Xanthan gum is a polysaccharide used as a food additive and rheology modifier (Davidson ch. 24). It is produced by a process involving fermentation of glucose or sucrose by the Xanthomonas campestris bacterium. Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. ... Food additives are substances added to food to preserve flavor or improve its taste and appearance. ... Rheology is the study of the deformation and flow of matter under the influence of an applied stress. ... For other uses, see Fermentation. ... Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. ... Flash point N/A Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Sucrose (common name: table sugar, also called saccharose) is a disaccharide (glucose + fructose) with the molecular formula C12H22O11. ... Binomial name Xanthomonas campestris (Pammel 1895) Dowson 1939 Synonyms Bacillus campestris Pammel 1895 Pseudomonas campestris (Pammel 1895) Smith 1897 Bacterium campestre (Pammel 1895) Smith 1897 Phytomonas campestris (Pammel 1895) Bergey et al. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ...

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. D and L forms Haworth projection of mannose in its α-D-mannopyranose form. ... The α-D form of glucuronic acid. ... Pyruvic acid (CH3COCO2H) is an alpha-keto acid which plays an important role in biochemical processes. ... An ketal is a functional group or molecule containing the functional group of a carbon bonded to two -OR groups. ... Acetyl is the radical of acetic acid. ...

Preparation

The polysaccharide is prepared by inoculating 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. 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. ... Isopropyl alcohol (also isopropanol or rubbing alcohol) is a common name for propan-2-ol, a colorless, flammable chemical compound with a strong odor. ...

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 1960s. (Whistler p. 486) It was approved for use in foods after extensive animal testing for toxicity in 1968. It is accepted as a safe food additive in the USA, Canada and Europe, with E number E415. USDA redirects here. ... A biopolymer is a polymer found in nature. ... Food additives are substances added to food to preserve flavor or improve its taste and appearance. ... For the mathematical constant see: E (mathematical constant). ...

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% and can be used in lower concentrations. 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. For other uses, see Viscosity (disambiguation). ... A pseudoplastic material is one in which viscosity decreases with the rate of shear (also termed shear thinning or thixotropy). ... For other uses, see PH (disambiguation). ...

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 by acting as an emulsifier. 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. Xanthan gum also helps thicken commercial egg substitutes made from egg whites to replace the fat and emulsifiers found in yolks. 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. A Colloid or colloidal dispersion is a type of homogeneous mixture. ... Creaming is a cooking technique used to blend one or more dry ingredients together with shortening of some form. ... An emulsion is a mixture of two immiscible substances. ...

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. The Oil industry brings to market what is currently considered the lifeblood of nearly all other industry, if not industrialized civilization itself. ... This article is about the unit of information. ... This article or section does not cite its references or sources. ... This article is about the construction material. ... For other uses, see Viscosity (disambiguation). ... The term washout can have various meanings. ...

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 coalescence. It has some skin hydrating properties. Bentonite - USGS Bentonite is an absorbent aluminium phyllosilicate generally impure clay consisting mostly of montmorillonite. ... In chemistry, hydration is the condition of being combined with water. ...

Allergy

Some people are allergic to xanthan gum, with symptoms of intestinal gripes, diarrhea, temporary high blood pressure, and migraine headaches. 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 bacterium that is fed corn to grow, some people allergic to corn will also react to it. Yellow Phrygian Husk is a common source of bacterium in which xanthan gum is created. ^[2]

References and footnotes

A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 325th day of the year (326th in leap years) in the Gregorian calendar. ...

External links

• Xanthan Gum, by J. Flores Candia & W. Deckwer, Encyclopedia of Bioprocess Technology, John Wiley & Sons Inc (1999)
• Xanthan Gum, by Martin Chaplin, accessed Dec 2007
• X Is for Xanthan Gum, by Lynn A. Cunt, Food Product Design, June 2007
• VanZan Xanthan Gum, by R.T. Vanderbilt Co Inc, Sep 2007
• Rosalind Jeanes and the invention of xanthan gum, by Chemical Heritage Foundation, accessed Dec 2007