Sweet potato

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Sweet Potato
Sweet potato in flower Hemingway, South Carolina
Scientific classification
Kingdom: Plantae Division: Magnoliophyta Class: Magnoliopsida Order: Solanales Family: Convolvulaceae Genus: Ipomoea Species: I. batatas
Binomial name
Ipomoea batatas (L.) Lam.[verification needed]

Raw Sweet Potato Nutritional value per 100 g (3.5 oz)
Energy 90 kcal   360 kJ
Carbohydrates     20.1 g - Sugars  4.2 g - Dietary fiber  3.0 g   Fat 0.1 g Protein 1.6 g Vitamin A equiv.  709 μg  79% - β-carotene  8509 μg  79% Thiamin (Vit. B1)  0.1 mg   8% Riboflavin (Vit. B2)  0.1 mg   7% Niacin (Vit. B3)  0.61 mg   4% Pantothenic acid (B5)  0.8 mg  16% Vitamin B6  0.2 mg 15% Folate (Vit. B9)  11 μg  3% Vitamin C  2.4 mg 4% Calcium  30.0 mg 3% Iron  0.6 mg 5% Magnesium  25.0 mg 7%  Phosphorus  47.0 mg 7% Potassium  337 mg   7% Zinc  0.3 mg 3%
Percentages are relative to US recommendations for adults. Source: USDA Nutrient database

The sweet potato (Ipomoea batatas), commonly though incorrectly called a yam in parts of the United States is a crop plant whose large, starchy, sweet tasting tuberous roots are an important root vegetable. The young leaves and shoots are sometimes eaten as greens. The sweet potato is only distantly related to the potato (Solanum tuberosum). It is even more distantly related to the true yam (Dioscorea species), which is native to Africa and Asia. Thus, a sweet potato and a yam are in fact different foods.

The genus Ipomoea that contains the sweet potato also includes several garden flowers called morning glories, though that term is not usually extended to Ipomoea batatas. Some cultivars of Ipomoea batatas are grown as ornamental plants.

This plant is a herbaceous perennial vine, bearing alternate heart-shaped or palmately lobed leaves and medium-sized sympetalous flowers. The edible tuberous root is long and tapered, with a smooth skin whose color ranges between red, purple, brown and white. Its flesh ranges from white through yellow, orange, and purple.

Contents 1 Origin and distribution 2 Cultivation 2.1 Diseases 3 Nutrition and health benefits 4 Uses 4.1 Culinary uses 4.2 Non-culinary uses 4.3 Biofuel 5 Ethnomedical Uses 6 Names 7 References and external links

[edit] Origin and distribution

Sweet potatoes are native to the tropical parts of the Americas, and were domesticated there at least 5000 years ago. [1] [2] They spread very early throughout the region, including the Caribbean. They were also known before western exploration in Polynesia. How exactly they arrived there is the subject of a fierce debate which involves archaeological, linguistic and genetic evidence.

Sweet potatoes are now cultivated throughout tropical and warm temperate regions wherever there is sufficient water to support their growth.

According to 2004 FAO statistics world production is 127,000,000 tons [3]. The majority comes from China with a production of 105,000,000 tonnes from 49,000 km². About half of the Chinese crop is used for livestock feed [4].

Per-capita production is greatest in countries where sweet potatoes are a staple of human consumption, led by the Solomon Islands at 160 kg per person per year, Burundi at 130 kg and Uganda at 100 kg.

In New Zealand, sweet potato is known by its Māori name, kūmara. It was a staple food for Māori before European contact. Today, it is still very popular, although less popular than regular potatoes. There are about 85 commercial kūmara growers, with 1,220 hectares producing 20,000 tonnes of kūmara annually.

North Carolina, the leading U.S. state in sweet potato production, currently provides 40% of the annual U.S. production of sweet potatoes.

Mississippi is also a major sweet potato producing state, where they are grown on approximately 8,200 acres. Mississippi sweet potatoes contribute $19 million dollars to the economy of the state and around 150 Mississippi farmers presently grow sweet potatoes. Mississippi's top five sweet potato producing counties are Calhoun, Chickasaw, Pontotoc, Yalobusha, and Panola. The National Sweet Potato Festival is held annually the entire first week in November in Vardaman, which proclaims itself as "The Sweet Potato Capital".

The town of Benton, Kentucky celebrates the sweet potato annually with its Tater Day Festival on the first Monday of April. The town of Gleason, Tennessee celebrates the sweet potato on Labor Day weekend with its Tater Town Special.

[edit] Cultivation

The plant does not enjoy frost. It grows best at an average temperature of 24 °C (75 °F), abundant sunshine and warm nights. Annual rainfalls of 750-1000 mm are considered most suitable, with a minimum of 500 mm in the growing season. The crop is sensitive to drought at the tuber initiation stage 50-60 days after planting and is not tolerant to water-logging, as it may cause tuber rots and reduce growth of storage roots if aeration is poor (Ahn, 1993).

Depending on the cultivar and conditions, tuberous roots mature in two to nine months. With care, early-maturing cultivars can be grown as an annual summer crop in temperate areas, such as the northern USA. Sweet potatoes rarely flower when the daylight is longer than 11 hours, as is normal outside of the tropics. They are mostly propagated by stem or root cuttings or by adventitious roots called "slips" that grow out from the tuberous roots during storage. True seeds are used for breeding only.

Under optimal conditions of 85 to 90 % relative humidity at 13 to 16 °C (55 to 61 °F), sweet potatoes can keep for six months. Colder temperatures injure the roots.

They grow well in many farming conditions and have few natural enemies; pesticides are rarely needed. Sweet potatoes are grown on a variety of soils, but well-drained light and medium textured soils with a pH range of 4.5-7.0 are more favourable for the plant (Woolfe, 1992; Ahn, 1993). They can be grown in poor soils with little fertilizer. However, sweet potatoes are very sensitive to aluminium toxicity and will die about 6 weeks after planting if lime is not applied at planting in this type of soil (Woolfe, 1992). Because they are sown by vine cuttings rather than seeds, sweet potatoes are relatively easy to plant. Because the rapidly growing vines shade out weeds, little weeding is needed, and farmers can devote time to other crops. In the tropics the crop can be maintained in the ground and harvested as needed for market or home consumption. In temperate regions sweet potatoes are most often grown on larger farms and are harvested before frosts set in.

China is the largest grower of sweet potatoes; providing about 80% of the world's supply, 130 million tons were produced in one year (in 1990; about half that of common potatoes). Historically, most of China's sweet potatoes were grown for human consumption, but now most (60%) are grown to feed pigs. The rest are grown for human food and for other products. Some are grown for export, mainly to Japan. China grows over 100 varieties of sweet potato.

After introduction there, sweet potatoes very early became popular in the islands of the Pacific ocean, from Japan to Polynesia. One reason is that they were a reliable crop in cases of crop failure of other staple foods due to typhoon flooding. They are featured in many favorite dishes in Japan, Taiwan, the Philippines , and other island nations. Indonesia, Vietnam, India, and some other Asian countries are also large sweet potato growers. Uganda (the third largest grower after Indonesia), Rwanda, and some other African countries also grow a large crop which is an important part of their peoples' diets. North and South America, the original home of the sweet potato, together grow less than three percent of the world's supply. Europe has only a very small sweet potato production, mostly in Portugal. In the Caribbean, a variety of the sweet potato called the boniato is very popular. Interestingly, the flesh of the boniato is cream-colored, rather than the more popular orange hue seen in other varieties. Boniatos aren't as sweet and moist as other sweet potatoes, but many people prefer their fluffier consistency and more delicate flavor. Boniatos have been grown throughout the subtropical world for centuries, but became an important commercial crop in Florida in recent years.

Sweet potatoes were an important part of the diet in the United States for most of its history, especially in the Southeast. In recent years however they have become less popular. The average per capita consumption of sweet potatoes in the United States is only about 1.5-2 kg (4 lbs) per year, down from 13 kg (31 lb) in 1920. Southerner Kent Wrench writes: "The Sweet Potato became associated with hard times in the minds of our ancestors and when they became affluent enough to change their menu, the potato was served less often."

New Zealanders grow enough kūmara to provide each person with 7kg (15.4 lbs) a year, and also import substantially more than this from China.

[edit] Diseases

Main article: List of sweet potato diseases

[edit] Nutrition and health benefits

Besides simple starches, sweet potatoes are rich in complex carbohydrates, dietary fiber, beta carotene (a vitamin A equivalent nutrient), vitamin C, and vitamin B6.

In 1992, the Center for Science in the Public Interest compared the nutritional value of sweet potatoes to other vegetables. Considering fiber content, complex carbohydrates, protein, vitamins A and C, iron, and calcium, the sweet potato ranked highest in nutritional value. According to these criteria, sweet potatoes earned 184 points, 100 points over the next on the list, the common potato.(NCSPC)

Sweet potato varieties with dark orange flesh have more beta carotene than those with light colored flesh and their increased cultivation is being encouraged in Africa where Vitamin A deficiency is a serious health problem. Despite the name "sweet", it may be a beneficial food for diabetics, as preliminary studies on animals have revealed that it helps to stabilize blood sugar levels and to lower insulin resistance.^[1] Some Americans, including television personality Oprah Winfrey, are advocating increased consumption of sweet potatoes both for their health benefits and because of their importance in traditional Southern cuisine.

[edit] Uses

The roots are most frequently boiled, fried, or baked. They can also be processed to make starch and a partial flour substitute. Industrial uses include the production of starch and industrial alcohol.

[edit] Culinary uses

Although the leaves and shoots are also edible, the starchy tuberous roots are by far the most important product. In some tropical areas, they are a staple food-crop.

Candied sweet potatoes are a side dish consisting mainly of sweet potatoes prepared with brown sugar, marshmallows, maple syrup, molasses, or other sweet ingredients. Often served on American Thanksgiving, this dish represents traditional American cooking and indigenous food.

Sweet potato pie is also a traditional favorite dish in southern U.S. cuisine.

Baked sweet potatoes are sometimes offered in restaurants as an alternative to baked potatoes. They are often topped with brown sugar and butter.

Sweet potato fries are another common preparation, and are made by julienning and deep frying sweet potatoes, in the fashion of French fried potatoes.

Sweet potato leaves are a common side dish in Taiwanese cuisine, often boiled with garlic and vegetable oil and dashed with salt before serving. They are commonly found at biàndāng restaurants, as well as dishes featuring the sweet potato root.

The young leaves and vine tips of sweet potato leaves are widely consumed as a vegetable West African countries (Guinea, Sierra Leone and Liberia for example). According to FAO leaflet No. 13 - 1990, sweet potato leaves and shoots are a good source of vitamins A, C, and B2 (Riboflavin), and according to research done by A. KHACHATRYAN, are an excellent source of lutein.

Steamed/Boiled chunks, for a simple and healthy snack, chunks of sweet potato may be boiled in water or cooked in the microwave.

Sweet potato chips can be sliced, fried, and eaten just like potato chips or french fries.

Raw sweet potatoes can be eaten as well, most easily in chip form. They taste somewhat like a sweet carrot.

Sweet Potato Butter can be cooked into a gourmet spread.

Japanese cuisines: Boiled sweet potato is the most common way to eat it at home. Also, the use in vegetable tempura is common. Yaki-imo (roasted sweeted potato) is a delicacy in winter, sold by hawkers. Daigaku-imo is a baked sweet potato dessert. In Imo-gohan, slices or small blocks of sweet potato are cooked in rice. It is also served in nimono or nitsuke, boiled and flavoured with typically soy sauce, Mirin and Dashi. Because it is sweet and starchy, it is used in Imo-kinton or some other wagashi. Shōchū is a Japanese spirit made from fermentation of rice and sweet potato.

In New Zealand, Māori traditionally cooked their kūmara in hāngi (earth ovens). Rocks were placed on a fire in a large hole. When the fire died out, kūmara and other food was wrapped in leaves and placed on the hot rocks, then covered with earth. The kūmara was dug up again several hours later. The resulting food was very soft and tender, as though steamed.

In Korean cuisine, sweet potato starch is used to produce dangmyeon (cellophane noodles).

[edit] Non-culinary uses

In South America, the juice of red sweet potatoes is combined with lime juice to make a dye for cloth. By varying the proportions of the juices, every shade from pink to purple to black can be obtained. (Verrill p. 47)

All parts of the plant are used for animal fodder.

Sweet potatoes or camotes are often found in Moche ceramics.^[2]

Several selections are cultivated in gardens as ornamental plants for their attractive foliage, including the dark-leafed cultivars 'Blackie' and 'Ace of Spades' and the chartreuse-foliaged 'Margarita'.

[edit] Biofuel

Taiwanese companies are making alcohol fuel from sweet potato.^{[citation needed]}

[edit] Ethnomedical Uses

• The aerial parts are used as a galactogogue.
• The leaves are used to treat diabetes, hookworm, hemorrhage, and abscesses.
• The tuber is used to treat asthma.

[edit] Names

Often called a yam, the sweet potato is not in the Yam family, but that is only the beginning of the confusion (see yams). Nor is the sweet potato closely related to the common potato, although both are Solanales plants. Although yams and sweet potatoes are both angiosperms (flowering plants), they are not related botanically. Yams are a monocot (a plant having one embryonic seed leaf) and from the Dioscoreaceae or Yam family. Sweet Potatoes, often called ‘yams’, are a dicot (a plant having two embryonic seed leaves) and are from the Convolvulacea or morning glory family. The first Europeans to taste sweet potatoes were members of Columbus' expedition to Haiti in 1492. Later explorers found many varieties under an assortment of local names, but the name which stayed was the Haitian name of batata. This name was later transferred to the ordinary potato, causing a confusion from which it never recovered. The first record of the name "sweet potato" is found in the Oxford English Dictionary of 1775. Kūmara is the Polynesian name for an orangey-fleshed vegetable that looks like a sweet potato, and is a tuberous relative of the morning glory. It has a rich nutty taste.

The moist-fleshed, orange cultivars of sweet potato are often referred to as "yams" in the United States. One explanation of this usage is that Africans brought to America took to calling American sweet potatoes Nyamis, perhaps from the Fulani word nyami (to eat) or the Twi word anyinam, which refers to a true yam. The true yam, which is native to Africa and Asia, can grow up to 2 m (6 ft) in length (sometimes with knuckle-like ends) and has a scaly skin, a pinkish white center, and a thick, almost oily feel to the tongue.

In Kenya "Ngwaci" is the Kikuyu word for sweet potatoes. The Kiswahili word is "viazi vitamu", literally sweet potatoes.

The Indonesian word for sweet potato is "ubi jalar". This given name is probably from the growing characteristics of its vines. They are creeping on the ground or above soil surface. Furthermore, the storage roots, which are produced by the vines in the soil, could also be found elsewhere, far from the base of the plant.

"Batata" or "Bataka" is the commonly used word for all varieties of Potato in Marathi and Gujarati, the two languages of Western states of India. "Ratala" is however, the name only reserved for sweet potatoes in marathi.

Later on many farmers and stores began marketing American-grown sweet potatoes as yams; the name stuck. In more recent times there has been an effort to stop the use of “yam” for sweet potatoes, but this has only been partially successful. USDA branding regulations require the word “yam” to be accompanied by the words “sweet potato” when referring to these moister sweet potatoes.

Starchy, white-fleshed types are sometimes called batatas or boniatos, from generic Spanish terms for all types of sweet potato.

Substratum names used in local varieties of English include kumara (from the Māori word kūmara), as it was the staple food of the native Māori diet, in the UK and Australasia (in NSW it is sometimes spelled as "Kumera", although "sweet potato" is more common in Australia, at least in Victoria). The term is also used in indigenous languages of Melanesia, as well as "peteita", and camote (from Nahuatl camohtli via Spanish) in the southwestern United States and in the Philippines as alternate name for Sweet potato. In Fiji and Vanuatu it is known as kūmala. In the Papua New Guinean language of Tok Pisin is it known as cau cau.

In Hawaiʻi substratum names are used for the yellow Japanese variety and the purple Okinawan variety, both of which are commonly available in the marketplace. The local Japanese names are widely recognized, with Satsumaimo “Satsuma potato” used by recent Japanese immigrant families and yamaimo (“mountain potato”) by other groups. (Technically, yamaimo is the proper name in Japanese of the native yam; however, as in English, it is often used to refer to the sweet potato.) However, naming often depends on personal ancestry, with e.g. Sāmoan ʻumala among Sāmoans, Tagalog kamote among Filipinos, and Hawaiian ʻuala among Native Hawaiians. The orange-fleshed variety common in the mainland U.S. and sold alongside the Japanese and Okinawan cultivars is locally called "sweet potato" or "yam." The purple Okinawan sweet potato is sometimes confused with the purple yam called ube. In Vietnamese the tubers are called khoai lang and the leaves are called rau lang.

In Hindi it is called shakarkand("शकरकंद").

[edit] References and external links

1. ^ Sweet potatoes
2. ^ Berrin, Katherine & Larco Museum. The Spirit of Ancient Peru:Treasures from the Museo Arqueológico Rafael Larco Herrera. New York: Thames and Hudson, 1997.

• Ahn, P.M., 1993, "Tropical soils and fertilizer use", Intermediate Trop. Agric. Series. Longman Sci. and Tech. Ltd. UK.
• Sweet Potato Butter
• Batatas, not potatoes
• The mystery of the sweet potato
• Sweet Potato Growing and Harvesting Information
• Purple sweetpotato Exotic sweetpotatoes can have purple flesh.
• Six Varieties of Sweet Potatoes Explanation of the six major varieties of sweet potatoes, with pictures of the exterior and interiors of four varieties.
• Consultative Group on International Agricultural Research (CGIAR), "Sweet Potato"
• Food and Agricultural Organization of the United Nations (FAO), 1990, "Roots, tubers, plantains and bananas in human nutrition"

"Leaflet No. 13 - 1990 - Sweet Potato"

• The Japanese Society of Root and Tuber Crops (JRT), "Mini White Paper: Sweetpotato in Japan" 2000
• North Carolina Sweet Potato Commission (NCSPC)
• Verrill, A.H., Foods America Gave the World, 1937, Boston : L.C. Page & Co.
• Wrench, K., "The Sweet Potato Patch"
• Woolfe, J.A., 1992, "Sweetpotato: an untapped food resource", Cambridge Univ. Press and the International Potato Center (CIP). Cambridge, UK.
• Sweetpotato DiagNotes is a free comprehensive tool for sweetpotato management, providing information across the disciplines of plant pathology, crop nutrition, entomology and pest management, all integrated in a single expert system.
• Mississippi Sweet Potato Growers Association website highlights the efforts of Wardell Sanders and his pursuits in Mound Bayou, Mississippi. The SPGA serves to provide a lasting agri-economy, strengthen the area farming communities, heighten Mississippi Delta pride, and to include Delta youth in all phases of its operations.
• Sweet Potato Awareness, education about the differences between yams and sweet potatoes, with a downloadable flyer to distribute.
• The Straight Dope answers "What's the difference between yams and sweet potatoes?"
• Identification of sweet potato leaves (Ipomoea batatas) as an excellent source of lutein. A. KHACHATRYAN
• Recipe for stir fried sweet potato leaves.
• Dining in Japan: The Purple Sweet Potato
• World's Healthiest Foods: Benefits of Sweet Potatoes
• North Carolina Sweet Potato Commission
• Can camote tops cure dengue? - 01/25/2008
• Sweetpotato Forum - 03/24/2008