''Tylosema esculentum'', with
common name
In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...
s gemsbok bean and marama bean or morama bean, is a long-lived
perennial
A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...
legume
A legume () is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Legumes are grown agriculturally, primarily for human consumption, for livestock f ...
native to
arid
A region is arid when it severely lacks available water, to the extent of hindering or preventing the growth and development of plant and animal life. Regions with arid climates tend to lack vegetation and are called xeric or desertic. Most ar ...
areas of southern
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 ...
. Stems grow at least , in a prostrate or trailing form, with forked tendrils that facilitate
climbing
Climbing is the activity of using one's hands, feet, or any other part of the body to ascend a steep topographical object that can range from the world's tallest mountains (e.g. the eight thousanders), to small boulders. Climbing is done fo ...
. A
raceme
A raceme ( or ) or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the s ...
up to long, containing many yellow-orange flowers, ultimately produces an ovate to circular pod, with large brownish-black
seeds
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosperm pl ...
.
Form
The marama bean is adapted to its native region of Southern Africa and therefore grows in dry and low-moisture soils. Its drought tolerance is accordingly high. The fact that the marama bean is adapted to harsh environments offers potential to extend the agricultural activity into regions which are dry or unproductive at the moment. Nevertheless, it needs to be investigated whether it can grow on different soil types.
Summer growth is typically prodigious, particularly in plants older than one year, due in part to its large underground
tuber
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 ...
. The plant is dormant over winter in its native home —
South Africa
South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...
,
Namibia
Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...
and
Botswana
Botswana (, ), officially the Republic of Botswana ( tn, Lefatshe la Botswana, label=Setswana, ), is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory being the Kalahar ...
— but might possibly remain evergreen in less harsh environments.
The nutritional value of the marama bean is astonishingly high for an unimproved legume. The tubers have a high protein content of 9.0% and also have a high amino acid content. The tubers of
cassava
''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 ...
, for comparison, only have a protein content of 1-3%, while
yam has one of 7%. Also the grain is relatively high in protein with a share of 30-39%. The concentration of sulphur-containing amino acids is high as well (with a lysine content of 5.0% and a methionine content of 0.7%). This shows that the protein content of the seeds is comparable to the one of commercial soybeans, which have a content of 38-40%. Therefore, the potential of the marama bean is high to replace the soybean as a protein source, once there have been genetical improvements.
The seeds develop in typical legume pods, albeit large and squat in shape, typically one or two seeds per pod.
The tuber can grow very large; commonly, at least , and often much larger. In Botswana, a tuber of has been found.
Uses
The plant is a significant food-source for the people of the
Kalahari
The Kalahari Desert is a large semi-arid sandy savanna in Southern Africa extending for , covering much of Botswana, and parts of Namibia and South Africa.
It is not to be confused with the Angolan, Namibian, and South African Namib coastal de ...
because of the high protein and oil content of its large seeds ( each). The seeds are usually roasted, imbuing them with a more palatable flavour, comparable to
cashew
The cashew tree (''Anacardium occidentale'') is a tropical evergreen tree native to South America in the genus ''Anacardium'' that produces the cashew seed and the cashew apple accessory fruit. The tree can grow as tall as , but the dwarf cult ...
or
chestnut
The chestnuts are the deciduous trees and shrubs in the genus ''Castanea'', in the beech family Fagaceae. They are native to temperate regions of the Northern Hemisphere.
The name also refers to the edible nuts they produce.
The unrelat ...
. The seeds can also be ground or boiled. The beans keep well, due to their hard outer shell. The tuber is also edible, but must be harvested from young plants (one or two years old) to avoid the tuber being
astringent
An astringent (sometimes called adstringent) is a chemical that shrinks or constricts body tissues. The word derives from the Latin ''adstringere'', which means "to bind fast". Calamine lotion, witch hazel, and yerba mansa, a Californian plant ...
and
fibrous
Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorporate ...
.
The flour of ''Tylosema esculentum'', prepared from heated or unheated marama beans, has a potential as a functional food ingredient. Although studies about its nutritional and physicochemical properties are lacking, the flour is protein-rich. Protein-based ingredients of marama bean are similar to those commercially available from
soybean
The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean, which has numerous uses.
Traditional unfermented food uses of soybeans include soy milk, from which tofu an ...
. Therefore, this flour has the potential to be used as a protein supplements in composite flours with cereals to improve the protein quality.
Marama milk
The milk of the marama bean is a creamy white water extract, very similar to dairy milk or
soymilk
Soy milk (simplified Chinese: 豆浆; traditional Chinese: 豆漿) also known as soya milk or soymilk, is a plant-based drink produced by soaking and grinding soybeans, boiling the mixture, and filtering out remaining particulates. It is a sta ...
. The milk can be consumed in the form of a refreshing and nutritious beverage just like
dairy milk
Milk is a white liquid food produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals (including breastfed human infants) before they are able to digest solid food. Immune factors and immune-modulating ...
or
soymilk
Soy milk (simplified Chinese: 豆浆; traditional Chinese: 豆漿) also known as soya milk or soymilk, is a plant-based drink produced by soaking and grinding soybeans, boiling the mixture, and filtering out remaining particulates. It is a sta ...
. However, it is not available commercially.
This milk has high levels of
sodium
Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...
(47.9 mg/100 g) and
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 ...
(3.7 mg/100 g) compared to soymilk and
dairy milk
Milk is a white liquid food produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals (including breastfed human infants) before they are able to digest solid food. Immune factors and immune-modulating ...
, with much a lower
calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to ...
content (6.8 mg/100 g).
In order to produce marama milk, several processing steps are involved: Thermal treatment (
blanching
Blanch or blanching may refer to:
People
* Andrea Blanch (born 1935), portrait, commercial, and fine art photographer
* Arnold Blanch (1896–1968), born and raised in Mantorville, Minnesota
* Stuart Blanch, Baron Blanch (1918–1994), Anglican bi ...
and
roasting
Roasting is a cooking method that uses dry heat where hot air covers the food, cooking it evenly on all sides with temperatures of at least from an open flame, oven, or other heat source. Roasting can enhance the flavor through caramelization ...
of the beans),
cracking,
milling, suspending in water,
boiling
Boiling is the rapid vaporization of a liquid, which occurs when a liquid is heated to its boiling point, the temperature at which the vapour pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmosphere. Th ...
and
filtration
Filtration is a physical separation process that separates solid matter and fluid from a mixture using a ''filter medium'' that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filter ...
to obtain a milk-like phase.
Forage
The potential uses of the marama bean go beyond the role of only being a food plant. The foliage of the plant serves as forage for livestock and wildlife in Southern Africa because the leaves are highly palatable. Since the marama bean is used to grow in harsh environments it could be used as a feed crop in the drier parts of Africa. While using it as forage one does also protect the soil by conserving its moisture and preventing from soil erosion by wind and water. Furthermore, there would be a build-up in organic matter, which would be beneficial for soils which are poor in nutrients.
Propagation
The seed's hard outer shell means that
scarification
Scarification involves scratching, etching, burning/branding, or superficially cutting designs, pictures, or words into the skin as a permanent body modification or body art. The body modification can take roughly 6–12 months to heal. In the p ...
is necessary in order to ensure satisfactory
germination
Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fer ...
rates. As for most legumes, a
pH neutral soil is preferred. The plant typically grows in very sandy loam, where waterlogging would not be a problem. Despite much global interest in this plant, propagation rates are still fairly low.
The plant can be grown outside, unsheltered, as far north as Zone 8 in the United States and perhaps further north; above-ground growth is killed back by winter freezing, but the plant reemerges each spring in late May. The greatest impediment to producing a crop of seeds is the long maturation time for the seed pods – which is right up to the first hard freeze of the year. Waterlogging is indeed an issue – leading to root rot – and a well-drained sandy loam is preferred, but not essential.
Curiously, this and the other three members of the genus ''
Tylosema
The genus ''Tylosema'' is in the plant family Fabaceae and encompasses four accepted species of perennial legumes native to southern and central Africa. These are semi-woody viniferous plants broadly distributed from Sudan and Ethiopia south to ...
'' are possibly unique within the family
in the fact they exhibit
heterostyly
Heterostyly is a unique form of polymorphism and herkogamy in flowers. In a heterostylous species, two or three morphological types of flowers, termed "morphs", exist in the population. On each individual plant, all flowers share the same morph. ...
.
This reduces propagation potential, and obviously reduces seed production rates for cropping.
Pests
It is known that two fungi are coinfecting the pods of marama beans leading to
necrotic
Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...
lesions. The fungi were revealed to be ''
Alternaria tenuissima
''Alternaria tenuissima'' is a saprophyte, saprophytic fungi, fungus and opportunistic plant pathogen. It is Cosmopolitan distribution, cosmopolitan in distribution, and can colonize a wide range of plant hosts. Colonies of ''A. tenuissima'' prod ...
'' and ''
Phoma
''Phoma'' is a genus of common coelomycetous soil fungi. It contains many plant pathogenic species.
Description
Spores are colorless and unicellular. The pycnidia are black and depressed in the tissues of the host. ''Phoma'' is arbitrarily lim ...
'' spp.
Insect pests could have been observed causing seed damage.
Chemical and nutritional composition
It is most common to eat the marama beans as mature beans when the seeds are surrounded by a hard and woody seed coat, which has a reddish to brownish color. But the beans can also be eaten when they are still immature green beans.
Moisture
The marama bean has a very low
moisture content
Water content or moisture content is the quantity of water contained in a material, such as soil (called soil moisture), rock, ceramics, crops, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed as a ...
as the
dry matter
The dry matter or dry weight is a measurement of the mass of something when completely dried.
Analysis of food
The dry matter of plant and animal material consists of all its constituents excluding water. The dry matter of food includes carboh ...
content ranges from 93.4% to 98.7%. The
moisture content
Water content or moisture content is the quantity of water contained in a material, such as soil (called soil moisture), rock, ceramics, crops, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed as a ...
may also vary due to external factors.
Lipids
It was reported that the content of
lipids
Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include ...
ranges between 24% and 42%. This high amount of
lipids
Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include ...
is an advantage, especially in
Southern Africa
Southern Africa is the southernmost subregion of the African continent, south of the Congo and Tanzania. The physical location is the large part of Africa to the south of the extensive Congo River basin. Southern Africa is home to a number of ...
where it helps improving the status of the undernourished people.
The
lipid
Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include ...
content of the marama beans can be compared to
sunflower seeds
The sunflower seed is the seed of the sunflower (''Helianthus annuus''). There are three types of commonly used sunflower seeds: linoleic (most common), high oleic, and sunflower oil seeds. Each variety has its own unique levels of monounsatu ...
(22-36 %) and
rapeseed
Rapeseed (''Brassica napus ''subsp.'' napus''), also known as rape, or oilseed rape, is a bright-yellow flowering member of the family Brassicaceae (mustard or cabbage family), cultivated mainly for its oil-rich seed, which naturally contains a ...
(22-49 %) and almost reaching the amount that is found in
peanut
The peanut (''Arachis hypogaea''), also known as the groundnut, goober (US), pindar (US) or monkey nut (UK), is a legume crop grown mainly for its edible Seed, seeds. It is widely grown in the tropics and subtropics, important to both small ...
s (45-55 %).
The amount of lipids is twice as high as found in soybeans (17-20 %).
Protein
The
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 ...
range of marama beans ranges from 29% to 39% on a
dry matter
The dry matter or dry weight is a measurement of the mass of something when completely dried.
Analysis of food
The dry matter of plant and animal material consists of all its constituents excluding water. The dry matter of food includes carboh ...
basis. Thus, it is comparable or slightly higher to most other
legumes
A legume () is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Legumes are grown agriculturally, primarily for human consumption, for livestock fo ...
. This amount of
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 ...
makes the marama bean a great nutritive food but can be also used as a protein-rich ingredient for supplementing other products.
Local and community uses
''Tylosema esculentum'', also known as the Marama bean, is a perennial legume that grows in arid Southern African environments. Indigenous natural food sources, such as this specific perennial legume, are essential for rural livelihoods, especially for communities living in extremely harsh environmental conditions where there is little to no rainfall. The plant's ability to be cultivated in harsh and arid environments is due to its large tuber structure that stores high amount of water and soil nutrients, making ''Tylosema esculentum'' a drought-tolerant crop. Many families of Southern African regions grow the Marama bean locally, but are unaware of its high nutritional value.
Sixteen samples of ''Tylosema esculentum'' from Botswana, Namibia, and South Africa were tested, and the plant's chemical composition was analyzed. The results showed that the Marama bean seeds contained high lipid and protein levels (29-38% protein content, 32-42% lipid content, and 19-27% dietary fiber content), which are higher in value than other legumes. ''Tylosema esculentum'' can also be used for other nutritional sources such as for oil, milk, and flour. After learning more about the benefits of nutrition of this perennial legume, many families hope to have the Marama bean as part of the commercial market in order to stabilize food security and improve food diversity.
Scarification and seed germination
''Tylosema esculentum'' have hard seed coats, which lead to many ecological benefits such as an accumulation of seed banks in soils and a higher percentage of germinating, establishing, and completing a successful life cycle. In order to optimize germination and growth of this perennial legume and increase its importance in the food market, germination behavior of untreated ''Tylosema esculentum'' seeds compared to seeds undergoing various dormancy-breaking treatments was investigated. The results indicated that seed germination was greatest when scratching and cracking of the seed coat with sandpaper, also known as mechanical
scarification
Scarification involves scratching, etching, burning/branding, or superficially cutting designs, pictures, or words into the skin as a permanent body modification or body art. The body modification can take roughly 6–12 months to heal. In the p ...
, was applied. Other types of scarification include immersion of seed in water or acid.
Another experiment in Greece discovered that the seed germination of ''Tylosema esculentum'' increases significantly in speed and emergence when the seeds are immersed in hot water for two to four minutes or dry heating for five minutes at 100 to 150 degrees Celsius. Soil is also an important factor to consider when growing this perennial legume plant. ''Tylosema esculentum'' grows best in a sandy soil texture, instead of a clay loam soil texture, because a sandy soil has optimal physical properties that allow the Marama bean to germinate quickly.
Heterostyly and its evolutionary significance
''Tylosema esculentum'' is
heterostylous
Heterostyly is a unique form of polymorphism and herkogamy in flowers. In a heterostylous species, two or three morphological types of flowers, termed "morphs", exist in the population. On each individual plant, all flowers share the same morph. ...
, meaning that two or three morphological types of flowers exist in the population. For this specific legume, its pistil and anthers show reciprocal heights in two morphological types. Experiments involving
in vivo fertilization (naturally occurring crosses of living organisms) and
in vitro fertilization
In vitro fertilisation (IVF) is a process of fertilisation where an egg is combined with sperm in vitro ("in glass"). The process involves monitoring and stimulating an individual's ovulatory process, removing an ovum or ova (egg or eggs) ...
(crosses done in a laboratory setting) indicated that a two-allele self-incompatibility system exists in ''Tylosema esculentum.'' Having a successful self-incompatibility system evolutionarily benefits this plant because it promotes more out-crossing and in turn creates more diversity within a population. Diversity in a population is important and beneficial because the population has a stronger defense against a lethal or harmful virus or bacteria infecting the entire population. The evolutionary significance of ''Tylosema esculentum'' is that the discovery of the function heterostylous plant was the first in the family Fabaceae.
References
External links
"Functional Heterostyly in ''Tylosema esculentum''" ''Annals of Botany''
at Food and Agricultural Organisation of the United Nations
Morama Engaged: Increasing community awareness and utilization of indigenous grains to improve nutrition security and livelihoods in Botswana and Namibia morama.org
{{Taxonbar, from=Q1892273
Cercidoideae
Edible legumes
Botswana cuisine