Starch spherulites

These concepts have to be correlated with the inherent helical form of the starch molecule, and attempts which have been made to determine the orientation of the portions of the molecules in the crystallites will be dealt with later (in the Section on x-ray diffraction studies—see p. 376). In this connection, the work on the orientation of synthetic crystalline polymers into spherulites containing helically arranged molecules23 may be important. 

Ziegler, G. R., Creek, J. A., and Runt, J. (2005). Spherulitic crystallization in starch as a model for starch granule initiation. Biomacromolecules 6,1547-1554. 

Nordmark, T. S., Ziegler, G. R. (2002). Spherulitic crystallization of gelatinized maize starch and its fractions. Carbohydr. Polym., 49,439 48. 

Figure 15.8 SEM image of spherulite aggregates of jet cooked high amylose starch dispersion slowly cooled without stirring. (Reprinted from Fanta et al., 2008, with permission from Elsevier).

Fanta, G. F., Felker, F. C., Shogren, R. L., Saleh, J. H. (2008). Preparation of spherulites from jet cooked mixtures of high amylose starch and fatty acids. Effect of preparative conditions on spherulite morphology and yield. Carbohydrate polymers, 71, 253-262. 

Figure 5.4 X-ray powder diffractogram recorded for (a) A-type amylodextrins and (b) B-type amylodextrins grown as spherulites. X-ray fiber diffraction patterns (fiber axis vertical) for (c) A-amylose (fiber spacing 1.04 nm) and (d) B-amylose (fiber spacing 1.05 nm). (Reproduced with permission from references 30 and 31). Microcrystal of (e) A-starch and (f) B-starch observed by low dose electron microscopy. Inset the electron diffraction diagrams recorded under frozen wet conditions (e). (Reproduced with permission from references 32 and 34)...

The classical thermodynamic and kinetic model is that of a rigid sphere impenetrable by water. A spherical geometry has been observed in many polysaccharide systems, notably hyaluronic acid-protein complexes (Ogston and Stainer, 1951), dispersed gum arabic (Whistler, 1993), and spray-dried ungelatinized starch granules (Zhao and Whistler, 1994). Spherulites of short-chain amylose were obtained by precipitation with 30% water-ethanol (Ring et al., 1987), and spherulites of synthetic polymers were obtained... 

Starch can be found in various parts of a plant, such as the seed endosperm, the root, the leaf and the fruit pulp. It is deposited in the form of semicrystalline granules which are insoluble in cold water and resemble spherulites [15] of alternating amorphous and crystalline (or semi-crystalline) lamellae. 

Shogren, R.L., Fanta, G.F. and Felker, F.C. (2006) X-Ray Drflraction study of crystal transformations in spherulitic amylose/lipid complexes from jet-cooked starch. Carbohydrate Polymers, 64,444- 51. van Soest, J.J.G., Hulleman, S.H.D.,de Wit, D. tmd Vliegenthart, J.F.G. (1999) Changes in the mechanical properties of thermoplastic potato starch in relation with changes in B-type crystallinity. Carbohydrate Polymers, 29, 225-232. 

An additional goal of microfocus SAXS is to explore minuscule free or restrained entities. For instance, molecular structure has become accessible by tracking the polymorphic transformation in 2D spherulite crystals, oil crystallization in oil in water droplets, and pressure-induced gelatinization of distinct starch granules in a diamond anvil ceU. Motifs assembled by nanoscale organization at snrfaces have great potential for multiple fields of technology. 

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