Monday, December 6, 2010

Healthy Fruit: Tomato

The tomato is a savory, typically red, edible fruit, as well as the plant (Solanum lycopersicum) which bears it. Originating in South America, the tomato was spread around the world following the Spanish colonization of the Americas, and its many varieties are now widely grown, often in greenhouses in cooler climates. The tomato fruit is consumed in diverse ways, including raw, as an ingredient in many dishes and sauces, and in drinks. While it is botanically a fruit, it is considered a vegetable for culinary purposes, which has caused some confusion. The fruit is rich in lycopene, which may have beneficial health effects.
The tomato belongs to the nightshade family. The plants typically grow to 1–3 metres (3–10 ft) in height and have a weak, woody stem that often vines over other plants. It is a perennial, although often grown outdoors in temperate climates as an annual.
The tomato is native to South America. Genetic evidence shows the progenitors of tomatoes were herbaceous green plants with small green fruit and a center of diversity in the highlands of Peru. One species, Solanum lycopersicum, was transported to Mexico where it was grown and consumed by Mesoamerican civilizations. The exact date of domestication is not known. The first domesticated tomato may have been a little yellow fruit, similar in size to a cherry tomato, grown by the Aztecs of Central Mexico. Aztec writings mention tomatoes were prepared with peppers, corn and salt. The word tomato comes from the Aztec tomatl, literally "the swelling fruit".
The tomato is now grown worldwide for its edible fruits, with thousands of cultivars having been selected with varying fruit types, and for optimum growth in differing growing conditions. Cultivated tomatoes vary in size from tomberries, about 5mm in diameter, through cherry tomatoes, about the same 1–2 centimetres (0.4–0.8 in) size as the wild tomato, up to beefsteak tomatoes 10 centimetres (4 in) or more in diameter. The most widely grown commercial tomatoes tend to be in the 5–6 centimetres (2.0–2.4 in) diameter range. Most cultivars produce red fruit; but a number of cultivars with yellow, orange, pink, purple, green, black, or white fruit are also available. Multicolored and striped fruit can also be quite striking. Tomatoes grown for canning and sauces are often elongated, 7–9 centimetres (3–4 in) long and 4–5 centimetres (1.6–2.0 in) diameter; they are known as plum tomatoes, and have a lower water content.
About 130 million tons of tomatoes were produced in the world in 2008. China, the largest producer, accounted for about one quarter of the global output, followed by United States and Turkey. For one variety, known as plum or processing tomatoes, California accounts for 90% of U.S. production and 35% of world production. There are many (around 7500) tomato varieties grown for various purposes. Tomato varieties are roughly divided into several categories, based mostly on shape and size.
  • "Slicing" or "globe" tomatoes are the usual tomatoes of commerce, used for a wide variety of processing and fresh eating.
  • Beefsteak tomatoes are large tomatoes often used for sandwiches and similar applications. Their kidney-bean shape, thinner skin, and shorter shelf life makes commercial use impractical.
  • Oxheart tomatoes can range in size up to beefsteaks, and are shaped like large strawberries.
  • Plum tomatoes, or paste tomatoes (including pear tomatoes), are bred with a higher solid content for use in tomato sauce and paste and are usually oblong.
  • Pear tomatoes are obviously pear shaped and based upon the San Marzano types for a richer gourmet paste.
  • Cherry tomatoes are small and round, often sweet tomatoes generally eaten whole in salads.
  • Grape tomatoes, a more recent introduction, are smaller and oblong, a variation on plum tomatoes, and used in salads.
  • Campari tomatoes are also sweet and noted for their juiciness, low acidity, and lack of mealiness. They are bigger than cherry tomatoes, but are smaller than plum tomatoes.
Early tomatoes and cool-summer tomatoes bear fruit even where nights are cool, which usually discourages fruit set. There are also varieties high in beta carotenes and vitamin A, hollow tomatoes and tomatoes which keep for months in storage. Tomatoes that are not yet ripe are optimally stored at room temperature uncovered, out of direct sunlight, until ripe. In this environment, they have a shelf life of 3 to 4 days. When ripe, they should be used 1 to 2 days. Tomatoes should only be refrigerated when well ripened, but this will affect flavor.
The tomato is now grown and eaten around the world. It is used in diverse ways, including raw in salads, and processed into ketchup or tomato soup. Unripe green tomatoes can also be breaded and fried, used to make salsa, or pickled. Tomato juice is sold as a drink, and is used in cocktails such as the Bloody Mary. Tomatoes are acidic, making them especially easy to preserve in home canning whole, in pieces, as tomato sauce or paste. The fruit is also preserved by drying, often in the sun, and sold either in bags or in jars with oil.
Tomatoes are used extensively in Mediterranean cuisine, especially Italian and Middle Eastern cuisines. They are a key ingredient in pizza, and is commonly used in pasta sauces. They are also used in gazpacho (Spanish cuisine) and pa amb tomaquet (Catalan cuisine). Though it is botanically a berry, a subset of fruit, the tomato is a vegetable for culinary purposes, because of its savory flavor.
Fruit or Vegetable ?
Botanically, a tomato is a fruit: the ovary, together with its seeds, of a flowering plant. However, the tomato has a much lower sugar content than other fruits, and is therefore not as sweet. Typically served as part of a salad or main course of a meal, rather than at dessert, it is considered a vegetable for most culinary purposes. One exception is that tomatoes are treated as a fruit in home canning practices: they are acidic enough to be processed in a water bath rather than a pressure cooker as "vegetables" require. Tomatoes are not the only foodstuff with this ambiguity: eggplants, cucumbers, and squashes of all kinds (such as zucchini and pumpkins) are all botanically fruits, yet cooked as vegetables.
Tomatoes have been designated the state vegetable of New Jersey. Arkansas took both sides by declaring the "South Arkansas Vine Ripe Pink Tomato" to be both the state fruit and the state vegetable in the same law, citing both its culinary and botanical classifications. In 2009, the state of Ohio passed a law making the tomato the state's official fruit. Tomato juice has been the official beverage of Ohio since 1965. A.W. Livingston, of Reynoldsburg, Ohio, played a large part in popularizing the tomato in the late 19th century, his efforts are commemorated in Reynoldsburg with an annual Tomato Festival. In 2001 the Council of the European Union in a directive stated that tomatoes should be considered fruits.
Tomatoes are now eaten freely throughout the world, and their consumption is believed to benefit the heart among other things. They contain lycopene, one of the most powerful natural antioxidants. In some studies lycopene, especially in cooked tomatoes, has been found to help prevent prostate cancer but other research contradicts this claim. Lycopene has also been shown to improve the skin's ability to protect against harmful UV rays. Natural genetic variation in tomatoes and their wild relatives has given a genetic treasure trove of genes that produce lycopene, carotene, anthocyanin, and other antioxidants. Tomato varieties are available with double the normal vitamin C (Doublerich), 40 times normal vitamin A (97L97), high levels of anthocyanin (P20 Blue), and two to four times the normal amount of lycopene (numerous available cultivars with the high crimson gene).
Tomato consumption has been associated with decreased risk of breast cancer, head and neck cancers and might be strongly protective against neurodegenerative diseases.
Red Tomatoes, raw : Nutritional value per 100 g (3.5 oz)
Energy 75 kJ (18 kcal) | Carbohydrates 4 g
Sugars 2.6 g | Dietary fiber 1 g
Fat 0.2 g | Protein 1 g | Water 95 g
Vitamin C 13 mg (22%)
Percentages are relative to US recommendations for adults.
Source: USDA Nutrient database

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