Rheology and fracture of mixed ι- and κ-carrageenan gels: Two-step gelation

Parker, Alan; Brigand, G.; Miniou, Christian; Trespoey, A.; Vallée, Philippe

doi:10.1016/0144-8617(93)90097-n

Cited by 59 publications

(22 citation statements)

References 18 publications

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“…For pure ι‐carrageenan, a leveling off is observed at low temperatures. The shape of the cooling curve of pure ι‐carrageenan is in good agreement with cooling curves published before 10, 26. The shape of the G ′ vs temperature curve is similar to that of the curve of the optical rotation versus temperature, showing the relation between the helix formation and gelation.…”

Section: Resultssupporting

confidence: 87%

Coil–helix transition of ι‐carrageenan as a function of chain regularity

et al. 2002

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A series of iota-carrageenans containing different amounts of nu-carrageenan (0-23 monomer %) have been prepared from neutrally extracted carrageenan of Eucheuma denticulatum. nu-Carrageenan is the biochemical precursor of iota-carrageenan. The conformational order-disorder transition and rheological properties of these carrageenans were studied using optical rotation, rheometry, size exclusion chromatography coupled to multiangle laser light scattering, and high-sensitivity differential scanning calorimetry. The helix forming capacity of iota-carrageenan turns out to decrease monotonously with increasing amount of nu-units. In contrast, the rheological properties of iota-carrageenan are remarkably enhanced by the presence of a small amount of nu-units, yielding a maximum twofold increase in G' at 3% nu-units. It is concluded that the structure-forming capacity of iota-carrageenan, containing a small amount of nu-carrageenan, is significantly higher than that of pure iota-carrageenan. This phenomenon is explained in terms of the balance between the helical content and the number of cross-links between chains, taking into consideration the fact that nu-units introduce "kinks" in the chain conformation enabling neighboring chains to connect. Increasing amounts of nu-units increase the number of cross-links in the network, resulting in increased gel strength. On the other hand, a reduced length of the helical strands weakens the cross-links between the different chains and, consequently, the gel.

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Section: Resultssupporting

confidence: 87%

Coil–helix transition of ι‐carrageenan as a function of chain regularity

et al. 2002

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“…For instance, in the case of t-carrageenan in the presence of monovalent salts, the time evolution of G' as a function of temperature has a monotonic sigmoidal profile, which is not influenced by the nature ofthe counterion (Na+ or K+) [344].…”

Section: From Solutions To Gelsmentioning

confidence: 99%

Rheology of polysaccharide systems

Lapasin

Pricl

1995

Rheology of Industrial Polysaccharides: Theory and Applications

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The transport properties and, specifically, the rheological behavior of real and complex materials such as polysaccharide systems can be significantly affected by several factors, mainly related to molecular and supermolecular features. Most of these factors are common to all polymeric systems, as they have universal character; others are peculiar to carbohydrate polymers. If we bear in mind the concepts discussed in §1.4, we can easily imagine for polysaccharides a variety of structural conditions much wider than that generally observed for synthetic polymers. On both molecular and supermolecular scales, polysaccharides possess special characteristics that reflect specific behavior so that different classes of materials can be identified.Let us consider the molecular scale first: at this level, the polymer backbone and its related features, such as its length in solution, shape, stitfuess and the eventual presence of ionizable groups, playa major role in determining the macroscopic properties of the system, including its rheology. Many of these molecular parameters correlate among themselves (e.g. chain stitfuess and length); others must be combined with external factors such as, for instance, the characteristics of the solvent medium. These latter may, in turn, exert an influence on the conformation adopted by the macromolecule in the medium itself, as well as on the possibility of forming supermolecular structures. In other words, changes in ionic strength, the nature of counterions, temperature or other solvent parameters may induce a conformational transition, thus modifying the hydrodynamic resistance of the macromolecule to flow. Also, if the polymer concentration is high enough, the variations described above may promote structural changes at a supermolecular level and, accordingly, modifications in the rheological behavior. Before leaving this brief comment on solvent characteristics we must mention the viscosity although, R. Lapasin et al. (eds.), Rheology of Industrial Polysaccharides: Theory and Applications

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“…1). 5,8 Furthermore, by selecting the salt conditions, it is possible to make the lC-carrageenan step occur either at lower or at higher temperature than the 1-carrageenan step. It is a general observation that mixed carrageenans do not form mixed helices.…”

Section: Gelation Of Carrageenans: Phenomenologymentioning

confidence: 99%

Gelation of (Some) Seaweed Polysaccharides

et al. 1994

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The mechanism of gelation of carrageenans is discussed in the light of recent experimental and theoretical results. It is concluded that association of helices, rather than the double-helix formation in itself, provides the junctions of the gel network. Although the helical regions are typically much shorter than the carrageenan chains, the average number of helical regions on a chain is insufficient to generate crosslinking. The effects of gelpromoting cations and gel-impeding anions on the gelation (helix aggregation) is caused by the binding of these ions to the carrageenan helices, whereby the electrostatic helix-helix repulsion is affected through the decreased (for cation binding) or increased (for anion binding) charge density of the helix.

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Rheology and fracture of mixed ι- and κ-carrageenan gels: Two-step gelation

Cited by 59 publications

References 18 publications

Coil–helix transition of ι‐carrageenan as a function of chain regularity

Coil–helix transition of ι‐carrageenan as a function of chain regularity

Rheology of polysaccharide systems

Gelation of (Some) Seaweed Polysaccharides

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