MLDS: they are characterized by being all exudates; they are always heteropolysaccharides, but in fact they are called gums because of their peculiar and particular origin.
- Arabic gum : obtained by incision from the trunk of African trees belonging to the Leguminose family and to the genus Acacia and Acacia senegal . There are cultivated plantations in which the trees are engraved, obtaining this exudate that coagulates in the air, giving a yellow, yellow - ocher color, with a shiny and hard surface. If placed in solution, this exudate forms a colloid, varying the surface tension of the water. Depending on their concentration in the aqueous solution, these gums determine various colloidal conditions and can be used in the formulation of countless types of products. Gum arabic is also used as a medical - surgical facility, as a lubricant for diagnostic tools for bodily inspections. The functional uses are rather reduced, mostly limited to their use as excipients. Gum arabic and gum tragacanth are present in aromatic tablets, to give particular consistency to the tablet, but also to give sensitivity to the palate.
- Tragacanth gum : very similar to gum arabic, it is similarly obtained, again by incision of an African cultivated tree, the Astragalus gumnifer, belonging to the Leguminosae family.
- Rubber sterculia : derived from the engraving of South African plants belonging to the genus Sterculia.
- Guar rubber : improperly called rubber. In fact, its use, very similar to that of the other rubbers, means that - despite being a product derived from the processing of the seeds of a plant belonging to the genus Cyamopsis - it is called rubber. In reality, however, guar gum is a polysaccharide product characterized by the hemicellulose cells of these seeds.
There are also gum of biotechnological origin; in this case, selected and isolated bacterial cultures are bred in culture media to which a carbohydrate substrate is added. These microorganisms biotransform this substrate producing a hetero polysaccharide. The latter is then isolated from the culture through a simple procedure; it is in fact sufficient to add isopropyl alcohol and these carbohydrates precipitate. They behave neither more nor less like tires, only that they are of biotechnological derivation; it is therefore the product of a microbial biotransformation operated by a microorganism, capable of producing a gum that maybe does not exist in nature, but which is ideal for certain herbal, dietary, cosmetic and pharmaceutical preparations. This is the example of the XANTHANA RUBBER, where a bacterium belonging to the Xanthomonas genus is used for this purpose. This bacterium has been selected to produce a specific type of heteropolysaccharides, which in fact act as a gum in aqueous solution.
All these rubbers in the raw state are marketed in the form of powder, so it is for psyllium and agar, although in some cases they can be sold in flakes. The gum arabic and the tragacanth are instead collected in fragments of yellow-ocher color and then subsequently pulverized.
