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- Bertoft, Eric
(författare)
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The molecular structures of starch components and their contribution to the architecture of starch granules: A comprehensive review
- 2010
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Ingår i: Starch/Stärke. - : Wiley. - 0038-9056 .- 1521-379X. ; 62, s. 389-420
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Forskningsöversikt (refereegranskat)abstract
- Recent developments in methods and instrumentation have contributed to major advances in our understanding of the fine structure of amylose and amylopectin. The structure of the starch granule slowly unravels with new insight into key structural features. Following a brief presentation of the structural features common to all starches, the most recent findings for the structure of amylose and amylopectin are reported. The organization of different types of chains in amylopectin is discussed with a critical review of the 'cluster' model leading to the presentation of alternative models. The locations of molecular components in the starch granule are described according to a progress structural order The description of the crystalline components is followed by a presentation of their supramolecular arrangements. The crystalline components comprise platelet nanocrystals which have already been identified and characterized, and other less well characterized 'blocklet components'. The location and state of amylose within the granule is also presented. This comprehensive review aims at distinguishing between those structural features that have received widespread acceptance and those that are still under debate, with the ambition of being educational and to provide stimulation for further fundamental investigation into the starch granule as a macromolecular assembly.
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- Lundström-Hämälä, Lisa, et al.
(författare)
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Polyelectrolyte Multilayers from Cationic and Anionic Starch : Influence of Charge Density and Salt Concentration on the Properties of the Adsorbed Layers
- 2010
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Ingår i: Starke (Weinheim). - : Wiley. - 0038-9056 .- 1521-379X. ; 62:2, s. 102-114
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the present work was for identify limits for the formation of stable polyelectrolyte multilayers (PEMs) from cationic and anionic starches (with degrees of substitution of 0.04-0.09) on SiO2 surfaces, taking account of the effect of the charge density of the starches and the salt concentration in the surrounding water phase. The experiments were performed at a pH of 6.3 using stagnation point adsorption reflectometry (SPAR) and quartz crystal microbalance with dissipation (QCM-D). From these experiments it was concluded that it is possible to form PEMs by the adsorption of oppositely charged starches on SiO2 surfaces; it was also found that adsorption of the first layer is controlled both by electrostatic, non-ionic interactions and by pure steric restrictions, Le, geometrical restrictions, at the surface. The results also indicate that the charge density of the starch must exceed a certain value to allow multilayer formation and that this critical charge density increases with increasing salt concentration. The combination of charge densities of the cationic/anionic starches was also found to influence the adsorption behaviour, and the formed polyelectrolyte multilayers had a high water content of 69-92%.
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| 4. |
- Pérez, Daysi, et al.
(författare)
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Enzymatic hydrolysis of Canna indica, Manihot esculenta and Xanthosoma sagittifolium native starches below the gelatinization temperature
- 2013
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Ingår i: Stärke. - : Wiley. - 0038-9056 .- 1521-379X. ; 65:1-2, s. 151-161
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Tidskriftsartikel (refereegranskat)abstract
- The susceptibility to enzymatic hydrolysis of starch extracted from raw roots of Canna indica, Manihot esculenta and Xanthosoma sagittifolium, grown in Bolivia, were studied below the gelatinization temperature. The granule size and amylose content were as followed: C. indica>M. esculenta>X. sagittifolium. The hydrolysis showed a rapid rate at the initial stage, followed by a progressive decrease thereafter. At 30, 40 and 50 degrees C, during the initial stage, the rate of hydrolysis was observed to be influenced by the size of the granules, being the highest for the small sized granules X. sagittifolium, followed by the medium sized granules M. esculenta and the lowest rate was for the large sized granules C. indica starch. During the slow phase, A-type M. esculenta and B-type C. indica showed higher hydrolysis rates than A-type X. sagittifolium. At 60 degrees C, a positive correlation was found between the amylose content and the rate of hydrolysis among the starches. Microscopic observations showed a pattern of attack by the enzyme towards C. indica starch granules, suggesting that high amylose content is concentrated around the hilum.
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