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Information about Xanthan Gum

Xanthan gum is a polysaccharide used as a food additive and rheology modifier. It is produced by a process involving fermentation of glucose or sucrose by the Xanthomonas campestris bacterium.

Chemical structure

The backbone of the polysaccharide chain consists of two β-D-glucose units linked through the 1 and 4 positions. The side chain consists of two mannose and one glucuronic acid, so the chain consists of repeating modules of five sugar units. The side chain is linked to every other glucose of the backbone at the 3 position. About half of the terminal mannose units have a pyruvic acid group linked as a ketal to its 4 and 6 positions. The other mannose unit has an acetyl group at the 6 positions. Two of these chains may be aligned to form a double helix, giving a rather rigid rod configuration that accounts for its high efficiency as a viscosifier of water. The molecular weight of xanthan varies from about one million to 50 million depending upon how it is prepared.

Preparation

The polysaccharide is prepared by innoculating a sterile aqueous solution of carbohydrate(s), a source of nitrogen, di-potassium monohydrogen phosphate, and some trace elements. The medium is well-aerated and stirred, and the polymer is produced extracellularly into the medium. The final concentration of xanthan produced is about three to five percent by weight. After fermentation over about four days, the polymer is precipitated from the medium by the addition of isopropyl alcohol and dried and milled to give a powder that is readily soluble in water or brine.

History

It was discovered by an extensive research effort by Allene Rosalind Jeanes and her research team at the United States Department of Agriculture, which involved the screening of a large number of biopolymers for their potential uses. It was brought into commercial production by the Kelco Company under the trade name Kelzan in the early 1960's. It was approved for use in foods after extensive animal testing for toxicity in 1969. It is accepted as a safe food additive in the USA, Canada and Europe, with E number E415.

Uses

One of the most remarkable properties of xanthan gum is its capability of producing a large increase in the viscosity of a liquid by adding a very small quantity of gum, on the order of one percent. In most foods, it is used at 0.5%, or even as low as 0.05%. The viscosity of xanthan gum solutions decreases with higher shear rates; this is called pseudoplasticity. This means that a product subjected to shear, whether from mixing, shaking or even chewing, will thin out, but once the shear forces are removed, the food will thicken back up. A practical use would be in salad dressing: The xanthan gum makes it thick enough at rest in the bottle to keep the mixture fairly homogeneous, but the shear forces generated by shaking and pouring thins it so it can be easily poured. When it exits the bottle, the shear forces are removed and it thickens back up so it clings to the salad. Unlike other gums, it is very stable under a wide range of temperatures and pH.

In foods, xanthan gum is most often found in salad dressings and sauces. It helps to stabilize the colloidal oil and solid components against creaming. Also used in frozen foods and beverages, xanthan gum creates the pleasant texture in many ice creams. Toothpaste often contains xanthan gum, where it serves as a binder to keep the product uniform. Xanthan gum is also used in gluten-free baking. Since the gluten (found in wheat) must be omitted, xanthan gum is used to give the dough or batter a "stickiness" that would otherwise be achieved with the gluten. It is also a preferred method of thickening liquids for those with swallowing disorders, since it does not change the color or flavor of foods or beverages.

In the oil industry, xanthan gum is used in large quantities, usually to thicken drilling fluids. These fluids serve to carry the solids cut by the drilling bit back to the surface. The widespread use of horizontal drilling and the demand for good control of drilled solids has led to the expanded use of xanthan gum. Xanthan gum has also been added to concrete poured underwater, in order to increase its viscosity and prevent washout.

In cosmetics xanthan gum is used to prepare water gels usually in conjunction with bentonite clays. Is also used in oil in water emulsions to help stabilise the oil droplets against coelesence. It has some skin hydrating properties.

Allergy

Some people are allergic to xanthan gum, with symptoms of intestinal gripes and diarrhea. Workers exposed to xanthan gum dust exhibit nose and throat irritation as well as work-related illness, with symptoms becoming more prevalent with increasing exposure.[1]

Also, since xanthan gum is produced by a bacteria that is fed corn to grow, some people allergic to corn will also react to it.

References and footnotes

1. ^ Sargent EV, Adolph J, Clemmons MK, Kirk GD, Pena BM, Fedoruk MJ. (1990). "Evaluation of flu-like symptoms in workers handling xanthan gum powder.". J Occup Med. 32 (7). 
  • Davidson, Robert L., ed., Handbook of Water-soluble Gums and Resins, McGraw Hill (1980) ISBN 0-07-015471-6.
  • Whistler, Roy, L, and BeMiller, James N., eds Industrial Gums: Polysaccharides and their Derivatives Academic Press (1973) ISBN 0-12-746252-x.

External links

Polysaccharides are relatively complex carbohydrates. They are polymers made up of many monosaccharides joined together by glycosidic bonds. They are therefore very large, often branched, macromolecules. They tend to be amorphous, insoluble in water, and have no sweet taste.
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Food additives are substances added to food to preserve flavor or improve its taste and appearance. Some additives have been used for centuries; for example, preserving food by pickling (with vinegar), salting, as with bacon, preserving sweets or using sulfur dioxide as in some
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Rheology is the study of the deformation and flow of matter under the influence of an applied stress, which might be shear stress or extensional stress. Rheology dealing with shear stress is called shear rheology.
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Fermentation is a process of energy production in a cell under anaerobic conditions (with no oxygen required). In common usage fermentation is a type of anaerobic respiration, however a more strict definition exists which defines fermentation as respiration under anaerobic
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Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. The living cell uses it as a source of energy and metabolic intermediate.
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Sucrose (common name: table sugar, also called saccharose) is a disaccharide (glucose + fructose) with the molecular formula C12H22O11. Its systematic name is α-D-glucopyranosyl-(1→2)-β-D-fructofuranose.
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Xanthomonas campestris
(Pammel 1895) Dowson 1939

Synonyms
Bacillus campestris Pammel 1895
Pseudomonas campestris (Pammel 1895) Smith 1897
Bacterium campestre (Pammel 1895) Smith 1897

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Bacteria

Phyla

Actinobacteria
Aquificae
Chlamydiae
Bacteroidetes/Chlorobi
Chloroflexi
Chrysiogenetes
Cyanobacteria
Deferribacteres
Deinococcus-Thermus
Dictyoglomi
Fibrobacteres/Acidobacteria
Firmicutes
Fusobacteria
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Mannose is a sugar monomer of the hexose series of carbohydrates.

Metabolism

Mannose enters the carbohydrate metabolism stream in two steps:
  • First it undergoes phosphorylation to mannose-6-phosphate by hexokinase.

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Pyruvic acid (CH3COCO2H) is an alpha-keto acid which plays an important role in biochemical processes. The carboxylate anion of pyruvic acid is known as pyruvate.

Chemistry

Pyruvic acid is a colorless liquid with a smell similar to acetic acid.
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A ketal is a functional group or molecule containing the functional group of a carbon bonded to two -OR groups, where O is oxygen and R represents any alkyl group. It is essentially equivalent to an acetal, and often the term acetal is used instead.
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acetyl (ethanoyl), is a functional group, the acyl of acetic acid, with chemical formula -COCH3. It is sometimes abbreviated as Ac (not to be confused with the element actinium). The acetyl radical contains a methyl group single-bonded to a carbonyl.
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Dipotassium phosphate (also phosphoric acid, dipotassium salt; dipotassium hydrogen orthophosphate; potassium phosphate, dibasic) (K2HPO4) is a soluble salt which is used as a fertilizer and as a food additive.
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Isopropyl alcohol (also isopropanol, iso, rubbing alcohol, or the abbreviation IPA) is a common name for 2-propanol, a colorless, flammable chemical compound with a strong odor.
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United States Department of Agriculture

Logo of the USDA

Seal of the Department of Agriculture
Agency overview
Formed February 15, 1889

Jurisdiction Federal government of the United States

Employees
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Biopolymers are a class of polymers produced by living organisms. Starch, proteins and peptides, DNA, and RNA are all examples of biopolymers, in which the monomer units, respectively, are sugars, amino acids, and nucleic acids.
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Food additives are substances added to food to preserve flavor or improve its taste and appearance. Some additives have been used for centuries; for example, preserving food by pickling (with vinegar), salting, as with bacon, preserving sweets or using sulfur dioxide as in some
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E numbers are codes for food additives and are usually found on food labels throughout the European Union. The numbering scheme follows that of the International Numbering System (INS) as determined by the Codex Alimentarius committee.
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Viscosity is a measure of the resistance of a fluid to deform under either shear stress or extensional stress. It is commonly perceived as "thickness", or resistance to flow.
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A pseudoplastic material is one in which viscosity decreases with increasing rate of shear (also termed shear thinning). This property is found in certain complex solutions, such as ketchup, whipped cream, blood, paint, and nail polish.
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    pH is a measure of the acidity or alkalinity of a solution. Aqueous solutions at 25 ℃ with a pH less than seven are considered acidic, while those with a pH greater than seven are considered basic (alkaline). The pH of 7.
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    A Colloid or colloidal dispersion is a type of heterogeneous mixture. A colloid consists of two separate phases: a dispersed and balls phase and a continuous phase. In a colloid, the dispersed phase is made of tiny particles or droplets that are distributed evenly throughout
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    Creaming, in cooking, is the technique of blending ingredients — usually granulated sugar — together with a solid fat like shortening or butter. The technique is most often used in making cake batter or cookie dough.
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    The petroleum industry operates on the petroleum market. Petroleum is vital to nearly all other industries, if not industrialized civilization itself, and thus is critical concern to many nations.
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    Directional drilling (sometimes known as slant drilling outside the oil industry) is the science of drilling non-vertical wells. Directional drilling can be broken down into three main groups: Oilfield Directional Drilling, Utility Installation Directional Drilling (commonly
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    Concrete is a construction material that consists of cement (commonly Portland cement) as well as other cementitious materials such as fly ash and slag cement, aggregate (generally a coarse aggregate such as gravel limestone or granite, plus a fine aggregate such as sand or
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