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Prepared at the 37th JECFA (1988), published in FNP 38 (1988) and in FNP 52 (1992) |
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SYNONYMS |
INS No. 415 |
DEFINITION |
A high molecular weight polysaccharide gum produced by a pure-culture fermentation of a carbohydrate with Xanthomonas campestris, purified by recovery with ethanol or isopropanol, dried and milled; contains D-glucose and D-mannose as the dominant hexose units, along with D-glucuronic acid and pyruvic acid, and is prepared as the sodium, potassium or calcium salt; its solutions are neutral. |
C.A.S. number |
11138-66-2 |
Assay |
Yields, on the dried basis, not less than 4.2% and not more than 5.0% of carbon dioxide (CO2), corresponding to between 91.0% and 108.0% of xanthan gum. |
DESCRIPTION |
Cream-coloured powder |
FUNCTIONAL USES |
Thickener, stabilizer |
CHARACTERISTICS | |
IDENTIFICATION | |
Solubility |
Soluble in water; insoluble in ethanol |
Gel formation |
To 300 ml of water, previously heated to 80o 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 the sample and 1.5 g of carob bean gum. Stir until the mixture goes into solution, and then continue stirring for 30 min longer. Do not allow the water temperature to drop below 60o during stirring. Discontinue stirring, and allow the mixture to cool at room temperature for at least 2 h. A firm rubbery gel forms after the temperature drops below 40o, but no such gel forms in a 1% control solution of the sample prepared in the same manner but omitting the carob bean gum. |
PURITY | |
Loss on drying |
Not more than 15% (105o, 2½ h) |
Ash (total) |
Not more than 16% after drying (105o, 4 h) |
Pyruvic acid |
Not less than 1.5% See description under TESTS |
Nitrogen |
Not more than 1.5% |
Isopropyl alcohol |
Not more than 500 mg/kg See description under TESTS |
Microbiological criteria |
Total plate count: Not more than 10,000 colonies per gram Yeast and mould: Not more than 300 colonies per gram Coliform: Negative by test Salmonella: Negative by test |
Arsenic |
Not more than 3 mg/kg (Method II) |
Lead |
Not more than 5 mg/kg |
Heavy metals |
Not more than 30 mg/kg Test 0.5 g of the sample as directed in the Limit Test (Method II) using a platinum crucible for the ignition and 15 µg of lead ion (Pb) in the control. |
TESTS | |
PURITY TESTS | |
Pyruvic acid |
Sample preparationWeigh 600 mg of the sample to the nearest 0.1 mg and dissolve in sufficient water to make 100 ml. Transfer 10.0 ml of the solution into a 50-ml glass-stoppered flask. Pipette 20 ml of N hydrochloric acid into the flask, weigh the flask, and reflux for 3 h, taking precautions to prevent loss of vapours. Cool to room temperature, and add water to make up for any weight loss during refluxing. Pipette 1.0 ml of a 1 in 200 solution of 2,4- dinitrophenylhydrazine in 2 N hydrochloric acid into a 30-ml separatory funnel, then add 2.0 ml of the sample solution, mix, and allow to stand at room temperature for 5 min. Extract the mixture with 5 ml of ethyl acetate, and discard the aqueous layer. Extract the hydrazone from the ethyl acetate with three 5-ml portions of sodium carbonate TS, collecting the extracts in a 50-ml volumetric flask. Dilute to volume with sodium carbonate TS and mix.
Standard preparationWeigh 45 mg of pyruvic acid, to the nearest 0.1 mg, and transfer into a 500-ml volumetric flask. Dilute to volume with water, and mix. Transfer 10.0 ml of this solution into a 50-ml glass-stoppered flask, and continue as directed under "Sample preparation", beginning with "Pipette 20 ml of N hydrochloric acid into the flask..".
ProcedureDetermine the absorbance of each solution with a suitable spectrophotometer in 1-cm cells at the maximum of about 375 nm, using sodium carbonate TS as the blank. The absorbance of the "Sample preparation" is equal to or greater than that of the "Standard preparation". |
Isopropyl alcohol |
IPA Standard SolutionTransfer 500.0 mg of chromatographic quality isopropyl alcohol into a 50-ml volumetric flask, dilute to volume with water, and mix. Pipet 10 ml of this solution into a 100-ml volumetric flask, dilute to volume with water, and mix.
TBA Standard SolutionTransfer 500.0 mg of chromatographic quality tert-butyl alcohol into a 50-ml volumetric flask, dilute to volume with water, and mix. Pipet 10 ml of this solution into a 100-ml volumetric flask, dilute to volume with water, and mix.
Mixed Standard SolutionPipet 4 ml each of the IPA Standard Solution and of the TBA Standard Solution into a 125-ml graduated Erlenmeyer flask, dilute to about 100 ml with water, and mix. This solution contains approximately 40 µg each of isopropyl alcohol and of tert-butyl alcohol per ml.
Sample preparationDisperse 1 ml of a suitable antifoam emulsion, such as Dow-Corning G-10 or equivalent, in 200 ml of water contained in a 1000-ml 24/40 round-bottom distilling flask. Add about 5 g of the sample, accurately weighed, and shake for 1 h, on a wrist-action mechanical shaker. Connect the flask to a fractionating column, and distil about 100 ml, adjusting the heat so that foam does not enter the column. Add 4.0 ml of TBA Standard Solution to the distillate to obtain the Sample Preparation.
ProcedureInject about 5 µl of the Mixed Standard Solution into a suitable gas chromatograph equipped with a flame-ionization detector and a 1.8-m x 2.3-mm stainless steel column packed with 80/100-mesh Porapak QS or equivalent. The carrier is helium flowing at 80 ml per min. The injection port temperature is 200o, the column temperature is 165o, and the detector temperature is 200o. The retention time of isopropyl alcohol is about 2 min, and that of tert-butyl alcohol about 3 min.
Determine the areas of the IPA and TBA peaks, and calculate the response factor, f, by the formula AIPA/ATBA in which AIPA is the area of the isopropyl alcohol peak, and ATBA is the area of the tert-butyl alcohol peak.
Similarly, inject about 5 µl of the Sample Preparation, and determine the peak areas, recording the area of the isopropyl alcohol peak as aIPA, and that of the tert-butyl alcohol peak as aTBA. Calculate the isopropyl alcohol content, in mg/kg, in the sample taken by the formula:
where W = the weight of the sample taken (g) |
METHOD OF ASSAY |
Proceed as directed in the test for Carbon Dioxide Determination by Decarboxylation using 1.2 g of the sample accurately weighed. |