Starch characterization

Organic-Phase SEC for Starch Characterization Dimethylsulfoxide or Its Mixture as the Mobile Phase Packing Materials and Mobile Phase... 

Comparison of Aqueous SEC, DMSO SEC, and DMAc SEC for Starch Characterization... 

Most SEC papers published in scientific journals for starch characterization use an aqueous mobile phase. Because of the instability of the starch in aqueous solution, the sample is usually analyzed within 1 h after it is prepared. It is difficult to use an autosampler in an aqueous SEC system. 

A. Bertolini, Starches Characterization, Properties, and Applications, CRC Press, 2009. 

In the second part, the main results obtained in the domain of starch characterization were recalled showing the necessity to adopt a multidetection system for the analysis of starch molecular weight distribution. Nevertheless, the major problem remains the preparation of a good solution avoiding aggregates and with no adsorption on the gel matrix. 

Iodine addition proves to be an important diagnostic method for starch characterization. Amylose absorbs up to 20% iodine and stains blue. Bonding with lipids. 

Com and rice starches have been oxidized and subsequently cyanoethylated (97). As molecular size decreases due to degradation during oxidation, the degree of cyanoethylation increases. The derivatized starch shows pseudoplastic flow in water dispersion at higher levels of cyanoethylation the flow is thixotropic. Com and rice starches have been oxidized and subsequently carboxymethylated (98). Such derivatives are superior in the production of textile sizes. Potato starch has been oxidized with neutral aqueous bromine and fully chemically (99) and physically (100) characterized. Amylose is more sensitive to bromine oxidation than amylopectin and oxidation causes a decrease in both gelatinization temperature range and gelatinization enthalpy. 

These products are characterized in terms of moles of substitution (MS) rather than DS. MS is used because the reaction of an ethylene oxide or propylene oxide molecule with ceUulose leads to the formation of a new hydroxyl group with which another alkylene oxide molecule can react to form an oligomeric side chain. Therefore, theoreticaUy, there is no limit to the moles of substituent that can be added to each D-glucopyranosyl unit. MS denotes the average number of moles of alkylene oxide that has reacted per D-glucopyranosyl unit. Because starch is usuaUy derivatized to a considerably lesser degree than is ceUulose, formation of substituent poly(alkylene oxide) chains does not usuaUy occur when starch is hydroxyalkylated and DS = MS. 

Alpha-amylases are characterized by attacking the starch polymer in an endo fashion, randomly cleaving internal 1,4-bonds to yield shorter, water-soluble dextrins. They are the preferred type of amylase for laundry detergents, and are included in both powder and Hquid formulations in many countries. 

Fractionation/characterization of nb/lcb fraction of potato starch glucan... 

In the matrix of PLA/ polycaprilactone (PCL)/OMMT nano-composites, the silicate layers of the organoclay were intercalated and randomly distributed (Zhenyang et at, 2007). The PLA/PCL blend significantly improved the tensile and other mechanical properties by addition of OMMT. Thermal stability of PLA/PCL blends was also explicitly improved when the OMMT content is less than 5%wt. Preparation of PLA/thermoplastic starch/MMT nano-composites have been investigated and the products have been characterized using X-Ray diffraction, transmission electron microscopy and tensile measurements. The results show improvement in the tensile and modulus, and reduction in fracture toughness (Arroyo et ah, 2010). 

Dragunski, D. C. and PawHcka A. (2001). Preparation and characterization of starch Grafted with Toluene Poly (propylene oxide) diisocyanate. Mater. Res., 4, 77-81. 

The, chain voAiantS are characterized by the presence of two abnormal components, an abnormal Hb-F (02 /2) and an abnormal Hb-A (tt2 32) Of these two, the 02 2 component dominates and the 02 32 component Is often difficult to detect. The methods of choice are starch gel electrophoresis and anion-exchange chromatography using DEAE-Sephadex or DE-52 Cellulose. Chain analyses of these Isolated hemoglobin components will lead to a definitive Identification. 

Pectinases from Rhizopus sp. Efficient in Enhancing the Hydrolyzation of Raw Cassava Starch Purification and Characterization... 

John J. Meister, Damodar R. Patil, Margaret C. Jewell, Kyle Krohn, Synthesis, Characterization, and Properties in Aqueous Solution of Poly(Starch-g- [(l-amidoethylene)-co-(sodium l-(2-methylprop-2N-yl-l-sulfonate)amidoethylene)]), Proceedings of the American Chemical Society Division of Polymeric Materials,... 

The labile nature of the components necessitates that, for fundamental investigations, the starch should preferably be extracted from its botanical source, in the laboratory, under the mildest possible conditions.26 Industrial samples of unknown origin and treatment should not be used. The characterization of the starch would appear to entail (1) dissolution of the granule without degradation, (2) fractionation without degradation, (3) complete analysis of the finer details of structure of the separated components (including the possibilities of intermediate structures between the extremes of amylose and amylopectin), and (4) the estimation of the size, shape, and molecular-weight distribution of these fractions. 

It is obviously important that the fractionation products should be adequately characterized. The only accurate method for ascertaining the purity of the starch components, and also the amylose/amylopectin ratio in whole starch, is to determine potentiometrically the amount of iodine bound.8 38 Colorimetric methods which have been suggested37 38 are useful for comparative measurements, but are often not absolute. The yield of... 

Further measurements appear necessary before the molecular weights of the amylopectin component of starches can be adequately characterized, and it may well be that light-scattering is the only method which can be satisfactorily applied to these polysaccharides of very high molecular weight. Certainly, it is the only method which enables studies of very dilute solutions to be made with high accuracy, particularly in the case of aqueous solutions. 

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