Gellan gum

Gellan gum

Copolymer

Greyish-white powder

Fixed

• Soluble in water ( viscous solution )
• Insoluble in ethanol

Gellan is a multiple sugar that is produced based on plants by microorganisms on sugar-containing culture medium and used in the food industry.

Construction

Gellan belongs to the carbohydrates and in the narrower sense of the polysaccharides. Gellan has a linear structure, but, in contrast to known linear polysaccharides such as cellulose or amylose, which consist only of a single identical device from a plurality of different building blocks.

It consists of one rhamnose, one glucuronic acid, and two glucose repeat units which are esterified with acetic acid and glyceric acid. Glucuronic acid is present as a mixed potassium, calcium, sodium and magnesium salts. The molar mass is about 500,000 g / mol.

Production

Gellan is produced by fermentation of carbohydrates by the bacterial strain Pseudomonas elodea. The culture broth is deacylated by heating ( cleavage of the ester groups), and the resulting precipitated gellan with isopropyl alcohol, then dried and milled. From the fermentation processes usually small amounts of nitrogen-containing residues in the product remain.

Use

As a food additive (E 418), it is used in the food industry as gelling and thickening agents. It is used mostly for jams, fruit spreads, jams, confectionery, soy milk, etc.. As dietary fiber is not absorbed by the body, aids digestion and has a laxative effect.

And in pharmaceutical preparations, gellan is used as the cation concentration -dependent gelling agent: Thus, it is in the absence of mono-or divalent cations in the sol state (colloidal dispersion ) before, and swells in the presence of these (eg, tear fluid ) to form a gel. Which is used for example in eye drops, in order to prolong the residence time of the drug on the eye, and thus, the available time for a penetration. Thereby, the local bioavailability to be improved, and the application frequency can be reduced.

As a gelling agent for culture media and plant crops, it is used in microbiology alternatively agar and marketed under trade names such as Nanogel TC Grovgel, AppliedGel, phytagel or Gelrite. As it survives Term peratures of 120 ° C, it is interesting for the in vitro cultivation of thermophilic organisms.