|
The Guar or cluster bean, with the botanical name ''Cyamopsis tetragonoloba'', is an annual legume and the source of guar gum. It is also known as Gavar, Guwar 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 senegalesis''. It was further domesticated in India and Pakistan, where it has been cultivated for many centuries. Guar grows well in semiarid areas, but frequent rainfall is necessary. This legume is a very valuable plant within 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 Minnesota () Accessed November 8, 2012.〕 In fact, agriculturists in semi-arid regions of Rajasthan follow crop-rotation and use guar as a source to replenish the soil with essential fertilizers and nitrogen fixation, before the next crop. Guar as a plant has a multitude of different functions for human and animal nutrition but its gelling-agent-containing seeds (guar gum) are today the most important use.〔 Demand is rising rapidly due to industrial use of guar gum in hydraulic fracturing (oil shale gas).〔 About 80% of world production occurs in India and Pakistan, but due to strong demand, the plant is being introduced into new areas. ==Biology== ''Cyamopsis tetragonoloba'' grows upright, reaching a maximum height of up to 2–3 m. It has a main single stem with either basal branching or fine branching along the stem. Thanks to taproots, the guar plant can access soil moisture in low soil depths.〔 Additionally, this legume develops root nodules with nitrogen-fixing soil bacteria rhizobia in the surface part of its rooting system. Its leaves and stems are mostly hairy, dependent on the cultivar. Its fine leaves have an elongated oval shape (5 to 10 cm length) and of alternate position. Clusters of flowers grow in the plant axil and are of white to blueish color. The developing pods are rather flat and slim containing 5 to 12 small oval seeds of 5 mm length (TGW = 25-40 g). Usually, mature seeds are white or gray, but in case of 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 very remarkable characteristic. Its kernel consists of a protein-rich germ (43-46%) and a relatively large endosperm (34-40 %), containing big amounts of the galactomannan.〔 The latter is polysaccharide containing polymers of mannose and galactose 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.〕 Thanks to the latter, it exhibits a great hydrogen bonding activity 〔 having a viscosifying effect in liquids. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「guar」の詳細全文を読む スポンサード リンク
|