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What is the Japan Market standard for Gellan Gum?

Gellan Gum

Gellan Polysaccharides

Definition  Gellan Gum mainly consists of polysaccharides, obtained from the cultured solution of Sphingomonas species (Sphingomonas elodea).

Content  Gellan Gum, when dried, contains 85.0 – 108.0 % of Gellan Gum.

Description  Gellan Gum occurs as a white to brownish powder and has a slight odor.

Identification  (1) Gellan Gum is soluble in water and forms viscous solution.

(2) To 1 g of Gellan Gum, add 100 ml of water, and stir for 2 hours.  Take small amount of the solution into the pipette, add the solution to 10 % calcium chloride solution, immediately a linear gel is formed.

 (3) To 90 ml of the solution obtained under (2), add 0.50 g of sodium chloride.  Heat the solution to 80 °C while stirring and allow for 1 minute.  Cool to room temperature without stir, a gel is formed.

Purity  (1) Total Nitrogen  Not more than 3 %.  Weigh accurately about 1 g of Gellan Gum, and proceed as directed under Kjeldahl Method for Nitrogen Determination.

(2) Lead  Not more than 2.0 µg/g as Pb (5.0 g, Method 1).

(3) Arsenic  Not more than 4.0 µg/g as As₂O₃ (0.50 g, Method 3, Apparatus B).

(4) 2-Propanol  Not more than 0.075 %.

(i) Apparatus

An outline is illustrated in the figure below.

B: Ground-glass joint

C: Delivery tube with spray trap

D: Condenser

E: Measuring flask (100 ml)                (Unit: mm)

(ii) Procedure

Test Solution  Weigh accurately about 2 g of Gellan Gum, place in the flask A, add 200 ml of water, several pieces of boiling tips, and about 1 ml of silicone resin, and mix well.  Measure exactly 4 ml of the internal standard solution, transfer into the measuring flask E, and assemble the apparatus.  Moisten the ground-glass joints B’s with water.  Distill the Gellan Gum solution while adjusting the distilling rate to 2 - 3 ml/min so that no bubbles enter into the delivery tube with stray trap C, collect about 90 ml of the distillate, and add water to make exactly 100 ml.  As the internal standard solution, use tert-butanol solution (1→1000).

Standard Solution  Weigh accurately about 0.5 g of 2-propanol, and add water to make exactly 50 ml.  Measure exactly 5 ml of the solution, and add water to make exactly 50 ml.  Measure exactly 3 ml of the solution and 8 ml of the internal standard solution, mix, and add water to make exactly 200 ml.

With 2.0 µl of each of the test solution and the standard solution, perform Gas Chromatography under the operating conditions below.  Determine the ratios of the peak area of 2-propanol to that of tert-butanol for the test solution and the standard solution, denoted by Q_T and Q_S respectively, and calculate the content of 2-propanol in Gellan Gum by the following formula

Content of 2-propanol

Operating Conditions

Detector: Hydrogen flame ionization detector.

Column packing material: 180- to 250-µm styrene-divinylbenzene porous resin for gas chromatography.

Column tube: A glass tube of 3 mm in internal diameter and 2 m in length.

Column temperature: A constant temperature of about 120 °C.

Injection port temperature: A constant temperature of about 200 °C.

Carrier gas: Nitrogen or Helium.

Flow rate: Adjust so that the retention time of 2-propanol is about 10 minutes.

Loss on Drying  Not more than 15.0 % (105°C, 2.5 hours).

Ash  Not more than 16.0 % (on the dried basis).

Microbial limits  Proceed as directed under Microbial Limit Tests.  The total viable aerobic count is not more than 10,000/g.  No Escherichia coli is observed, provided that 1 g of Rhamsan Gum is used as the sample.

Assay  Take about 1.0 g diatomaceous earth for chromatography, place into a glass filter(1G3), and spread uniformly. Dry at 105°C for 5 hours, allow to cool in a desiccator, and weigh accurately. Weigh accurately about 0.2 g of dried Gellan Gum, add 50 ml of water, and dissolve while stirring in a water bath. Add 200ml of 2-propanol warmed at 60 – 70°C previously, mix well, and allow to stand over night. Filter the gained precipitate by the glass filter as mentioned above, using 2-propanol. Wash the residue 3 times with each 20 ml of 78% vol 2-propanol, and wash twice with each 10 ml of 78% vol 2-propanol.  Dry the desiccator over night at 105°C, and weigh accurately. Calculate the content by the following formula

Content of Gellan Gum