Sunday, October 9, 2011

Cassava Cultivation

cassava plant (Manihot esculenta)

Scientific classification

Kingdom         : Plantae
(unranked)      : Angiosperms
(unranked)      : Eudicots
(unranked)      : Rosids
Order              : Malpighiales
Family             : Euphorbiaceae
Subfamily        : Crotonoideae
Tribe               : Manihoteae
Genus             : Manihot
Species           : M. esculenta
Binomial name : Manihot esculenta 
Cassava(simili alu/topioca)

Large storage root and palmately-divided leaf of the cassava plant (Manihot esculenta), a member of the diverse Euphorbia Family (Euphorbiaceae). Other common names for this important root crop include yuca,
cassava(simili alu/topioca) plant

manioc and tapioca. In fact, the starchy root is the source of tapioca pudding. Cassava is the staff of life for millions of people living in tropical countries where cereals and potatoes will not grow. It is followed in
cassava(simili alu) from mozambique

importance by sweet potatoes (Ipomoea batatas) and true yams (Dioscorea).

Tapioca is a starch extracted from the root of plant species Manihot esculenta. This species, native to the Amazon, Brazil, Colombia, Venezuela, Cuba, Puerto Rico, Haiti, the Dominican Republic, Honduras, and most of the West Indies, is now cultivated worldwide and has many names, including cassava, bitter-cassava, manioc, mandioca, aipim, macaxeira, manioca, boba, tapioca plant, yuca . In India, the term 'Tapioca' is used to represent the root of the plant (Cassava), rather than the starch . In Vietnam, it is called bột năng. In Indonesia, it is called singkong. In the Philippines, it is called sago.


Description

The cassava root is long and tapered, with a firm, homogeneous flesh encased in a detachable rind, about 1mm thick, rough and brown on the outside. Commercial varieties can be 5 to 10 cm in diameter at the top, and around 15 cm to 30 cm long. A woody cordon runs along the root's axis. The flesh can be chalk-white or yellowish. Cassava roots are very rich in starch, and contain significant amounts of calcium (50 mg/100g), phosphorus (40 mg/100g) and vitamin C (25 mg/100g). However, they are poor in protein and other nutrients. In contrast, cassava leaves are a good source of protein, and are rich in the amino acid lysine, though deficient in methionine and possibly tryptophan.


Tapioca is a staple food in some regions and is used worldwide as a thickening agent, mainly in foods. Tapioca is gluten-free, and almost completely protein-free.

The cassava plant has either red or green branches with blue spindles on them. The toxin found in the root of the red-branched variant is less harmful to humans than the green-branched variety. Therefore, while the root of the red/purple-branched variant can be consumed directly, the root of the green-branched variant requires treatment to remove the toxin. Konzo (also called mantakassa) is a paralytic disease associated with several weeks of almost exclusive consumption of insufficiently processed bitter cassava.

Commercially, the starch is processed into several forms: powder, fine or coarse flakes or meal, rectangular sticks, and spherical "pearls". Pearls are the most widely available shape; sizes range from about 1 mm to 8 mm in diameter, with 2–3 mm being the most common.

Nigeria, Brazil, and Thailand are the world's largest producers of cassava. Thailand accounts for 60% of worldwide exports.
 
Cassava is the third-largest source of carbohydrates for meals in the world. Nigeria is the world's largest producer of cassava. It is classified as sweet or bitter, depending on the level of toxic cyanogenic glucosides. (However, bitter taste is not always a reliable measure. Improper preparation of cassava can leave enough residual cyanide to cause acute cyanide intoxication and goiters, and has been linked to ataxia or partial paralysis. Nevertheless, farmers often prefer the bitter varieties because they deter pests, animals, and thieves. In some locations the more toxic varieties serve as a fall-back resource in times of famine.


Economic impact

World production of cassava root was estimated to be 184 million tonnes in 2002, rising to 230 million tonnes in 2008. (FAO). The majority of production in 2002 was in Africa where 99.1 million tonnes were grown, 51.5 million tonnes were grown in Asia and 33.2 million tonnes in Latin America and the Caribbean. Nigeria is the world's largest producer of cassava. However, based on the statistics from the FAO of the United Nations, Thailand is the largest exporting country of dried cassava, with a total of 77% of world export in 2005. The second-largest exporting country is Vietnam, with 13.6%, followed by Indonesia (5.8%) and Costa Rica (2.1%). Worldwide cassava production increased by 12.5% between 1988 and 1990.
In the subtropical region of southern China, cassava is the fifth largest crop in term of production, after rice, sweet potato, sugar cane, and maize. China is also the largest export market for cassava produced in Vietnam and Thailand. Over 60% of cassava production in China is concentrated in a single province, Guangxi, averaging over seven million tons annually.
Uses
West Indies

Tapioca was used by the first inhabitants of the West Indies as a staple food from which they made main dishes such as pepper pot and also used it to make alcohol. It was also used to clean their teeth and to this day is used as a base in toothpaste. Currently it is still a very popular food in the islands, used as a provision cooked with meats or fish and in desserts such as cassava pone.

Asia

In various Asian countries such as China, India, Pakistan, Bangladesh, Myanmar, Philippines, Malaysia, and Taiwan, tapioca pearls are used and can be mistaken for sago pearls, also known as sagudana or sabudana (Pearl Sago) also called 'Sabba Akki'  in Kannada. The pearls (sagudana or sabudana) are also used to make snacks.

India

Local words in India include - Hindi sāgūdānā (literally, 'grains of sago'), Urdu sābūdānā , Malayalam kappa or maraccīni, Tamil maravaḷḷikkilanku, and Kannada marageṇasina. In Indian cuisine, the granular preparation of cassava starch, is known as sāgūdānā'. It can also be used to thicken puddings.



Tapioca is widely consumed in the state of Kerala. It is either boiled or cooked with spices. Tapioca is regarded as a staple food of the common man in Kerala.The tapioca pearls are known as "Sabu dana" in Marathi. It is commonly used as a Khichdi preparation during fasting, popularly called Sabudana Khichadi, among Hindus in Western and central part of India .



In Tamil Nadu, one of the 28 states of India, the National Highway 68 between Thalaivasal and Attur has many cassava-processing factories alongside it—indicating an abundance of it in the neighborhood. Cassava is widely cultivated and eaten as a staple food in Andhra Pradesh and in Kerala.

In Tamil Nadu, tapioca is cultivated more in the districts of Erode, Namakkal and Salem. In Tamil Nadu, there are many tapioca processing units called "sago factories". A large number of tapioca industries are found in Attur Taluk, Salem District. Salem City has a marketing center for the sago (known as javvarisi).



The cultivation of tapioca is manpower intensive only at the time of plantation and harvest. It provides a steady income to the farmers.

In Northern India during the festival season , Sabudana is usually consumed during Fasts (Vrat in Hindi), either prepared as a "Khichdi" (savory) Sabudana Khichadi or Kheer (sweet).

Sri Lanka

It is known as "Mangnokka" in Sri Lanka and Mauritius also by its Sinhalese and Tamil names, generally eaten boiled with a chili onion mixture called "Lunu Miris Sambol" (type of a salsa) or coconut sambol. At the same time, it is very popular to have tapioca pearls, prepared as a delicacy. In early days, tapioca pearls were used to starch clothes by boiling tapioca pearls with the clothes.

Southeast Asia

In Southeast Asia, the cassava root is commonly cut into slices, wedges or strips, fried, and served as a snack, similar to potato chips, wedges or french fries. Another method is to boil large blocks until soft, and serve them with grated coconut as a dessert, either slightly salted or sweetened, usually with palm sugar syrup.

Tapai is made by fermenting large blocks with a yeast-like bacteria culture to produce a sweet and slightly alcoholic dessert. A variation of the chips popular amongst the Malays is kerepek pedas, where the crisps are coated with a hot, sweet and tangy chili and onion paste, or sambal, usually with fried anchovies and peanuts added.

Krupuk, or crackers, is a major use of tapioka scratch in Indonesia.

Commercially prepared tapioca has many uses. Tapioca powder is commonly used as a thickener for soups and other liquid foods, and is also used as a binder in pharmaceutical tablets and natural paints. The flour is used to make tender breads, cakes, biscuits, cookies, and other delicacies (see also Maida flour). Tapioca flakes are used to thicken the filling of pies made with fruits having a high water content.

United Kingdom

The popular savory snack Skips is made of tapioca and flavored like prawn cocktail as well as other flavors.

Tapioca is also widely available in its dried forms and is used to make tapioca pudding.



Brazil

In Brazilian cuisine, tapioca is used for different types of meals. A restaurant which specializes in tapioca-based dishes (mostly fillings) is called in Brazil a tapiocaria. In Colombia and Venezuela, arepas may be made with tapioca flour rather than cornmeal. Tapioca arepas probably predate cornmeal arepas; among traditional cultures of the Caribbean the name for them is casabe.

United States

While frequently associated with dessert in the United States, tapioca is now being used by some cooks in other courses as well.




Ghana

Tapioca is widely enjoyed in Ghana. It is taken mainly as a breakfast meal.






In Guyana, the casabe is simply called cassava bread. It is prepared with an instrument called a matape by the natives of the Rupununi Savanah and other areas of the country that have a high concentration of Amerinidians. In Jamaica, it is called bammy.

Pearl tapioca

Pearl tapioca is also known as boba to some cultures. It is produced by passing the moist starch through a sieve under pressure. Pearl tapioca is a common ingredient in Asian desserts such as kolak, in tapioca pudding, and in sweet drinks such as bubble tea, fruit slush and taho, where they provide a chewy contrast to the sweetness and texture of the drink. Small pearls are preferred for use in puddings; large pearls are preferred for use in drinks. These large pearls most often are brown, not white (and traditionally are used in black or green tea drinks), but are available in a wide variety of pastel colors. Not only are they used in the aforementioned drinks, they are also available as an option in shaved ice and hot drinks. The most famous drink called boba/pearl milk tea can be found in many places.

Biodegradable bags

Tapioca root can also be used to manufacture biodegradable plastic bags. A polymer resin produced from the plant is a viable plastic substitute that is not only biodegradable, but can be composted, is renewable, and is recyclable. The product reverts in less than one year, versus thousands of years for traditional plastics.










Uses
Culinary

Cassava-based dishes are widely consumed wherever the plant is cultivated; some have regional, national, or ethnic importance. Cassava must be cooked properly to detoxify it before it is eaten.

Cassava can be cooked in various ways. The soft-boiled root has a delicate flavor and can replace boiled potatoes in many uses: as an accompaniment for meat dishes, or made into purées, dumplings, soups, stews, gravies, etc. Deep fried (after boiling or steaming), it can replace fried potatoes, with a distinctive flavor. Fufu is made from the starchy cassava-root flour. Tapioca (or fecula), essentially a flavourless starchy ingredient produced from treated and dried cassava (manioc) root, is used in cooking. It is similar to sago and is commonly used to make a milky pudding similar to rice pudding. Boba tapioca pearls are made from cassava root. It is also used in cereals for which several tribes in South America have used it extensively. It is also used in making cassava cake, a popular pastry. Cassava is used in making eba, a popular food in Nigeria. Gari soakings is a delicacy in Ghana that cost less than US$1. One can simply soak gari in cold water, add a bit of sugar and roasted groundnut (peanut) to taste, and add whatever quantity of evaporated milk one desires. Gari soakings prepared with coconut water may taste better.

The juice of the bitter cassava, boiled to the consistency of thick syrup and flavored with spices, is called cassareep. It is used as a basis for various sauces and as a culinary flavoring, principally in tropical countries. It is exported chiefly from Guyana.

The leaves can be pounded to a fine chaff and cooked as a palaver sauce (as is done in Liberia and Sierra Leone), usually with palm oil, but other vegetable oils can also be used. Palaver sauces contain meat and fish as well. It is necessary to wash the leaf chaff several times to remove the bitterness.

In Indonesia, cassava is an important food material. It can be cooked by frying or boiling or processed by fermentation to make tapai and getuk cake, while the starch is made into krupuk crackers. In time of famine or food shortage, cassava is used to replace rice.


Cassava was also used to make alcoholic beverages. The English explorer and naturalist Charles Waterton reported in Wanderings in South America (1836) that the natives of Guyana used cassava to make liquor, which they abandoned when rum became available. Hamilton Rice, in 1913, also remarked on liquor being made from cassava in the Brazilian rainforest.

The Indian tribes in northern Brazil and Surinam – Tiriós and Erwarhoyanas – make a beverage called sakurá with the sweet manioc variety of cassava, yuca. The same beverage is made by the Jivaro in Ecuador and Peru (the Shuara, Achuara, Aguaruna and Mayna people); they call it nijimanche. As Michael Harner describes it:



After the mash has been prepared it is transferred to a beer storage jar and left to ferment. … The resultant liquid tastes somewhat like a pleasingly alcoholic buttermilk and is most refreshing. The Jivaros consider it to be far superior to plain water, which they drink only in emergencies.

Biofuel from cassava


In many countries, significant research has begun to evaluate the use of cassava as an ethanol biofuel feedstock. Under the Development Plan for Renewable Energy in the Eleventh Five-Year Plan in the People's Republic of China, the target is to increase the application of ethanol fuel by nongrain feedstock to 2 million tonnes, and that of biodiesel to 200 thousand tonnes by 2010. This will be equivalent to a substitute of 10 million tonnes of petroleum. As a result, cassava (tapioca) chips have gradually become a major source for ethanol production. On December 22, 2007, the largest cassava ethanol fuel production facility was completed in Beihai, with annual output of two hundred thousand tons, which would need an average of 1.5 million tons of cassava. In November 2008, China-based Hainan Yedao Group reportedly invested $51.5m (£31.8m) in a new biofuel facility that is expected to produce 33 million US gallons (120,000 m3) a year of bio-ethanol from cassava plants.

Animal feed

Cassava is used worldwide for animal feed as well. Cassava hay is produced at a young growth stage at three to four months, harvested about 30–45 cm above ground, and sun-dried for one to two days until it has final dry matter of at least 85%. The cassava hay contains high protein content (20-27% crude protein) and condensed tannins (1.5-4% CP). It is used as a good roughage source for dairy or beef cattle, buffalo, goats, and sheep by either direct feeding or as a protein source in the concentrate mixtures.


Ethnomedicine

The bitter variety leaves are used to treat hypertension, headache, and pain.
Cubans commonly use cassava to treat irritable bowel syndrome, the paste is eaten in excess during treatment.

As cassava is a gluten-free natural starch, there have been increasing incidences of its appearance in Western cuisine as a wheat alternative for sufferers of celiac disease.

Food use, processing and toxicity

Cassava roots and leaves should not be consumed raw because they contain two cyanogenic glucosides, linamarin and lotaustralin. These are decomposed by linamarase, a naturally-occurring enzyme in cassava, liberating hydrogen cyanide (HCN). Cassava varieties are often categorized as either sweet or bitter, respectively signifying the absence or presence of toxic levels of cyanogenic glucosides. The so-called sweet (actually not bitter) cultivars can produce as little as 20 milligrams of cyanide (CN) per kilogram of fresh roots, whereas bitter ones may produce more than 50 times as much (1 g/kg). Cassavas grown during drought are especially high in these toxins. A dose of 40 mg of pure cassava cyanogenic glucoside is sufficient to kill a cow.[citation needed] Excess cyanide residue from improper preparation is known to cause acute cyanide intoxication, and goiters, and has been linked to ataxia (a neurological disorder affecting ability to walk). It has also been linked to tropical calcific pancreatitis in humans, leading to chronic pancreatitis.

Societies that traditionally eat cassava generally understand some processing (soaking, cooking, fermentation, etc.) is necessary to avoid getting sick.

Symptoms of acute cyanide intoxication appear four or more hours after ingesting raw or poorly processed cassava: vertigo; vomiting; collapse. In some cases death may result within one or two hours. It can be treated easily with a shot of thiosulphate (which makes sulfur available for the patient's body to detoxify by converting the poisonous cyanide into thiocyanate).

"Chronic, low-level cyanide exposure is associated with the development of goiter and with tropical ataxic neuropathy, a nerve-damaging disorder that renders a person unsteady and uncoordinated. Severe cyanide poisoning, particularly during famines, is associated with outbreaks of a debilitating, irreversible paralytic disorder called konzo and, in some cases, death. The incidence of konzo and tropical ataxic neuropathy can be as high as 3 percent in some areas.

Brief soaking (4 hours) of cassava is not sufficient, but soaking for 18–24 hours can remove up to half the level of cyanide. Drying may not be sufficient, either.

For some smaller-rooted sweet varieties, cooking is sufficient to eliminate all toxicity. The cyanide is carried away in the processing water and the amounts produced in domestic consumption are too small to have environmental impact. The larger-rooted, bitter varieties used for production of flour or starch must be processed to remove the cyanogenic glucosides. and then ground into flour, which is then soaked in water, squeezed dry several times, and toasted. The starch grains that float to the surface during the soaking process are also used in cooking. The flour is used throughout South America and the Caribbean. Industrial production of cassava flour, even at the cottage level, may generate enough cyanide and cyanogenic glycosides in the effluents to have a severe environmental impact.





The reliance on cassava as a food source and the resulting exposure to the goitrogenic effects of thiocyanate has been responsible for the endemic goiters seen in the Akoko area of southwestern Nigeria.

People dependent on cassava risk cyanide poisoning and malnutrition diseases such as kwashiorkor and endemic goiter.

A project called "BioCassava Plus" is developing a cassava with lower cyanogen glucosides and fortified with Vitamin A, iron and protein to help the nutrition of people in sub-saharan Africa. In 2011 the director of the program said he hoped to obtain regulatory approvals by 2017.


Harvesting

Cassava is harvested by hand by raising the lower part of the stem and pulling the roots out of the ground, then removing them from the base of the plant. The upper parts of the stems with the leaves are plucked off before harvest. Cassava is propagated by cutting the stem into sections of approximately 15 cm, these being planted prior to the wet season.

Postharvest handling and storage

Cassava undergoes postharvest physiological deterioration, or PPD, once the tubers are separated from the main plant. The tubers, when damaged, normally respond with a healing mechanism. However, the same mechanism, which involves coumaric acids, initiates about 15 minutes after damage, and fails to switch off in harvested tubers. It continues until the entire tuber is oxidized and blackened within two to three days after harvest, rendering it unpalatable and useless.

PPD is one of the main obstacles currently preventing farmers from exporting cassavas abroad and generating income. Cassava can be preserved in various ways such as coating in wax or freezing.

The major cause of losses during cassava chip storage is infestation by insects. A wide range of species that feed directly on the dried chips have been reported as the cause of weight loss in the stored produce. Some loss assessment studies and estimations on dried cassava chips have been carried out in different countries.

Plant breeding has resulted in cassava that is tolerant to PPD. Sánchez et al.identified four different sources of tolerance to PPD. One comes from Walker's Manihot (M. walkerae) of southern Texas in the United States and Tamaulipas in Mexico. A second source was induced by mutagenic levels of gamma rays, which putatively silenced one of the genes involved in PPD genesis. A third source was a group of high-carotene clones. The antioxidant properties of carotenoids are postulated to protect the roots from PPD (basically an oxidative process). Finally, tolerance was also observed in a waxy-starch (amylose-free) mutant. This tolerance to PPD was thought to be cosegregated with the starch mutation, and is not a pleiotropic effect of the latter.

Pests


List of cassava diseases

In Africa, the cassava mealybug (Phenacoccus manihoti) and cassava green mite (Mononychellus tanajoa) can cause up to 80% crop loss, which is extremely detrimental to the production of subsistence farmers. These pests were rampant in the 1970s and 1980s, but were brought under control following the establishment of the Biological Control Center for Africa of the IITA under the leadership of Dr. Hans Rudolf Herren. The Centre investigated biological control for cassava pests; two South American natural enemies Apoanagyrus lopezi (a parasitoid wasp) and Typhlodromalus aripo (a predatory mite) were found to effectively control the cassava mealybug and the cassava green mite, respectively.

The cassava mosaic virus causes the leaves of the cassava plant to wither, limiting the growth of the root. The virus caused a major African famine in the 1920s. The virus is spread by the whitefly and by the transplanting of diseased plants into new fields. Sometime in the late 1980s, a mutation occurred in Uganda that made the virus even more harmful, causing the complete loss of leaves. This mutated virus has been spreading at a rate of 50 miles per year, and as of 2005 may be found throughout Uganda, Rwanda, Burundi, the Democratic Republic of the Congo and the Republic of the Congo.

Recently, brown streak disease has been identified as a major threat to cassava cultivation worldwide.

A wide range of plant parasitic nematodes have been reported associated with cassava worldwide. These include Pratylenchus brachyurus., Rotylenchulus reniformis, Helicotylenchus.spp, Scutellonema spp. and Meloidogyne spp., of which Meloidogyne incognita and Meloidogyne javanica are the most widely reported and economically important. Meloidogyne spp. feeding produces physically damaging galls with eggs inside them. Galls later merge as the females grow and enlarge, they interfere with water and nutrient supply. Cassava roots become tough with age and restrict the movement of the juveniles and the egg release. It is therefore possible that extensive galling can be observed even at low densities following infection. Other pest and diseases can gain entry through the physical damage caused by gall formation leading to rots.They have not been shown to cause direct damage to the enlarged storage roots, but plants can have reduced height if there was loss of enlarged root weight.

Research on nematode pests of cassava is still in the early stages, results on the response of cassava is therefore not consistent, ranging from negligible to seriously damaging. Since nematodes have such a seemingly erratic distribution in cassava agricultural fields, it is not easy to clearly define the level of direct damage attributed to nematodes and thereafter quantify the success of a chosen management method. It has been found that the use of nematicides results in a lower number of galls per feeder root compared to a control, coupled with a lower number of rots in the storage roots. The nematicide (Femaniphos) when used did not affect crop growth and yield parameter variables measured at harvest. Nematicide use in cassava is neither practical nor sustainable, currently the use of tolerant and resistant varieties is the most practical and sustainable management method.







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