboflavin 0Niacin 0Vitamin B 6 0.1Folate15 μgVitamin E 0