Modified starches analysis

S. K. Patil and Associates (2007). "Global Modified Starch products Usage—Analysis and Review.", May 2007. Munster, IN, USA. 

A method of determining airborne iodine has also been reported.241 Here, iodine is absorbed into 5% aqueous KI and spectrophotometrically determined at 590 nm in the form of its complex with starch. This method is selective with respect to bromine and chlorine, and the sensitivity of this method is 0.25 mg of I2 per m3 of air. The concentration of the, 31I isotope in water can be determined by a method involving isotope exchange in the starch-iodine complex.242 Flow-injection determination of ascorbic acid (0.1-40 mg/mL) has been proposed.243 Iodine is generated in the flow system as I3- ions, which are in turn exposed to starch to produce a steady signal at 350 and 580 nm. Ascorbic acid provides inversed maxima which are measured. This method is recommended for analysis of ascorbic acid in fruit juice, jam, and vitamin-C preparations. Use of the blue complex has also been reported for determination of sodium dichloro-isocyanurate in air.244 Obviously the blue reaction is applicable in the determination of amylose, amylopectin, and starch,245-252 as well as modified starches.245,253-255... 

Figure 3. Sorption Isotherm of Starch Determined at 25°C by Modified Frontal Analysis and Frontal Method.

The X-ray diffraction analysis indicated that during chemical modification process, several crystalline structures of native starch were destroyed, and a new structure of organic acid-modified starch was formed (Figure 7.3). The diffraction peaks for StM and CMSt look like a V-type crystalline structure. According to the literature data [92], there can be observed a typical A-style crystallinity in the native corn starch. This... 

According to the X-ray diffraction analysis, organic acid modified starch microparticles CMSt presented an amorphous characteristic, but some crystalline peaks at around 20 = 20 were also evidenced. 

Fig. 8 Dynamic surface tension of mixtures between a highly surface-active model suspension and modified starches having the same cationicity, but different degrees of benzylation, DSbn. at a mixing ratio (volume suspensionrvolume starch) of 10 1 surface tension was measured using a profile analysis tensiometer (t = 1,200 s) [67]...

The case of contradictory findings for the analysis of dietary fiber are due to differences among analytical methods employed. The AO AC total dietary fiber method measures all compounds not digested by amylase and protease and insoluble in 80% aqueous ethanol. While cellulose, pectin, hemicelluloses, gums and lignin do meet these criteria, extrusion-modified starches and proteins could also be measured as fiber. Sites formerly accessible to digestion by enzymes may be involved in new bonds or physically-hindered. Many materials used to add dietary fiber to foods contain far less than 100% fiber. Artz and co-workers (1990) found no difference in X-ray diffraction patterns of corn fiber-corn starch blends after extrusion, which was expected since very little crystalline cellulose was present. The com bran isolate used as a fiber source actually contained only 16.6% cellulose. Amorphous hemicelluloses comprised the remainder of the dietary fiber fraction. 

In addition to the analysis of modified starch nanoparticles after they were isolated and stripped of AOT, li t scattering experiments were also performed to characterize unmodified AOT-coated starch nanoparticles. Light scattering studies in toluene at 30° showed that these particles have a unimodal size distribution and diameters that range from 5 to 350 nm (Figure 5). 

Modifications in order to improve starch matrix-starch nanoparticles nanocomposites were also proposed. For example, Ma et al. (2008c), proposed the fabrication and characterization of citric acid-modified starch nanoparticles/plasti-cized pea starch composites. In dynamic mechanical thermal analysis, the introduction of CA-S-NP could improve the storage modulus and the glass transition temperature of pea starch/CA-S-NP composites. The tensile yield strength and Young s modulus increased Irom 3.94 to 8.12 MPa and from 49.8 to 125.1 MPa, respectively, when the CA-S-NP contents varied fiom 0 to 4 wt%. 

Figure 5 gives the results obtained in the following reaction conditions starch 12g, butadiene ca 40g, catalyst Pd(OAc)2/TPPTS 1/3, aqueous NaOH (O.IM) 50ml/iPrOH 10ml, 3h. At 90°C, with 0.5 wt.% of Pd(OAc)2, the DS reached almost 0.6 while less than 0.3 was achieved with 0.12 wt% catalyst. At 50°C, the DS was lower but much less affected by the catalyst/starch ratio, thus the DS decreased from 0.15 to 0.08 as the amount of catalyst decreased from 0.5% to 0.05%. This is because at 90°C Pd/TPPTS complex is unstable and decomposes progressively into palladium metal whereas at 50°C the catalyst is stable enough. When the reaction was performed in the presence of 0.25% palladium acetate, 0.08 wt% residual palladium was detected by chemical analysis of modified starch after reaction at 50°C. In contrast, no palladium was detected in the modified polymer when the reaction was conducted in the presence of 0.05% palladium. An optimum DS of 0.06 suitable for application in latex preparation for decorative paints was obtained with 0.03% palladium at 50X. 

MaX, Jian R, Chang PR, Yu J (2008) Fabrication and characterization of citric acid-modified starch nanoparticles/plasized-starch composites. Biomacromol 9 3314-3320 Molnar-Perl I, Morvai M (1987) Esterification of aliphatic hydroxyl acids to n-propyl esters in aqueous solutions for their gas chromatographic analysis. Chromatographia 23 760-763 Bouchard EF, Meritt EG (1984) Citric acid. In Kirk-Othmer Encyclopedia of Chemical Technology, 3rd edn, vol 6. Wiley-Interscience, New York, pp 150-176 Prokop M, Milewska MJ (2009) An improved synthesis of trisodium -homocitrate from citric acid. Polish J Chem 83 1317-1322... 

When a thermal treatment was applied to starch before the analysis, a very different behavior (Fig. 23b) was obtained. After such a treatment, no maximum was observed for the viscosity which increased slowly up to 82°C. In the case of starch modified with octadienyl chains (DS 0.055 (Fig. 23c) and DS 0.1 (Fig. 23d)), the viscosities were much lower than for native starch (b) in both cases. The presence of hydrophobic chains at the surface of the material could prevent the interaction of water molecules with the macromolecules after the splitting, thus avoiding the formation of a gel. 

For the analysis of water-soluble polymers (such as surfactants, oligosaccharides, PEGS, lignosulfonates, polyacrylates, polysaccharides, PVA, cellulose derivatives, PEG, polyacrylic acids, polyacrylamides, hyaluronic acids, CMC, starches, gums) and for separations of oligomers and small molecules, columns that are comprised of macroporous material with hydrophilic functionalities may be used. The requirement for these columns in SEC mode is to eliminate or minimize ionic and hydrophobic effects that make aqueous SEC (otherwise known as GFC) very demanding. The interaction of analytes with neutral, ionic, and hydrophobic moieties must be suppressed. It is often necessary to modify the eluent (addition of salt) in order to avoid sample-to-sample and sample-to-column interactions that can result in poor aqueous SEC separations and low recoveries. 

Partial oxidations [104,105] of polysaccharides is commonly done, both during stmctural analysis and to modify their properties. Oxidation introduces both carbonyl and carboxylate functions at different positions, and especially in alkaline systems, can result in chain cleavage, i. e., depolymerization [108]. Oxidation using sodium hypochlorite by itself [109] or in combination with sodium bromide [110] is practiced in the starch industry, both to introduce specific properties into the product and for depol)merization. This oxidation is non-specific. 

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