Light Scattering Investigation of ι-Carrageenan Aqueous Solutions. Concentration Dependence of Association

Bongaerts, Karin; Paoletti, Sergio; Denef, B; Vanneste, Katrien; Cuppo, Fábio Luiz Sant'Anna; Reynaers, Harry

doi:10.1021/ma000996y

Cited by 33 publications

(38 citation statements)

References 33 publications

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“…Such deviations from the ideal formulae are consistent with ∼ 11% iota‐segments in the applied kappa‐carrageenan or 7% kappa‐segments in the iota‐carrageenan. Almost the same composition was found by H NMR11, 12 or NMR/IR14 experiments on Sigma fine chemicals prior to and after purification.…”

Section: Resultsmentioning

confidence: 95%

Physicochemical characterization of carrageenans—A critical reinvestigation

Berth¹,

Vuković

Lechner

2008

J of Applied Polymer Sci

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Kappa-, iota-, and lambda-carrageenan (food grade) were analyzed by static light scattering (MALS in batch mode) in 0.1M NaNO 3 at 25 and 60 C, earlier heated up to 90 C or not. At 25 C, there was a strong tendency for a concentration-dependent aggregation in the order lambda < kappa < iota. At 60 C, all samples were molecularly dispersed. The strongly temperature-dependent refractive index increments (equilibrium dialysis) differ. Data interpretation in terms of the wormlike chain model using the Skolnik-Odijk-Fixman approach led to an intrinsic persistence length around 3 to 4 nm and expansion factors as high as 1.5 and above in a thermodynamically good solvent for all three types. and a nearly identical molar mass dependence of the radius of gyration. HPSEC at 25 C on kappa-carrageenan confirmed formation of soluble aggregates. Special emphasis was put on analytical and methodological aspects. The reliability of the experimental data was demonstrated by analogous measurements on dextran calibration standards.

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Section: Resultsmentioning

confidence: 95%

Physicochemical characterization of carrageenans—A critical reinvestigation

Berth¹,

Vuković

Lechner

2008

J of Applied Polymer Sci

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“…The existence of the single helices as the ordered conformation of both j-and i-carrageenan has been established at low polymer concentrations using light and X-ray scattering techniques (LALLS, WALLS and SAXS). [36][37][38] These single helices or single-helical regions aggregate into large aggregates of multiple helices to form a gel upon increasing salt or carrageenan concentration or decreasing temperature. On the other hand, X-ray fibre diffraction data showed a double-helical structure for both j-and i-carrageenan in the solid state.…”

Section: Discussionmentioning

confidence: 99%

The structure of κ/ι-hybrid carrageenans II. Coil–helix transition as a function of chain composition

Velde

Antipova

Rollema

et al. 2005

Carbohydrate Research

102

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This paper describes the effect of the kappa/iota-ratio on the physical properties of kappa/iota-hybrid carrageenans (synonyms: kappa-2, kappa-2, weak kappa, weak gelling kappa). To this end, a series of kappa/iota-hybrid carrageenans ranging from almost homopolymeric kappa-carrageenan (98 mol-% kappa-units) to almost homopolymeric-carrageenan (99 mol-% iota-units) have been extracted from selected species of marine red algae (Rhodophyta). The kappa/iota-ratio of these kappa/iota-hybrids was determined by NMR spectroscopy. Their rheological properties were determined by small deformation oscillatory rheology. The gel strength (storage modulus, G') of the kappa/iota-hybrids decreases with decreasing kappa-content. On the other hand, the gelation temperature of the kappa-rich kappa/iota-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 kappa/iota-hybrids was studied using optical rotation and high-sensitivity differential scanning calorimetry. High-sensitivity DSC showed that the total transition enthalpy of the kappa/iota-hybrids goes through a minimum at 60 mol-% kappa-units, whereas for the mixture of kappa- and iota-carrageenan, the total transition enthalpy is a linear function of the composition. With respect to the ordering capability, the kappa/iota-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 kappa- and iota-sequences in these copolymers are close to those of their parent homopolymers. The critical sequence length for kappa-sequences is 2-fold of that for iota-sequences.

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“…This effect is overcome when an excess of counterions is present, for example, at high ionic strength. In the present case, K + could bind to the ι-carrageenan helix and promote helix aggregation through reduction of the charge density, resulting in gelation 22,34 . While mixtures were in the liquid state at 80°C and higher, suggesting that KCl concentrations were not high enough to give rise to ι-carrageenan gelation, the added KCl could have promoted the coil → helix transition to a greater extent, altering both polymer rigidity and increasing molecular weight through association 35 .…”

Section: Discussionmentioning

confidence: 81%

“…Cations like K + can promote the aggregation of ι-carrageenan helices 22 . Moreover, ι-carrageenan gels formed in the presence of K + are similar to gelatin gels, i.e., very compliant, transparent, and not susceptible to syneresis 23 .…”

Section: Resultsmentioning

confidence: 99%

Phase Behavior of the ι-Carrageenan/Maltodextrin/Water System at Different Potassium Chloride Concentrations and Temperatures

Wang

Ziegler

2009

Food Biophysics

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Equilibrium phase diagrams of the ι-carrageenan/ maltodextrin/water system have been established at potassium chloride (KCl) concentrations of 0.1, 0.2, and 0.3 M and 80, 85 and 90°C. All pseudo-binary phase diagrams of ι-carrageenan/maltodextrin mixtures suggested classic segregative phase separation. The binodal was heavily skewed toward the maltodextrin axis. The high asymmetry of the ι-carrageenan/maltodextrin/water phase diagram determined by the phase-volume-ratio method was consistent with the compositional analysis of phase-separated ι-carrageenan/ maltodextrin samples and can be explained in terms of the Flory-Huggins interaction parameter, reflecting a higher water-binding ability of the charged ι-carrageenan than neutral maltodextrin. Increasing the concentration of ι-carrageenan-gel-promoting KCl from 0.1 to 0.3 M at 80°C enlarged the two-phase domain, whereas increasing temperature from 80 to 90°C at 0.3 M KCl enhanced biopolymer compatibility. The effects of salt concentration and temperature have been related to the differences in the Flory-Huggins interaction parameters of the two biopolymers with water as well as the helix formation of ι-carrageenan in the presence of KCl through the changes in the slopes of tie lines of phase-separated samples.

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Light Scattering Investigation of ι-Carrageenan Aqueous Solutions. Concentration Dependence of Association

Cited by 33 publications

References 33 publications

Physicochemical characterization of carrageenans—A critical reinvestigation

Physicochemical characterization of carrageenans—A critical reinvestigation

The structure of κ/ι-hybrid carrageenans II. Coil–helix transition as a function of chain composition

Phase Behavior of the ι-Carrageenan/Maltodextrin/Water System at Different Potassium Chloride Concentrations and Temperatures

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