''Manihot esculenta'',
commonly called cassava (), manioc,
or yuca (among numerous regional names), is a woody
shrub
A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...
of the
spurge
''Euphorbia'' is a very large and diverse genus of flowering plants, commonly called spurge, in the family Euphorbiaceae. "Euphorbia" is sometimes used in ordinary English to collectively refer to all members of Euphorbiaceae (in deference to t ...
family,
Euphorbiaceae
Euphorbiaceae, the spurge family, is a large family of flowering plants. In English, they are also commonly called euphorbias, which is also the name of a genus in the family. Most spurges, such as ''Euphorbia paralias'', are herbs, but some, e ...
, native to South America. Although a perennial plant, cassava is extensively cultivated as an annual
crop
A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydroponic ...
in
tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
and
subtropical
The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...
regions for its edible
starch
Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...
y
tuberous root
Tubers are a type of enlarged structure used as storage organs for nutrients in some plants. They are used for the plant's perennation (survival of the winter or dry months), to provide energy and nutrients for regrowth during the next growing ...
, a major source of
carbohydrate
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or ma ...
s. Though it is often called ''yuca'' in parts of Spanish America and in the United States, it is not related to
yucca
''Yucca'' is a genus of perennial shrubs and trees in the family Asparagaceae, subfamily Agavoideae. Its 40–50 species are notable for their rosettes of evergreen, tough, sword-shaped leaves and large terminal panicles of white or whitish flo ...
, a shrub in the family
Asparagaceae
Asparagaceae, known as the asparagus family, is a family of flowering plants, placed in the order Asparagales of the monocots. The family name is based on the edible garden asparagus, ''Asparagus officinalis''. Those who live in the temperate c ...
. Cassava is predominantly consumed in boiled form, but substantial quantities are used to extract cassava starch, called
tapioca
Tapioca (; ) is a starch extracted from the storage roots of the cassava plant (''Manihot esculenta,'' also known as manioc), a species native to the North Region, Brazil, North and Northeast Region, Brazil, Northeast regions of Brazil, but wh ...
, which is used for food, animal feed, and industrial purposes. The Brazilian farinha, and the related ''
garri
In West Africa, ''garri (also known as gari, galli'', or ''gali)'' is the flour of the fresh starchy cassava root.
In the Hausa language, ''garri'' can also refer to the flour of guinea corn, maize, rice, yam, plantain and millet. For ...
'' of West Africa, is an edible coarse flour obtained by grating cassava roots, pressing moisture off the obtained grated pulp, and finally drying it (and roasting both in the case of farinha and garri).
Cassava is the third-largest source of food carbohydrates in the tropics, after
rice
Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima
''Oryza glaberrima'', commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown i ...
and
maize
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...
.
Cassava is a major
staple food
A staple food, food staple, or simply a staple, is a food that is eaten often and in such quantities that it constitutes a dominant portion of a standard diet for a given person or group of people, supplying a large fraction of energy needs and ...
in the developing world, providing a basic diet for over half a billion people. It is one of the most
drought-tolerant
Drought tolerance is the ability to which a plant maintains its biomass production during arid or drought conditions. Some plants are naturally adapted to dry conditions'','' surviving with protection mechanisms such as desiccation tolerance, detox ...
crops, capable of growing on marginal soils. Nigeria is the world's largest producer of cassava, while Thailand is the largest exporter of cassava starch.
Cassava is classified as either sweet or bitter. Like other roots and tubers, both bitter and sweet varieties of cassava contain
antinutritional factors and toxins, with the bitter varieties containing much larger amounts.
It must be properly prepared before consumption, as improper preparation of cassava can leave enough residual
cyanide
Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms.
In chemistry, a cyanide () is a chemical compound that contains a functional group. This group, known as the cyano group, consists of ...
to cause acute
cyanide intoxication,
goiter
A goitre, or goiter, is a swelling in the neck resulting from an enlarged thyroid gland. A goitre can be associated with a thyroid that is not functioning properly.
Worldwide, over 90% of goitre cases are caused by iodine deficiency. The term is ...
s, and even
ataxia
Ataxia is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in eye movements. Ataxia is a clinical manifestation indicating dysfunction of ...
, partial paralysis, or death. The more toxic varieties of cassava have been used in some places as
famine food
A famine food or poverty food is any inexpensive or readily available food used to nourish people in times of hunger and starvation, whether caused by extreme poverty, such as during economic depression or war, or by natural disasters such as ...
during times of
food insecurity
Food security speaks to the availability of food in a country (or geography) and the ability of individuals within that country (geography) to access, afford, and source adequate foodstuffs. According to the United Nations' Committee on World F ...
.
Farmers often prefer the bitter varieties because they deter pests, animals, and thieves.
Description
The cassava root is long and tapered, with a firm, homogeneous flesh encased in a detachable rind, about thick, rough and brown on the outside. Commercial
cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture, ...
s can be in diameter at the top, and around long. A woody vascular bundle runs along the root's
axis
An axis (plural ''axes'') is an imaginary line around which an object rotates or is symmetrical. Axis may also refer to:
Mathematics
* Axis of rotation: see rotation around a fixed axis
*Axis (mathematics), a designator for a Cartesian-coordinate ...
. The flesh can be chalk-white or yellowish. Cassava roots are very rich in
starch
Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...
and contain small amounts of calcium (16 milligrams per 100 grams), phosphorus (27 mg/100 g), and
vitamin C (20.6 mg/100 g). However, they are poor in
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
and other
nutrient
A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...
s. In contrast, cassava leaves are a good source of protein for
animal
Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...
and
human
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
nutrition, but deficient in the
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...
methionine
Methionine (symbol Met or M) () is an essential amino acid in humans. As the precursor of other amino acids such as cysteine and taurine, versatile compounds such as SAM-e, and the important antioxidant glutathione, methionine plays a critical ro ...
.
Genome
The complete and haplotype-resolved African cassava (TME204) genome was reconstructed and made available using the Hi-C technology.
The genome shows abundant novel gene loci with enriched functionality related to chromatin organization, meristem development, and cell responses.
Differentially expressed transcripts of different haplotype origins were enriched for different functionality during tissue development. In each tissue, 20–30% of transcripts showed allele-specific expression differences with <2% of direction-shifting. Despite high gene synteny, the HiFi genome assembly revealed extensive chromosome rearrangements and abundant intra-genomic and inter-genomic divergent sequences, with significant structural variations mostly related to long terminal repeat retrotransposons.
Storage tuber
(FT) is a gene producing FT proteins which affect the formation of storage roots in many plants, including this one.
Alleles in cassava include ''MeFT1'' and ''MeFT2''.
''MeFT1''
expression
Expression may refer to:
Linguistics
* Expression (linguistics), a word, phrase, or sentence
* Fixed expression, a form of words with a specific meaning
* Idiom, a type of fixed expression
* Metaphorical expression, a particular word, phrase, o ...
in leaves seems to not be
photoperiodic
A circadian rhythm (), or circadian cycle, is a natural, internal process that regulates the sleep–wake cycle and repeats roughly every 24 hours. It can refer to any process that originates within an organism (i.e., endogenous) and responds to ...
, while ''MeFT2'' clearly is.
''MeFT1'' expression encourages motivation of
sucrose
Sucrose, a disaccharide, is a sugar composed of glucose and fructose subunits. It is produced naturally in plants and is the main constituent of white sugar. It has the molecular formula .
For human consumption, sucrose is extracted and refined ...
towards the reproductive organs, as shown by experimental
overexpression reducing storage root accumulation.
Taxonomy
History
![Albert_Eckhout_-_Mandioca](https://upload.wikimedia.org/wikipedia/commons/7/7e/Albert_Eckhout_-_Mandioca.jpg)
Wild populations of ''M. esculenta'' subspecies ''flabellifolia'', shown to be the progenitor of domesticated cassava, are centered in west-central Brazil, where it was likely first domesticated no more than 10,000 years
BP. Forms of the modern domesticated species can also be found growing in the wild in the south of Brazil. By 4,600 BC, cassava pollen appears in the
Gulf of Mexico
The Gulf of Mexico ( es, Golfo de México) is an oceanic basin, ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of ...
lowlands, at the
San Andrés archaeological site. The oldest direct evidence of cassava cultivation comes from a 1,400-year-old
Maya
Maya may refer to:
Civilizations
* Maya peoples, of southern Mexico and northern Central America
** Maya civilization, the historical civilization of the Maya peoples
** Maya language, the languages of the Maya peoples
* Maya (Ethiopia), a populat ...
site,
Joya de Cerén
Joya de Cerén (''Jewel of Cerén'' in the Spanish language) is an archaeological site in La Libertad Department, El Salvador, featuring a pre-Columbian Maya farming village.
The ancient Maya site of Joya de Cerén is located in the Zapotitán V ...
, in
El Salvador
El Salvador (; , meaning " The Saviour"), officially the Republic of El Salvador ( es, República de El Salvador), is a country in Central America. It is bordered on the northeast by Honduras, on the northwest by Guatemala, and on the south b ...
. With its high food potential, it had become a
staple food
A staple food, food staple, or simply a staple, is a food that is eaten often and in such quantities that it constitutes a dominant portion of a standard diet for a given person or group of people, supplying a large fraction of energy needs and ...
of the native populations of northern South America, southern Mesoamerica, and the
Taino people in the
Caribbean islands
Almost all of the Caribbean islands are in the Caribbean Sea, with only a few in inland lakes. The largest island is Cuba. Other sizable islands include Hispaniola, Jamaica, Puerto Rico and Trinidad and Tobago. Some of the smaller islands are re ...
, who grew it using a high-yielding form of
shifting agriculture
Shifting cultivation is an agricultural system in which plots of land are cultivated temporarily, then abandoned while post-disturbance fallow vegetation is allowed to freely grow while the cultivator moves on to another plot. The period of cu ...
by the time of European contact in 1492. Cassava was a staple food of
pre-Columbian
In the history of the Americas, the pre-Columbian era spans from the original settlement of North and South America in the Upper Paleolithic period through European colonization, which began with Christopher Columbus's voyage of 1492. Usually, th ...
peoples in the Americas and is often portrayed in
indigenous art
Indigenous may refer to:
*Indigenous peoples
*Indigenous (ecology), presence in a region as the result of only natural processes, with no human intervention
* Indigenous (band), an American blues-rock band
* Indigenous (horse), a Hong Kong racehor ...
. The
Moche people often depicted yuca in their ceramics.
Spaniards
Spaniards, or Spanish people, are a Romance peoples, Romance ethnic group native to Spain. Within Spain, there are a number of National and regional identity in Spain, national and regional ethnic identities that reflect the country's complex Hist ...
in their early occupation of Caribbean islands did not want to eat cassava or maize, which they considered insubstantial, dangerous, and not nutritious. They much preferred foods from Spain, specifically wheat bread, olive oil, red wine, and meat, and considered maize and cassava damaging to Europeans. The cultivation and consumption of cassava were nonetheless continued in both Portuguese and Spanish America. Mass production of cassava bread became the first Cuban industry established by the Spanish. Ships departing to Europe from Cuban ports such as
Havana
Havana (; Spanish: ''La Habana'' ) is the capital and largest city of Cuba. The heart of the La Habana Province, Havana is the country's main port and commercial center. ,
Santiago
Santiago (, ; ), also known as Santiago de Chile, is the capital and largest city of Chile as well as one of the largest cities in the Americas. It is the center of Chile's most densely populated region, the Santiago Metropolitan Region, whose ...
,
Bayamo
Bayamo is the capital city of the Granma Province of Cuba and one of the largest cities in the Oriente region.
Overview
The community of Bayamo lies on a plain by the Bayamo River. It is affected by the violent Bayamo wind.
One of the most ...
, and
Baracoa
Baracoa, whose full original name is: ''Nuestra Señora de la Asunción de Baracoa'' (“Our Lady of the Assumption of Baracoa”), is a municipality and city in Guantánamo Province near the eastern tip of Cuba. It was visited by Admiral Christop ...
carried goods to Spain, but sailors needed to be provisioned for the voyage. The Spanish also needed to replenish their boats with dried meat, water, fruit, and large amounts of cassava bread. Sailors complained that it caused them digestive problems. Tropical Cuban weather was not suitable for wheat planting and cassava would not go stale as quickly as regular bread.
Cassava was introduced to Africa by Portuguese traders from Brazil in the 16th century. Around the same period, it was also introduced to Asia through
Columbian Exchange
The Columbian exchange, also known as the Columbian interchange, was the widespread transfer of plants, animals, precious metals, commodities, culture, human populations, technology, diseases, and ideas between the New World (the Americas) in ...
by Portuguese and Spanish traders, planted in their colonies in Goa, Malacca, Eastern Indonesia, Timor and the Philippines.
Maize
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...
and cassava are now important staple foods, replacing native African crops in places such as Tanzania. Cassava has also become an important crop in Asia. While it is a valued food staple in parts of eastern Indonesia, it is primarily cultivated for starch extraction and bio-fuel production in Thailand, Cambodia and Vietnam. Cassava is sometimes described as the "bread of the tropics" but should not be confused with the tropical and equatorial
bread tree ''(Encephalartos)'', the
breadfruit
Breadfruit (''Artocarpus altilis'') is a species of flowering tree in the mulberry and jackfruit family (Moraceae) believed to be a domesticated descendant of ''Artocarpus camansi'' originating in New Guinea, the Maluku Islands, and the Philippi ...
''(Artocarpus altilis)'' or the
African breadfruit
''Treculia africana'' is a tree species in the genus ''Treculia'' which can be used as a food plant and for various other traditional uses. The fruits are hard and fibrous, can be the size of a volleyball and weight up to . Chimpanzees
The ...
''(Treculia africana)''. This description definitely holds in Africa and parts of South America; in Asian countries such as Vietnam fresh cassava barely features in human diets.
[Mota-Guttierez and O'Brien]
Cassava consumption and the occurrence of cyanide in cassava in Vietnam, Indonesia and Philippines
Public Health Nutrition, 2019
There is a legend that cassava was introduced in 1880–1885 CE to the South Indian state of
Kerala
Kerala ( ; ) is a state on the Malabar Coast of India. It was formed on 1 November 1956, following the passage of the States Reorganisation Act, by combining Malayalam-speaking regions of the erstwhile regions of Cochin, Malabar, South ...
by the King of
Travancore
The Kingdom of Travancore ( /ˈtrævənkɔːr/), also known as the Kingdom of Thiruvithamkoor, was an Indian kingdom from c. 1729 until 1949. It was ruled by the Travancore Royal Family from Padmanabhapuram, and later Thiruvananthapuram. At ...
, Vishakham Thirunal Maharaja, after a great famine hit the kingdom, as a substitute for rice.
[Saraswathy Nagarajan]
"How tapioca came to Travancore"
''The Hindu'', June 27, 2019 However, there are documented cases of cassava cultivation in parts of the state before the time of Vishakham Thirunal Maharaja. Cassava is called kappa or maricheeni in
Malayalam
Malayalam (; , ) is a Dravidian language spoken in the Indian state of Kerala and the union territories of Lakshadweep and Puducherry (Mahé district) by the Malayali people. It is one of 22 scheduled languages of India. Malayalam was des ...
. It is also referred to as
tapioca
Tapioca (; ) is a starch extracted from the storage roots of the cassava plant (''Manihot esculenta,'' also known as manioc), a species native to the North Region, Brazil, North and Northeast Region, Brazil, Northeast regions of Brazil, but wh ...
in Indian English usage.
Cultivation
Pests
A major cause of losses during cassava storage is infestation by insects.
A wide range of species that feed directly on dried cassava chips have been reported as a major factor in spoiling stored cassava, with losses between 19% and 30% of the harvested produce.
In
Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
, a previous issue was the cassava mealybug (''
Phenacoccus manihoti'') and cassava green mite (''
Mononychellus tanajoa''). These pests can cause up to 80 percent crop loss, which is extremely detrimental to the production of
subsistence
A subsistence economy is an economy directed to basic subsistence (the provision of food, clothing, shelter) rather than to the market. Henceforth, "subsistence" is understood as supporting oneself at a minimum level. Often, the subsistence econo ...
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 of the
International Institute of Tropical Agriculture
The International Institute of Tropical Agriculture (IITA) is a nonprofit organization that works with partners to enhance crop quality and productivity, reduce producer and consumer risks, and generate wealth from agriculture, with the ultimate ...
(IITA) under the leadership of
Hans Rudolf Herren
Hans Rudolf Herren (born 30 November 1947 in Mühleberg, Switzerland) is a Swiss entomologist, farmer and development specialist. He was the first Swiss to receive the 1995 World Food Prize and the 2013 Right Livelihood Award for leading a major ...
. The Centre investigated
biological control
Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also invo ...
for cassava pests; two
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
n natural enemies ''Anagyrus lopezi'' (a
parasitoid
In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...
wasp) and ''
Typhlodromalus
''Typhlodromalus'' is a genus of mites in the Phytoseiidae
The Phytoseiidae are a family of mites which feed on thrips and other mite species. They are often used as a biological control agent for managing mite pests. Because of their usefuln ...
aripo'' (a predatory mite) were found to effectively control the cassava mealybug and the cassava green mite, respectively.
Several viruses are of economic importance. The
African cassava mosaic virus
''African cassava mosaic virus'' (ACMV, ICTV approved acronym) is a plant pathogenic virus of the family ''Geminiviridae'' that may cause either a mosaic appearance to plant leaves, or chlorosis, a loss of chlorophyll. In ''Manihot esculenta'' ...
causes the leaves of the cassava plant to wither, limiting the growth of the root. An outbreak of the virus in Africa in the 1920s led to a major famine.
The virus is spread by the
whitefly
Whiteflies are Hemipterans that typically feed on the undersides of plant leaves. They comprise the family Aleyrodidae, the only family in the superfamily Aleyrodoidea. More than 1550 species have been described.
Description and taxonomy
The A ...
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 spread at a rate of per year, and as of 2005 was found throughout
Uganda
}), is a landlocked country in East Africa
East Africa, Eastern Africa, or East of Africa, is the eastern subregion of the African continent. In the United Nations Statistics Division scheme of geographic regions, 10-11-(16*) territor ...
,
Rwanda
Rwanda (; rw, u Rwanda ), officially the Republic of Rwanda, is a landlocked country in the Great Rift Valley of Central Africa, where the African Great Lakes region and Southeast Africa converge. Located a few degrees south of the Equator ...
,
Burundi
Burundi (, ), officially the Republic of Burundi ( rn, Repuburika y’Uburundi ; Swahili language, Swahili: ''Jamuhuri ya Burundi''; French language, French: ''République du Burundi'' ), is a landlocked country in the Great Rift Valley at the ...
, the
Democratic Republic of the Congo
The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...
and the
Republic of the Congo
The Republic of the Congo (french: République du Congo, ln, Republíki ya Kongó), also known as Congo-Brazzaville, the Congo Republic or simply either Congo or the Congo, is a country located in the western coast of Central Africa to the w ...
. Altogether viruses are a severe production limitation in the tropics. They are the primary reason for the complete lack of yield increases in the 25 years .
Cassava brown streak virus disease
Cassava brown streak virus disease (CBSD) is a damaging disease of cassava plants, and is especially troublesome in East Africa. It was first identified in 1936 in Tanzania, and has spread to other coastal areas of East Africa, from Kenya to Moza ...
has been identified as a major threat to cultivation worldwide.
Cassava mosaic virus
''Manihot esculenta'', common name, commonly called cassava (), manioc, or yuca (among numerous regional names), is a woody shrub of the spurge family, Euphorbiaceae, native to South America. Although a perennial plant, cassava is extensively ...
(CMV) is widespread in Africa, causing cassava mosaic disease (CMD).
Bredeson et al 2016 find the ''M. esculenta''
cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture, ...
s most widely used on that continent have
''M. carthaginensis'' subsp. ''glaziovii'' genes of which some appear to be CMD
resistance genes.
Although the ongoing CMD
pandemic
A pandemic () is an epidemic of an infectious disease that has spread across a large region, for instance multiple continents or worldwide, affecting a substantial number of individuals. A widespread endemic (epidemiology), endemic disease wi ...
affects both
East- and
Central- Africa, Legg ''et al.'', 2014 finds these two areas have two distinct
subpopulation
In statistics, a population is a set of similar items or events which is of interest for some question or experiment. A statistical population can be a group of existing objects (e.g. the set of all stars within the Milky Way galaxy) or a hypothe ...
s of the
vector
Vector most often refers to:
*Euclidean vector, a quantity with a magnitude and a direction
*Vector (epidemiology), an agent that carries and transmits an infectious pathogen into another living organism
Vector may also refer to:
Mathematic ...
, ''
Bemisia tabaci
The silverleaf whitefly (''Bemisia tabaci'', also informally referred to as the sweet potato whitefly) is one of several species of whitefly that are currently important agricultural pests. A review in 2011 concluded that the silverleaf whitefly ...
'' whiteflies.
[
]
A wide range of plant parasitic nematodes have been reported associated with cassava worldwide. These include ''
Pratylenchus brachyurus
''Pratylenchus brachyurus'' is a plant parasitic nematode.
Introduction
''Pratylenchus brachyurus'', like many other plant-parasitic nematodes, are microscopic worms that can be damaging to many agricultural crops. Across the world, many bill ...
'', ''
Rotylenchulus reniformis
''Rotylenchulus reniformis'', the reniform nematode, is a species of parasitic nematode of plants with a worldwide distribution in the tropical and subtropical regions.Ferris, H''Rotylenchulus reniformis''.Nemaplex. Department of Nematology. U ...
'', ''
Helicotylenchus
''Helicotylenchus'' is a genus of nematodes in the family Hoplolaimidae. They are known generally as spiral nematodes.O'Bannon, J. H. and R. N. Inserra''Helicotylenchus'' species as crop damaging parasitic nematodes.Nematology Circular 165. Flori ...
'' spp., ''
Scutellonema
''Scutellonema'' is a genus of nematodes belonging to the family Hoplolaimidae
Hoplolaimidae is a family of plant pathogenic nematodes. It has two subfamilies, Hoplolaiminae and Rotylenchulinae. Typically hoplolaimids are ectoparasite, ecto- or ...
'' spp. and ''
Meloidogyne
Root-knot nematodes are plant-parasitic nematodes from the genus ''Meloidogyne''. They exist in soil in areas with hot climates or short winters. About 2000 plants worldwide are susceptible to infection by root-knot nematodes and they cause appro ...
'' spp., of which ''
Meloidogyne incognita
''Meloidogyne incognita'' (root-knot nematode - RKN), also known as the "southern root-nematode" or "cotton root-knot nematode" is a plant-parasitic roundworm in the family Heteroderidae. This nematode is one of the four most common species world ...
'' and ''
Meloidogyne javanica
''Meloidogyne javanica'' is a species of plant-pathogenic nematodes. It is one of the tropical root-knot nematodes and a major agricultural pest in many countries. It has many hosts. ''Meloidogyne javanica'' reproduces by obligatory mitotic part ...
'' 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, and 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 pests 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.
The use of nematicides has been found to result in lower numbers of galls per feeder root compared to a control, coupled with a lower number of rots in the storage roots. The organophosphorus nematicide
femaniphos, when used, did not affect crop growth and yield parameter variables measured at harvest. Nematicide use in cassava is not terribly effective at increasing harvested yield, but lower infestation at harvest and lower subsequent storage loss provide a higher effective yield. The use of tolerant and resistant cultivars is the most practical management method in most locales.
This crop suffers from a
rust
Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO(OH ...
, caused by ''
Uromyces manihotis
''Uromyces'' is a genus of rust fungi in the family Pucciniaceae. The genus was described by Franz Unger in his 1833 work ''Die Exantheme der Pflanzen''. They have a worldwide distribution but large occurrences happen in North America and Europe. ...
''.
[
]
Harvesting
Cassava is harvested by hand by raising the lower part of the stem, pulling the roots out of the ground, and 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.
Cassava growth is favorable under temperatures ranging from , but it can tolerate temperatures as low as and as high as .
Postharvest handling and storage
Cassava undergoes post-harvest physiological deterioration (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 acid Coumaric acid is a phenolic derivative of cinnamic acid having a hydroxy group
In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In ...
s, starts 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 related to the accumulation of
reactive oxygen species
In chemistry, reactive oxygen species (ROS) are highly reactive chemicals formed from diatomic oxygen (). Examples of ROS include peroxides, superoxide, hydroxyl radical, singlet oxygen, and alpha-oxygen.
The reduction of molecular oxygen () p ...
(ROS) initiated by cyanide release during mechanical harvesting. Cassava shelf life may be increased up to three weeks by overexpressing a cyanide-insensitive alternative oxidase, which suppressed ROS by 10-fold. PPD is one of the main obstacles preventing farmers from exporting cassavas abroad and generating income. Fresh cassava can be preserved like potato, using
thiabendazole
Tiabendazole (INN, BAN), also known as thiabendazole (AAN, USAN) or TBZ and the trade names Mintezol, Tresaderm, and Arbotect, is a preservative, an antifungal agent, and an antiparasitic agent.
Uses
Preservative
Tiabendazole is used primar ...
or bleach as a fungicide, then wrapping in plastic, coating in wax or freezing.
While alternative methods for PPD control have been proposed, such as preventing ROS effects by use of plastic bags during storage and transport, coating the roots with wax, or freezing roots, such strategies have proved to be economically or technically impractical, leading to
breeding
Breeding is sexual reproduction that produces offspring, usually animals or plants. It can only occur between a male and a female animal or plant.
Breeding may refer to:
* Animal husbandry, through selected specimens such as dogs, horses, and rab ...
of cassava varieties more tolerant to PPD and with improved durability after harvest.
Plant breeding has resulted in different strategies for cassava tolerance to PPD.
One was induced by
mutagen
In genetics, a mutagen is a physical or chemical agent that permanently changes nucleic acid, genetic material, usually DNA, in an organism and thus increases the frequency of mutations above the natural background level. As many mutations can ca ...
ic levels of
gamma ray
A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically ...
s, which putatively silenced one of the genes involved in PPD genesis, while another was a group of high-
carotene
The term carotene (also carotin, from the Latin ''carota'', "carrot") is used for many related unsaturated hydrocarbon substances having the formula C40Hx, which are synthesized by plants but in general cannot be made by animals (with the exc ...
clones in which the
antioxidant
Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricant ...
properties of
carotenoid
Carotenoids (), also called tetraterpenoids, are yellow, orange, and red organic compound, organic pigments that are produced by plants and algae, as well as several bacteria, and Fungus, fungi. Carotenoids give the characteristic color to pumpki ...
s are postulated to protect the roots from PPD.
Production
In 2020, global production of cassava root was 303 million
tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s, with
Nigeria
Nigeria ( ), , ig, Naìjíríyà, yo, Nàìjíríà, pcm, Naijá , ff, Naajeeriya, kcg, Naijeriya officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf o ...
as the world's largest producer, producing 20% of the world total (table). Other major growers were
Democratic Republic of the Congo
The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...
and
Thailand
Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...
.
[
Cassava is one of the most ]drought-tolerant
Drought tolerance is the ability to which a plant maintains its biomass production during arid or drought conditions. Some plants are naturally adapted to dry conditions'','' surviving with protection mechanisms such as desiccation tolerance, detox ...
crops, can be successfully grown on marginal soils, and gives reasonable yields where many other crops do not grow well. Cassava is well adapted within latitudes 30° north and south of the equator, at elevations between sea level and above sea level, in equatorial temperatures, with rainfalls from annually, and to poor soils with a pH ranging from acidic to alkaline. These conditions are common in certain parts of Africa and South America.
Cassava is a highly productive crop when considering food energy produced per unit land area per day – , as compared with for rice, for wheat and for maize.
Toxicity
Cassava roots, peels and leaves should not be consumed raw because they contain two cyanogenic glucosides, linamarin
Linamarin is a cyanogenic glucoside found in the leaves and roots of plants such as cassava, lima beans, and flax. It is a glucoside of acetone cyanohydrin. Upon exposure to enzymes and gut flora in the human intestine, linamarin and its methylated ...
and lotaustralin
Lotaustralin is a cyanogenic glucoside found in small amounts in Fabaceae austral trefoil (''Lotus australis''), cassava (''Manihot esculenta''), lima bean (''Phaseolus lunatus''), roseroot (''Rhodiola rosea'') and white clover (''Trifolium repen ...
. These are decomposed by linamarase Linamarase, or beta-D-glucosidase (), is an enzyme found in many plants including cassava and the butter bean.
In cassava it is found in the cell walls. When the plant is chewed or ground, it exposes the enzyme to compounds like linamarin and lo ...
, a naturally occurring enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
in cassava, liberating hydrogen cyanide
Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on an ...
(HCN). Cassava varieties are often categorized as either bitter or sweet, signifying the presence or absence of toxic levels of cyanogenic glucosides, respectively. The so-called sweet (more accurately non-bitter) cultivars can produce as little as 20 milligrams of cyanide
Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms.
In chemistry, a cyanide () is a chemical compound that contains a functional group. This group, known as the cyano group, consists of ...
(CN) per kilogram of fresh roots, whereas bitter ones may produce more than 50 times as much (1 g/kg). Cassavas grown during drought
A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...
are especially high in these toxins. A dose of 25 mg of pure cassava cyanogenic glucoside, which contains 2.5 mg of cyanide, is sufficient to kill a rat. 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 the ability to walk, also known as ''konzo
Konzo is an epidemic paralytic disease occurring among hunger-stricken rural populations in Africa where a diet dominated by insufficiently processed cassava results in simultaneous malnutrition and high dietary cyanide intake. Konzo was first ...
''). It has also been linked to tropical calcific pancreatitis
Pancreatitis is a condition characterized by inflammation of the pancreas. The pancreas is a large organ behind the stomach that produces digestive enzymes and a number of hormones. There are two main types: acute pancreatitis, and chronic pancr ...
in humans, leading to chronic pancreatitis.
Symptoms of acute cyanide intoxication appear four or more hours after ingesting raw or poorly processed cassava: vertigo, vomiting, and collapse. In some cases, death may result within one or two hours. It can be treated easily with an injection of thiosulfate
Thiosulfate ( IUPAC-recommended spelling; sometimes thiosulphate in British English) is an oxyanion of sulfur with the chemical formula . Thiosulfate also refers to the compounds containing this anion, which are the salts of thiosulfuric acid, ...
(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
A goitre, or goiter, is a swelling in the neck resulting from an enlarged thyroid gland. A goitre can be associated with a thyroid that is not functioning properly.
Worldwide, over 90% of goitre cases are caused by iodine deficiency. The term is ...
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
Konzo is an epidemic paralytic disease occurring among hunger-stricken rural populations in Africa where a diet dominated by insufficiently processed cassava results in simultaneous malnutrition and high dietary cyanide intake. Konzo was first ...
and, in some cases, death. The incidence of konzo and tropical ataxic neuropathy
Tropical ataxic neuropathy (TAN, also known as Strachan-Scott Syndrome and prisoners of war neuropathy) is a disease or category of diseases that commonly causes disability and increases mortality. The causes of TAN are not understood; there is no ...
can be as high as three percent in some areas."
During the shortages in Venezuela
Shortages in Venezuela of regulated food staples and basic necessities have been widespread following the enactment of price controls and other policies under the government of Hugo Chávez and exacerbated by the policy of withholding United ...
in the late 2010s, dozens of deaths were reported due to Venezuelans resorting to eating bitter cassava in order to curb starvation. Cases of cassava poisoning were also documented during the famine accompanying the Great Leap Forward
The Great Leap Forward (Second Five Year Plan) of the People's Republic of China (PRC) was an economic and social campaign led by the Chinese Communist Party (CCP) from 1958 to 1962. CCP Chairman Mao Zedong launched the campaign to reconstruc ...
(1958–1962) in China.
Societies that traditionally eat cassava generally understand that some processing (soaking, cooking, fermentation, etc.) is necessary to avoid getting sick. Brief soaking (four 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. 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 flow with the water during the soaking process are also used in cooking. The flour is used throughout South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
and the Caribbean
The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...
. 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.
Uses
Alcoholic beverages
Alcoholic beverage
An alcoholic beverage (also called an alcoholic drink, adult beverage, or a drink) is a drink that contains ethanol, a type of alcohol that acts as a drug and is produced by fermentation of grains, fruits, or other sources of sugar. The c ...
s made from cassava include cauim
Cauim is a traditional alcoholic beverage or beer of the indigenous peoples in Brazil since pre-Columbian times. It is still made today in remote areas throughout Panama and South America. Cauim is made by fermenting manioc (a large starchy root), ...
and tiquira (Brazil), kasiri
Kasiri, also known as kaschiri and cassava beer, is an alcoholic drink made from cassava by Amerindians in Suriname and Guyana.
The roots of the cassava plant are grated, diluted in water, and pressed in a cylindrical basketwork press to extract t ...
(Guyana, Suriname), impala (Mozambique), masato (Peruvian Amazonia chicha), parakari
Parakari is a fermented alcoholic beverage made by Amerindians of Guyana. Like other cassava alcoholic beverages, parakari is made by dual fermenting cassava (a large starchy root), which involves the use of an amylolytic mold (Rhizopus sp., Mucora ...
or kari (Guyana), nihamanchi
Nihamanchï is a beer brewed from manioc (''Manihot esculenta'') by indigenous peoples of South America. It is also known as nihamanci, nijimanche,Howell 49 or nijiamanchi, and is related to chicha.
Jívaro women make it by chewing manioc tuber ...
(South America) also known as (Ecuador and Peru), ö döi (chicha de yuca, Ngäbe-Bugle, Panama), sakurá (Brazil, Suriname), and tarul ko (Darjeeling, Sikkim, India).
Culinary
Cassava-based dishes
A great variety of cassava-based dishes are consumed in the regions where cassava (''Manihot esculenta'', also called 'manioc' or 'yuca') is cultivated, and the ingredient is included many national or ethnic specialities.
As a food ingredient, ca ...
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 many ways. The root of the sweet variety has a delicate flavor and can replace potatoes. It is used in cholent
Cholent and other Sabbath stews ( yi, טשאָלנט, tsholnt ''or'' tshulnt) are traditional Jewish stews. It is usually simmered overnight for 10–12 hours or more, and eaten for lunch on Shabbat (the Sabbath). Shabbat stews were developed ...
in some households. It can be made into a flour that is used in breads, cakes and cookies. In Brazil, detoxified cassava is ground and cooked to a dry, often hard or crunchy meal known as ''farofa
''Farofa'' () is a type of meal made from toasted cassava. It is eaten mainly in Brazil. It can be found commercially produced and packaged but can also be prepared at home based on family recipes. Most recipes will also contain varying amount ...
'' used as a condiment, toasted in butter, or eaten alone as a side dish.
Preparation
A safe processing method known as the "wetting method" is to mix the cassava flour with water into a thick paste, spread it in a thin layer over a basket and then let it stand for five hours at 30 °C in the shade. In that time, about 83% of the cyanogenic glycoside
In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. ...
s are broken down by the linamarase Linamarase, or beta-D-glucosidase (), is an enzyme found in many plants including cassava and the butter bean.
In cassava it is found in the cell walls. When the plant is chewed or ground, it exposes the enzyme to compounds like linamarin and lo ...
; the resulting hydrogen cyanide escapes to the atmosphere, making the flour safe for consumption the same evening.
The traditional method used in West Africa is to peel the roots and put them into water for three days to ferment. The roots are then dried or cooked. In Nigeria and several other west African countries, including Ghana, Cameroon, Benin, Togo, Ivory Coast, and Burkina Faso, they are usually grated and lightly fried in palm oil to preserve them. The result is a foodstuff called ''gari''. Fermentation is also used in other places such as Indonesia (see Tapai
''Tapai'' (also ''tapay'' or ''tape'') is a traditional fermented preparation of rice or other starchy foods, and is found throughout much of Southeast Asia, especially in Austronesian cultures, and parts of East Asia. It refers to both the ...
). The fermentation process also reduces the level of antinutrient
Antinutrients are natural or synthetic compounds that interfere with the absorption of nutrients. Nutrition studies focus on antinutrients commonly found in food sources and beverages. Antinutrients may take the form of drugs, chemicals that natura ...
s, making the cassava a more nutritious food. The reliance on cassava as a food source and the resulting exposure to the goitrogen
Goitrogens are substances that disrupt the production of thyroid hormones. This triggers the pituitary to release thyroid-stimulating hormone (TSH), which then promotes the growth of thyroid tissue, eventually leading to goiter.
Goitrogenic drugs ...
ic effects of thiocyanate
Thiocyanate (also known as rhodanide) is the anion . It is the conjugate base of thiocyanic acid. Common derivatives include the colourless salts potassium thiocyanate and sodium thiocyanate. Mercury(II) thiocyanate was formerly used in pyrot ...
has been responsible for the endemic goiter
A goitre, or goiter, is a swelling in the neck resulting from an enlarged thyroid gland. A goitre can be associated with a thyroid that is not functioning properly.
Worldwide, over 90% of goitre cases are caused by iodine deficiency. The term is ...
s seen in the Akoko
The Akoko are a large Yoruba cultural sub-group in the Northeastern part of Yorubaland. The area spans from Ondo state to Edo state in southwest Nigeria. The Akokos as a subgroup make up 20.3% of the population of Ondo state. Out of the present ...
area of southwestern Nigeria
Nigeria ( ), , ig, Naìjíríyà, yo, Nàìjíríà, pcm, Naijá , ff, Naajeeriya, kcg, Naijeriya officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf o ...
.
A project called "BioCassava Plus" uses bioengineering
Biological engineering or
bioengineering is the application of principles of biology and the tools of engineering to create usable, tangible, economically-viable products. Biological engineering employs knowledge and expertise from a number o ...
to grow cassava with lower cyanogenic glycosides
In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides ...
combined with fortification
A fortification is a military construction or building designed for the defense of territories in warfare, and is also used to establish rule in a region during peacetime. The term is derived from Latin ''fortis'' ("strong") and ''facere'' ...
of vitamin A
Vitamin A is a fat-soluble vitamin and an essential nutrient for humans. It is a group of organic compounds that includes retinol, retinal (also known as retinaldehyde), retinoic acid, and several provitamin A carotenoids (most notably bet ...
, iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
and protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
to improve the nutrition of people in sub-Saharan Africa
Sub-Saharan Africa is, geographically, the area and regions of the continent of Africa that lies south of the Sahara. These include West Africa, East Africa, Central Africa, and Southern Africa. Geopolitically, in addition to the List of sov ...
.
Nutrition
Raw cassava is 60% water, 38% carbohydrates
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or may ...
, 1% protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
, and has negligible fat
In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food.
The term often refers spec ...
(table). In a reference serving, raw cassava provides of food energy
Food energy is chemical energy that animals (including humans) derive from their food to sustain their metabolism, including their muscle, muscular activity.
Most animals derive most of their energy from aerobic respiration, namely combining the ...
and 25% of the Daily Value
The Reference Daily Intake (RDI) used in nutrition labeling on food and dietary supplement products in the U.S. and Canada is the daily intake level of a nutrient that is considered to be sufficient to meet the requirements of 97–98% of health ...
(DV) of vitamin C
Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits and vegetables, also sold as a dietary supplement and as a topical 'serum' ingredient to treat melasma (dark pigment spots) an ...
, but otherwise has no micronutrients
Micronutrients are nutrient, essential dietary elements required by organisms in varying quantities throughout life to orchestrate a range of physiological functions to maintain health. Micronutrient requirements differ between organisms; for exam ...
in significant content (i.e. above 10% of the relevant DV). Cooked cassava starch has a digestibility
Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substances are absorbed through the small intest ...
of over 75%.
Cassava, like other foods, also has antinutritional and toxic factors. Of particular concern are the cyanogenic glucosides of cassava (linamarin
Linamarin is a cyanogenic glucoside found in the leaves and roots of plants such as cassava, lima beans, and flax. It is a glucoside of acetone cyanohydrin. Upon exposure to enzymes and gut flora in the human intestine, linamarin and its methylated ...
and lotaustralin
Lotaustralin is a cyanogenic glucoside found in small amounts in Fabaceae austral trefoil (''Lotus australis''), cassava (''Manihot esculenta''), lima bean (''Phaseolus lunatus''), roseroot (''Rhodiola rosea'') and white clover (''Trifolium repen ...
). On hydrolysis, these release hydrogen cyanide
Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on an ...
(HCN). The presence of cyanide in cassava is of concern for human and for animal consumption. The concentration of these antinutritional and unsafe glycosides varies considerably between varieties and also with climatic and cultural conditions. Selection of cassava species to be grown, therefore, is quite important. Once harvested, bitter cassava must be treated and prepared properly prior to human or animal consumption, while sweet cassava can be used after boiling.
Comparison with other major staple foods
A comparative table shows that cassava is a good energy source. In its prepared forms, in which its toxic or unpleasant components have been reduced to acceptable levels, it contains an extremely high proportion of starch compared to most staples. However, cassava is a poorer dietary source of protein and most other essential nutrients. Though an important staple, its main value is as a component of a balanced diet.
Comparisons between the nutrient content of cassava and other major staple foods when raw must be interpreted with caution because most staples are not edible in such forms and many are indigestible, even dangerously poisonous or otherwise harmful. For consumption, each must be prepared and cooked as appropriate.
Biofuel
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 (People's Republic of China), Eleventh Five-Year Plan in the People's Republic of China, the target was to increase the production of ethanol fuel from nongrain feedstock to two million tonnes, and that of biodiesel to 200 thousand tonnes by 2010. This is equivalent to the replacement of 10 million tonnes of petroleum. This push for non-grain ethanol was further increased to a goal of 300 million tons of cellulosic and non-grain based ethanol combined by 2020. As a result, cassava (tapioca) chips have gradually become a major source of ethanol production. On 22 December 2007, the largest cassava ethanol fuel production facility was completed in Beihai, with annual output of 200 thousand tons, which would need an average of 1.5 million tons of cassava. In November 2008, China-based Hainan Yedao Group invested US$51.5 million in a new wikt:biofuel, biofuel facility that is expected to produce a year of bioethanol from cassava plants.
Animal feed
Cassava tubers and hay are used worldwide as animal feed. Cassava hay is harvested at a young growth stage (three to four months) when it reaches about above ground; it is then sun-dried for one to two days until its final dry matter content approaches 85 percent. Cassava hay contains high protein (20–27 percent Protein (nutrient), crude protein) and condensed tannins (1.5–4 percent CP). It is valued as a good roughage source for ruminants such as cattle.
Laundry starch
Cassava is also used in a number of commercially available laundry products, especially as starch for shirts and other garments. Using cassava starch diluted in water and spraying it over fabrics before ironing helps stiffen collars.
Economic importance
Cassava, Yam (vegetable), yams (''Dioscorea'' spp.), and sweet potatoes (''Ipomoea batatas'') are important sources of food in the tropics. The cassava plant gives the third-highest yield of carbohydrates
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or may ...
per cultivated area among crop plants, after sugarcane and sugar beets. Cassava plays a particularly important role in agriculture in developing countries, especially in sub-Saharan Africa
Sub-Saharan Africa is, geographically, the area and regions of the continent of Africa that lies south of the Sahara. These include West Africa, East Africa, Central Africa, and Southern Africa. Geopolitically, in addition to the List of sov ...
, because it does well on poor soils and with low rainfall, and because it is a perennial that can be harvested as required. Its wide harvesting window allows it to act as a famine reserve and is invaluable in managing labor schedules. It offers flexibility to resource-poor farmers because it serves as either a subsistence or a cash crop.
Worldwide, 800 million people depend on cassava as their primary food staple. No continent depends as much on root and tuber crops in feeding its population as does Africa. In the humid and sub-humid areas of tropical Africa, it is either a primary staple food or a secondary costaple. In Ghana, for example, cassava and yams occupy an important position in the agricultural economy and contribute about 46 percent of the agricultural gross domestic product. Cassava accounts for a daily caloric intake of 30 percent in Ghana and is grown by nearly every farming family. The importance of cassava to many Africans is epitomised in the Ewe language, Ewe (a language spoken in Ghana, Togo and Benin) name for the plant, ''agbeli'', meaning "there is life".
In Tamil Nadu, India, there are many cassava processing factories alongside National Highway 68 (India)(old numbering), National Highway 68 between Thalaivasal and Attur. Cassava is widely cultivated and eaten as a staple food in Andhra Pradesh and in Kerala
Kerala ( ; ) is a state on the Malabar Coast of India. It was formed on 1 November 1956, following the passage of the States Reorganisation Act, by combining Malayalam-speaking regions of the erstwhile regions of Cochin, Malabar, South ...
. In Assam it is an important source of carbohydrates especially for natives of hilly areas.
In the subtropical region of southern China, cassava is the fifth-largest crop in terms of production, after rice
Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima
''Oryza glaberrima'', commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown i ...
, sweet potato, sugar cane, and maize
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...
. China is also the largest export market for cassava produced in Vietnam and Thailand. Over 60 percent of cassava production in China is concentrated in a single province, Guangxi, averaging over seven million tonnes annually.
See also
* Akyeke
* Attiéké a side dish made from cassava that is a part of the cuisine of Côte d'Ivoire in Africa
* Columbian Exchange
The Columbian exchange, also known as the Columbian interchange, was the widespread transfer of plants, animals, precious metals, commodities, culture, human populations, technology, diseases, and ideas between the New World (the Americas) in ...
* Couac
* Fufu
* Cassava-based dishes#Africa, Kwanga
* Kasiri
* Maní (Amazonian legend)
* Tapioca industry of Thailand
* Yellow cassava
References
External links
Cassava – Purdue University Horticulture
{{Authority control
Manihoteae
Biofuels
Caribbean cuisine
Central American cuisine
Crops originating from South America
Crops
Flora of Jamaica
Flora of South America
French Guianan cuisine
Jamaican cuisine
Root vegetables
Staple foods
Tropical agriculture
Tubers
Crops originating from indigenous Americans
Flora without expected TNC conservation status