Starch, modified dextrinization

Despite present trends toward use of synthetic polymers developed over the last 10 or 20 years, starches are still being widely used as an adhesive in such applications as the production of paper and paperboard products, warp sizing, and bonding charcoal briquettes. Because of a unique combination of properties and low cost, these adhesives are almost impossible to exclude from many applications, especially those involving the use of hot paste (size) for anchoring fibers. For starch molecules to act as an adhesive, they must be chemically or thermally hydrated. Then, their adhesive character is developed and modified in different ways by chemicals or other additives for different end uses. As renewable resources that are both economical and reliable, starch and dextrin are likely to continue to be significant factors in the adhesive market for many years. 

In the past several years, between 100 and 150 million pounds of starches and dextrins have been used by the textile industry for weaving and finishing cloth, almost 85% of which is acid-modified and derivatized starches. Very little dextrin or unmodified starch is used in warp sizing. 

The main vegetable adhesives are based on starch and dextrine the latter is a modified form of starch. Each has wide applications. 

Bakers yeast extract Baker s yeast glycan Calcium acetate Calcium alginate Calcium carboxymethyl cellulose Calcium carrageenan Calcium chloride Calcium furcelleran Calcium gluconate Calcium glycerophosphate Calcium lactate Calcium sulfate Calcium sulfate dihydrate Carboxymethylcellulose sodium Carrageenan (Chondrus crispus) Carrageenan (Chondrus crispus) extract Cassia gum Cellulose Chitin Chitosan Corn (Zea mays) starch Corn starch, waxy Corn syrup Dextrin Distarch phosphate Ethyl hydroxyethyl cellulose Ferrous sulfate anhydrous Food starch, modified ... 

As used in this chapter, a starch modification refers to starch molecules which have a general change in the polyglucan structure without the addition of a chemical sustituent. Examples include depolymerized starches and dextrins (including pyrodextrins and cycloamylases). Derivatized starches have had the addition of chemical groups at the hydroxyls. These include the starch ethers and esters. Oxidized starches can be both modified (when depolymerized) and derivatized (with carboxyl and carbonyl groups). 

Starch derivatives make up the majority of the natural adhesives that are used today, with approximately 65% of all natural adhesives based on starch derivatives, that is, pure starch, modified starch, and dextrin. IntertechPira forecasts that starch and other plant-derived adhesives will experience single digit growth rates in the range of 3%—4% over the next 10 years, compared with the 2.7% growth rate expected for all adhesives and the 3.1% growth rate expected for all natural adhesives. 

Starch, food, modified. See Food starch, modified Starch gum. See Dextrin... 

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. 

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. 

Of the myriad of modified starch systems tested, ranging from simple enzymically dextrinized starches to covalently attached amino acids and peptides onto dextrinized and/or oxidized (hypochlorite or periodate) corn starch bases, two polymers were selected as holding promise. The first system was a low dextrose equivalent (DE 5.7) enzyme-modified corn starch. The second starch-based polymer developed was a periodate-oxidized, amylase-dextrinized, covalently-attached phenylalanine glycoamine. 

Among enzyme modified starch derivatives,cyclo dextrins behave as empty molecular capsules with the ability to entrap guest molecules of appropriate geometry and polarity.The included molecules are protected from surroundings light, heat,oxidation, etc. The flavor cyclodextrin com -plexes show the above advantageous properties while they are in the dry,solld state.On contact with water,cyclodextrin complexes release their flavor content. In Hungary,the spice flavor beta-cyclodextrin complexes have been on the market, since 1982. 

Bulk powders are made in considerable variety, but they consist always of nitrocellulose fibers which are stuck together but are not completely colloided. Some contain little else but nitrocellulose others contain, in addition to potassium and barium nitrates, camphor, vaseline, paraffin, lampblack, starch, dextrine, potassium dichromate or other oxidizing or deterrent salts, and diphenylamine for stabilization, and are colored in a variety of brilliant hues by means of coal-tar dyes. In the United States bulk powders are manufactured by one or the other of two processes, either one of which, however, may be modified considerably the materials are incorporated under wooden wheels, grained, and partially gelatinized, or the grains arc formed in a still where a water suspension of ptdped nitrocellulose is stirred and heated with a second liquid, a solvent for nitrocellulose which is volatile and immiscible with water. 

These cocoa substitutes are of two kinds. First, they consist of otherwise unprocessed bulking agents with added flavor and color. The bulking agents employed are soybean flour, modified food starches, dextrins, or mixtures thereof. They are definitely offered as extenders none of the manufacturers recommend that they be used as a total replacement for cocoa. Manufacturers include Cargill, Inc., Minneapolis, Minnesota (Cocoa-Max), McCormick Company, Inc., Hunt Valley, Maryland, (McCormick Cocoa Extenders), and National Starch Chemical Corp., Bridgewater, New Jersey (N-Liven Cocoa). A.E. Staley Mfg. Co., Decatur, Illinois, entered the field but quickly dropped out. 

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. 

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