Applications of Oxidized Starches

Applications of oxidized starches have been reviewed.442,541-543 

Several copolymers and condensates of oxidized starches with polymers have been developed. For example, products of starch dialdehyde condensation with acrylamide were prepared for further copolymerization with various monomers to form resins for coatings, molding powders,585 and materials for immobilization of enzymes, for instance, alpha amylase.586 Hypochlorite-oxidized starches were also reacted with acrylonitrile.507,521 Hypochlorite-oxidized starches were allowed to react with allylated starch dialdehyde,587 polycondensates of ammonia-dimethylamine-epichlorohydrin,588 polycondensates of starch dialdehyde with melamine,589 urea433,541,590 capable of precipitation of tannin591, carboxyamides,411 urea and formaldehyde,592 proteins,524,593,594 polyfyinyl alcohol),595 alkylammonium salts,519,596 alkoxyalkylamines,597 

Polysulfates of oxidized starches, being heparin-like compounds, show blood anticoagulant activity. Their activity increases with the number of sulfate residues, and the 6-carboxyl groups decreased the toxicity of the compound.533-536,619 Complexes of these anticoagulants with pepsin had no proteolytic activity.620,621 Methyl 

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Application of Oxidized Starch-Containing Reagents (OSR) as Binding Agents in Production of Resin-Bonded Chipboard and Cane Fiber Board... 

An alternative method to apply starch to paper, especially to paperboard grades, is to use a water box at the calender. Water boxes are used for wet-finishing of paper-board prior to coating application. Use of starch in the water box will increase surface strength and lessen fiber reswelling after coating application. Dilute dispersions of oxidized starch are used, frequently in conjunction with a lubricant to prevent calender roll picking. 

In the manufacture of paper, starch-based adhesives are used either to strengthen the paper base or for coating the surface of the paper. Raw starch is unsuitable for either purpose. To achieve sufficient adhesive power with raw starch would require the application of a solution that was far too thick for practical use. Instead, chemically modified starch, with a much lower viscosity in solution, is used. As an economical alternative to modifying the starch with aggressive oxidizing agents, the starch can be treated with enzymes ( df-amylases) to obtain the same thinning effect... 

Other applications of fluidization have been made to such materials as sodium chloride liable salt), soda ash. sodium phosphate, sodium sulfate, starch, talc, magnesium oxide, dry clay, bone acid, hydrated lime, and various high polymers in powdered or head" form. Fluidization is especially effective in loading and unloading materials from railroad cars and trucks, as well as in moving them aboul within the plant. 

An interesting possible application in our society is in super absorbers, which are currently made with polyacrylates, but these suffer from poor biodegradability. Since the demand for short-use super absorbers is growing, a product with a short lifetime and therefore a quick and safe disposal is required. Carboxylated starch can be such a product, but first, an efficient method to oxidize starch needs to be developed. Currently used methods produce stoichiometric amounts of waste products, so the search for a catalytic process is ongoing. 

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. 

Anionic starches are obtained by reaction with phosphoric acid and alkali metal phosphates or by derivatization with carboxymethyl groups.30,31 This modification is primarily used to introduce amphoteric properties into cationic com starch for application on the wet end of the paper machine. Anionic starches with carboxymethyl substitution are used as thickeners in coating colors or as binders in coatings for specialty paper grades. Oxidized starches are inherently anionic but without thickening action. Potato starch already carries sufficient natural anionic charge to provide amphoteric properties after cationization.32... 

Candy coatings are applied via repeated, successive application of dextrin and sugar solutions, followed by drying. Dextrins and monosubstituted starch hydrolyzates are used in candy coatings because of their clear, appetizing films. In this application, clarity, sheen and reduced cracking are desired. Oxidized waxy maize starches are also used.12 Starch used as an impressionable bed for casting candies is typically dent com starch with several tenths of a percent of mineral oil. The oil causes the starch to retain the imprinted shape for a more precisely formed candy piece. 

Oxidized starch reagents may be used in washing powders as substituents of polyphosphates [11]. As investigations show OSR possess the number of unique physical-chemical properties allowing hoping on their application as one of the main components of detergents. 

Starches have been chemically modified to improve their solution and gelling characteristics for food applications. Common modifications involve the cross linking of the starch chains, formation of esters and ethers, and partial depolymerization. Chemical modifications that have been approved in the United States for food use, involve esterification with acetic anhydride, succinic anhydride, mixed acid anhydrides of acetic and adipic acids, and 1-octenylsuccinic anhydride to give low degrees of substitution (d.s.), such as 0.09 [31]. Phosphate starch esters have been prepared by reaction with phosphorus oxychloride, sodium trimetaphosphate, and sodium tripolyphosphate the maximum phosphate d.s. permitted in the US is 0.002. Starch ethers, approved for food use, have been prepared by reaction with propylene oxide to give hydroxypropyl derivatives [31]. 

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