Dextrin

Dextrin
Identifiers
CAS number 9004-53-9 Y
UNII 2NX48Z0A9G Y
KEGG C00721 Y
Properties
Molecular formula (C6H10O5)n
Molar mass variable
Appearance white or yellow powder
 N (verify) (what is: Y/N?)
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[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 flavour, colour, 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]

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.

Contents

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.

White dextrins are used as:

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

Main article: maltodextrin

Maltodextrin is a shortchain starch sugar, gelatin hybrid base, (dextrin) 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 have hardly any flavor at all.

Main article: 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.

See also

Notes and 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. ^ 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)[1]

External links