|Molecular formula of the repeating unit||C 6 H 10 O 5|
|Molar mass of the repeating unit||162.14 g mol −1|
|Type of polymer|
white crystalline powder
soluble in water
|As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .|
Dextrins , also known as starch gums or maltodextrins , are homologous starch breakdown products that are somewhere between oligosaccharides and starch in terms of their molecular size . They usually come in the form of white or light yellow powder. They are mainly obtained from wheat, potato and corn starch through dry heating (> 150 ° C) or under the influence of acids. For example, in nature, dextrin is produced by Bacterium macerans . Dextrins are also created by the enzymatic breakdown of starch by amylase .
In the human body, in addition to glucose and maltose , short-chain oligosaccharides are formed in the course of digestion from amylopectin and amylose (components of starch ), which are often mistaken for dextrins. During the enzymatic breakdown of starch, the polymers are broken down into mono- ( dextrose ), di- (maltose) and oligosaccharides. The products formed are called maltodextrin or glucose syrup , depending on their degree of degradation ( dextrose equivalent or DE value) . Amylopectin and amylose are split into oligosaccharides by the α- amylase , which in turn can be split by β-amylase into maltose and finally into α-D-glucose (also called dextrose or grape sugar) using α-glucosidase .
Dextrins also form in the crust of pastries and in roux . They arise from polysaccharides , in the absence of water and at high temperatures from 150 ° C. Among other things, they give the pastry its color and typical taste. In the past, dextrins were also known as roasted dextrins or British gum , because the high temperatures and dry heat meant that they were made like roasting. Yellow or white dextrins are produced. Dextrins that can no longer be broken down by β-amylase are called borderline dextrins . This treatment makes some of the dextrins insensitive to the digestive enzymes in the human body and is not broken down in the small intestine, which enables dextrins to be used as dietary fiber.
Nowadays, dextrins are largely tasteless thanks to modern manufacturing processes. Indigestible (resistant) dextrins are used as soluble fiber in food.
Dextrin dissolves very well in water ; only part of the product dissolves in ethanol , depending on its composition.
Dextrins are used, among other things, as binders for watercolors and as adhesives e.g. B. with cigarette filter paper.
Due to the special structure of their molecules, so -called cyclodextrins can be used as "encapsulation protection" for volatile aromatic substances and vitamins in foods or medicines.
- ↑ a b c d e data sheet dextrin white, pure (PDF) from Carl Roth , accessed on July 30, 2017.
- ^ A b Ternes, Täufel, Tunger, Zobel: Lebensmittel-Lexikon , Behr's Verlag, 4th edition 2005, ISBN 3-89947-165-2 .
- ↑ Helen Mitchell: Sweeteners and Sugar Alternatives in Food Technology. Wiley, 2008, ISBN 978-0-470-99599-0 , p. 399 ( limited preview in Google book search).