7-Dextrins

Dextrins (white dextrin) are prepared by heating starch, which has been moistened with a small quantity of dilute nitric acid and dried at 110-120 °C. Dextrin may contain up to 15% soluble starch. Yellow dextrins are more completely decomposed and, unlike the white variety, they contain appreciable amounts of maltose which may be detected and estimated by their reducing power. 

Plant hydrocolloids may be linear or branched, they may have acidic or neutral characteristics and show a wide range of molecular dimensions. 

Branched hydrocolloids form gels rather than viscous solutions at higher concentrations. They tend to be sticky when moistened a common feature which is of advantage for adhesive purposes. They rehydrate more readily than linear hydrocolloids, which is an important property for drag formulas that must be reconstituted immediately before use. 

Several plant exudates (gums and mucilages) have been used for pharmaceutical purposes and they still find significant application. However, the production of gums is laborious and expensive and their use will probably continue to decline. 

Gum arabic °/ /o Tragacanth Carrageenan Sodium alginate Guaran 

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. 

Add to the rest of the solution three times its volume of alcohol. Filter off the precipitated dextrin and wash twice with alcohol. Dissolve a little of the precipitate and test its reducing power with Fehling s solution. Determine the color produced by iodine solution. How does the color compare with that obtained during the intermediate stages of the hydrolysis of starch by acid (experiment 152g page 124). 

PZC/IEP of Unspecified Sample of Dextrin Electrolyte T Method Instrument 

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Diastase (or amylase) liver, etc., malt starch (amylum) maltose and dextrin 6-0 (liver) 5-2 (malt)... 

Diastase or amylase is formed when malt is produced by the germination of barley grains. Malt is therefore a good source of the enzyme. Diastase is also secreted by the salivary glands (when it is known as ptyalin), and also by the pancreas. Its function is to hydrolysef starch to a mixture of maltose and dextrin ... 

Carbohydrates may be divided into monosaccharides, disaccharides and polysaccharides. The monosaccharides under certain conditions react as polyhydroxy-aldehydes or polyhydroxy-ketones two important representatives are glucose CjHjjO (an aldose) and fructose (laevulose) CgHuO, (a ketose). Upon hydrolysis di- and polysaccharides 3deld ultimately monosaccharides. Common disaccharides are sucrose, lactose and maltose (all of molecular formula C,2H2. 0,), whilst starch, dextrin and cellulose, (CjHjoOj), in which n > 4, are typical polysaccharides. 

Dextrin Polyethylene glycol 400 Use 5 mL of 2% aqueous solution of chloride-free dextrin per 25 mL of 0. IM halide solution. Prepare a 50% (v/v) aqueous solution of the surfactant. Use 5 drops per 100 mL end-point volume. 

Borated dextrin Borate glass Borate glasses Borates... 

Limit dextrins Limiting amino acid Limiting current... 

Maltitol solutions Maltitol syrups Malto-dextrin... 

Unasyn Oral Unborated dextrin Uncinula necator... 

The protein fraction is filtered and dried to become high (60%) protein content com gluten meal. The starch slurry can be dewatered and dried to produce regular com starch. Dry starch can be sold as is or heat treated in the presence of acid catalysts to produce dextrins. Or, it is chemically modified before dewatering and drying to produce modified starches used in food and industrial appHcations. Lasdy, it can be hydroly2ed to produce corn sweeteners. 

Inclusion compounds of the Cg aromatic compounds with tris((9-phenylenedioxy)cyclotriphosphazene have been used to separate the individual isomers (43—47). The Schardinger dextrins, such as alpha-cyclodextrin, beta-dextrin, and gamma-dextrin are used for clathration alpha-dextrin is particularly useful for recovering PX from a Cg aromatic mixture (48,49). PyromeUitic dianhydride (50) and beryllium oxybenzoate (51) also form complexes, and procedures for separations were developed. 

Lead azide is not readily dead-pressed, ie, pressed to a point where it can no longer be initiated. However, this condition is somewhat dependent on the output of the mixture used to ignite the lead azide and the degree of confinement of the system. Because lead azide is a nonconductor, it may be mixed with flaked graphite to form a conductive mix for use in low energy electric detonators. A number of different types of lead azide have been prepared to improve its handling characteristics and performance and to decrease sensitivity. In addition to the dextrinated lead azide commonly used in the United States, service lead azide, which contains a minimum of 97% lead azide and no protective colloid, is used in the United Kingdom. Other varieties include colloidal lead azide (3—4 pm), poly(vinyl alcohol)-coated lead azide, and British RE) 1333 and RE) 1343 lead azide which is precipitated in the presence of carboxymethyl cellulose (88—92). 

Cyclo dextrin Molecular weight Solubihty in water, g/100 mL r 1 Diameter of cavity, nm Diameter of outer periphery, nm... 

A wide variety of special malts are produced which impart different flavor characteristics to beers. These malts are made from green (malt that has not been dried) or finished malts by roasting at elevated temperatures or by adjusting temperature profiles during kilning. A partial Hst of specialty malts includes standard malts, ie, standard brewers, lager, ale, Vienna, and wheat caramelized malts, ie, Munich, caramel, and dextrine and roasted products, ie, amber, chocolate, black, and roasted barley. 

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. 

The adhesives (qv) used to form tube seams and bag bottoms include unborated dextrin, borated dextrin, casein, latex—casein, latex, poly(vinyl acetate), vinyl acetate copolymers, and hot-melt materials (10,27). Dextrin and casein adhesives are more commonly used in the production of grocery sacks vinyl acetate-type adhesives are commonly used in ah paper multiwah bags. The hot-melt adhesives are typicahy used to tack the phes of the multiwah bag together and to form the seam and bottom joints when polymer film phes or coated paper phes are used in bag constmction. 

Pyrotechnic mixtures may also contain additional components that are added to modify the bum rate, enhance the pyrotechnic effect, or serve as a binder to maintain the homogeneity of the blended mixture and provide mechanical strength when the composition is pressed or consoHdated into a tube or other container. These additional components may also function as oxidizers or fuels in the composition, and it can be anticipated that the heat output, bum rate, and ignition sensitivity may all be affected by the addition of another component to a pyrotechnic composition. An example of an additional component is the use of a catalyst, such as iron oxide, to enhance the decomposition rate of ammonium perchlorate. Diatomaceous earth or coarse sawdust may be used to slow up the bum rate of a composition, or magnesium carbonate (an acid neutralizer) may be added to help stabilize mixtures that contain an acid-sensitive component such as potassium chlorate. Binders include such materials as dextrin (partially hydrolyzed starch), various gums, and assorted polymers such as poly(vinyl alcohol), epoxies, and polyesters. Polybutadiene mbber binders are widely used as fuels and binders in the soHd propellant industry. The production of colored flames is enhanced by the presence of chlorine atoms in the pyrotechnic flame, so chlorine donors such as poly(vinyl chloride) or chlorinated mbber are often added to color-producing compositions, where they also serve as fuels. 

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