Cassava

Cassava (Manihot esculenta ), Illustration from Köhler's Medicinal Plants

The cassava (Manihot esculenta ) is a species of the genus Manihot of the family of Euphorbiaceae ( Euphorbiaceae ). Other names for this crop and its agricultural product ( the harvested tubers ) are Mandioca (Brazil, Argentina, Paraguay), cassava, cassava or yuca in Spanish speaking Latin America. The cultivation of the plant is widely used because of their starchy tubers. She is originally from South America and has been used for food by the Europeans by the natives before the discovery of America. Meanwhile, it is grown in many parts of the tropics and subtropics worldwide. Other species of the genus Manihot be used as a source of starch.

Cassava is known under various names. The name is derived from the word cassava Maniot the widespread originally on the Brazilian Atlantic coast Tupi language. In Brazil, cassava is now known as mandioca, which is derived from the name of the woman Mandi - Oca (or mãdi'og ) - her body is, according to a legend of Brazilian natives, have sprung from the cassava plant. The name is derived from the cassava Arawak word Kasabi, and the word Yuca corresponds to the language of the Caribs.

Description

Cassava plants are shrubs with a height of 1.5 to 5 meters. All parts of the plant cause milky sap. First seedlings form a taproot. The fibrous lateral roots thicken and form large, spindle-shaped root tubers. The stems depending on the variety show different growth patterns: with profuse branching from the base or with a continuous, slightly branched main stem. The leaves are palmately divided into three to nine segments; each measure 8 to 18 inches in length and 1.5 to 4 inches in width. The leaves are of 6 to 35 inches long petioles. At the base of the petiole there are two triangular to lanceolate stipules. These are 5-7 millimeters long, they are entire or divided into a few segments stachelspitzige. The leaves are shed during dry periods.

The paniculate, 5-8 cm large inflorescences can be terminal or stand in the leaf axils. There are male and female flowers, both of which occur on a plant ( monoecious ). The male flowers consist of five reddish sepals that have grown up to half their length or less with each other. On the inside they are hairy. The female flowers also have five grown together petals, these are slightly larger than the male flowers with 1 centimeter in length. The capsule is oval fruit, 1.5 to 1.8 centimeters in length from 1 to 1.5 centimeters in width. It has six longitudinal ribs and contains three smooth, slightly triangular, about 1 centimeter seeds.

Ecology

The female flowers mature before the male ( Protogynie ), so that a self-pollination is prevented. In artificially -run, self -pollination leads to inbreeding depression. The flowers contain nectar which attracts insects as pollinators. The fruits burst open when ripe and throw out the seeds.

Cassava plants prefer sandy or sandy- loamy soils. The growth substrate is to slightly acidic best, but there will be a wide range of pH 4 to 8 tolerated. Cassava copes well with typical tropical soils, which have a high content of aluminum and manganese and little available nutrients. Drying times they are, by throwing off leaves, after the onset of rains drive them quickly out again. Cassava requires a sunny location, temperatures below 10 ° C can not be tolerated.

Dissemination

Cassava is known only from culture, he probably originated as allotetraploide plant from South American manioc species. The origin of the cassava plant is not clearly understood, both South and Central America come as the origin in question. The oldest archaeological finds from cassava remains were made in Mexico, their age is estimated to be 2800 years old. Another places of origin Goiás, the hinterland of Bahia or the Amazon region come into question. It is also conceivable that the cassava was domesticated in Central and South America independently.

It is clear that the cassava came to the Caribbean from South America. The Caribs and Arawaks knew cassava already, as they colonized the Caribbean islands from the south, and they already had in their migration also knowledge about propagation, cultivation and processing of plants.

The oldest European description of cassava comes from the year 1494. Spaniards encountered in the Caribbean and the Portuguese in Brazil today at the plant, they told of bread from poisonous roots. In the Central and South American colonial societies cassava quickly gained great importance in the diet of the settlers and the slaves. During the fertile land has been used for sugarcane cultivation, planted one less fertile fields with cassava. Impoverished farmers and runaway slaves built on cassava and sold him to the cities and to the sugar planters. The durable even in tropical temperatures cassava served soldiers and conquerors ( Bandeirantes ) as provisions.

The Portuguese brought cassava to Africa, both in the form of flour or bread as food for the slaves during their transport from Africa to America, and in the form of plants that should be replicated in Africa. Along with the plants had to be passed on the knowledge of its cultivation and especially the correct processing. It succeeded the Portuguese only in today's Angola to introduce cassava, which is probably due to the good relations with the ruling in the 15th century Bakongo kings. Especially in the rain forest of the Congo today, the cassava spread rapidly.

In West Africa, where the Portuguese had tried in vain to introduce the cassava, the plant was accepted only in the 19th century by the population. The cassava cultivation was of freed slaves who had returned from America, conveys the colonialists promoted the cassava as a measure to avoid famine. In East Africa, cassava was introduced in the 18th century by the Portuguese and French, although even the latter had difficulties to convey the correct processing of the roots: in Madagascar, the first attempts of Maniokanbaus were associated with mass poisoning.

In Asia began in the 17th century, introducing the cassava. This initially succeeded in the Moluccas, Java, and later on in the 18th century in Goa and on the islands in the Indian Ocean. In Indonesia and India was promoted with the aim of avoiding famine of cassava by the colonial powers. Cassava came to China, but is there only grown to a limited extent as animal feed.

As the cassava came to the Pacific Islands, is not clearly understood. A Spanish expedition reported already in 1770 by cassava cultivation on Easter Island, which would support theories of colonization of Oceania from South America. Is well documented that the plant was brought by the British to Tahiti in the 19th century and spread from there to all other Pacific Islands. Today is cassava grown widely in the tropics, especially in regions with a dry season.

Economic Importance

In 2011, about 252 million tonnes of cassava (manioc ) were harvested worldwide. The 15 largest producing countries harvested together around 214 million tonnes, representing approximately 85.1 % of the world crop.

*) Estimate of FAO **) Determined by the statistical method of imputation

Use

Food

Mainly used the tuberous roots as food, sometimes the leaves as a vegetable. The 15 to 100 centimeters long and 3-15 centimeters thick tubers can reach a weight up to 10 kilograms. They are surrounded by a corked, usually reddish-brown outer layer, inside they are usually white, sometimes yellow or reddish.

Ingredients

In the raw state, the tubers are poisonous because they contain glucosides, mainly linamarin. Cyanogenic glycoside that is stored in the vacuole of said plant cell, and has no toxic effect. If the plant is, however, violated ( eg predators ), the substance comes into contact with the enzyme linamarase and D-glucose is split off. The resulting acetone cyanohydrin can now spontaneously or catalyzed by the enzyme hydroxy nitrile lyase decompose to acetone and hydrogen cyanide. The content of toxic substances is strongly dependent on the type, so-called " sweet " varieties contain little glucoside.

Poisoning symptoms include ataxia or atrophy. Hydrocyanic acid evaporates done at room temperature, but to effect a complete outgassing, the tuber must be thoroughly crushed. Methods to detoxify the plants be to grind the plant into flour and then wash with boiling water, fermenting and heating. An alternative method was developed by Howard Bradbury and colleagues. The plant is ground into flour and mixed with water. The mixture is then spread out in the shade thin ( about 1 cm). There it is allowed to rest for five to six hours. How can outgas almost the entire cyanide.

Since cassava has a low content of protein (about 2-3 % of dry matter ) and very few essential amino acids (risk of kwashiorkor syndrome ), the additional consumption of protein-rich ( recommended for strong maniokbasierter diet for example, about 30 % of dry matter) cassava leaves to counteract deficiencies. Since this is not common in many African countries, is currently also working on a Manioksorte, the provitamin A and other micronutrients produced in the root.

100 g of cassava tubers have a calorific value of 620 kJ (148 kcal), the leaves corresponding to 381 kJ (91 kcal).

Processing

The treatment is mainly based on procedures that were especially practiced by the Indians in the Amazon region for detoxification and were mentioned by chroniclers in the 16th century, such as 1587 by Gabriel Soares de Sousa in his book Tratado descriptivio do Brasil. Traditionally, the tubers are peeled, crushed or grated and then soaked. After a few days you pressed the mass of, washed by the so-called tipiti and roasts them in ovens. The residual mass in the press provides the cassava or mandioca flour ( in Brazilian: farinha ). A by-product of the production of manioc flour is starch, which is called in Brazil polvilho, or after roasting tapioca. There is also the opportunity to cook the peeled and shredded tubers essbereit in salt water for some ( glykosidarmen ) varieties.

Cassava flour can be used similarly as wheat flour. People with allergies to wheat and other grains therefore commonly use cassava flour as a substitute.

The flour is processed differently depending on the region. Man preparing inter alia, from a kind of cake ( for example, the Brazilian Beiju ), which is our bread more or less similar, or the mandioca flour mixed with wheat flour, such as when Conaque in the Antilles. In Brazil, the supplement farofa and the drink Tarubá from cassava flour are produced. While one understands the wheat flour in Germany under the name of flour, then in Brazil, the term farinha synonymous with manioc flour, while wheat flour is called farinha de trigo.

In most Latin American countries, cassava is also prepared similarly as boiled potatoes and served as a side dish. The cassava root can be fried after cooking and then similar to French fries. In Sudan, the tuber cubes are fried. A mainly in Peru extremely popular dish is yuca a la huancaína; fried Yuquitas there are in all the major fast food chains as a snack.

In Africa (especially Cameroon, Gabon and Congo ), the flour for a type of dumpling dough ( Fufu ) will be used. The tuber is often boiled or fried in steam or in water. Very popular and very chaotic for European palates are wrapped in palm leaves Maniokstangen, called Bobolo.

The fresh root is also used as a remedy for ulcers. The seeds of some varieties have a laxative and emetic arousing.

Feed

Cassava or tapioca can be used as a feed additive for meat production, since it is a cheaper raw material.

This results in the producing countries to export-oriented monocultures and can thus jeopardize by land and uses competition the diet of the people. About 25 % of global cassava are now used for animal feed. In Africa and Asia this figure is 17 % and 24 %, Latin America 47%. The proportion of cassava in the mixed feed composition of the EU -27 in 2007 was only 0.5 %. Early 90s, the proportion still 6%. Of the total feed imports made ​​cassava in 2007 just 0.2 % of.

A renewable resource

A great potential is attributed to cassava for bioethanol production. Currently, the production of ethanol from cassava is, however, rather than only in China and Thailand. The production costs of ethanol are at about 0.27 € / l and the ethanol yield at 3.5 to 4 m3/ha. As realizable biofuel yield from cassava in Asia about 78 GJ / ha can be specified.

Cassava plays a role as a source of starch for fermentation industry. Manioc starch which may be used for the production of bioplastics ( polylactide based on lactic acid ), as is planned for example, in Thailand. Thus, the market volume of the Thai cassava industry could, according to estimates of the National Innovation Agency ( NIA) to almost € 3 billion more than double.

The Food and Agriculture Organization ( FAO) sees great potential for the use of cassava as a renewable resource in the context that current yields are only 20% of the attainable under optimal conditions levels. However, should the fact that cassava about 1 billion people to care about one-third of their daily calorie intake and thus is a major staple food, prevent the further use as a renewable resource in the context of the discussion about the conflict between food production and industrial use.