Guar (Cyamopsis tetragonoloba syn. C. psoralioides), also known as Cluster bean, is an annual legume grown principally in India and Pakistan, with smaller crops grown in the USA, Australia and Africa. The most important growing area centres on Jodhpur in Rajasthan, India.
Guar is drought-tolerant and can be eaten green like snap beans, fed to cattle, or used as a green manure.
Guar beans have a large endosperm that contains galactomannan gum, a substance which forms a gel in water. This is commonly known as guar gum and is used in dairy products like ice cream and as a stabilizer in cheese and cold-meat processing. It can also be used in industrial applications such as the paper and textile industry, ore flotation or the manufacturing of explosives. Guar gum has also proven a useful substitute for locust bean gum (from carob).
The current demand for guar gum outstrips supply and guar is being introduced into new growing areas. At this moment about 40% of the world production of guar gum comes from India.
Galactomannan (Guar Gum)
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-linked alpha-D-galactopyranose).
In order of increasing number of mannose-to-galactose ratio:
- Fenugreek gum, mannose:galactose ~1:1
- Guar gum, mannose:galactose ~2:1
- Tara gum, mannose:galactose ~3:1
- Locust bean gum or carob gum, mannose:galactose ~4:1
Galactomannans are often used in food products to viscosify the water phase.
Guar gum is an edible thickening agent extracted from the guar bean (Cyamopsis tetragonoloba).
Guar gum is a cold water soluble polysaccharide, consisting of mannose and galactose units. This ability to hydrate without heating makes it very useful in many industrial and food applications.
Solutions with different gum concentrations can be used as emulsifiers and stabilizers because they prevent oil droplets from coalescing. Guar gum is also used as suspension stabilizer.
Industrial applications of Guar Gum
- Textile industry – sizing, finishing and printing
- Paper industry – improved sheet formation, folding and denser surface for printing
- Explosives industry – as waterproofing agent mixed with ammonium nitrate, nitroglycerine etc.
- Pharmaceutical and cosmetics industry - as thickener in toothpastes and shampoos and binder in tablets.
- Oil and gas drilling