Starch components

M NaCl eluent. Because of the good performance of the TSK PW system in the low dp range, DMSO was shifted outside the selective separation range > 50 ml) and aqueous eluent-dissolved starch components could he analyzed in terms of absolute degree of polymerization distributions (mass m ... 

Dang, J. M. C., Braet, F., and Copeland, L. (2006). Nanostructural analysis of starch components by atomic force microscopy. /. Microsc. 224,181-186. 

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... 

V. Properties of the Starch Components in Solution 1. The Determination of Molecular Weight... 

Methods which can be used to determine the size and shape of polysaccharides have been reviewed.107 (A critical survey of these has recently been given by Sadron108 and by Ogston.109) Special problems exist in the case of the undegraded starch components. In view of the branched nature of amylopectin and the large size of the amylose molecule, chemical methods of estimating size are inadequate, and it is questionable whether results are valid.38 The free components may also aggregate in aqueous solution. Study of derivatives is therefore more convenient, and the preparation of these is an essential preliminary to estimations of molecular size. 

The viscosity of polymer solutions has been considered theoretically by Flory,130 but although this theory has been applied to cellulose esters,131 no applications have yet been made in the case of the starch components. Theoretical predictions of the effect, on [17], of branching in a polymer molecule have been made,132 and this may be of importance with regard to the viscometric behavior of amylopectin. 

Light-scattering measurements are of great intrinsic value for studying the starch components, but few measurements have been carried out. Recently, the question of the absolute value of the standards used in tur-bidimetry has been discussed,133 and several new instruments have been described.133 134 It is to be hoped that more use will be made of this method in the future. 

Few sedimentation or diffusion measurements have been made on the starch components, although methods of estimating polymolecularity of samples from sedimentation136 and diffusion136 measurements have been evaluated. The molecular-weight distribution can also be obtained from comparisons of Mn, Mw, and Mz, 137 and more directly by fractional pre-... 

All these methods and theoretical advances should be applicable to the starch components, for obtaining accurate estimates of their molecular weight and its distribution. 

Indeed, notwithstanding extensive investigations on the starch components, many problems requiring the application of physical methods remain incompletely solved. 

The effect of alkali treatment on molecular weight (compare with the case of the starch components) has been studied treating a 5% solution of rabbit-liver glycogen in 2 N sodium hydroxide, for 90 minutes at 100°, decreased the sedimentation constant (Sits X 1013) from 86 to 57 (that is, by 34%).237... 

The production of CDs via enzymatic reaction with starch has been recently reviewed (i 7). CGTase is an extracellular protein and is usually isolated as a crude mixture from the medium. This crude protein is used directly for industrial fermentations. The basic process involves standard enz3miatic fermentation, with careful attention to reaction temperature. All three CDs and some Unear oligosaccharides are normally produced. Yields are highly dependent on the source of starch substrate. Potato starch is normally used or an extract of potato starch is often added to other starches 18-19), The potato starch component(s) responsible for stimulating CD formation have not been determined. Low starch concentrations (5%-10%) are normally used industrially. Published yields are in the 50% - 80% conversion range. 

Colonna, R, Mercier, C. (1984). Macromolecular structure of wrinkled- and smooth-pea starch components. Carbohydrate Research, 126,233-247. 

Semenova, M.G., Myasoedova, M.S., Antipova, A.S. (2001a). Effect of starch components and derivatives on the surface behaviour of a mixture of protein and small-molecule surfactants. In Dickinson, E., Miller, R. (Eds). Food Colloids Fundamentals of Formulation. Cambridge, UK Royal Society of Chemistry, pp. 233-241. 

A further factor that causes the non-homogeneity of nitrostarch is the presence of the two components, amylose and amylopectin in starch. It has been demonstrated by nitrating each of these starch components separately that the nitration products differ from one another. Berl and Kunze [37] detected that amylopectin yields a product of a considerably higher viscosity than that resulting from the nitration of amylose. This effect may be attributable to the higher molecular weight of amylopectin. 

Lipids in starchy foods may occur in the free as well as bound forms. The latter being either in the form of amylose inclusion complexes or linked via ionic or hydrogen bonding to the hydroxyl groups of the starch components. Free lipids are easily extractable at ambient temperatures, while use of nonalcoholic solvents for a prolonged period or disruption of the granular structure by acid hydrolysis (see Basic Protocol 4) may be required for the efficient extraction of bound lipids. While acid hydrolysis allows the release and quantitation of lipids, the procedure leads to destruction of the starch components therefore, the alcohol extraction system involving propanol and water would be most desirable in these cases. This system removes both nonpolar and polar lipids from samples. 

Aging of gelatinized starch was studied by cross-relaxation NMR method [99]. Relatively immobile starch components increased and components with liquid-like mobility decreased during aging. Two spectral components were observed in cross-relaxation spectra. According to the theory mentioned above(5.5.1.), the broader one correlates with the degree of crystallinity and the narrower one with starch chains having mobility intermediate between... 

Non-mutant normal) reserve and transitory starch granules are composed primarily of amylose and amylopectin. Amy lose is essentially a linear polymer consisting of (1—4)-linked a-D-glucopyranosyl units. Amylopectin is a branched polymer of a-D-glucop-yranosyl units primarily linked by (1—>4) bonds with branches resulting from (1—6) linkages. Properties of these two major starch components are summarized in Table 3.1. 

Changes in the Protein Fractions of Corn Grains. Changes in the starch component determine the principal mechanical properties of dough... 

We have observed that the same mechanical properties of doughs prepared from lime or calcium hydroxide-treated corn were achieved when com was treated with magnesium hydroxide. It seems reasonable to consider that the elaboration of products from nixtamalized corn is based mostly on the physical-chemical changes occurring in the starch component of the com grain. This is substantiated further by the fact that other starchy foods can be lime treated to yield products similar to those obtained from com. 

It is to be expected that different enzymes must have different functions in the synthesis of the starch components, amylose and amylopectin,... 

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