Dextrin

Homoglycan

White crystalline powder

Fixed

Soluble in water

Dextrins, also called starch gum or maltodextrins, starch degradation products, which are of their molecular size forth between oligosaccharides and starch. Usually they come in the form of white or light yellow powder. They are derived mainly from wheat, potato and maize starch by dry heating (> 150 ° C) or exposed to acids. In nature dextrin is produced for example by Bacterium macerans. Dextrins are also formed by enzymatic degradation of starch by amylase.

In the human body in addition to glucose and maltose, short-chain oligosaccharides arise in the course of digestion of amylopectin and amylose ( constituents of the starch ), which are often confused with the dextrins. In the enzymatic cleavage of starch polymers in mono ( dextrose), di- ( maltose) and oligosaccharides are cleaved. The products formed are, depending on their degree of degradation ( dextrose equivalent or DE value ) called maltodextrin or glucose syrup. Amylopectin and amylose are cleaved by the α - amylase in the oligosaccharides, which can be cleaved by α -glucosidase, in turn, (also known as dextrose or glucose) of β -amylase into maltose and finally to α -D-glucose.

Dextrins are also formed in the crust of baked goods and Roux. They are formed from polysaccharides, in the absence of water and at high temperatures above 150 ° C. They give the biscuits among others, the color and characteristic taste. Earlier dextrins were referred to as roasted dextrins or British gum, because the production is equivalent to the high temperatures and a dry heat roasting. Are produced yellow or white dextrins. Dextrins, which can not be further broken down by β -amylase, known as limit dextrins. By this treatment a part of the dextrin is insensitive to the digestive enzymes in the human body and is not degraded in the small intestine, allowing the use of dextrins as fiber.

Dextrins are nowadays largely tasteless by modern production methods. Indigestible ( resistant ) dextrins are used as soluble fiber in food use.

In water, dextrin can solve very good, in ethanol, only a part of the product depending on the composition dissolves.

Dextrins are used among other things as a binder for watercolor paints and adhesives as for example in cigarette filter paper.

So-called cyclodextrins can be used by the particular structure of their molecules as " Verkapselungsschutz " for volatile aroma compounds and vitamins in foods or drugs.