Gellan gum is the generic name for extracellular polysaccharide produced by bacterium Pseudomonas elodea.
Kaneko and Kang discovered the polymer in the laboratory of the Kelco Division of Merck and Co., California, USA in 1978.
It had previously been referred to by the code names S-60 or PS-60. The gellan gum-producing microorganism was isolated from the Elodea plant tissue.
Further studies revealed that the bacterium was a new strain of the species Pseudomonas, and hence termed
as Pseudomonas elodea.
In 1994, it was discovered that gellan-producing bacterium was Sphingomonas paucimobilis, and classified in the a-4 subclass of the Proteobacteria. Successful toxicity trials were completed and gellan gum received approval for use in food in Japan in 1988.The US FDA approved gellan gum for use as a food additive in 1992.
Specifications for gellan gum are summarized in below Table.
Definition
Gellan gum is high molecular mass polysaccharide gum produced by a pure culture fermentation of carbohydrates by Pseudomonas elodea, purified by recovery with isopropyl alcohol, dried, and milled.The high molecular mass polysaccharide is principally composed of tetracyclic repeating unit of one rhamnose, one glucuronic acid, and two glucose units and is substituted with acyl group as the O-glycosidically-linked esters. The glucuronic acid is converted to potassium, sodium, calcium and magnesium salt. It usually contains small amount of nitrogen-containing compounds resulting from fermentation procedures
Molecular mass
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Approximately 500 000
|
Description
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Off-white powder
|
Functional uses
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Thickening agent, gelling agent, stabilizer, etc.
|
Solubility
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Soluble in water, forming viscous solution; insoluble in ethanol
|
Loss during drying
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Not more than 15 % (105 °C, 2.5 h)
|
Lead
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Not more than 2 mg/kg
|
Nitrogen
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Not more than 3 %
|
Gel test with calcium ion
Add 1.0 g of sample to 99 mL of water, and stir for about 2 h. Draw a small amount of this solution
into a wide bore pipette and transfer to a 10 % solution of calcium chloride. A tough worm-like gel
will be formed immediately.
into a wide bore pipette and transfer to a 10 % solution of calcium chloride. A tough worm-like gel
will be formed immediately.
Gel test with sodium ion
To the 1 % solution of the sample, add 0.5 g of sodium chloride, heat to 80 °C by stirring and hold at
80 °C for 1 min. Allow solution to cool to room temperature. A firm gel will form
80 °C for 1 min. Allow solution to cool to room temperature. A firm gel will form
Isopropyl alcohol Not more than 750 mg/kg
Microbiological criteria
1. Total plate count Not more than 10 000 colonies per gram
2. E. coli Negative by test
3. Salmonella Negative by test
4. Yeasts and moulds Not more than 400 colonies per gram
