Corn starch analysis

Polymer Selection. The selection of corn starch as the starting material was made due to its low cost, ready availability, multitude of previous derivatization literature work and favorable chemical and physical properties (i.e., inert, readily deriva-tized homopolysaccharide capable of forming high solids content aqueous dispersions with relatively low viscosities). The corn starch used in this study was purchased in bulk from a local food cooperative. Table I gives the proximate analysis of a typical corn starch. 

Diets are isocaloric. The composition of the test and control (reference protein) diet (calculated on a dry weight basis) is 10% protein (1.6% nitrogen), 1 % AIN vitamin mix 76,3.5% AIN mineral mixture 76 (Nutritional Biochemicals), 0.2% choline bitartrate, 5% cellulose (only if test food is <5% total dietary fiber), corn oil to 10% total fat, and corn starch to total 100%. To account for differences in the protein content of the test diet, the level of corn starch can be adjusted (Joint FAO/WHO Expert Consultation, 1991). The chemical composition (proximate analysis) of the test protein must be measured before test diets are formulated. The proximate analysis of the test and control diets are to be measured after the diets are formulated, but before they are fed, to ensure that the protein content is the same for all diets, and that the diets are isocaloric. 

Starch, as ordinarily prepared either in the laboratory or commercially, requires very little additional purification. It is one of the few natural organic substances that can be obtained readily in a high state of purity. A typical analysis of a standard grade of commercial corn starch shows that it contains, on a dry basis, approximately 99.0% starch, 0.05-0.07% nitrogen, 0.02% phosphorus, 0.08-0.10% ash, and 0.5-1.0% fatty substance. Normally, the starch contains 10-12% moisture. The fatty material and a part of the phosphorus can be removed by extraction with 85% methanol - - or by extraction with ethanol containing a small amount of nitric acid, although the latter treatment may cause some degradation of the starch. 

Maize or Corn Starch.—The structure of a grain of maize is similar to that of a grain of wheat already described. The average analysis of maize is starch 55, other carbohydrates 15, proteins 10-5, fat 5, ash 2-5, water 12 per cent. Of the proteins present one is soluble in water, and the gluten is soluble in dilute caustic alkali. 

Process design the CER includes articles which discuss the creation of products having lower environmental impact, (e.g. target-specific agrochemicals and biodegradable plastics from corn starch). Life cycle analysis is also discussed. 

Singh N and Cheryan M. Process design and economic analysis of a ceramic membrane system for microfiltration of corn starch hydrolysate. J. Food Eng. 1998 38 57-67. 

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... 

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. 

We extended the methodology developed for molecular characterization of cotton fiber to analysis of other polysaccharides. In this report, we present the results obtained from MWDs determined by SEC for various complex carbohydrate samples dissolved in DMAC-LiCl. Applications include cotton fiber, corn and wheat starch flours, and avocado cell walls. Relationships are evaluated between the respective MWDs and cotton fiber development, variety, inheritance, textile processing, and strength starch extrusion conditions and stage of ripening in avocado. 

Unconventional layers have also been employed in the TLC analysis of pigments of sour cherry and blueberry. Basehne separations were carried out on corn and rice starch layers in the n-butanol-glacial acetic acid-water-benzene (30 20 10 0.5, v/v) mobile phase [4]. A considerable number of carotenoid standards can be separated in one run as demonstrated in Table 1, showing the Rf values of carotenoids in various eluent systems [5]. 

Starch is usually obtained from corn, potato and cassava, although it may be obtained from other sources as well. The fact that it is obtained from foods, that require fertile soil for cultivation, has been much questioned, considering that more than 10% of the world population is still undernourished today. From the viewpoint of the life-cycle analysis, products from plant or food wastes are highly favored. 

An a-D-glucosidase purified from flint corn by precipitation with ammonium sulphate, ion-exchange chromatography, and gel-filtrations was homogeneous in ultracentrifugal and disc electrophoretic analysis. The enzyme (6.5 Sy mol. wt. 6.5 X 10 by gel filtration) showed a pH optimum of 3.6 for both maltose and soluble starch. The ratio of velocities of hydrolysis for maltose, phenyl a-D-glucopyranoside, and soluble starch was estimated to be 100 14.3 6.1. The a-o-glucosidase hydrolysed soluble starch by an exo action. 

This chapter consists of two distinct parts. In the first part, a cursory overview of chemometric methods, as applicable to analysis of and quantitation with NIR data is presented. In Section 10.2 common methods for preprocessing NIR spectra are described. Section 10.3 discusses multivariate methods for developing predictive calibration models with NIR spectra. In Section 10.4, strategies for sample and model validation are presented that exploit the multivariate nature of NIR spectra. The performance of the multivariate methods discussed in Section 10.2 through Section 10.4 are applied to a set of 80 NIR reflectance data of corn flour for determination of four physical properties moisture, oil, protein, and starch. 

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