Cassava
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? Cassava |
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| Manihot esculenta Crantz |
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The cassava or manioc (Manihot esculenta) is a woody perennial shrub of the Euphorbiaceae (spurge family) that is extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy tuberous root, a major source of carbohydrate.
Cassava is called mandioca, aipim, or macaxeira in Portuguese, mandio in Guaraní, yuca in Spanish, balinghoy in Tagalog, and maniok in Danish.
Description
The root is long and tapered, with a firm homogeneous flesh encased in a detachable rind, about 1 mm thick, rough and brown on the outside. Commercial varieties can be 5 to 10 cm in diameter at the top, and 50 to 80 cm long. A woody cordon runs along the root's axis. The flesh can be chalk-white or yellowish; it breaks like a carrot's, and darkens quickly upon exposure to the air. For this reason, the skinned root must be kept under water until it is ready to be cooked. The root's flavor spoils in a day or so, even if kept unskinned and under refrigeration, which is a problem for supermarkets.
The cassava plant is the highest producer of food energys per cultivated area per day among crop plants, except possibly for sugarcane. Cassava roots are very rich in starch, but poor in protein and other nutrients. In contrast, cassava leaves are a good source of protein if supplemented with the amino acid methionine.
History and economic impact
The species Manihot esculenta originated in South America. It was domesticated before recorded history in Brazil and Paraguay, and forms of the modern domesticated species can be found growing spontaneously in the south of Brazil. While there are several wild Manihot species, all varieties of M. esculenta are cultigens.
World production of cassava root was estimated to be 184 million tonnes in 2002, the majority of production is 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.
Processing
The root cannot be consumed raw, since it contains free and bound cyanogenic glucosides which are converted to cyanide in the presence of linamarase, a naturally occurring enzyme in cassava. Cassava varieties are often categorized as either "sweet" or "bitter", 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 mg of HCN per kg of fresh roots, while "bitter" ones may produce more than 50 times as much (1 g/kg). Cassavas grown during a drought are especially high in these toxins.
For some smaller-rooted "sweet" varieties, cooking is sufficient to eliminate all toxicity. The larger-rooted "bitter" varieties used for production of flour or starch must be processed before eating to remove the cyanogenic glicosides. The large roots are peeled 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.
Uses
Cooked in various ways, cassava is used in a great variety of dishes. The soft-boiled root has a delicate flavor and can replace boiled potatoes in many uses: as an accompaniment for meat dishes made into purées, dumplings and gnocchi, soups, stews, gravies, etc.. Deep fried (after boiling or steaming), it can replace fried potatoes, with a distinctive flavor. Cassava flour can also replace wheat flour, and is so-used by some people with allergies to other grain crops. Tapioca and foufou are made from the starchy cassava root flour.
Pre-Columbian America
Cassava was, and still is, a major staple food for many native tribes of tropical South America, since pre-Colombian times. It was grated into flour and made into pancakes; bitter varieties were detoxified by washing the flour. Fermentation of cassava gruel produced cauim, a mild alcoholic beverage consumed in vast quantities by natives at parties and ceremonies.
Brazil
Cassava is heavily featured in the cuisine of Brazil. The dish vaca atolada ("mud-stranded cow") is a meat and cassava stew, cooked until the root has turned into a paste; and pirão is a thick gravy-like gruel prepared by cooking fish bits (such as heads and bones) with cassava flour. In the guise of farofa (lightly roasted flour), cassava combines with rice and beans to make the basic meal of lower class Brazilians. Farofa is also a standard side dish for feijoada, the famous meat-and-beans stew. Boiled cassava is also made into a popular sweet pudding. Deep-fried (after boiling), it is often eaten as a snack or side dish.
Peru
Cassava is also popular in Peru, where it is used both boiled and fried. Boiled cassava is usually served as a side dish, while fried cassava is usually served together with onions and peppers as an apperitif or accompanying beer.
Africa
In the humid and sub-humid areas of tropical Africa, cassava is either a primary staple food or a secondary co-staple. In West Africa, particularly in Nigeria, cassava is commonly prepared as Eba or Garri. The cassava is grated,pressed,fermented and fried then mixed with boiling water to form a thick paste. People economically forced to depend on cassava risk chronic poisoning diseases, such as tropical ataxic neuropathy (TAN), or such malnutrition diseases as kwashiorkor and endemic goitre.
India
In the state of Kerala, India, cassava is a secondary staple food. It is eaten with fish or meat curry. In TamilNadu, the State Highway between Thalaivasal and Attur has lots of Casava processing factories (Local Name Sago Factory) - indicating the large produce in the neighborhood.
Indonesia
Cassava is widely eaten in Indonesia. It is boiled, or fried (after steaming), or added to the kolak dessert. It is also fermented to make peuyeum, and tape, a sweet paste which can be mixed with sugar and made into a drink.
Animal feed
Cassava is used as animal feed in Latin America and the Caribbean, China, Nigeria and the EU.
Cassava pests
In Africa the cassava mealybug (Phenacocus manihoti) and cassava green mite (Monoychellus 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 Centre for Africa. The Centre investigated biological control for cassava pests and two South American insects Epidinicarsis lopezi and Typhlodromalus aripo were found to effectively control the cassava mealybug and the cassava green mite respectively.