The guar or cluster bean, with the botanical name ''Cyamopsis tetragonoloba'', is an annual

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 ...

and the source of

guar gum Guar gum, also called guaran, is a galactomannan polysaccharide extracted from guar beans that has thickening and stabilizing properties useful in food, feed, and industrial applications. The guar seeds are mechanically dehusked, hydrated, mil ...

. It is also known as gavar, gawar, or guvar bean. The origin of ''Cyamopsis tetragonoloba'' is unknown, since it has never been found in the wild.Whistler R.L. and Hymowitz T. 1979. Guar: agronomy, production, industrial use and nutrition. Purdue University Press, West Lafayette It is assumed to have developed from the African species ''

Cyamopsis senegalensis ''Cyamopsis'' is a genus of the family Fabaceae. Its species are distributed across Africa, Asia and the Pacific. Species ''Cyamopsis'' comprises the following species: * ''Cyamopsis dentata'' (N.E.Br.) Torre * '' Cyamopsis senegalensis'' Gui ...

''. It was further domesticated in

South Asia South Asia is the southern subregion of Asia, which is defined in both geographical and ethno-cultural terms. The region consists of the countries of Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka.;;;;;;;; ...

, where it has been cultivated for centuries. Guar grows well in semiarid areas, but frequent rainfall is necessary. This legume is a valuable plant in a crop rotation cycle, as it lives in symbiosis with nitrogen-fixing bacteria.Undersander D.J., Putnam D.H., Kaminski A.R., Doll J.D., Oblinger E.S. and Gunsolus J.L. 1991. Guar. University of Wisconsin-Madison, University of Minnesot

Accessed November 8, 2012. Agriculturists in semi-arid regions of Rajasthan follow crop rotation, crop-rotation and use guar to replenish the soil with essential fertilizers and

nitrogen fixation Nitrogen fixation is a chemical process by which molecular nitrogen (), with a strong triple covalent bond, in the air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. Atmo ...

, before the next crop. Guar has many functions for human and animal nutrition, but the gelling agent in its seeds (guar gum) is the most important use. Demand is rising due to the use of guar gum in hydraulic fracturing (

oil shale gas Oil shale gas (also: retort gas or retorting gas) is a synthetic non-condensable gas mixture (syngas) produced by oil shale thermal processing (pyrolysis). Although often referred to as shale gas, it differs from the natural gas produced from shale ...

).. It is also a major ingredient of the toy

slime Slime may refer to: Biology * Slime mold, a broad term often referring to roughly six groups of Eukaryotes * Biofilm, an aggregate of microorganisms in which cells adhere to each other and/or to a surface * Slimy (fish), also known as the pony ...

. About 80% of world production occurs in

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

, but due to strong demand, the plant is being introduced elsewhere.

Biology

''Cyamopsis tetragonoloba'' grows upright, reaching a maximum height of up to . It has a main single stem with either basal branching or fine branching along the stem. Guar taproots can access soil moisture in low soil depths. This

develops root nodules with nitrogen-fixing soil bacteria

rhizobia Rhizobia are diazotrophic bacteria that fix nitrogen after becoming established inside the root nodules of legumes (Fabaceae). To express genes for nitrogen fixation, rhizobia require a plant host; they cannot independently fix nitrogen. In gene ...

in the surface part of its rooting system. Its leaves and stems are mostly hairy, depending on the cultivar. Its fine leaves have an elongated oval shape () and of alternate position. Clusters of flowers grow in the plant axil and are white to blueish in color. The developing pods are rather flat and slim containing 5 to 12 small oval seeds of length (TGW = ). Usually mature seeds are white or gray, but with excess moisture they can turn black and lose germination capacity. The chromosome number of guar seeds is 2n=14."Guarbohne (Cyamopsis tetragonolobus [L.] Taub. [=C. psoralioides DC.])"
Accessed November 8, 2012. The seeds of guar beans have a remarkable characteristic. Its kernel consists of a protein-rich germ (43-46%) and a relatively large endosperm (34-40%), containing large amounts of the galactomannan. This is a polysaccharide containing polymers of

mannose Mannose is a sugar monomer of the aldohexose series of carbohydrates. It is a C-2 epimer of glucose. Mannose is important in human metabolism, especially in the glycosylation of certain proteins. Several congenital disorders of glycosylation ...

and

galactose Galactose (, '' galacto-'' + '' -ose'', "milk sugar"), sometimes abbreviated Gal, is a monosaccharide sugar that is about as sweet as glucose, and about 65% as sweet as sucrose. It is an aldohexose and a C-4 epimer of glucose. A galactose molec ...

in a ratio of 2:1 with many branches.Garti N. and Leser M.E 2001. Emulsification properties of hydrocolloids. Polymers for Advanced Technologies 12: 123-135. Thus, it exhibits a great hydrogen bonding activity having a viscosifying effect in liquids.

Cultivation

Climate requirements

Guar is drought-tolerant and sun-loving, but it is susceptible to frost. Although it can cope with little but regular rainfall, it requires sufficient soil moisture before planting and during maturation of seeds. Frequent drought periods can lead to delayed maturation. On the contrary, excessive moisture during the early growth phase and after maturation lead to lower seed quality. Guar is also produced near to coastal areas in the Gandhidham region of Kutch, Gujarat, India.

Soil requirements

''Cyamopsis tetragonoloba'' (L.) can grow on a wide range of soil types. Preferably in fertile, medium-textured and sandy

loam Loam (in geology and soil science) is soil composed mostly of sand (particle size > ), silt (particle size > ), and a smaller amount of clay (particle size < ). By weight, its mineral composition is about 40–40–20% concentration of sand–sil ...

soils that are well-drained, since waterlogging decreases plant performance. Guar grows best in moderate alkaline conditions (pH 7-8) and is tolerant of salinity. Its taproots are inoculated with rhizobia nodules, thus it produces nitrogen-rich biomass and improves soil quality.

Cultural practices

Cultivation areas

Guar is grown principally in north-western India and Pakistan with smaller crops grown in the semiarid areas of the high plains of Texas in the US, Australia and Africa. The most important growing area centres on Jodhpur in Rajasthan, India where demand for guar for fractionation produced an agricultural boom as in 2012. Currently, India is the main producer of cluster bean, accounting for 80% production of the world's total, while the

Rajasthan Rajasthan (; lit. 'Land of Kings') is a state in northern India. It covers or 10.4 per cent of India's total geographical area. It is the largest Indian state by area and the seventh largest by population. It is on India's northwestern si ...

Gujarat Gujarat (, ) is a state along the western coast of India. Its coastline of about is the longest in the country, most of which lies on the Kathiawar peninsula. Gujarat is the fifth-largest Indian state by area, covering some ; and the ninth ...

and Kutch regions occupy the largest areas (82.1% of total) dedicated to guar cultivation. In addition to its cultivation in India, the crop is also grown as a cash crop in other parts of the world. Several commercial growers have converted their crops to guar production to support the increasing demand for guar and other organic crops in the United States.

Varieties

Pusa Naubahar and Pusa Sadabahar. Seeds at the rate of 30 kilograms/hectare (9–11 lb/acre) are planted at a spacing of 45-60 x 20–30 cm (18–24 x 8–12 in) in February–March and June–July. During the rainy season, seeds are sown 2–3 cm (~1 in) deep on ridges and in furrows during summer months. FYM is applied at the rate of 25 tonnes/ha (11.1 tons/acre). N, P₂O₅ and K₂O recommendation for the crop is 20:60:80 kg/ha (18:53:71 lb/acre). Average yield is 5 to 6 tonnes/ha (2.2–2.6 tons/acre). Meager information is available for genetic variability in cluster bean addressing the qualitative traits (Pathak et al. 2011).

Uses

Guar plant

Agriculture *

Forage Forage is a plant material (mainly plant leaves and stems) eaten by grazing livestock. Historically, the term ''forage'' has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used m ...

: Guar plants can be used as cattle feed, but due to hydrocyanic acid in its beans, only mature beans can be used. *

Green manure In agriculture, a green manure is a crop specifically produced to be incorporated into the soil while still green. Typically, the green manure's biomass is incorporated with a plow or disk, as is often done with (brown) manure. The primary goal ...

: Guar plantings increase the yield of subsequent crops as this legume conserves soil nutrient content. Domestic use *

Vegetable Vegetables are parts of plants that are consumed by humans or other animals as food. The original meaning is still commonly used and is applied to plants collectively to refer to all edible plant matter, including the flowers, fruits, stems, ...

: Guar leaves can be used like spinach, and the pods are prepared like salad or vegetables. Its beans are nutritious, but guar protein is not usable by humans unless toasted to destroy the

trypsin inhibitor A trypsin inhibitor (TI) is a protein and a type of serine protease inhibitor (serpin) that reduces the biological activity of trypsin by controlling the activation and catalytic reactions of proteins. Trypsin is an enzyme involved in the breakdown ...

Guar gum

The seeds of the guar bean contain a large endosperm. This endosperm consists of a large polysaccharide of galactose and mannose. This polymer is water-soluble and exhibits a viscosifying effect in water. Guar gum has a multitude of different applications in food products, industrial products, and extractive industry.

Food

In several food and beverages guar gum is used as additive to change its viscosity or as fiber source. Partially hydrolyzed guar gum (PHGG) is produced by the partial enzymatic

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

of guaran, the

galactomannan Galactomannans are polysaccharides consisting of a mannose backbone with galactose side groups, more specifically, a (1-4)-linked beta-D-mannopyranose backbone with branchpoints from their 6-positions linked to alpha-D-galactose, (i.e. 1-6-linke ...

of the endosperm of guar seeds (

). It is a neutral

polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wa ...

consisting of a

backbone chain with single

side units occurring on almost two out of every three mannose units. The average

molecular weight A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...

is about 25,000 Daltons. This gives a PHGG that still assays and functions as a soluble dietary fiber. PHGG as sold commercially is completely soluble, acid and heat stable, unaffected by ions, and will not gel at high concentrations. Commercial PHGG is approximately 75% dietary fiber and has minimal effect on taste and texture in food and beverage items. PHGG is fully fermentable in the large bowel, with a high rate of volatile fatty acid formation. The pH of the feces is lowered along with an increase in fecal bulk that mainly consists of bacterial cell mass and water. Clinical studies have demonstrated a prebiotic effect of PHGG. Studies have shown that PHGG can be used to maintain regularity. PHGG is used in foods for particulate suspension, emulsification, anti

staling Staling, or "going stale", is a chemical and physical process in bread and similar foods that reduces their palatability - stale bread is dry and hard. Mechanism and effects Staling is not simply a drying-out process due to evaporation. One im ...

, ice crystal control, and reduced fat baked goods. Gawar Phali With Aaloo (Guar Bean With Potatoes)

Industry

Derivatives of guar gum that have been further reacted are used in industrial applications, such as the paper and textile industries, ore flotation, the manufacture of explosives and

hydraulic fracturing Fracking (also known as hydraulic fracturing, hydrofracturing, or hydrofracking) is a well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid. The process involves the high-pressure injection of "frack ...

(fracking) of oil and gas formations.NY Times
/ref> Guar gum is often crosslinked with boron or chromium ions to make it more stable and heat-resistant. The crosslinking of guar with metal ions results in a gel that does not block the formation and helps efficiently in formation cleaning process. Guar and its derivatives make gel complexes with ions of Aluminium, Zirconium, Titanium, Chromium and Boron. The borate–guar reaction is reversible, and depends on the pH (hydrogen ion concentration) of the solution. This reaction is used to give the toy "slime" its consistency. Crosslinking of guar with borate occurs at high pH (approximately 9–10) of the solution. Guar gum has proven as useful substitute for

locust bean gum Locust bean gum (LBG, carob gum, carob bean gum, carobin, E410) is a galactomannan vegetable gum extracted from the seeds of the carob tree and used as a thickening agent (gelling agent) in food technology. Production Locust bean gum is extra ...

(made from

carob The carob ( ; ''Ceratonia siliqua'') is a flowering evergreen tree or shrub in the Caesalpinioideae sub-family of the legume family, Fabaceae. It is widely cultivated for its edible fruit pods, and as an ornamental tree in gardens and landscap ...

seeds).

Feeds

Guar meal korma and Guar meal Churi are widely used as raw material for Producing various kinds of Cattle feeds, Aqua feeds, Fish feeds, Poultry Feeds, Dairy feeds, Swine feeds etc.

Fracking agent

The use of guar gum in the

(fracking) extraction of oil and shale gas has increased demand substantially. Only 10% of Indian production is used domestically. The remaining 90% is exported for shale gas and oil industries. Consequently, many former cotton or wheat fields are converted into guar fields as production costs are lower. The increase of guar gum prices also has other reasons.

References

{{Authority control Indigofereae Edible legumes Crops originating from Africa Crops originating from Asia