 | |
| Names | |
|---|---|
| Other names Gum gellan; E418; [D-Glc(β1→4)D-GlcA(β1→4)D-Glc(β1→4)L-Rha(α1→3)]n | |
| Identifiers | |
| ECHA InfoCard | 100.068.267 |
| EC Number |
|
| E number | E418(thickeners, ...) |
| UNII | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Gellan gum is a water-solubleanionicpolysaccharide produced by the bacteriumSphingomonas elodea (formerlyPseudomonas elodea based on the taxonomic classification at the time of its discovery).[1] The gellan-producing bacterium was discovered and isolated by the former Kelco Division ofMerck & Company, Inc. in 1978 from the lily plant tissue from a natural pond inPennsylvania. It was initially identified as a gelling agent to replaceagar at significantly lower concentrations in solid culture media for the growth of various microorganisms.[2] Its initial commercial product with the trademark as Gelrite gellan gum, was subsequently identified as a suitable agar substitute as gelling agent in various clinical bacteriological media.[3]
The repeating unit of the polymer is a tetrasaccharide, which consists of two residues ofD-glucose and one of each residues ofL-rhamnose andD-glucuronic acid. The tetrasaccharide repeat has the following structure:
[D-Glc(β1→4)D-GlcA(β1→4)D-Glc(β1→4)L-Rha(α1→3)]n
Gellan gum products are generally put into two categories, low acyl and high acyl depending on number ofacetate groups attached to the polymer. The low acyl gellan gum products form firm, non-elastic, brittle gels, whereas the high acyl gellan gum forms soft and elastic gels.[4]
Gellan gum is initially used as a gelling agent, alternative toagar, in microbiological culture. It is able to withstand 120 °C heat. It was identified as an especially useful gelling agent in culturingthermophilic microorganisms.[5] One needs only approximately half the concentration of gellan gum as agar to reach an equivalent gel strength, though the exact texture and quality depends on the concentration of the divalentcations present.Gellan gum is also used as gelling agent inplantcell culture onPetri dishes, as it provides a very clear gel, facilitatinglight microscopical analyses of thecells andtissues. Although advertised as beinginert, experiments with themossPhyscomitrella patens have shown that choice of the gelling agent—agar or Gelrite—does influencephytohormone sensitivity of the plant cell culture.[6]
As afood additive, gellan gum was first approved for food use in Japan (1988). Gellan gum has subsequently been approved for food, non-food, cosmetic and pharmaceutical uses by many other countries such as US, Canada, China, Korea and the European Union etc. It is widely used as athickener,emulsifier, andstabilizer. It hasE number E418. It was an integral part of the now defunctOrbitz soft drink.It is used as the gelling agent, as an alternative togelatin, in the manufacture of vegan varieties of "gum" candies.
It is used inplant-based milks to keep plant protein suspended in the milk.[7] Gellan has also become popular inhaute cuisine, and in particular inmolecular gastronomy and other scientifically-informed schools of cooking, to make flavorful gels; British chefHeston Blumenthal and American chefWylie Dufresne are generally considered to be the earliest chefs to incorporate gellan into high-end restaurant cooking, but other chefs have since adopted the innovation.[8]
Gellan gum, when properly hydrated, can be used in ice cream and sorbet recipes that behave as a fluid gel after churning. The benefit of using gellan gum is that the ice cream or sorbet can be set in a dish of flaming alcohol without actually melting.[9]
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Gellan was discovered and developed as a commercial biogumhydrocolloid product by Kelco, then a division ofMerck & Co. In the United States, Kelco was responsible for obtaining food approval for gellan gum worldwide. In other markets that are fond of innovative food ingredients, such as Japan, food approval has been obtained by local food and beverage manufacturers. Kelco, now the CP Kelco family of companies owned byJ.M. Huber Corporation historically, produced the majority of food grade gellan gum. However, since the entry into the segment ofRoyal DSM, the Dutch science and food nutrition conglomerate, users of food grade gellan gum now procure from 2 high quality suppliers. Chinese suppliers have also been increasingly aggressive in gellan gum production. However, the lack of consistent quality production, adherence to stringent food grade requirements and lack of a strong technical and application support means that such gellan gum is primarily destined for use in personal care or household care applications.
Pure gellan gum is one of the most expensive hydrocolloids. Its cost in use, however, is competitive with other much lower-priced hydrocolloids.[clarification needed]
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