Dextrin
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| Dextrin | |
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| Identifiers | |
| CAS number | [] |
| 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 |
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Dextrins are a group of low-molecular-weight carbohydrates produced by the hydrolysis of starch. Dextrins are mixtures of linear α-(1,4)-linked D-glucose polymers starting with an α-(1,6) bond.
Digestion of starch starts in mouth by the salivary alpha amylase to maltose gives intermediate products as dextrins which, according their colour with iodine, can be called erythrodextrin (dextrin that colours red) and achrodextrin (giving no colour).
During malting and mashing process of the grain also dextrins are produced during the fermentation of starch. Dextrins are also formed on the surface of bread during the baking process and contribute to the flavour and colour and crispness.
Industrial production is roasting starch powder under more or less acidic conditions causing hydrolysis and rebranching of the starch molecule. These type of dextrins are also called pyrodextrins. White and yellow dextrins are partially or fully water-soluble low viscous powders that are optically active. Under analysis, dextrins can be detected with iodine solution, giving a red coloration. Starch roasted with little or no acid is called british gum.
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[edit] Uses
Yellow dextrins are used as water-soluble glues in remoistable envelop adhesives and paper tubes, in the mining industry as additive in froth flotation, in the foundry industry as green strength additive in sand casting, as binder 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 fire formulas, allowing them to solidify as pellets or "stars.", in sparklers
Due to the rebranching, dextrins are less digestible, indigestible dextrin are developed as soluble fiber supplements for food products.
[edit] Other dextrin types
- Maltodextrin
Maltodextrin is a short chained starch sugar, dextrin, that is used as a food additive. It is produced also by enzymatic hydrolyse from 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. Maltodextin are mostly classified with a DE (dextrose equivalent) of 20 or higher.
- 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 produced by enzymatic hydrolysis of the alfa-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 hydrolyse of amylopectine with alpha amylase
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