Dextrin

Dextrin

Identifiers
CAS Number	9004-53-9
KEGG	C00721
PubChem	62698
UNII	2NX48Z0A9G
Properties
Chemical formula	(C6H10O5)n
Molar mass	variable
Appearance	white or yellow powder
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Dextrins are a group of low-molecular-weight carbohydrates produced by the hydrolysis of starch^[1] or glycogen.^[2] 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,^[3] 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 flavor, color, and crispness. Dextrins produced by heat are also known as pyrodextrins. During roasting under acid condition the starch hydrolyses and short chained starch parts partially rebranch with α-(1,6) bonds to the degraded starch molecule.^[4] See also Maillard Reaction.

Dextrins are white, yellow, or brown powders that are partially or fully water-soluble, yielding optically active solutions of low viscosity. Most of them 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.

A dextrin with α-(1→4) and α-(1→6) glycosidic bonds

Uses

Yellow dextrins are used as water-soluble glues ^[5] 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, as printing thickener for batik resist dyeing, and as binders in gouache paint and also in the leather industry.

White dextrins are used as:

• a crispness enhancer for food processing, in food batters, coatings, and glazes, (INS number 1400)
• a textile finishing and coating agent to increase weight and stiffness of textile fabrics
• a thickening and binding agent in pharmaceuticals and paper coatings.
• 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 stand alone fiber supplements and for adding to processed food products.^[6]

Other types

• Maltodextrin

Maltodextrin is a shortchain starch sugar used as a food additive. It is produced also by enzymatic hydrolysis from gelled starch and is usually found as a creamy-white hygroscopic spray dried powder. Maltodextrin is easily digestible, being absorbed as rapidly as glucose, and might either be moderately sweet or 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 be 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 hydrolysis of amylopectin with beta amylase, which cannot hydrolyse the alpha-1,6 bonds at branch points.
• (Alpha) Limit dextrin is a short chained branched amylopectin remnant, produced by hydrolysis of amylopectin with alpha amylase.
• Highly branched cyclic dextrin is a dextrin produced from enzymatic breaking of the amylopectin in clusters and using branching enzyme to form large cyclic chains.^[7]

See also

• Brewing
• Cellodextrin, breakdown of cellulose
• Dextrose equivalent
• Icodextrin
• Modified starch
• Starch gelatinization

References

1. An Introduction to the chemistry of plants - Vol II: Metabolic processes, P. Haas and T. G. Hill, London (Longmans, Green & Co.), 1913; pages 123-127
2. Salway, JG. Medical Biochemistry at a Glance. Second Edition. Malden, MA (Blackwell Publishing), 2006; page 66
3. Michael Lewis, Tom W. Young (2002), "Brewing", Kluwer Academic, ISBN 0-306-47274-0.
4. Alistair M. Stephen, Glyn O. Phillips, Peter A. Williams (2006), "Food polysaccharides and their applications 2nd edition", p 92-99, CRC Press, Taylor & Francis Group, ISBN 0-8247-5922-2
5. Jack Augustus Radley (1976). "Industrial uses of starch and its derivatives", Applied Science Publishers Ltd, ISBN 0-85334-691-7.
6. http://www.webmd.com/diet/fiber-health-benefits-11/compare-dietary-fibers
7. T. Hiroki, K. Iwao, T. Noboru,S. Yuji, Y. Mikio, Journal: Seibutsu Kogakkaishi, Vol:84; No:2; Page: 61-66 (2006), Industrial Production of Branching Enzyme and Its Application to Production of Highly Branched Cyclic Dextrin (Cluster Dextrin)

External links

• Dextrins at the US National Library of Medicine Medical Subject Headings (MeSH)
• EAFUS