Xanthan Gum

Xanthan Gums

Xanthan Gum is a natural polysaccharide. It was discovered in the late fifties in the research laboratories of the U.S. Department of Agriculture during research work into the industrial applications of microbial biopolymers.

Extensive research revealed that the bacterium Xantphomonas campestris found on cabbage plants produces a high molecular weight polysaccharide, which protects the bacterium. This polysaccharide, called Xanthan Gum, proved to have technically and economically interesting properties.

The industrial importance of Xanthan Gum is based upon its exceptional qualities as a rheology control agent in aqueous systems and as a stabilizer for emulsions and suspensions.

Its numerous areas if application cover a broad spectrum in various industries.

Chemistry And Structure Of Xanthan Gum
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The backbone of the Xanthan Gum molecule is similar to that of cellulose. The side chains consist of mannose-acetate, mannose and glucuronic acid. Pyruvate compounds are attached to some single unit side chain by ketal linkages.

Electron microscopy shows the helix conformation of the Xanthan Gum molecular. The molecular weight is several million.

Manufacture:

The industrial production of Xanthan Gum imitates the natural process, but under optimum conditions. A medium containing a carbo-hydrate, a nitrogen source and nutrient salts form the basis for the fermentation process. The fermentation itself is conducted in a sterile environment, with pH, oxygen content and temperature being carefully monitored. At the conclusion of the fermentation process, the broth is sterilized and the Xanthan Gum is recovered by precipitation, then dried and milled.

Regulatory Status
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Prior to its approval as a food ingredient, Xanthan Gum had been extensively investigated with respect to toxicology and safety. In most countries Xanthan Gum is already accepted as a valuable additive for food use.

It was cleared as a food additive by the FDA (the US Food and Drug Administration) in 1969 (Fed. Reg. 34:5376) and is registered in the Code of Federal Regulations (21 CFR 172.695) for use as stabilizer and thickener. In 1980 the EEC approved Xanthan Gum and it joined the list of permitted thickeners and stabilizers under the number E 415.

The regulatory status of Xanthan Gum should be investigated carefully in each country before any use. Xanthan Gum fully meets the purity criteria and standards of identity issued by the US FDA, FCC (Food Chemicals Codex), NF (National Formulary), FAO/WHO and EEC directives.

Properties:

Xanthan Gum is a white to cream-coloured free flowing powder soluble both in hot and cold water, but insoluble in most organic solvents. Its industrial importance is based upon its ability to control the rheology of water-based systems. Even at the low concentrations Xanthan Gum solutions show a high degree of viscosity in comparison with other polysaccharide solutions. This property makes it a very effective thickener and stabilizer.

Xanthan Gum solutions are highly pseudoplastic and show a distinct yield-value. AT rest and up to a certain shear stress the solution behaves like a solid medium due to a micro-gel matrix structure. Exceeding this point, the solution flows. Xanthan Gum solutions are pseudoplastic but not thixotropic, i.e. even after thigh shear rates the initial viscosity is rebuild instantaneously.

Xanthan gum is more pseudoplastic than any other hydrocolloid. This pseudoplasticity enhances sensory qualities (flavour release, mouth feel) in final products and guarantees high-degree mix-, pump- and pourablility.


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