Converted starches dextrinization

Converted starches, also called thin-boiling starches, are produced by degradation of the starch chains into small segments. They can be cooked in water at higher concentrations than native starches. Low-viscosity starches are needed in applications where a high solid starch paste with a pumpable and workable viscosity is required. There are four classes of commercial converted starches dextrins (hydrolysis in solid-state) acid-modified starches (hydrolysis in a slurry) oxidized starches and enzymically depolymerized starches. 

Prior to 1939, however, it was not known whether the cyclodextrins were products of the synthetic metabolism of Bacillus macerans, and therefore, perhaps, quite different from the components of starch, or whether they were formed by a single enzyme and therefore closely related to the starch structure. Then, Tilden and Hudson announced the discovery of a cell-free enzyme preparation from cultures of Bacillus macerans which had the ability to convert starch into the Schardinger dextrins without the production of maltose, glucose, or any other reducing sugars. They thus concluded that the Schardinger dextrins were either the true components of starch or closely related to such true components. 

Spallanzani in 1783 (Sumner and Somers, 1953), the enzymatic hydrolysis of taimin was described by Scheele in 1786 (Tauber, 1949), in 1814 Kirchhoff observed that a glutinous component of wheat is capable of converting starch to sugar and dextrin, and Vogel showed in 1817 that an iirfusion of oats would produce a fermentable sugar from milk (Roberts et a/., 1995). 

Alpha amylase—Converts starch into dextrin used in the manufacture of glucose syrup. 

Diatase found in the germinating seeds of barley and other grains and in Aspergillus oryzce, etc., converts starch to maltose and dextrin. 

Aspergillus oryzee is a yellowish-green to brown mold which secretes diastase, a valuable digestive ferment, having the power of converting starch into sugar and dextrin. For centuries the Japanese have employed this species in the preparation of rice mash for... 

Preparation and Properties of Dextrin (section 377).— Heat about 5 grams of starch for one-half hour at 220°-225° in an oil-bath or air-bath. Pour the product into a mortar, add 2 cc. of water, and notice the adhesive quality of the mixture. Add 25 cc. of water and grind with a pestle. If there is a residue of starch which has not been converted into dextrin, filter through a folded filter. Use 2 cc. of the solution to determine whether the product reduces Fehling s solution. Test 2 cc. of the solution with a drop of iodine solution and note the color. 

The same authors " prepared copoly(vinyl alcohol-styrenesulfonic acid) resins which catalyze the hydrolysis of cubohydrates, among them dextrin and sucrose. Also, cation-exchanger membranes (from radiochemical grafting of styrene followed by reaction with chlorosulfonic add) were patented for the hydrolysis of dextrin to D-glucose. The results discussed may be useful for introducing subtle modifications into dextrins already prepared. A review on modified (converted) starches appeared in 1987. 

Chemically the process is a hydrolysis. That is, by the addition of water to the starch molecules, the latter are split into more soluble materials. The products obtained depend upon the agent used, and, also, upon whether the action is allowed to go to completion. Many researches have been made in the study of this subject. C. O Sullivan (J.C.S. 1872, S79> 1876, 725), showed that the products of diastatic action are maltose and dextrin, and that the proportion of maltose in the product decreases as the temperature of conversion is raised above 63°C. According to Brown, Heron and Morris (J.C.S. 1879,596), malt extract at room temperature converts starch paste into 80.9 parts of maltose and 19.1 parts of dextrin, and the same change occurs at all temperatures to 6o°C. The intermediate dextrins were investigated by Brown and Morris (J.C.S. 1885, S27>... 

Dextrose is formed as the result of the hydrolysis of a number of polysaccharides. Starch, dextrin, and maltose are completely converted into dextrose when heated with water in the presence of a small amount of acid. The reaction in the case of starch is represented by the equation,—... 

Dextrins are the product of dry-roasting starch in the presence of an acid catalyst. Although potato, tapioca, and sago starches are the easiest to convert to dextrins, the low cost and ready availability of cornstarch, make it the most commonly used starch. Dextrins are generally divided into three categories white dextrins, canary or yellow... 

Some methods available offer the use of am-yloglucosidase alone. Work done with com and potato starches illustrated that even vmder ideal conditions amyloglucosidase does not fully convert starch to dextrose, although the shortfall is small. The limit dextrin was more noticeable in corn starch hydrolysis. Proof was obtained by studying the reaction kinetics, and analyzing the hydrolysates by ion chromatography using pulsed amperometric detection. There remained always a small amount of a limit dextrin, and in the case of potato starch some other low molecular mass residues. 

The use of starch for the preparation of glucose syrups has led to a commercial success in the industrial production of this material [132], However, starch is chemically converted to dextrin or dextrose syrups. Crystalline dextrose (glucose) is the major product of the starch conversion industry from com, milo-maize, grain sorghum, and other vegetable starches with acid under pressure and at high temperature [133], Starch hydrolysis is an equilibrium reaction and depending upon the... 

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