Starch iron complex

Wet-Chemical Determinations. Both water-soluble and prepared insoluble samples must be treated to ensure that all the chromium is present as Cr(VI). For water-soluble Cr(III) compounds, the oxidation is easily accompHshed using dilute sodium hydroxide, dilute hydrogen peroxide, and heat. Any excess peroxide can be destroyed by adding a catalyst and boiling the alkaline solution for a short time (101). Appropriate ahquot portions of the samples are acidified and chromium is found by titration either using a standard ferrous solution or a standard thiosulfate solution after addition of potassium iodide to generate an iodine equivalent. The ferrous endpoint is found either potentiometricaHy or by visual indicators, such as ferroin, a complex of iron(II) and o-phenanthroline, and the thiosulfate endpoint is ascertained using starch as an indicator. 

The water-soluble iron tetrasulfophthalocyanine (FePcS) complex, which is cheap and available on an industrial scale, was also a very active and selective catalyst for the oxidation reaction. Starches of different origin (potatoes, rice, wheat, com) were oxidized by H202 following two operating modes, viz. oxidation in aqueous suspension and oxidation by incipient wetness. 

A good source of starch, B-complex vitamins, iron, potassium, zinc, and other essential minerals... 

Microbiological action in starch dispersions results in a drop in pH, loss of viscosity and the development of odor. Retrogradation may be accelerated by the drop in pH or especially if butanol, which complexes with amylose, is generated via starch fermentation. Sulfate-reducing bacteria will cause black deposits due to reaction with iron in the process water. For quality control, preservatives are added to starch slurry, cooked starch, surface size and coating color. 

However, the relatively high enzyme costs form an obstacle to commercialization. Inefficient laccase use is a result of its instability towards the oxidizing reaction conditions. We have recently shown that the stability of the laccase under reaction conditions can be improved by immobilization as a cross-linked enzyme aggregate (see Chapter 9). It has also been shown that a water-soluble iron complex of a sulfonated phthalocyanine ligand is an extremely effective catalyst for starch oxidation with hydrogen peroxide in an aqueous medium [11]. 

Starch-iron complexes are reported as biologically active sources of iron.627 628 In one report, it is warned that such complexes may produce sarcomas as a result of long-term exposure.629 Investigations630 have shown that, independently of the ferric salt used, the maximum capacity of the salt in starch is 2-7 mg%. Because pH 5.8 is more conducive to stability than low pH values (3 or lower), higher concentrations of ferric salt are not advisable. Shi Decheng631 recommended blending starch (100 g) with trisodium citrate (25g) and 2 M FeCl3 (500 mL) in water (2500 mL) at... 

It is well known that starch-iron complexes are suitable for fortifying bread and flour with iron. The state of iron in flour, dough, and bread was investigated by Leichter and Joslyn.643 Iron salts influence the whiteness of sweet-potato starch, but this effect is variable.644 It was also reported645 that colloidal iron interacts with starch, a process which is used to fractionate starch into three portions The first portion (80% of the total amount) is formed by colloidal iron itself, the second (9% of the total) is formed by iron and electrolytes, and the third portion (11% of the total) is not precipitated at all. 

Specific indicators owe their behavior to a reaction with one of the participants in the titration. The best-known specific indicator is starch, which forms a dark blue complex with triiodide ion. Also, potassium thiocyanate is used as a specific indicator, for example, in titration of iron(III) with solutions of titanium(III) sulfate. 

J). Bread components other than phytate were examined for their ability to bind metals. Fiber, protein and starch of wheat formed stable complexes with zinc and calcium, and later iron was found to share this behavior. The metals combined with protein or wheat starch, however, were released during digestion with peptidases and amylases (2,1)5). By contrast dietary fiber, being resistant to digestive secretions, retained bound metal intact. Removal of phytate, which had in the past been held to be the main source of metal complexation by bread, did not decrease but tended to enhance the binding of the metal (J2.). Further doubt about the role of... 

When microscopically examined, this group of precipitates lack defined shape and generally assumes a color reflective of the wine. Precipitates in this category include protein and phenolics (and complexes of the two), polysaccharides (glucans, pectin, and starch), and metal casses (copper and iron). 

Biosensitisers and photosensitisers are nsed to obtain PE with predictable life times. Iron complexes Fe(iii)-acetylacetonate, Fe(iii)-2-hydroxy-methylacetophenoneoxime, transition metal (Co, Ni, Cr, Zn)-N,N -diethyldiselenocarbamates or other metallic complexes, and blends with natural polymers (starch, cellulose, lignin, proteins) are mostly used. 

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