Starch oxidizing agent, sodium

Due to potential benefits associated with maintaining some undefined concentration of oligomer (e.g., DP >8 5), oligosaccharides of a DE of 10 or less were produced. Initially, a further constraint was desired for the development of a starch-based wall material. Food ad Drug Administration acceptability. Therefore, sodium hypochlorite was the oxidizing agent of choice for the early oxidation attempts (36). 

Alpha-amylase is most active at its pH optimum of 6.3 to 6.8.108,109 It is inactive at pH values below 4 and above 9. Enzymic starch conversion is terminated by raising the temperature until enzyme denaturation occurs or by the addition of enzyme poisons, such as the ions of copper, mercury or zinc. Inactivation can also be achieved by moving the pH outside the enzyme s active limits or by the addition of oxidizing agents, such as sodium hypochlorite, hydrogen peroxide or barium peroxide. 

The recovery of iodine from waste liquids.—E. Beilsteini2 recovered iodine from laboratory residues by evaporation to dryness with an excess of sodium carbonate and calcination until the organic matter is all oxidized. The mass is dissolved in sulphuric acid and treated with the nitrous fumes, obtained by treating starch with nitric acid, until all the iodine is precipitated. The iodine is washed in cold water, dried over sulphuric acid, and sublimed. Other oxidizing agents less unpleasant than the nitrous fumes employed by F. Beil stein—e.g. hydrogen peroxide—-were recommended by G. Torossian for the residues obtained in copper titrations. F. Beilstein s process is applicable to soluble but not to insoluble, oxidized forms of ioffine. F. D. Chattaway... 

The procedure is now illustrated by an example. Wheat starch and poly (styrene) (PS) are blended together. To this blend, citric acid and sodium bicarbonate is added. Citric acid acts as the oxidizing agent and sodium bicarbonate is the substance for degrading the starch. This blend is extrusion-cooked at a temperature of 140°C and a pressure of approximately 20 M Pa. 

A common redox reaction is the reaction of an oxidizing agent with excess potassium iodide solution to form iodine. The iodine is then titrated with sodium thiosulfate solution, using starch as an indicator (Figure 9.15). 

Treatment of starch with acids, enzymes or oxidizing agents (such as sodium hypochlorite) are commonly used to reduce the molecular weight of starch and thus decrease the viscosity and modify the gelling properties of aqueous starch dispersions. Starches that have been partially depolymerized by acids or enzymes are commonly referred to as dextrins. Conversely, the swelling and solubility of starch granules can be reduced by cross-linking. 

Definition Starch treated with sodium hypochlorite or other oxidizing agent, characterized by whiter color, increased paste clarity, and a low, stable vise, on storage of the paste... 

Sodium chlorite oxidation of com and rice starches is recommended for the production of textile sizes (101) and oxidized starch is recommended as a hardening agent in the immobilization of microbial cells within gelatin (102). 

Chlorine gas may be identified readdy by its distinctive color and odor. Its odor is perceptible at 3 ppm concentration in air. Chlorine may be measured in water at low ppm by various titrimetry or colorimetric techniques (APHA, AWWA and WEF. 1999. Standard Methods for the Examination of Water and Wastewater, 20th ed. Washington DC American Pubhc Health Association). In iodometric titrations aqueous samples are acidified with acetic acid followed by addition of potassium iodide. Dissolved chlorine liberates iodine which is titrated with a standard solution of sodium thiosulfate using starch indicator. At the endpoint of titration, the blue color of the starch solution disappears. Alternatively, a standardized solution of a reducing agent, such as thiosulfate or phenylarsine oxide, is added in excess to chlorinated water and the unreacted reductant is then back titrated against a standard solution of iodine or potassium iodate. In amperometric titration, which has a lower detection limit, the free chlorine is titrated against phenyl arsine oxide at a pH between 6.5 and 7.5. 

Anticaking agents commonly used include calcium carbonate, phosphate, silicate, and stearate cellulose (microcrystalline) kaolin magnesium carbonate, hydroxide, oxide, silicate, and stearate myristates palmitates phosphates silica (silicon dioxide) sodium ferrocyanide sodium silicoa-lummale and starches. 

Iodometric titration involves the reaction of iodine with a known amount of reducing agent, usually sodium thiosulfate (Na2S203) or phcnylarsine oxide (PAO). Starch solution is used as an indicator to detect the end point of the titration. Thus, the exact amount of iodine that would react with a measured volume of sodium thiosulfate of known strength is determined. From this, the concentration of the analyte in the sample, which is proportional to the amount of iodine reacted with thiosulfate or PAO, is then calculated. 

The TEMPO - sodium hypochlorite - sodium bromide system has been applied to starch ether derivatives, particularly hydroxyethyl starch, which has a primary hydroxyl group on the hydroxyethyl ether group that can also be oxidized to a carboxyl group and carboxymethyl starch. The apparent goal was improved sequestering agents via higher carboxyl content and the proper multidentate conformations... 

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