Yam is the common name for several plant species in the Dioscorea genus (Dioscoreaceae family) that form edible tubers. Ubi is an annual herbaceous vine cultivated for the consumption of their starch bulbs in many regions of the temperate and subtropical world. Tuber itself is also called "yam", has many cultivars and related species.
In some parts of the United States and Canada, "yam" is sometimes used to refer to unrelated sweet potato varieties ( Ipomoea batatas ).
Video Yam (vegetable)
Etymology
The name, yam, seems to come from the Portuguese inhame or Canarian (Spanish) ÃÆ' Â ± ame , which may be derived from the West African language. The main derivation borrows from the verb meaning "to eat".
Other uses of the term yam
Some other unrelated root vegetables are sometimes referred to as "yams", including:
- Sweet potatoes ( Ipomoea batatas ), especially those with orange meat, are often referred to as "sweet potatoes" in the United States. Today, the US Department of Agriculture obliges sweet potatoes labeled with the term "yam" to be accompanied by the term "sweet potato".
- Purple sweet potato in Okinawa.
- Oca ( Oxalis tuberosa ) in New Zealand is usually referred to as "yam".
- Konjac corms - Japanese vegetables with the same uses - often colloquially referred to as "yam", though not related.
- Taro in Malaysia and Singapore is referred to as "yam".
Yam has various common names in different regions of the world.
Maps Yam (vegetable)
Description
Monocots associated with lilies and grasses, sweet potatoes are powerful herbs, providing edible tubers. They are from Africa, Asia, and America. Some yams are also invasive plants, often considered as "harmful weeds", outside the cultivation area. Tuber tubers vary in size from small potatoes to more than 60 kg (130 pounds). About 870 species of sweet potato are known, and 95% of these plants are grown in Africa.
Tuber bulbs can grow up to 15 m (49 ft) and 7.6 to 15.2 cm (3.0 to 6.0 inches) high. Tubers can grow into the soil to a depth of 1.5 meters (4.9 feet). Plants spread by seed.
The edible tuber has a rough skin that is difficult to peel, but softens after heating. The skin varies in color from dark brown to pink. The majority of vegetables consist of a much softer substance known as "meat". This substance ranges in color from white or yellow to purple or pink in cooked yam.
Cultivation
Tuber crops are started when whole tubers or tubers are planted into mounds or mountains, at the beginning of the rainy season. The harvest depends on how and where the set is planted, the size of the mound, the distance between the plants, the supply of pegs for the crops produced, the cassava species, and the desired bulb size at harvest. Small farmers in West and Central Africa often grow yams with cereals and vegetables. Sweet potato seedlings that are easily damaged and large to transport. Farmers who do not buy new seeds usually set aside 30% of their crops for next year's cultivation. Ornamental plants face the pressure of various insect pests and fungal and viral diseases, as well as nematodes. Their growth and their respective dormant phases correspond to the rainy and dry seasons. For maximum yield, sweet potatoes require a humid tropical environment, with annual rainfall of more than 1500 mm distributed evenly throughout the growing season. White, yellow, and water oranges usually produce single large bulbs per year, typically weighing 5 to 10 kg (11 to 22 pounds).
Despite high labor requirements and production costs, consumer demand for sweet potatoes is very high in certain sub-regions of Africa, making sweet potato cultivation quite beneficial to certain farmers.
Main cultivator
Many cassava cultivars are found in the humid tropics. The most important ones are economically discussed below.
D. rotundata and D. cayenensis
Dioscorea rotundata , white yam, and D. cayenensis , yam yam, originated from Africa. They are the most important cultivated yams. In the past, they were regarded as two separate species, but most taxonomists now regard them as the same species. More than 200 varieties among them are cultivated.
White cherry-shaped sweet potatoes, smooth and brown skin, and meat is usually white and hard. Yellow yolks have yellow flesh, which is caused by the presence of carotenoids. It looks similar to white yam in outward appearance; tuber skin is usually slightly firmer and slightly less grooved. Yellow yolks have longer vegetation periods and shorter dormancy than white yams.
The varieties 'Kokoro' are important in making dried yam chips.
They are big plants; the vines can be as long as 10 to 12 m (33 to 39 feet). The most common tubers weigh about 2.5 to 5 kg (5.5-11.0 pounds) each, but can weigh as much as 25 kg (55 pounds). After 7 to 12 months of growth, the tubers are harvested. In Africa, it is mostly pounded into pasta to make a traditional dish of "sweet potatoes", known as Fufu.
D. alata
D. alata , called "white yam", winged yam, sweet potato, and purple yam (not to be confused with Okinawa's purple "yam", which is sweet potato), first times cultivated in Southeast Asia. Although it does not grow in the same amount as African yams, it has the largest worldwide distribution of cultivated yams, grown in Asia, the Pacific islands, Africa and the West Indies. Even in Africa, the popularity of the sweet potato is the second after the white yam. The bulb shape is generally cylindrical, but may vary. Meat tubers are white and watery texture.
Uhi was taken to Hawaii by early Polynesian settlers and became a major crop in the 19th century when tubers were sold to visiting vessels as an easily stored food store for their trips.
D. polystachya
D. polystachya , Chinese yam, is from China. Chinese yam plant is somewhat smaller than Africa, with vines about 3 m (9.8 ft) long. It is tolerant to frost and can grow in colder conditions than other yams. It also grows in Korea and Japan.
It was introduced to Europe in the 19th century, when potato crops there fell victim to disease, and still grow in France for the Asian food market.
Tubers are harvested after about 6 months of growth. Some are eaten right after harvest and some are used as ingredients for other dishes, including noodles, and for traditional medicines.
D. bulbifera
D. bulbifera , air potatoes, found in Africa and Asia, with little difference between those found in each place. This is a great wine, 6 m (20 ft) or longer. It produces tubers, but the bulbs growing on the base of the leaves are the more important food products. They are about the size of the potato (hence the name "air potato"), weighing 0.5 to 2.0 kg (1.1-4.4 pounds).
Some varieties can be eaten raw, while some require soaking or boiling for detoxification before eating. It does not grow commercially because other sweet potato flavors are preferred by most people. However, it is popular in the home vegetable garden because it produces harvest after just four months of growth and continues to produce for the life of the vine, for two years. In addition, the bulbs are easily harvested and cooked.
In 1905, air potatoes were introduced to Florida and have since become invasive species in many states. Its rapid growth invades native vegetation and is very difficult to remove because it can grow back from tubers, and new vines can grow from bulbils even after being felled or burned.
D. esculenta
D. esculenta , a lower yam, is one of the first cultivated sweet potato types. It is native to Southeast Asia and is the third most cultivated species there, although it is cultivated very little in other parts of the world. The creepers rarely reach more than 3 m (9.8 ft) in length and the tubers are small enough in most varieties.
Tubers are eaten roasted, boiled, or fried like potatoes. Due to its small size of tubers, mechanical cultivation is possible, which along with its easy preparation and good taste, can help lower yams to become more popular in the future.
D. dumetorum
D. dumetorum , bitter yams, popular as vegetables in some parts of West Africa, partly because their cultivation requires less labor than other yams. Wild forms are highly toxic and sometimes used to poison animals when mixed with bait. It is said that they have also been used for criminal purposes.
D. trifida
D. trifida , cush-cush yam, is from Guyana region in South America and is the most cultivated New World yard. Because they come from tropical rainforest conditions, their growth cycle is less related to seasonal changes than other yams. Because they are relatively easy to cultivate and taste good, they are considered to have great potential for increased production.
Harvest
Sweet potatoes in western Africa are usually harvested using sticks, shovels, or diggers. Wood-based tools are preferred over metal tools because they tend to damage fragile bulbs; However, wood tools need to be replaced frequently. Yam Harvest is labor intensive and physically demanding. The harvest tubers involve standing, bending, squatting, and occasionally sitting on the ground depending on the size of the mound, the size of the tubers, or the depth of tuber penetration. Care should be taken to avoid damage to the tubers, because the damaged bulbs are not stored properly and quickly damaged. Some farmers use staking and mixed cropping, a practice that makes harvesting difficult in some cases.
In forest areas, tubers grow in areas where other tree roots are present. Harvesting bulbs then involves additional steps to free them from other roots. This often causes tuber damage.
Bulbs or air tubers are harvested by manual picking from tendrils.
Yields may increase and the cost of producing sweet potatoes will be lower if mechanization is developed and adopted. However, the current practice of crop production and species used raises considerable obstacles to successful mechanization of sweet potato production, especially for small-scale rural farmers. Extensive changes in traditional cultivation practices, such as mixed crops, may be necessary. Modification of tuber bulbs equipment is currently required considering the tuber's yard and physical properties are different.
Production
By 2014, the world's sweet potato production is 68.1 million tons, led by Nigeria with 66% of the global total (table). Nigeria grows 5.4 million hectares of yam, 70% of the world's land area of ​​7.8 million hectares devoted to sweet potato farming.
Average annual yield of sweet potatoes is 8.8 tons per hectare by 2014, with Ethiopia having the most productive agricultural land of 29.7 tons per hectare.
Storage
Roots and tubers like yams are living organisms. When stored, they continue to breathe, which results in the oxidation of starch (glucose polymer) contained in tuber cells, which convert it into water, carbon dioxide, and thermal energy. During the transformation of this starch, the problem of dry bulbs is reduced.
Among the main roots and tubers, well-kept yams are considered the most vulnerable. Successful storage of sweet potatoes requires:
- early selection of healthy and healthy yam
- appropriate treatment, if possible combined with fungicide treatment
- enough ventilation to remove the heat generated by tuber respiration
- Routine inspection during storage and removal of rotting bulbs and any growing sprouts
- protection from direct sunlight and rain
Storing sweet potatoes at low temperatures reduces the level of breathing. However, temperatures below 12Ã, Â ° C (54Ã, Â ° F) cause damage through cooling, causing internal tissue damage, increasing water loss and yam susceptibility to rot. The symptoms of cold injury are not always clear when the tubers are still in cold storage. The injury becomes apparent as soon as the tubers are returned to room temperature.
The best temperature for storing sweet potatoes is between 14 and 16 Â ° C (57 and 61 Â ° F), with humidity and climatic conditions controlled by high technology, after drying process. Most countries that grow cassava as staple food are too poor to buy high-tech storage systems.
Grows rapidly increases tuber respiration rate, and accelerates the rate at which food values ​​decrease.
Certain sweet potatoes are better than others. The easier to store sweet potatoes are those that adapt to dry climates, where they tend to stay in the active low-respiration stages longer than the sweet potato breeds adapted to the humid tropics, where they do not require dormancy. Yellow yams and cush-cush yams, naturally, have a much shorter dormancy period than sweet potato, white yam, or lower yams.
Loss of storage for sweet potatoes is very high in Africa, with insects alone causing more than 25% loss of harvest within 4 months.
Nutritional value
Raw yam has only moderate nutrient densities, with sufficient content (10% or more of Daily Value, DV) limited to potassium, vitamin B6, manganese, thiamin, dietary fiber, and vitamin C (tables). Yam supplies 118 Calories per 100 grams. Yam generally has a lower glycemic index, about 54% glucose per serving 150 grams, compared with potato products.
The content and quality of protein from root and tuber is lower than other staple foods, with about 2% sweet potato and potato content based on fresh weight. Ubi, with cassava, provides a much greater proportion of protein intake in Africa, ranging from 6% in East Africa and South Africa to about 16% in damp West Africa.
As a relatively low-protein food, sweet potatoes are not a good source of essential amino acids. Experts emphasize the need to supplement the yam-dominant diet with more protein-rich foods to support healthy growth in children.
Yam is an important dietary element for the people of Nigeria and West Africa. It accounts for more than 200 calories per person per day for more than 150 million people in West Africa, and is an important source of income. Yam is an attractive plant on a poor farm with limited resources. It is rich in starch, and can be prepared in various ways. It is available year-round, unlike other seasonal crops that are not reliable. This characteristic makes yam the preferred food and cultural crops of cultural importance in some sub-Saharan African countries.
Phytochemicals
Certain wild yam tubers, variants of kokoro yam and other species of Dioscorea, such as Dioscorea nipponica, are the source for the extraction of diosgenin, sapogenin steroids. Diosgenin extracted is used for the commercial synthesis of cortisone, pregnenolone, progesterone, and other steroidal products. Such preparations are used in early oral contraceptive pills. Unmodified steroids have estrogenic activity.
Comparison with other staple foods
The following table shows the main nutritional and nutritional nutritional content in the form of raw harvest. The raw form, however, is not edible and can not be digested. It must grow, or be prepared and cooked for human consumption. In the form of grown or cooked, the nutritional and relative antinutrition of each staple is very different from the raw form of this staple.
Consumption
Sweet potatoes are consumed in various preparations, such as whole flour or vegetable cuts in their various distributions in Asia, Africa, North America, Central America, Caribbean, South America, and Oceania.
Africa
Sweet potatoes from African species should be cooked to be safe to eat, as various natural substances in yams can cause illness if consumed raw. The most common cooking methods in West and Central Africa is to boil, fry or roast.
Among the Will from Ghana, boiled yam can be crushed with palm oil to eto in a similar way to a banana king dish matoke , and served with eggs. Boiled yam can also be ground with a traditional mortar and pestle to make a thick paste known as iyan (sweet potato) or fufu eaten with traditional sauces such as egusi and the pea soup.
Another way to consume is to let the pieces of raw sweet potato dried in the sun. When dry, the pieces turn into dark brown. This is then ground to make a known brown powder in Nigeria as elubo . The powder can be mixed with boiling water to make a thick kanji paste, a kind of pudding known as amal , which is then eaten with local soups and sauces.
Ubi is a major agricultural and cultural commodity in West Africa, where more than 95% of the world's cassava harvests are harvested. Sweet potatoes are still important to survive in this region. Some of these tuber varieties can be stored for up to six months without cooling, which makes them a valuable source for the annual period of food shortages early in the wet season. Yam cultivars are also cultivated in other humid tropical countries.
Yam is the main staple of Igbos in southern Nigeria where for centuries it plays a dominant role in its agricultural and cultural life. Celebrated with annual sweet potato festival
Philippines and Costa Rica
In the Philippines, a kind of purple sweet potato (Dioscorea alata ), eaten as a sweet dessert called aya halaya , and is also used as a Filipino dessert ingredient more, halo-halo . It is also used as a popular ingredient for ice cream. Vietnamese
In Vietnam, the same purple sweet pot is used to prepare a special soup canh khoai m? or yam fat soup. This involves pounding the yam and cooking it until done very well.
Indonesia
In Indonesia, the same purple sweet potatoes are used to prepare desserts. This involves pounding yams and mixing them with coconut milk and sugar. Sweet potatoes white and white skin are cut in cubes, cooked, fermented lightly, and eaten as an afternoon snack.
Japanese
The exception to the cooking rule is the mountain yam ( Dioscorea polystachya ), known as nagaimo and can be further classified into ich? Imo (lit. 'ginkgo-leaf yam'; kanji: ???), or yamatoimo (lit. Yamato yam; kanji: ???), depending on the shape of the root.
Nagaimo is eaten raw and grated, after only a relatively minimal preparation: whole tubers are soaked briefly in a water-vinegar solution to neutralize the oxidation of the crystalline oxalates found on their skin. Raw vegetables are floury and tasteless, mucilaginous when shredded, and can be eaten simply as a side dish, or added to noodles.
Another variety of sweet potato, jinenjo , is used in Japan as an ingredient in buckwheat noodles. In Okinawa, the purple sweet potato ( Dioscorea alata daijo or beniimo . Sweet purple is popular as light-fried tempura, also baked or boiled. In addition, purple sweet potato is a common ingredient of sweet potato ice cream with a purple color of the signature. Sweet purple is also used in traditional candy types, cakes, and candies.
India
In the central part of India, yams ( khamalu , suran , or chupri alu ) are prepared with finely sliced, seasoned with spices, and fried. In the southern part of India, known as kizhangu karunai in Tamil, this vegetable is a popular escort for rice dishes and fish curry. Also eaten in India, D. alata, purple pigmented species, known as ratalu or purple yam.
In the southern part, especially in Kerala, purple and white yams are locally known as kaachil or kavuttu .
In Karnataka, it is known as suvarna gadde in Kannada. In central India, it is also called garadu ". In Andhra Pradesh, it is known as gangisi gadda .
Nepal
Dioscorea root has traditionally been eaten at M? gh Sankr? nti (midwinter festival) in Nepal. In Nepal, it's called tarul and in Newari h? . Usually steamed and cooked with herbs.
Fiji Islands
Yam, known locally in Fiji as "uvi", can substitute cassava or taro as a staple, and be consumed boiled, roasted in lovo, or steamed with fish or meat with curry sauce or coconut milk and served with rice. Sweet potato costs are higher due to agricultural difficulties and relatively low production volumes in Fiji.
The West
Powdered yams are available in the West from traders specializing in African products, and can be used in the same way as instant mashed potato powder, although preparation is slightly more difficult because of the tendency to form clots. The sweet potato powder is sown in a pot of little boiling water, and stirred strongly. The resulting mixture is served with heated sauces, such as tomatoes and chili, poured onto it.
Because of their abundance and importance to survive, sweet potatoes are highly respected in the Jamaican ceremony and are part of many traditional West African ceremonies.
Toxicity
Unlike cassava, most of the edible, mature, and cultivated varieties of sweet potatoes do not contain toxic compounds. However, there are exceptions. Bitter compounds tend to accumulate in the immature tuber tissue of white and yellow yams. This may be a polyphenol compound or tannin.
The wild form of bitter yam does contain some bitter-tasting toxins, hence referred to as yam bitter. Bitter sweet potatoes are usually not eaten except in times of despair in poor countries and in times of local food scarcity. They are usually detoxified by soaking in a saltwater vessel, in cold or hot fresh water or in a river. The bitter compound in the sweet potato is a water-soluble alkaloid which, in consumption, produces severe and distressing symptoms. Severe cases of alkaloid poisoning can be fatal.
Yam sweet potatoes or potatoes have antinutritional factors. In Asia, the method of detoxification, involving water extraction, fermentation, and roasting of grated tubers, is used for the bitter cultivars of this sweet potato. Bitter compounds in sweet potatoes are also known locally as air potatoes including diosbulbin and possibly saponins, such as diosgenin. In Indonesia, air potato extract is used in the preparation of poison arrows.
Cultural aspects
Nigeria and Ghana
The sweet potato festival is usually held in early August at the end of the rainy season. People offer yams for gods and ancestors first, before distributing them to the villagers. This is the way they thank the spirits above them.
New Yam Festival
The New Yam Festival celebrates the main agricultural produce of Igbos, Idomas, and Tivs. The New Yam Festival, known as Orureshi in Owukpa in Idoma West and Ima-Ji , Iri-Ji or Ji Ji More
The historical record in West Africa and African yam in Europe dates from the 16th century. Cassava is brought to America through Portuguese and Spanish prekolonials on the border of Brazil and Guyana, followed by spread through the Caribbean.
Sweet potatoes are used in Papua New Guinea, where they are called kaukau . Their cultivation and harvest are accompanied by complicated rituals and taboos. The arrival of sweet potato (one of many versions of MarÃÆ'Â ©) is described in Pene Nengone (Loyalty Islands - New Caledonia).
References
External links
- IITA: Yam crop improvement
Source of the article : Wikipedia
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