Amylose potato

With sedimentation velocity we measure the change in solute distribution across a solution in an ultracentrifuge cell as a function of time. An example of such a change is given in Fig. 2a for potato amylose [29]. 

Figure 4 [29] shows the (s) versus profiles for potato amylose and the amylose/amylopectin mixture from wheat starch corresponding to the concentration versus radial displacement data of Fig. 3. The s data used in the concentration dependence plot of Fig. 3 for wheat amylopectin comes from (s) vs. s analysis data of Fig. 2b and similar. The concentrations shown in the abscissa in Fig. 4 have been obtained from the total starch loading concentration normalised by the weight fraction of the amylopectin component estimated from the (s) vs. s profiles.

Fig. 4 Sedimentation velocity g (s) profiles for starch polysaccharides using DCDT+. The profiles correspond to the radial displacement plots of Fig. 2. a Potato amylose, sample concentration 8 mg/ml in 90% in dimethyl sulphoxide. Rotor speed was 50 000 rpm at a temperature of 20 °C. b Wheat starch (containing amylose, left peak and the faster moving amylopectin, right peak), (total) sample concentration 8 mg/ml in 90% dimethyl sulphoxide. Rotor speed was 35 000 rpm at a temperature of 20 °C. From [29]...

FIGURE 6.15 AFM images of (A) potato amylose, (B) potato amylopectin (arrows branch points on the chains), and (C) rice amylose (arrows individual amylose structures). Reprinted with permission from Dang et al. (2006). 

Meyer31 has separated maize and potato amyloses into two fractions each, by (1) aqueous leaching, followed by (2) dissolution and precipitation of the remainder. His results of colorimetric, end-group determinations of size were ... 

Peterlin168 has shown that the viscometric data for potato amylose acetate in chloroform solution can be readily interpreted in terms of a random-coil model for the molecule, in which there is hindered rotation at the oxygen atom of the glucosidic linkage. 

Pure potato amylose type III and amylopectin (Sigma)... 

Figure E2.3.1 Plot of absorbance at 600 nm against percentage amylose (w/w) for mixtures of potato amylose and amylopectin with iodine. The absorbance of 0% amylose is due to the l2 affinity of the long outer branches of amylopectin.

Plot a standard curve (Fig. E2.3.1) for mixtures of pure potato amylose and amylopectin. 

Fig. 6.—Variation of Staudinger index [ij] of potato amylose (a) and amylopectin (b) as a function of specific viscosity (from Ref. 46).

Figure 6.5 Gel permeation chromatogram of isoamylase-treated potato amylose on Toyopearl HW-75F. Potato amylose (50 mg in 5 ml ) was incubated at 45°C with 5.5 U of Pseudomonas isoamylase in 20 mM acetate buffer (pH 3.5) for 2.5 h. An aliquot (1 ml.) was applied to the column — and , carbohydrate concentration and beta-amylolysis limit, respectively, of the isoamylase-treated amylose ., carbohydrate...

Table 10.6 compares the average size (DPn) and size distributions of six laboratory-purified amyloses and one commercial sample of potato amylose, which were determined by classic colorimetric and fluorescent-labeling techniques using 2-ami-nopyridine. The data by the two techniques are consistent and show that wheat and other cereal amyloses are smaller in size than those from root and tuber starches. The molar distribution technique indicated that wheat amylose contained two molecular species, compared with one for rice and com amyloses.209,210 Moreover, the molar size distributions for the cereal amyloses are much narrower than those of the tuber amyloses, and the cereal amyloses contain a preponderance of molecules of DPn < 1000 whereas the tuber amyloses contain 78-95% of molecules with DPn > 1000, and even 3-5% above DPn 10000. None of the amylose samples in Table 10.6 showed molecules with less than DPn 200, possibly because they had been purified as alcohol-inclusion complexes.209... 

The acetate of potato amylose is more flexible than cellulose acetate, but the persistent length of the latter is significantly higher.2026 Starch triacetate, amylose triacetate, and amylopectin triacetate are reported to be suitable for... 

Studies performed on the etherification of potato amylose and amylopectin with (diethylamino)ethyl chloride showed that amylose in the starch granule was more reactive than amylopectin.2429 However, the relative reactivity of both starch components could be changed by physical pretreatment of the granules, for instance, by milling, heat-moisture treatment, freeze-thawing, and chemisorption. The physicochemical properties of amino starches depend on the starch variety reacted 2430 Among potato, sweet potato, rice, wheat, and tapioca starch studied, the last reacted most readily. 

A high molecular weight potato amylose was prepared by the urea dispersion method and it was preserved as a wet precipitate in ethanol(6o ) at +4°C ( ). Potato amylopectin was isolated from potato starch by the same method, and trace quantities of amylose from amylopectin fraction were removed by adsorption on defatted cellulose ( ). Amylose and... 

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