Galactomannans are

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 ...

s consisting of a

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 ...

backbone with

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 ...

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 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 ...

, mannose:galactose ~2:1 *

tara gum Tara may refer to: Arts and entertainment Film and television * ''Tara'' (1992 film), an Indian film directed by Bijaya Jena * ''Tara'' (2001 film), an American film, also known as ''Hood Rat'', directed by Leslie Small * ''Tara'' (2010 film), a ...

, mannose:galactose ~3:1 *

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 ...

or ''carob gum'', mannose:galactose ~4:1 *

cassia gum Cassia gum is the flour and food additives made from the endosperms of the seeds of ''Senna obtusifolia'' and ''Senna tora'' (also called '' Cassia obtusifolia'' or ''Cassia tora''). It is composed of at least 75% polysaccharide, primarily galactom ...

, mannose:galactose ~5:1 Galactomannans are often used in food products to increase the viscosity of the water phase. Guar gum has been used to add viscosity to

artificial tears Artificial tears are lubricating eye drops used to relieve dryness and irritation of the ocular surface. Dry eye syndrome (keratoconjunctivitis sicca) is a common ocular surface disorder and is characterized by disruption of the tear film and inc ...

, but is not as stable as

carboxymethylcellulose Carboxymethyl cellulose (CMC) or cellulose gum is a cellulose derivative with carboxymethyl groups (-CH2-COOH) bound to some of the hydroxyl groups of the glucopyranose monomers that make up the cellulose backbone. It is often used as its sodium ...

Food use

Galactomannans are used in foods as stabilisers. Guar and locust bean gum (LBG) are commonly used in ice cream to improve texture and reduce ice cream meltdown. LBG is also used extensively in cream cheese, fruit preparations and salad dressings. Tara gum is seeing growing acceptability as a food ingredient but is still used to a much lesser extent than guar or LBG. Guar has the highest usage in foods, largely due to its low and stable price.

Clinical use

Galactomannan is a component of the cell wall of the mold ''

Aspergillus ' () is a genus consisting of several hundred mold species found in various climates worldwide. ''Aspergillus'' was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Miche ...

'' and is released during growth. Detection of galactomannan in blood is used to diagnose invasive

aspergillosis Aspergillosis is a fungal infection of usually the lungs, caused by the genus ''Aspergillus'', a common mould that is breathed in frequently from the air around, but does not usually affect most people. It generally occurs in people with lung dise ...

infections in humans. This is performed with monoclonal antibodies in a double-sandwich

ELISA The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971. The assay uses a solid-phase type of enzyme immunoassay (EIA) to detect the presence ...

; this assay from

Bio-Rad Bio-Rad Laboratories, Inc. is an American developer and manufacturer of specialized technological products for the life science research and clinical diagnostics markets. The company was founded in 1952 in Berkeley, California, by husband and ...

Laboratories was approved by the FDA in 2003 and is of moderate accuracy. The assay is most useful in patients who have had hemopoetic cell transplants (stem cell transplants). False positive Aspergillus Galactomannan test have been found in patients on intravenous treatment with some antibiotics or fluids containing gluconate or citric acid such as some transfusion platelets, parenteral nutrition or PlasmaLyte.

References

{{reflist Edible thickening agents Polysaccharides Carbohydrates Natural gums *