The repeating unit of the polymer is a tetrasaccharide, which consists of two residues of D-glucose and one of each residues of L-rhamnose and D-glucuronic acid. The tetrasacharide repeat has the following structure:
[D-Glc(β1→4)D-GlcA(β1→4)D-Glc(β1→4)L-Rha(α1→3)]n. As it is evident from the formula, the tetrasacharide units are connected by (α1→3) glycosidic bonds.
Microbiological gelling agent
Gellan gum, also branded by few suppliers as Nanogel-TC,"Gelrich" Grovgel, AppliedGel, Phytagel or Gelrite, is used primarily as a gelling agent, alternative to agar, in microbiological culture. It is able to withstand 120 °C heat, making it especially useful in culturing thermophilic organisms. One needs only approximately half the amount of gellan gum as agar to reach an equivalent gel strength, though the exact texture and quality depends on the concentration of divalent cations present. Gellan gum is used as gelling agent in plant cell culture on Petri dishes, as it provides a very clear gel, facilitating light microscopical analyses of the cells and tissues. Although advertised as being inert, experiments with the moss Physcomitrella patens have shown that choice of the gelling agent - agar or Gelrite - does influence phytohormone sensitivity of the plant cell culture.
As a food additive, gellan gum is used as a thickener, emulsifier, and stabilizer. It has E number E418. It was an integral part of the now defunct Orbitz soft drink. It is used as the gelling agent, as an alternative to gelatin, in the manufacture of vegan varieties "gummi" candies.
It is used in soy milks to keep the soy protein suspended in the milk.
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Gellan was developed by Kelco, then a division of Merck & Co. Kelco is solely responsible for obtaining food approval for gellan gum worldwide. Kelco, now the CP Kelco family of companies owned by J.M. Huber Corporation is virtually the only producer of gellan gum. A few sources exist in China but are small and little found in the market.
Pure gellan gum is one of the most expensive hydrocolloids. Its cost in use, however, is competitive with much lower priced hydrocolloids.
- Shungu D, Valiant M, Tutlane V, Weinberg E, Weissberger B, Koupal L, Gadebusch H, Stapley E.: GELRITE as an Agar Substitute in Bacteriological Media, Appl Environ Microbiol. 1983 Oct;46(4):840-5.
- Birgit Hadeler, Sirkka Scholz, Ralf Reski (1995): Gelrite and agar differently influence cytokinin-sensitivity of a moss. Journal of Plant Physiology 146, 369-371
- "CP Kelco Introduces KELCOGEL HS-B Gellan Gum. - Free Online Library". Thefreelibrary.com. 2005-02-22. Retrieved 2012-05-23.
- Dea, Ian C M (1989). "Industrial polysaccharides". Pure and Applied Chemistry 61 (7): 1315–1322. doi:10.1351/pac198961071315.
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