Proteins separation from starch

Western Australia and New South Wales, Australia and Nebraska, USA Quality ofwheat for salt noodle predicted by 1) separation of waxy proteins isolated from starch 2) polymerase chain reaction-based assay for null Wx-B1 locus in leafDNA 3) immunoassay (enzyme-linked immunosorbent assay) for total waxy proteins dissolved from starch 262-264... 

A method has been developed by Mares and Stone (1973a) for the isolation of wheat endosperm cell walls using 70% aqueous ethanol as the isolation medium. Aqueous ethanol is used instead of an aqueous medium to minimize loss of water-soluble polymeric components present in the native walls. In this method the cell walls are separated from starch and protein on the basis of their size difference. The endosperm components present in a coarse wheat flour are suspended in 70% aqueous... 

After cleaning to remove coarse material, ie, cobs, and fines (broken com, dust, etc), the com is steeped in a sulfurous acid solution to soften the com and render the starch granules separable from the protein matrix that envelopes them. About 7% of the kernel s dry substance is leached out during this step, forming protein-rich steep-water, a valuable feed ingredient and fermentation adjunct. 

The methods used to separate the starch vary, depending on the raw material. Maize is normally wet milled. Initially the maize kernels are steeped in dilute sulfuric acid for 40 50 hours to soften the kernels. Next, the kernels are milled to release the germ that contains the oil. The fibre is then separated from the endosperm by milling it finer. Centrifuges are then used to separate the starch from the protein. After this the starch is washed and dried. 

By means of gel electrophoresis on cross-linked, hydrolyzed starch,99 with simultaneous checking for proteins, lipids, and pectinesterase activity, it was found, however, that the product isolated after the separation on CM-Sephadex C-50 constitutes but one of five multiple forms of tomato pectinesterase, and is the one present in preponderant proportion98 (see Fig. 4). The accompanying lipid and sugar components were separated from this pectinesterase form in the course of the purification procedure. After analysis of the hydro-lyzate of the final product for fatty acids, as well as for carbohydrate components, it was possible to exclude the possibility of a lipoprotein,30 as well as glycoprotein,100 character of this form of tomato pectinesterase. 

The final pH of the initial extract from the vibrating screen was 7.5 but this increased to pH 9.6 and 10.2 for fababean and field pea, resp., during the second extraction. The filtrates were combined and centrifuged on a Fletcher basket centrifuge at 3400 rpm (1800 x g) to separate the starch and protein (Figure 2). 

The starch fraction was washed initially with 0.02% NaOH, the extract being added to the protein solution (Figure 2). The starch was then slurried in distilled water, separated by sedimentation, and dried at 30°C. The combined protein extracts were adjusted to pH 4.5 with IN HC1 and the whey separated from the curd by centrifugation in the basket centrifuge (1100 x g). The protein curd was washed twice with water adjusted to pH 4.5, then resuspended at pH 7.0 using IN NaOH. The proteinate was freeze-dried. 

In 1956, Smithies and Poulik first used 2-DE combining paper and starch gel electrophoresis to separate serum proteins. Nearly 20 years later, polyacrylamide was applied as a support medium. Charge-based protein separation followed as isoelectric focusing (IEF), applied to SDS-PAGE. Later, urea and nonionic detergents were used in IEF-2DE. The most significant achievement was the separation of proteins from E. coli. 

Many patented processes are used for the isolation of particular starches and the procedure adopted depends on the desired degree of purity and the nature of the compounds from which the starch has been obtained. Cereal starches, for example, have to be separated from cell debries, oil, and soluble proteins. 

A commercial fractionation process in which groats are dry-milled and the comminuted groats are soaked in a solution of cellulases and hemicellulases has been developed.9 In addition to the starch the process produces fiber and protein fractions. Unlike wheat starch, oat starch cannot be separated from the grain by selective hydration and centrifugation, because of hydrated bran and protein layers. 

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