(jel' an gum).
» Gellan Gum is a high molecular weight polysaccharide gum produced by a pure-culture fermentation of a carbohydrate with Pseudomonas elodea, purified by recovery with isopropyl alcohol, and then dried and milled. It is a heteropolysaccharide comprising a tetrasaccharide repeating unit of one rhamnose, one glucuronic acid, and two glucose units. The glucuronic acid is neutralized to mixed potassium, sodium, calcium, and magnesium salts. It may contain acyl (glyceryl and acetyl) groups as the O-glycosidically linked esters. It yields not less than 3.3 percent and not more than 6.8 percent of carbon dioxide, calculated on the dried basis.
Packaging and storage Preserve in well-closed containers, and store at room temperature.
A: Prepare a 1% solution of Gellan Gum by hydrating 1g in 99 mL of deionized water. Stir the mixture for about 2 hours, using a motorized stirrer and a propeller-type stirring blade. Draw a small amount of the solution obtained into a wide-bore pipet, and transfer it into a 10% calcium chloride solution. [noteReserve the remaining portion of this solution for Identification test B. ] A tough, wormlike gel will form instantly.
B: To the remaining solution prepared for Identification test A, add 0.5 g of sodium chloride, heat the solution to 80, stirring constantly, and hold at 80 for 1 minute. Stop heating and stirring the solution, and allow it to cool to room temperature. A firm gel will form.
Microbial enumeration tests 61 and Tests for specified microorganisms 62 It meets the requirements of the tests for absence of Salmonella species and Escherichia coli. The total aerobic microbial count is not more than 1000 cfu per g, and the total combined molds and yeasts count is not more than 100 cfu per g.
Loss on drying 731 Dry it at 105 for 2.5 hours: it loses not more than 15.0%.
Total ash 561: not less than 4.0% and not more than 14.0%, calculated on the dried basis.
Arsenic, Method II 211: not more than 3.0 µg per g.
Lead 251 Prepare a Test Preparation as directed, using a 2.0-g portion of Gellan Gum. Use 4 mL of Diluted Standard Lead Solution (4 µg of Pb) for the test: the limit is not more than 2.0 µg per g.
Limit of isopropyl alcohol Proceed as directed under Limit of isopropyl alcohol for Xanthan Gum, using about 5 g of Gellan Gum, accurately weighed, for the Test solution: not more than 750 µg per g is found.
Assay Proceed with Gellan Gum as directed for Procedure under Alginates Assay 311, using about 1.2 g of undried Gellan Gum, accurately weighed.
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USP35NF30 Page 1808Pharmacopeial Forum: Volume No. 30(4) Page 1328