Xanthan Gum

Synonyms: polysaccharide gum produced by the fermentation of carbohydrate with the bacterium xanthomonas campestris
cas number: 11138-66-2, molecular weight: polymer, chemical formula: (c35h49o29)n, einecs ec number: 234-394-2, fema: ----,
xanthan gum bp grade
ph eur
action and use: excipient.
Definition
high-molecular-mass anionic polysaccharide produced by fermentation of carbohydrates with xanthomonas campestris.
Xanthan gum has a relative molecular mass of approximately 1 ã— 106. It exists as the sodium, potassium or calcium salt.
Content: minimum 1.5 per cent of pyruvoyl groups (c3h3o2; mr 71.1) (dried substance).
Characters
appearance: white or yellowish-white, free-flowing powder.
Solubility: soluble in water giving a highly viscous solution, practically insoluble in organic solvents.
Identification
a. In a flask, suspend 1 g in 15 ml of 0.1 m hydrochloric acid . Close the flask with a fermentation bulb containing barium hydroxide solution and heat carefully for 5 min. The barium hydroxide solution shows a white turbidity.
B. To 300 ml of water, previously heated to 80 â°c and stirred rapidly with a mechanical stirrer in a 400 ml beaker, add, at the point of maximum agitation, a dry blend of 1.5 g of carob bean gum and 1.5 g of the substance to be examined. Stir until the mixture forms a solution, and then continue stirring for 30 min or longer. Do not allow the water temperature to drop below 60 â°c during stirring. Discontinue stirring and allow the mixture to stand for at least 2 h. A firm rubbery gel forms after the temperature drops below 40 â°c but no such gel forms in a 1 per cent control solution of the sample prepared in the same manner but omitting the carob bean gum.
Tests
ph: 6.0 to 8.0 for a 10.0 gl solution.
Viscosity: minimum 600 mpaâ·s.
2-propanol: to pass gas chromatography test. Limit 2-propanol: maximum 750 ppm.