Gellan Gum
[71010-52-1].
»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 3.3percent and not more than 6.8percent of carbon dioxide,calculated on the dried basis.
Packaging and storage— Preserve in well-closed containers,protected from moisture.Store in a cool,dry place.
Identification—
A: Prepare a 1%solution of Gellan Gum by hydrating 1g in 99mLof deionized water.Stir the mixture for about 2hours,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.[NOTE—Reserve the remaining portion of this solution for the Identification testB.]Atough,wormlike gel will form instantly.
B: To the remaining solution prepared for Identification test A,add 0.5g of sodium chloride,heat the solution to 80,stirring constantly,and hold at 80for 1minute.Stop heating and stirring the solution,and allow it to cool to room temperature.Afirm gel will form.
Microbial limits á61ñ— It meets the requirements of the tests for absence of Salmonellaspecies and Escherichia coli.The total aerobic microbial count is not more than 1000cfu per g,and the total combined molds and yeasts count is not more than 100cfu per g.
Loss on drying á731ñ— Dry at 105for 2.5hours:it loses not more than 15.0%.
Total ash á561ñ: not less than 4.0%and not more than 14.0%,calculated on the dried basis.
Arsenic,Method IIá211ñ: not more than 3.0µg per g.
Lead á251ñ— Prepare a Test Preparationas directed,using a 2.0-g portion of Gellan Gum.Use 4mLof Diluted Standard Lead Solution(4µg of Pb)for the test:the limit is not more than 2.0µg per g.
Limit of isopropyl alcohol— Proceed as directed under Limit of isopropyl alcohol for Xanthan Gum,using about 5g of Gellan Gum,accurately weighed,for the Test solution:not more than 750µg per g is found.
Assay— Proceed with Gellan Gum as directed for Procedureunder Alginates Assay á311ñ,using about 1.2g of undried Gellan Gum,accurately weighed.
Auxiliary Information— Staff Liaison:Elena Gonikberg,Ph.D.,Scientist
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 3010
Pharmacopeial Forum:Volume No.30(4)Page 1328
Phone Number:1-301-816-8251