View source for Guar gum

'''Guar gum''', also called [[guaran]], is a [[galactomannan]]. It is primarily the ground [[endosperm]] of [[guar bean]]s.  The guar seeds are dehusked, milled and screened to obtain the guar gum <ref>[http://www.fao.org/ag/agn/jecfa-additives/specs/monograph3/additive-218.pdf foa.org]</ref>.  It is typically produced as a free flowing, pale, off-white colored, coarse to fine ground powder. 

==Production==
Guar gum is extracted from the guar bean, where it acts as a food and water store. The guar bean is principally grown in [[India]] and [[Pakistan]], with smaller crops grown in the [[U.S.A.]], [[Australia]] and [[Africa]]. The drought-resistant guar bean can be eaten as a green bean, fed to [[cattle]], or used in [[green manure]]. Moreover China also started growing the crop of Guar.

==Properties==


===Solubility and Viscosity===
Guar gum is more soluble than [[locust bean gum]] and is a better emulsifier as it has more [[galactose]] branch points. Unlike locust bean gum, it is not self-gelling.<ref name="LSBU">Martin Chaplin "Water Structure and Behavior: Guar Gum". April 2006. London South Bank University</ref> However, either [[borax]] or [[calcium]] can [[cross-link]] guar gum, causing it to [[gel]]. In water it is [[nonionic]] and [[hydrocolloid]]al. It is not affected by ionic strength or [[pH]], but will degrade at pH extremes at temperature (e.g. pH 3 at 50°C).<ref name="LSBU" /> It remains stable in solution over pH range 5-7. Strong [[acid]]s cause [[hydrolysis]] and loss of viscosity, and alkalies in strong concentration also tend to reduce viscosity. It is insoluble in most hydrocarbon solvents.

Guar gum shows high low-shear [[viscosity]] but is strongly shear-thinning. It is very [[thixotropic]] above concentration 1%, but below 0.3% the thixotropy is slight. It has much greater low-shear viscosity than that of locust bean gum, and also generally greater than that of other hydrocolloids.  Guar Gum shows [[viscosity]] synergy with [[xanthan gum]]. Guar gum and [[micellar casein]] mixtures can be slightly thixotropic if a biphase system forms.<ref>Lynn A. Kuntz. "Special Effects With Gums". December 1999. Food Product Design</ref><ref name="LSBU" />

===Thickening===
Guar gum is economical because it has almost 8 times the water-thickening potency of [[cornstarch]] - only a very small quantity is needed for producing sufficient [[viscosity]]. Thus it can be used in various multi-phase formulations; as an [[emulsifier]] because it helps to prevent oil droplets from coalescing, and/or as a [[Stabilizer (chemistry)|stabilizer]] because it helps to prevent solid particles from settling.

===Ice-crystal growth===
Guar gum retards ice crystal growth non-specifically by slowing mass transfer across the solid/liquid interface. It shows good stability during freeze-thaw cycles.<ref name="LSBU" />

==Grading==
Manufacturers define different grades and qualities of guar gum by the particle size, the viscosity that is generated with a given concentration, and the rate at which that viscosity develops. Coarse-mesh guar gums, will typically -- but not always -- develop viscosity more slowly. They may achieve a reasonably high viscosity, but will take longer to achieve. On the other hand, they will disperse better than fine-mesh, all conditions being equal. A finer mesh, like a 200 mesh, requires more effort to dissolve <ref>[http://www.foodproductdesign.com/archive/2004/1004CS.html foodproductdesign.com]</ref>.

==Industrial applications ==
*  [[Textile]] industry &ndash; sizing, finishing and printing
*  [[Paper]] industry &ndash; improved sheet formation, folding and denser surface for printing
*  [[Explosive]]s industry &ndash; as waterproofing agent mixed with [[ammonium nitrate]], [[nitroglycerin]] etc.
*  [[Pharmaceutical]] industry &ndash; as binder or as disintegrator in tablets
*  [[Cosmetics]] and toiletries industries &ndash; thickener in [[toothpaste]]s, conditioner in [[shampoo]]s (usually in a chemically modified version)
*  [[Textile]]s
*  Oil and gas drilling, [[Hydraulic fracturing]]
*  [[Mining]]
*  [[Hydroseeding]] &ndash; formation of seed bearing "guar tack"<ref>[http://www.ssseeds.com/other_products_guar.html Product description: Guar Tack. S&S Seeds Inc. 2006]</ref>

== Food applications ==
The largest market for guar gum is in the [[food industry]].  It is generally recognized as safe (GRAS) in the US with differing percentages set for its allowable concentration in various food applications<ref>[http://vm.cfsan.fda.gov/%7Edms/eafus.html fda.gov]</ref>.  In Europe, guar gum has [[EU food additive code]] E412.

Applications include:

*[[Baked goods]] - increases [[dough]] yield, gives greater resiliency, and improves texture and shelf life; in [[pastry]] fillings, it prevents "weeping" (syneresis) of the water in the filling, keeping the pastry crust crisp. 

*[[Dairy]] - thickens [[milk]], [[yogurt]], [[kefir]], and liquid [[cheese]] products; helps maintain [[homogeneity]] and texture of [[ice cream]]s and [[sherbet]]s

*[[Meat]] - functions as [[lubricant]] and binder. 

*[[Dressing]] and [[sauce]]s - improves the stability and appearance of salad dressings, barbecue sauces, relishes, [[ketchup]]s and others

*Misc. - Dry soups, sweet desserts, canned fish in sauce, and frozen food items and animal feed.

== Nutritional and medicinal effects == 
Guar gum is a water-[[soluble fiber]] that acts as a bulk forming [[laxative]], and as such, it is claimed to be effective in promoting regular [[bowel]] movements and relieve [[constipation]] and chronic related functional bowel ailments; such as [[diverticulosis]], [[Crohn's disease]], [[colitis]] and [[irritable bowel syndrome]], among others. The increased mass in the [[intestine]]s stimulates the movement of waste and [[toxin]]s from the system, which is particularly helpful for good [[Colon (anatomy)|colon]] health, because it speeds the removal of waste and [[bacteria]] from the bowel and colon. In addition, because it is soluble, it is also able to [[absorb]] toxic substances (bacteria) that cause infective [[diarrhea]].

Several studies have found significant decreases in human serum [[cholesterol]] levels following guar gum ingestion. These decreases are thought to be a function of its high soluble fiber content.

Guar gum is of interest with regards to both weight loss and diabetic diets. It is a [[thermogenic]] substance.<ref>JC Brown & G Livesey. "Energy balance and expenditure while consuming guar gum at various fat intakes and ambient temperatures". Am J Clin Nutr. 1994. 60(6):956-64 (ISSN: 0002-9165)</ref> Moreover, its low digestibility lends its use in recipes as a filler, which can help to provide [[satiety]], or slow the digestion of a meal, thus lowering the [[glycemic index]] of that meal. In the late 1980s, guar gum was used and heavily promoted in several weight loss products. The [[USFDA]] eventually recalled these due to reports of esophageal blockage from insufficient fluid intake. For this reason, guar gum is no longer approved for use in over-the-counter weight loss aids in the United States. Moreover, a [[meta-analysis]] that combined the results of 11 [[randomize]]d controlled trials found that guar gum supplements were not effective in reducing body weight.<ref>Pittler MH, "Ernst E. Guar gum for body weight reduction: meta-analysis of randomized trials". Am J Med. 2001;110(9):724-730.</ref> 

Two Japanese studies using rats showed that guar gum supports increased absorption of [[calcium]] occurring in the [[Colon (anatomy)|colon]] instead of in the [[small intestine]]. This means that lesser amounts of calcium may be consumed in order to obtain its recommended minimum daily intake (RDI). This has obvious implications for reduced calorie diets, since calcium rich dairy products tend to be high in calories.

However, guar gum is also capable of reducing the absorbability of dietary minerals (other than calcium), when foods and/or [[nutritional supplement]]s containing them are consumed concomitantly with it. However, this is less of a concern with guar gum than with various nonsoluble dietary fibers.

Some studies have found guar gum to improve dietary [[glucose]] tolerance. Research has revealed that the water soluble fiber in it may help people with [[diabetes]] by binding with glucose in the [[gastrointestinal tract]], thus preventing its absorption. 

It also functions as an [[adjuvant]] for diabetic drugs that are sometimes employed for the treatment of noninsulin dependent diabetes. The effect is to help lower blood glucose levels. Thus, diabetic patients who are taking drugs should consult their doctors before supplementing with guar gum.

==External links==
*[http://www.fao.org/ag/agn/jecfa-additives/specs/monograph3/additive-218.pdf GUAR GUM]
*[http://www.lsbu.ac.uk/water/hygua.html Guar Gum]
*[http://www.nature.com/news/2004/040920/pf/040920-2_pf.html Swimming in a pool of guar gum slime is as easy as water]
*[http://www.dineshgum.com DINESH ENTERPRISES -EXPORTER OF GUAR GUM POWDER ]

==References==

{{reflist|2}}

==Sources==
*[http://www.cybercolloids.net/library/jecfa/index.php?submit=showspec&gum=additive-0765 Guar gum specification]
[[Category:Gums]]
[[Category:Edible thickening agents]]
[[Category:Pyrotechnic chemicals]]

[[de:Guaran]]
[[es:Goma guar]]
[[fr:Gomme de guar]]
[[it:Gomma di guar]]
[[ja:グアーガム]]
[[pl:Guma guar]]
[[ru:Гуаровая камедь]]
[[fi:Guarkumi]]
[[hu:Guargumi]]
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