Dextrin: Difference between revisions
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'''Dextrins''' are a group of low-molecular-weight [[carbohydrate]]s produced by the [[hydrolysis]] of [[starch]] | '''Dextrins''' are a group of low-molecular-weight [[carbohydrate]]s produced by the [[hydrolysis]] of [[starch]] and [[glycogen]]. Dextrins are mixtures of [[polymer]]s of D-[[glucose]] units linked by α-(1→4) or α-(1→6) [[glycosidic bonds]]. | ||
Dextrins can be produced from starch using [[enzyme]]s like [[amylase]]s, as during digestion in the human body and during [[Malt#Malting|malting]] and [[mashing]] in beer brewing | Dextrins can be produced from starch using [[enzyme]]s like [[amylase]]s, as during digestion in the human body and during [[Malt#Malting|malting]] and [[mashing]] in beer brewing or by applying dry heat under acidic conditions ([[pyrolysis]] or [[roasting]]). This procedure was first discovered in 1811 by [[Edme-Jean Baptiste Bouillon-Lagrange]]. 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'''. Starch hydrolyses during roasting under acidic conditions, and short-chained starch parts partially rebranch with α-(1,6) bonds to the degraded starch molecule. See also [[Maillard reaction]]. | ||
Dextrins are white, yellow, or brown powders that are partially or fully water-soluble, yielding [[Optical rotation|optically active]] solutions of low [[viscosity]]. Most of them can be detected with [[iodine test|iodine solution]], giving a red coloration; one distinguishes erythrodextrin (dextrin that colours red) and achrodextrin (giving no colour). | Dextrins are white, yellow, or brown powders that are partially or fully water-soluble, yielding [[Optical rotation|optically active]] solutions of low [[viscosity]]. Most of them can be detected with [[iodine test|iodine solution]], giving a red coloration; one distinguishes erythrodextrin (dextrin that colours red) and achrodextrin (giving no colour). | ||
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==Uses== | ==Uses== | ||
Yellow dextrins are used as water-soluble [[glue]]s | Yellow dextrins are used as water-soluble [[glue]]s in remoistenable 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 [[textile printing|printing thickener]] for [[batik]] [[resist dyeing]], and as binders in [[gouache]] paint and also in the leather industry. | ||
White dextrins are used as: | White dextrins are used as: | ||
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* a stabilizing agent for certain explosive metal [[Azide | azides]], particularly [[Lead(II) azide]] | * a stabilizing agent for certain explosive metal [[Azide | azides]], particularly [[Lead(II) azide]] | ||
Owing to their rebranching, dextrins are less digestible. Indigestible dextrins have been developed as soluble stand-alone [[fiber supplement]]s and for adding to processed food products. | Owing to their rebranching, dextrins are less digestible. Indigestible dextrins have been developed as soluble stand-alone [[fiber supplement]]s and for adding to processed food products. | ||
== Other types== | == Other types== | ||
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*(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. | *(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. | *(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. | * 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. | ||
== See also == | == See also == | ||
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* {{annotated link|Modified starch}} | * {{annotated link|Modified starch}} | ||
* {{annotated link|Starch gelatinization}} | * {{annotated link|Starch gelatinization}} | ||
==External links== | ==External links== | ||