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. Because branched amylopectin and glycogen also contain α-(1,6) bonds, which α-amylase cannot hydrolyze in humans, the digest resulting from this action contains a mixture of dextrins. They have the same general formula as carbohydrates but are of shorter chain length. Industrial production is, in general, performed by acidic hydrolysis of potato starch. Dextrins are water-soluble, white to slightly yellow solids that are optically active. Under analysis, dextrins can be detected with iodine solution, giving a red coloration.
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.
Dextrins find widespread use in industry, due to their non-toxicity and their low price. They are used as water-soluble glues, as thickening agents in food processing, and as binding agent in pharmaceuticals. In pyrotechnics, they are added to fire formulas, allowing them to solidify as pellets or "stars." Cyclodextrins find additional use in analytical chemistry as a matrix for the separation of hydrophobic substances, and as excipients in pharmaceutical formulations. Not all forms of dextrin are digestible, and indigestible dextrin is sometimes used in fiber supplements.
For example, maltodextrin either can be moderately sweet or have hardly any flavor at all. Maltodextrin is a polysaccharide that is used as a food additive. It is produced from starch and is usually found as a creamy-white hygroscopic powder. Maltodextrin is easily digestible, being absorbed as rapidly as glucose. The CAS registry number of maltodextrin is 9050-36-6.
Maltodextrin can be derived from any starch. In the US, this starch is usually rice, corn or potato; elsewhere, such as in Europe, it is commonly wheat. This is important for coeliacs, since the wheat-derived maltodextrin can contain traces of gluten. There have been recent reports of coeliac reaction to maltodextrin in the United States. This might be a consequence of the shift of corn to ethanol production and its replacement with wheat in the formulation. The fast food chain, Wendy's, footnotes maltodextrin in its list of gluten-free foods , which may be a sign of their receiving reports of this.