Dextrins are a group of low-molecular-weight
carbohydrates produced by the
hydrolysis of
starch. Dextrins are mixtures of linear a-(1,4)-linked D-glucose polymers starting with an a-(1,6) bond. Because branched amylopectin and glycogen also contain a-(1,6) bonds, which a-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.
