Dextrin acid process

Manufacture. Dextrine is obtained by heating starch from wheat, corn (maize), potato or sweet potato in powder form to 200 270°C. Or 0.15-0.3% of nitric acid or 0.4-0.5% hydrochloric acid is added to the starch uniformly, which is well dried and heated to 100 120°C. The former product is called calcinatory dextrine and is brownish the latter is called acid process dextrine and white or yellowish. 

According to the Polish Standard PN-87/A-74820 modified starch is native starch processed in a mode that changes one or more of its initial physical or chemical properties [59], They include roasted starches (e.g., white and yeUow dextrins), acidic and alkaline starches (treated with respectively acids and bases), bleached starches, enzymatically modified starches, physically modified starches (usually heat-treated), and chanically modified starches (via incorporation of specified chemical compounds or via oxidation). These starches, except for the chanically modified ones, are acknowledged by legal regulations as native and are not treated as additives. Hence, the additive substances include the chemically modified starches. 

Oxidation of Carbohydrates. Oxahc acid is prepared by the oxidation of carbohydrates (7—9), such as glucose, sucrose, starch, dextrin, molasses, etc, with nitric acid (qv). The choice of the carbohydrate raw material depends on availabihty, economics, and process operating characteristics. Among the various raw materials considered, com starch (or starch in general) and sugar are the most commonly available. Eor example, tapioka starch is the Brazihan raw material, and sugar is used in India. 

Dextrins (pyrodextrins) are made by heating dry starch with or without acid. Since it is a dry process, recovery of water-soluble materials is simpler than with aqueous fluidity and oxidized starches. Depending on reaction conditions, greater or lesser amounts of three reactions will occur (a) hydrolysis (b) transglycosidation and (c) repolymerization. According to which predominates, the product is a white dextrin, a yellow dextrin or a British gum. Like other converted materials, these products offer a way to use higher solids to increase performance. 

STADEX Dextrins are partially hydrolyzed starches that are prepared by heating or dry roasting starch in the presence of an acid catalyst. The conversion process - the change from starch to dextrin - changes the properties of the parent starch in several ways. Notably, the dextrin exhibits a thinner cooked-paste viscosity, an increased cold water solubility, and a color change from white to off-white or yellow. 

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