Effects of Potassium Chloride and Sodium Chloride on the Thermal Properties of Gellan Gum Gels

Moritaka, Hatsue; Nishinari, Katsuyoshi; Nakahama, Nobuko; Fukuba, Hiroyasu

doi:10.1271/bbb.56.595

Cited by 41 publications

(28 citation statements)

References 9 publications

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“…[1,[4][5][6] The structure-forming properties of gellan originate from a specific ordering of its molecules in solution that is largely affected by ions, polymer concentration, temperature, and cosolutes. [7][8][9][10] According to X-ray data, native gellan in the solid state adopts a half-staggered, parallel double helix of pitch 56 Å . [3,[11][12][13] The double helix is stabilized by hydrogen bonds involving hydroxymethyl, carboxylate, and glyceryl groups.…”

Section: Introductionmentioning

confidence: 99%

“…[35] These are known to promote various aggregated helical structures contributing substantially to the thermally induced order-disorder transition in gellan solution. [7,8,10,36,37] In order to avoid contributions related to secondary aggregation processes, we have used in this work a gellan sample in the form of tetramethylammonium (TMA) salt and Me 4 NCl as added salt. [17,[38][39][40] It was shown that the TMA gellan undergoes a reversible order-disorder conformational transition with minimal aggregation contribution confirmed by more recent studies.…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamics of the Double Helix‐Coil Equilibrium in Tetramethylammonium Gellan: High‐Sensitivity Differential Scanning Calorimetry Data

Grinberg¹,

Burova²,

Grinberg³

et al. 2003

Macromolecular Bioscience

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Full Paper: The order-disorder conformational transition in the tetramethylammonium salt of gellan has been studied by high-sensitivity differential scanning calorimetry as a function of concentration of the background electrolyte, Me 4 NCl (0.0025-0.5 M). The transition temperature and enthalpy increase with increasing salt concentration following a logarithmic relation. At the same time, there is a linear correlation between the transition enthalpy and temperature with a positive slope of 0.18 J g À1 K À1 . According to Kirchhoff's law, the slope can be considered as a heat capacity increment of the transition. This value is much larger than that expected to arise from electrostatic effects. Thus, it has been suggested that the transition is accompanied by an increase in water accessibility to some less hydrophilic fragments of the primary structure of gellan buried in its ordered conformation. The transition has an l-like heat capacity profile and can be therefore defined as a secondorder phase transition. This assignment is in agreement with predictions of a matching model of the double helix-coil transition. The model fits well to the integral transition curve at 0.5 M Me 4 NCl, assuming a cooperative length of gellan to be about eight repeating units. This value is close to the size of chain corresponding to the persistent length of gellan in the coil state. The cooperativity parameter in the matching model (s ¼ 0.62 AE 0.01) indicates a small contribution of the stacking effect into the cooperativity of the transition, while a larger contribution apparently originates from the loop factor. The free energy of transition at a reference temperature (273 K) is a logarithmic function of the concentration of the salt, D t G(C s ), as predicted by the counter condensation theory and the Poisson-Boltzmann (PB) model. The latter is preferable because of the low linear charge density parameter (x < 1) for the double helix of gellan. Analysis of the D t G(C s ) function in terms of the PB model showed that the linear charge density of gellan in the coil conformation needs to be higher than that estimated for the fully stretched chain.Correlation between the transition enthalpy and the transition temperature for the conformational order-disorder transition in the TMA gellan.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermodynamics of the Double Helix‐Coil Equilibrium in Tetramethylammonium Gellan: High‐Sensitivity Differential Scanning Calorimetry Data

Grinberg¹,

Burova²,

Grinberg³

et al. 2003

Macromolecular Bioscience

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show abstract

“…(1 where, AG = AH -TAS (2) Moritaka et al (1992) found that gelation of gellan solutions was exothemic, accompanied by a polymer reconfiguration from a random to a more ordered structure, leading to a decrease in entropy, -AS. This means the reaction was energy favoured but entropy hindered, thus, reaction spontaneity was dependent on temperature and the relative magnitudes of AH and AS.…”

Section: Ag5 Omentioning

confidence: 99%

Rheological Properties of Gellan Gels Containing Filler Particles

Jampen¹,

Britt²,

Yada³

et al. 2001

Journal of Food Science

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: Influences of rigid (glass) and deformable (gellan) particles dispersed in gellan gels were studied to better understand the effect of structure on the rheological properties of model composite foods. Composites with inclusions at 0%, 10%, 20%, and 30% volume fractions (VF) were tested under small deformation oscillatory shear. In gels containing rigid particles, the dynamic shear storage modulus (G′) decreased initially, exhibited a minimum around 20% VF, then increased at 30% VF behavior that was attributed to physical interactions among particles. In gels containing deformable particles, the linear decrease in G′ with increasing VF may be due to particle compliance under stress or to particle separation from the matrix, thereby causing gel weakening.

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“…With gellan gum, cations such as K + and Ca 2+ are required to form a gel (Huang et al, 1995;Moritaka et al, 1992). The physical properties of gellan gum gel are changed by cation concentration, as well as gellan gum concentration (Huang et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

Effect of Gellan Gum and MS Inorganic Salt Gel Formulations on the Vase Life of Cut Roses and Physical Properties of Gel

Ichimura

Niki

Kato

et al. 2009

J. Japan. Soc. Hort. Sci.

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The effects of gellan gum gels and Murashige and Skoog (MS) inorganic salts at various strengths on the vase life of 'Rote Rose' rose cut flowers were investigated. To form the gels, gellan gum was dissolved with MS salts at various concentrations. To simulate the transport of cut rose flowers, stems were placed in gellan gum gels and held at 23°C for 24 h or 48 h. Cut flowers were then transferred into distilled water and their fresh weight (FW) and vase life were determined. According to the observed vase life and changes in FW, gels formed with 0.2% gellan gum and standard-strength MS salts appear to be the most suitable for cut roses. Although the hardness of gellan gum gel increases with increased concentrations of gellan gum and MS salts, no correlation between vase life and gel hardness was observed. To determine the potential water availability of gellan gum gel, gels were placed in a centrifuge filter device, centrifuged at 3000 × g for 10 min and the amount of water released from the gel was measured. A highly positive correlation between the amount of water released from the gel and water uptake of flowers placed in gellan gum gels was observed. A positive correlation between the amount of water released and vase life was also observed. Thus, using centrifugation to measure the volume of water released from gellan gum gels appears to be a simple and rapid method for evaluating the performance of gellan gum gels as wetting agents.

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Effects of Potassium Chloride and Sodium Chloride on the Thermal Properties of Gellan Gum Gels

Cited by 41 publications

References 9 publications

Thermodynamics of the Double Helix‐Coil Equilibrium in Tetramethylammonium Gellan: High‐Sensitivity Differential Scanning Calorimetry Data

Thermodynamics of the Double Helix‐Coil Equilibrium in Tetramethylammonium Gellan: High‐Sensitivity Differential Scanning Calorimetry Data

Rheological Properties of Gellan Gels Containing Filler Particles

Effect of Gellan Gum and MS Inorganic Salt Gel Formulations on the Vase Life of Cut Roses and Physical Properties of Gel

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