dextrin

Dextrin
Identifiers
CAS number	9004-53-9
Properties
Molecular formula	(C6H10O5)n
Molar mass	variable
Appearance	white or yellow powder
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Dextrins are a group of low-molecular-weight carbohydrates produced by the hydrolysis of starch. Dextrins are mixtures of polymers of D-glucose units linked by α-(1,4) or α-(1,6) glycosidic bonds.

Dextrins can be produced from starch using enzymes like amylases, as during digestion in the human body and during malting and mashing, or by applying dry heat under acidic conditions (pyrolysis or roasting). The latter process is used industrially, and also occurs on the surface of bread during the baking process, contributing to flavour, colour and crispness. Dextrins produced by heat are also known as pyrodextrins.

Dextrins are white, yellow or brown powders that are partially or fully water-soluble, yielding optically active solutions of low viscosity. Most can be detected with iodine solution, giving a red coloration; one distinguishes erythrodextrin (dextrin that colours red) and achrodextrin (giving no colour).

White and yellow dextrins from starch roasted with little or no acid is called British gum.

Uses

Yellow dextrins are used as water-soluble glues in remoistable envelope adhesives and paper tubes, in the mining industry as additives in froth flotation, in the foundry industry as green strength additives in sand casting, and as binders in gouache paint.

White dextrins are used as:

• as crispness enhancer for food processing, in food batters, coatings and glazes,
• as textile finishing agent to increase weight and stiffness of textile fabrics,
• as thickening and binding agent in pharmaceuticals and paper coating formulations.

As pyrotechnic binder and fuel, they are added to fireworks and sparklers, allowing them to solidify as pellets or "stars."

Due to the rebranching, dextrins are less digestible; indigestible dextrin are developed as soluble fiber supplements for food products.

Other dextrin types

• Maltodextrin

Maltodextrin is a short chained starch sugar, gelatin hybrid base, (dextrin), that is used as a food additive. It is produced also by enzymatic hydrolysis from gelatinated starch and is usually found as a creamy-white hygroscopic spraydried powder. Maltodextrin is easily digestible, being absorbed as rapidly as glucose, and might either be moderately sweet or might have hardly any flavor at all.

• Cyclodextrin

The cyclical dextrins are known as cyclodextrins. They are formed by enzymatic degradation of starch by certain bacteria, for example, Bacillus macerans. Cyclodextrins have toroidal structures formed by 6-8 glucose residues.

• Amylodextrin is a linear dextrin or short chained amylose (DP 20-30) that can by produced by enzymatic hydrolysis of the alpha-1,6 glycosidic bonds, or debranching amylopectin. Amylodextrin colors blue with iodine.

• (Beta) Limit dextrin is the remaining polymer produced by enzymatic hydrolyse of amylopectine with beta amylase which cannot hydrolyse the alpha-1,6 bonds at branch points.

• (Alpha) Limit dextrin is a short chained branched amylopectine remain, produced by hydrolysis of amylopectine with alpha amylase.

See also

• Modified starch
• Starch gelatinization
• Dextran
• Brewing
• Icodextrin

References

External links

• EAFUS
• MeSH Dextrins