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Xanthan Gum

Xanthan Gum

Description

Xanthan gum is a polysaccharide produced by the bacterium Xanthomonas campestris. The structure and properties of this extracellular polysaccharide have been thoroughly reviewed and studied since xanthan gum's discovery in 1961. This gum is highly edible and a good source of dietary fiber. It has the ability to form mixed gels with certain other polysaccharides such as glucomannans.

Xanthan gum is added to some diets for its fiber content. Gum fiber, although not a true fiber, is considered a part of the dietary fiber complex because it elicits similar effects.

Both gums and pectins increase intestinal transit time, adsorb fecal water, influence glucose and lipid metabolism, mineral absorption and possibly reduce the risk of colon cancer. In industry, the term gum usually refers to polysaccharides (long chains of simple sugars) which are dispersible in either hot or cold water to produce viscous mixtures.

Numerous studies, particularly of the epidemiological variety, have suggested an adequate supply of dietary fiber protects against obesity, diabetes mellitus and coronary heart disease. Xanthan gum has particular clinical value in Dumping syndrome, diabetes and hyper-cholesterolemia, due to its viscosity. Xanthan gum has a therapeutically glutinous or viscous property that accounts for its use as a bulking agent in the above conditions.

Xanthan gum is produced by culturing Xanthomonas campetris NRRL B-1459 (NNRL stands for Northern Utilization Research and Development Division, U.S. Department of Agriculture) on a well-aerated medium containing commercial glucose, organic nitrogen sources, dipotassium hydrogen phosphate and appropriate trace elements.

When fermentation is finished, the culture fluids have a viscosity as high as 17,000 centipoises; they appear homogeneous and have very short flow characteristics. Following further precipitation, reprecipitation and filtration processes, most of the bacterial pigments are removed. Following fermentation, xanthan gum is recovered by precipitation in isopropyl alcohol, then dried and milled. The final product is sold under the trade name of Kelzan by the Kelco Company, a division of Merck & Company.

Xanthan gum is one of many gums used as stabilizers and thickeners in industry and by food processors. Other such gums include: guar gum (Cyamopsis spp.), locust bean gum or carob gum (Ceratonia spp.), gum arabic (Acacia senegal), gum tragacanth (Asiatic Astragalus spp.), and tara gum (Caesalpinia spp.).

Xanthan gum is an excellent bodying agent for toothpaste and ointments. Because of its pseudoplastic properties, xanthan gum is able to help both toothpaste and ointments hold their shape. The gum is also permitted as an ingredient in all nonmedical cosmetics for which no drug claims are made. This gum is also used in bakery products, dressings, sauces, food and drinks, and in syrups. Salad dressings make frequent use of xanthan gums due to its emulsification properties. Xanthan gum will be found in such common salad dressings as "Green Goddess", "Creamy Russian", "French Dressing", and "Creamy Italian." Common sauces using xanthan gum include: cheese sauce mixes, barbecue sauce mixes, spaghetti sauce mixes and white sauce mixes. In frozen pizzas, xanthan gum helps to produce a tomato-based sauce for frozen pizza with improved viscosity and freeze-thaw stability, which contributes to its extended shelf-life.

When xanthan gum is combined with locust bean gum and guar gum, the mixture provides for viscosity control of cottage cheese dressings, and stabilization of ice cream and ice milk products.

Method of Action

Xanthan gum has been found to contain repeating units of sugar residues by methylation analysis, and by uronic acid degradation followed by oxidation and elimination of the oxidized residue. The gum contains D-glucose, D-mannose, D-glucuronic acid, acetal-linked pyruvic acid and O-acetyl.

When used in citrus and fruit-flavored beverages, xanthan gum enhances mouth feel with full-bodied taste and good flavor release. It is also an excellent suspending agent for the desirable cloud and pulp in some of these type drinks. Additionally it is a stabilizer for flavor oil emulsions employed in certain beverages. Concentrations of xanthan gum in a finished drink may range from 0.001% to 0.15%.

Studies of the relationship between xanthan gum and diabetes have suggested the gum affects the endocrine activity of the gut in two ways. Intestinal distention, as produced by xanthan feeding, is known to influence the secretion of some enteric hormones. Xanthan gum appears to move the region of principal contact between nutrients and the intestinal lining to a more distal position. The latter effect is considered important since secretory cells for various enteric hormones are somewhat concentrated within different portions of the gut.

Therapeutic Approaches

Xanthan gum may be beneficial as a dietary fiber in reducing the risk of colon cancer. Gum fiber, although not a true fiber, is considered a part of the dietary fiber complex because of the similar effects they can elicit in the diet.

Gum fiber can affect the enteropathic circulation of bile salts which act as colon tumor promoters. Gum fiber not only can influence bile acid metabolism, thereby reducing the formation of potential tumor promoters in the colon, but also exerts a solvent-like effect in diluting potential carcinogens and cocarcinogens by its bulking effect. It is also able to bind bile acids and certain related carcinogenic compounds.

Dietary fiber may be of benefit to diabetics. Xanthan gum, among gums, is thought to affect gastric emptying and the secretion of enteric hormones in ways that restrain insulin release after a meal.

Xanthan gum has been shown to reduce total liver lipids in animals.

Toxicity Factors

The food-grade xanthan gum has been subjected to extensive feeding and toxicology studies. These studies established its safety for use as a food ingredient.

In short-term, subacute toxicological studies of xanthan gum, it was not possible to determine acute oral toxicity (LD50) in rats or dogs. The amount of xanthan gum that could be fed to experimental animals within a 24-hour period caused no deaths, no signs of toxicity, and no changes in internal organs of either rats or dogs given doses as great as 45 gr/kg of body weight for rats and 20 gr/kg for dogs.

Histopathological observations of rats subjected to long term oral administration up to 0.1 grams per kilogram of body weight showed no distinguishable differences between controls and test animals.

The Food and Drug Administration (FDA) issued a food additive regulation authorizing its unrestricted use in foods for which standards of identity do not preclude its use. The Canadian Governor-in-Council has also formally approved the general use of xanthan gum in foods. The FAO/WHO has issued an acceptable daily intake for xanthan gum.

References

Anonymous. Xanthan Gum - A Natural Biopolysaccharide for Scientific Water Control. 2nd Edition. Kelco, San Diego, CA. Division of Merck & Company Inc. 1976.

Baig, M. & Cerda. Citrus pectic polysaccharide-their in vitro interaction with low density serum lipioproteins. Unconventional Sources of Dietary Fiber. Furda .ed. American Chemical Society. Wash. DC 1983. p. 185.

Burkitt, D.P., A.R.P. Walker & N.S. Painter. Dietary fiber and disease. JAMA. 1974. 229(8); 1069-1074.

Cottrell, I.W., K.S. Kang & P. Kovacs. Xanthan gum. - Handbook of Water-Soluble Gums and Resins. R.L. Davidson. ed. McGraw-Hill. New York. 1980. pp. 24-1 to 24-31.

Council on Scientific Affairs. American Medical Association. Dietary fiber and health. JAMA. 1989. 262(4); 542-546.

Jansson, P.E., L. Kenne & B. Lindberg. Structure of the extracellular polysaccharide from Xanthomonas campestris. Carbohydrate Res. 1975. 45; 275-282.

Jeanes, A, J.E. Pittsley & F.R. Senti. Polysaccharide B-1459 - a new hydrocolloid polyectrolyte produced from glucose by bacterial fermentation. J Appl Polymer Sci. 1961 5(17); 519-526.

Jenkins, D.J.A. & T.M.S. Wolever. Slow release carbohydrate and the treatment of diabetes. Proc Nutr Soc. 1981. 40; 227-235.

Jenkins, D.J.A. Slow release carbohydrate and the treatment of diabetes. Proc Nutr Soc. 1981. 40; 227-235.

Kelsay, J.L. A review of research on the effects of fiber intake on man. Am J Clin Nutr. 1978. 31; 142-159.

McNeely, W.H. & K.S. Kang. Xanthan and some other biosynthetic gums. Industrial Gums - Polysaccharides and Their Derivatives. 2nd Edition.

Osilesi, O. D.L. Trout & E. Knight. Hepatic responses to edible gums during refeeding of starved rats. J Nutr. 1988. 118(4); 462-468.

Reddy, B.S., L. Cohen, G.D. McCoy, P. Hill, J.H. Weisburger & E.L. Wynder. Advances in Cancer Research. Academic Press. New York. 1980. pp. 237-345.

Rogovin, S.P., R.F. Anderson & P.A. Cadmus. J Biochem Microbiol Technol Eng. 1961 3; 51-57.

Rubino, M.A., B.A. Pethica & P. Zuman. Dietary Fibers - Chemistry and Nutrition. Academic Press. New York. 1979. pp. 251-281.

Sloneker, J.H. & A. Jeanes. Can J Chem. 1962. 40; 2066-2071.

Trout, D.L., R.O. Ryan & M.C. Bickard. The amount and distribution of water, dry matter, and sugars in the digestive tract of rats fed xanthan gum (41567). Proc Soc Exp Biol Med. 1983. 172; 340-345.

Trowell, H. Dietary fibre, ischemic heart disease and diabetes mellitus. Proc Nutr Soc. 1973. 32; 151-157.

Whistler, R.L. & J.N. BeMiller. Academic Press. New York. 1973. p. 484.