An improved model for analyzing the small angle x‐ray scattering of starch granules

Daniels, D. R.; Donald, Athene M.

doi:10.1002/bip.10341

Cited by 53 publications

(61 citation statements)

References 23 publications

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“…The first is based on the paracrystalline fitting model where randomly oriented stacks of infinite alternating crystalline and amorphous layers are embedded in an amorphous medium (amorphous growth rings) (Cameron & Donald, 1992). The second one, called side-chain liquid crystalline polymers model, considers starch as a finite stack of alternating lamellae that are allowed to thermally fluctuate both along the layer repeat direction and the transverse layer direction (Daniels & Donald, 2003). In both models, crystalline and amorphous lamellae are assumed to follow Gaussian distributions with the same degree of paracrystallinity, i.e.…”

Section: Introductionmentioning

confidence: 99%

On the lamellar width distributions of starch

Cardoso

Westfahl

2010

Carbohydrate Polymers

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Section: Introductionmentioning

confidence: 99%

On the lamellar width distributions of starch

Cardoso

Westfahl

2010

Carbohydrate Polymers

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“…[22][23][24][25][26][27][28] However, it has been difficult to obtain direct experimental evidence in support of this model. Our experimental evidence, in the form of SEM and AFM images, suggests that the starch granules contain alternating layers (growth rings) containing different degrees of semi-crystalline material.…”

Section: Discussionmentioning

confidence: 93%

“…Thus, these observations alone cannot distinguish between the two presently accepted but different models of the starch granule structure: the alternative models correspond, respectively, to the blocklet model 12,16-20 of starch structure, derived from transmission electron microscopy (TEM) and AFM studies, or the more widely accepted structure used for modelling the small angle X-ray scattering (SAXS) data on starch. [22][23][24][25][26][27][28] When the planed sections are mounted in water they immediately begin to hydrate and swell. Water is taken up in the protein bodies and cytoplasm, the cell wall, and sectioned starch, and the central 'pinched region' of the granules expands to form the distinctive hilum region (Figure 3a) sometimes with a crack-like void.…”

Section: Resultsmentioning

confidence: 99%

In situ Imaging of Pea Starch in Seeds

2008

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A method has been developed for the in situ imaging of starch in dry seeds by exploiting the tight packing of the starch and protein storage reserves within the cells of the embryo. The method can be adapted to prepare seed samples which are suitable for light microscopy (birefringence and iodine staining), scanning electron microscopy and atomic force microscopy. Its potential for imaging the internal structure of starch granules without any prior isolation process is demonstrated for round smooth peas. Using a standard ultramicrotome, thin sections were cut directly from selected regions of dry pea seeds and examined by light microscopy before and after hydration. The sectioning procedure left a planed surface with the internal structure of the starch granules exposed. This material was examined by scanning electron microscopy and atomic force microscopy directly or after controlled hydration. In the hydrated pea samples, the growth ring structure and blocklet sub-structure of individual starch granules within the seed were visualised directly by atomic force microscopy. Furthermore, the effects of hydration and staining were monitored and have been used to introduce contrast into the images. The observations have revealed new information on the blocklet distribution within pea starch granules and the physical origins of the growth ring structure of the granules: the blocklet distribution suggests that the granules contain alternating bands with different levels of crystallinity, rather than alternating amorphous and crystalline growth rings.

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“…The average number of repeat units appears to depend on the sample, but is in the order of 15-25 (Daniels and Donald 2003). The amorphous lamella consists of the internal part of the amylopectin molecule with most, or at least plenty, of the branches in amylopectin (French 1972).…”

Section: Lamellar Structurementioning

confidence: 98%

Fine Structure of Amylopectin

Bertoft

2015

Starch

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Starch granules consist of two major polyglucans, namely, branched amylopectin and essentially linear amylose. In all nonmutant starches, amylopectin is the major component and is responsible for the internal structure of starch granules, which is the native, semicrystalline form of starch. The granules, irrespective of the plant source, consist of granular rings of alternating amorphous and semicrystalline polymers. On a smaller scale, blocklets as well as crystalline and amorphous lamellae have been identified. Amylopectin is generally accepted as the contributor to the lamellar structure, but the nature of blocklets is only beginning to be resolved. Amylopectin consists of numerous chains of glucosyl units that are divided into short and long chains. These chains are organized as clusters that have been isolated by using endo-acting enzymes, and the fine structure of the clusters have been investigated. The clusters consist of still smaller, tightly branched units known as building blocks. The organization of the clusters and building blocks in the macromolecular structure of amylopectin is to date uncertain, and two schools exist at present suggesting that amylopectin either has a treelike branched cluster structure or a building block backbone structure. The structural features of amylopectin and the two models presently in debate are discussed in this chapter.

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An improved model for analyzing the small angle x‐ray scattering of starch granules

Cited by 53 publications

References 23 publications

On the lamellar width distributions of starch

On the lamellar width distributions of starch

In situ Imaging of Pea Starch in Seeds

Fine Structure of Amylopectin

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