Please use this identifier to cite or link to this item: http://hdl.handle.net/10316/14461
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dc.contributor.authorVan de Velde, Fred-
dc.contributor.authorAntipova, Anna S.-
dc.contributor.authorRollema, Harry S.-
dc.contributor.authorBurova, Tatiana V.-
dc.contributor.authorGrinberg, Nataliya V.-
dc.contributor.authorPereira, Leonel-
dc.contributor.authorGilsenan, Paula M.-
dc.contributor.authorTromp, R. Hans-
dc.contributor.authorRudolph, Brian-
dc.contributor.authorGrinberg, Valerij Ya.-
dc.date.accessioned2011-02-02T13:34:39Z-
dc.date.available2011-02-02T13:34:39Z-
dc.date.issued2005-05-02-
dc.identifier.citationVAN DE VELDE, Fred [et al.] - The structure of j/i-hybrid carrageenans II. Coil–helix transition as a function of chain composition. "Carbohydrate Research". ISSN 0008-6215. Vol. 340 nº 6 (2005) 1113-1129-
dc.identifier.issn0008-6215-
dc.identifier.urihttp://hdl.handle.net/10316/14461-
dc.description.abstractThis paper describes the effect of the k/i-ratio on the physical properties of k/i-hybrid carrageenans (synonyms: kappa-2, k-2, weak kappa, weak gelling kappa). To this end, a series of k/i-hybrid carrageenans ranging from almost homopolymeric k-carrageenan (98 mol% k-units) to almost homopolymeric-carrageenan (99 mol% i-units) have been extracted from selected species of marine red algae (Rhodophyta). The k/i-ratio of these k/i-hybrids was determined by NMR spectroscopy. Their rheological properties were determined by small deformation oscillatory rheology. The gel strength (storage modulus, G0) of the j/i-hybrids decreases with decreasing j-content. On the other hand, the gelation temperature of the k-rich k/i-hybrids is independent of their composition. This allows one to control the gel strength independent of the gelation or melting temperature. The conformational order–disorder transition of the k/i-hybrids was studied using optical rotation and high-sensitivity differential scanning calorimetry. High-sensitivity DSC showed that the total transition enthalpy of the k/i-hybrids goes through a minimum at 60 mol% k-units, whereas for the mixture of j- and i-carrageenan, the total transition enthalpy is a linear function of the composition. With respect to the ordering capability, the k/i-hybrid carrageenans seem to behave as random block copolymers with length sequence distributions truncated from the side of the small lengths. Intrinsic thermodynamic properties (e.g., transition temperature and enthalpy) of k- and i-sequences in these copolymers are close to those of their parent homopolymers. The critical sequence length for k-sequences is 2-fold of that for i-sequences.por
dc.language.isoengpor
dc.rightsopenAccesspor
dc.subjectCarrageenanpor
dc.subjectKappa/iota-Hybridspor
dc.subjectPolysaccharides-
dc.subjectCoil-to-helix transition-
dc.subjectStructural analysis-
dc.subjectDifferential scanning calorimetry-
dc.titleThe structure of j/i-hybrid carrageenans II. Coil–helix transition as a function of chain compositionpor
dc.typearticlepor
degois.publication.firstPage1113por
degois.publication.lastPage1129por
degois.publication.issue6-
degois.publication.titleCarbohydrate Researchpor
dc.peerreviewedYespor
dc.identifier.doi10.1016/j.carres.2005.02.015-
degois.publication.volume340por
uc.controloAutoridadeSim-
item.fulltextCom Texto completo-
item.languageiso639-1en-
item.grantfulltextopen-
crisitem.author.deptFaculty of Sciences and Technology-
crisitem.author.parentdeptUniversity of Coimbra-
crisitem.author.researchunitMARE - Marine and Environmental Sciences Centre-
crisitem.author.orcid0000-0002-6819-0619-
Appears in Collections:FCTUC Ciências da Vida - Artigos em Revistas Internacionais
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