description
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. They have the same general formula as carbohydrates but are of shorter chain length. Industrial production is generally performed by acidic hydrolysis of potato starch. Dextrins are water soluble, white to slightly yellow solids which are optically active. Analytically, dextrins can be detected with iodine solution, giving a red coloration with green spots.
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.
application
For example, some react with iodine to give a reddish-brown color, others a blue, and still others yield no color at all. For commerical use dextrin is prepared by heating dry starch or starch treated with acids to produce a colorless or yellowish, tasteless, odorless powder which, when mixed with water, forms a strongly adhesive paste. It is used widely in adhesives, e.g., for postage stamps, envelopes, and wallpapers, and for sizing paper and textiles.
