Galactomannan

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A segment of galactomannan showing mannose backbone (below) with a branching galactose unit (top) Galactomannan.png
A segment of galactomannan showing mannose backbone (below) with a branching galactose unit (top)

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).

Contents

In order of increasing number of mannose-to-galactose ratio: [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, but is not as stable as carboxymethylcellulose. [2]

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, [3] [ unreliable medical source? ] 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 [4] and is released during growth. Detection of galactomannan in blood is used to diagnose invasive aspergillosis infections in humans. This is performed with monoclonal antibodies in a double-sandwich ELISA; this assay from Bio-Rad Laboratories was approved by the FDA in 2003 and is of moderate accuracy. [5] The assay is most useful in patients who have had hemopoietic 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. [6] [7]

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<span class="mw-page-title-main">Guar</span> Species of flowering plant in the bean family Fabaceae

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, gawar, or guvar bean. The genus name Cyamopsis means bean-like. The specific name is from Latin: tetragōnoloba meaning four-lobed.

<span class="mw-page-title-main">Guar gum</span> Vegetable gum from the guar bean, Cyamopsis tetragonoloba

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, milled and screened according to application. It is typically produced as a free-flowing, off-white powder.

<span class="mw-page-title-main">Mannans</span> Polysaccharides formed from mannose

Mannans are polymers containing the sugar mannose as a principal component. They are a type of polysaccharide found in hemicellulose, a major source of biomass found in higher plants such as softwoods. These polymers also typically contain two other sugars, galactose and glucose. They are often branched.

<span class="mw-page-title-main">Carob</span> Small tree grown for its edible pods and landscaping

The carob 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, which takes the form of seed pods, and as an ornamental tree in gardens and landscapes. The carob tree is native to the Mediterranean region and the Middle East. Portugal is the largest producer of carob, followed by Italy and Morocco.

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Glucomannan is a water-soluble polysaccharide that is considered a dietary fiber. It is a hemicellulose component in the cell walls of some plant species. Glucomannan is a food additive used as an emulsifier and thickener. It is a major source of mannan oligosaccharide (MOS) found in nature, the other being galactomannan, which is insoluble.

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<span class="mw-page-title-main">Cassia gum</span>

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Tara spinosa, commonly known as tara (Quechua), also known as Peruvian carob or spiny holdback, is a small leguminous tree or thorny shrub native to Peru. T. spinosa is cultivated as a source of tannins based on a galloylated quinic acid structure. This chemical structure has been confirmed also by LC–MS. It is also grown as an ornamental plant because of its large colorful flowers and pods.

<span class="mw-page-title-main">Beta-glucan</span> Class of chemical compounds

Beta-glucans, β-glucans comprise a group of β-D-glucose polysaccharides (glucans) naturally occurring in the cell walls of cereals, bacteria, and fungi, with significantly differing physicochemical properties dependent on source. Typically, β-glucans form a linear backbone with 1–3 β-glycosidic bonds but vary with respect to molecular mass, solubility, viscosity, branching structure, and gelation properties, causing diverse physiological effects in animals.

<span class="mw-page-title-main">Locust bean gum</span> Vegetable gum from the carob bean Ceratonia siliqua

Locust bean gum is a galactomannan vegetable gum extracted from the seeds of the carob tree and used as a thickening agent in food technology.

Fibre supplements are considered to be a form of a subgroup of functional dietary fibre, and in the United States are defined by the Institute of Medicine (IOM). According to the IOM, functional fibre "consists of isolated, non-digestible carbohydrates that have beneficial physiological effects in humans".

<span class="mw-page-title-main">Stabiliser (food)</span> Food additive

A stabiliser or stabilizer is an additive to food which helps to preserve its structure. Typical uses include preventing oil-water emulsions from separating in products such as salad dressing; preventing ice crystals from forming in frozen food such as ice cream; and preventing fruit from settling in products such as jam, yogurt and jellies. Some of these food additives may promote the growth of specific microorganisms in the gastrointestinal tract that can ferment them. The following hydrocolloids are the most common ones used as stabilisers:

<span class="mw-page-title-main">Chronic pulmonary aspergillosis</span> Fungal infection

Chronic pulmonary aspergillosis is a long-term fungal infection caused by members of the genus Aspergillus—most commonly Aspergillusfumigatus. The term describes several disease presentations with considerable overlap, ranging from an aspergilloma—a clump of Aspergillus mold in the lungs—through to a subacute, invasive form known as chronic necrotizing pulmonary aspergillosis which affects people whose immune system is weakened. Many people affected by chronic pulmonary aspergillosis have an underlying lung disease, most commonly tuberculosis, allergic bronchopulmonary aspergillosis, asthma, or lung cancer.

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<i>Aspergillus candidus</i> Species of fungus

Aspergillus candidus is a white-spored species of fungus in the genus Aspergillus. Despite its lack of pigmentation, it is closely related to the most darkly-pigmented aspergilli in the Aspergillus niger group. It is a common soil fungus worldwide and is known as a contaminant of a wide array of materials from the indoor environment to foods and products. It is an uncommon agent of onychomycosis and aspergillosis. The species epithet candidus (L.) refers to the white pigmentation of colonies of this fungus. It is from the Candidi section. The fungi in the Candidi section are known for their white spores. It has been isolated from wheat flour, djambee, and wheat grain.

<span class="mw-page-title-main">Sour cream</span> Fermented dairy product

Sour cream is a dairy product obtained by fermenting regular cream with certain kinds of lactic acid bacteria. The bacterial culture, which is introduced either deliberately or naturally, sours and thickens the cream. Its name comes from the production of lactic acid by bacterial fermentation, which is called souring. Crème fraîche is one type of sour cream with a high fat content and less sour taste.

References

  1. Peter A. Williams; Glyn O. Phillips (2004). Gums and Stabilisers for the Food Industry 12. Royal Society of Chemistry. p. 311. ISBN   978-0-85404-891-5.
  2. Simmons, P.A. (May 2004). "Modeling of Ocular Viscosity for Mid–viscosity Artificial Tear Preparations". Investigative Ophthalmology & Visual Science . 45 (13): 3893.
  3. "CAROB AND LOCUST BEAN GUM - LBG PROPERTIES". CyberColloids Ltd.
  4. Bart-Delabesse E, Basile M, Al Jijakli A, et al. (October 2005). "Detection of Aspergillus galactomannan antigenemia to determine biological and clinical implications of beta-lactam treatments". J. Clin. Microbiol. 43 (10): 5214–20. doi:10.1128/JCM.43.10.5214-5220.2005. PMC   1248458 . PMID   16207986.
  5. Pfeiffer CD, Fine JP, Safdar N (2006). "Diagnosis of invasive aspergillosis using a galactomannan assay: a meta-analysis". Clin Infect Dis. 42 (10): 1417–27. doi: 10.1086/503427 . PMID   16619154.
  6. Martin-Rabadan, P.; Gijon, P.; Alonso Fernandez, R.; Ballesteros, M.; Anguita, J.; Bouza, E. (18 May 2012). "False-positive Aspergillus Antigenemia Due to Blood Product Conditioning Fluids". Clinical Infectious Diseases. 55 (4): e22–e27. doi: 10.1093/cid/cis493 . PMID   22610929.
  7. Spriet, Isabel; Lagrou, Katrien; Maertens, Johan; Willems, Ludo; Wilmer, Alexander; Wauters, Joost; Warnock, D. W. (March 2016). "Plasmalyte: No Longer a Culprit in Causing False-Positive Galactomannan Test Results". Journal of Clinical Microbiology. 54 (3): 795–797. doi: 10.1128/JCM.02813-15 . PMC   4767971 . PMID   26719444.