Rheology and gelation of deacylated gellan polysaccharide with Na+ as the sole counterion

  • E. R. MorrisEmail author
  • R. K. Richardson
  • L. E. Whittaker
Conference paper
Part of the Progress in Colloid and Polymer Science book series (PROGCOLLOID, volume 114)


The effect of NaCl on the formation, melting, and mechanical properties of Na+ gellan gels can be divided into five regions of rheological response.
  1. 1.

    Small additions of salt, up to a total Na+ concentration of about 25 mM, have virtually no effect on the rheological properties of the ordered polymer at low temperature; the solutions remain fluid on cooling, and give mechanical spectra similar to those of entangled polysaccharide coils.

  2. 2.

    Slightly higher concentrations (about 40 mM Na+) induce formation of “weak gels” (i.e. solutions that remain pourable but give gel-like mechanical spectra). Network formation is attributed to Na+ ions promoting helix-helix aggregation by binding to carboxyl groups of the polymer and thus reducing charge density, and by suppressing residual electrostatic repulsion by nonspecific charge screening.

  3. 3.

    Na+ concentrations in the approximate range 100–300 mM give true, self-supporting, gels whose strength and setting point (T o) increase with increasing concentration of salt and which melt in two steps, attributed to dissociation of unassociated helices and cation-mediated aggregates, respectively.

  4. 4.

    To continues to increase with Na+ concentration over the range 300–750 mM, but the gel strength falls, suggesting destabilisation of the network structure by association of helices into a progressively smaller number of progressively larger aggregates.

  5. 5.

    At NaCl concentrations above about 750 mM, T o drops sharply. It is tentatively suggested that this reduction in the stability of the helix structure is of lyotropic origin.


Key words

Gellan polysaccharide Gelation Rheology Coil-helix transition Helix—helix transition 


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  1. 1.
    Rees DA, Morris ER, Thorn D, Madden JK (1982) In: Aspinall GO (ed) The polysaccharides, vol 1. Academic Press, New York, pp 195–290Google Scholar
  2. 2.
    Morris ER, Rees DA, Thorn D, Boyd J (1978) Carbohydr Res 66: 145–154CrossRefGoogle Scholar
  3. 3.
    Morris ER, Powell DA, Gidley MJ, Rees DA (1982) J Mol Biol 155: 507–516CrossRefGoogle Scholar
  4. 4.
    Chandrasekaran R, Thailambal VG (1990) Carbohydr Polym 12: 431–442CrossRefGoogle Scholar
  5. 5.
    Chandrasekaran R, Millane RP, Arnott S, Atkins EDT (1988) Carbohydr Res 175: 1–15CrossRefGoogle Scholar
  6. 6.
    Whittaker LE, Hember MWN, Morris ER (1999) Carbohydr Polym (submitted)Google Scholar
  7. 7.
    Whittaker LE, Hember MWN, Morris ER (1999) Carbohydr Polym (submitted)Google Scholar
  8. 8.
    Grasdalen H, Smidsrød O (1987) Carbohydr Polym 7: 371–393CrossRefGoogle Scholar
  9. 9.
    Sanderson GR, Clark R (1984) In: Phillips GO, Wedlock DJ, Williams PA (eds) Gums and stabilisers for the food industry 2. Pergamon, Oxford, pp 201–210Google Scholar
  10. 10.
    Manning CE (1992) PhD thesis. Cranfield Institute of Technology, Silsoe College, Bedford, UKGoogle Scholar
  11. 11.
    Manning CE, Morris ER (1999) Carbohydr Polym (submitted)Google Scholar
  12. 12.
    Jansson P-E, Lindberg Sandford PA (1983) Carbohydr Res 124: 135–139CrossRefGoogle Scholar
  13. 13.
    O’Neill MA, Selvendran RR, Morris VJ (1983) Carbohydr Res 124: 123–133CrossRefGoogle Scholar
  14. 14.
    Morris ER (1984) In: Phillips GO, Wedlock DJ and Williams PA (eds) Gums and stabilisers for the food industry 2. Pergamon, Oxford, pp 57–78Google Scholar
  15. 15.
    Ross-Murphy SB (1984) In: Chan HW-S (ed) Biophysical methods in food research. Critical reports on applied chemistry. SCI, London, pp 195–290Google Scholar
  16. 16.
    Richardson RK, Goycoolea FM (1994) Carbohydr Polym 24: 223–225CrossRefGoogle Scholar
  17. 17.
    Hermansson A-M (1989) Carbohydr Polym 10: 163–181CrossRefGoogle Scholar
  18. 18.
    Clark AH, Ross-Murphy SB (1987) Adv Polym Sci 83: 57–192CrossRefGoogle Scholar
  19. 19.
    Milas M, Shi X, Rinaudo M (1990) Biopolymers 30: 451–464CrossRefGoogle Scholar
  20. 20.
    Frangou SA, Morris ER, Rees DA, Richardson RK, Ross-Murphy SB (1982) J Polym Sci Polym Lett Ed 20: 531–538CrossRefGoogle Scholar
  21. 21.
    Gidley MJ, Eggleston G, Morris ER (1992) Carbohydr Res 231: 185–196CrossRefGoogle Scholar
  22. 22.
    Norton IT, Morris ER, Rees DA (1984) Carbohydr Res 134: 89–101CrossRefGoogle Scholar
  23. 23.
    Austen KRJ, Goodall DM, Norton IT (1985) Carbohydr Res 140: 251–262CrossRefGoogle Scholar
  24. 24.
    Poland D, Scheraga HA (1970) Theory of helix-coil transitions in biopolymers. Academic Press, New YorkGoogle Scholar
  25. 25.
    Chandrasekaran R, Puigjaner LC, Joyce KL, Arnott S (1988) Carbohydr Res 181: 23–40CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 1999

Authors and Affiliations

  • E. R. Morris
    • 1
    Email author
  • R. K. Richardson
    • 1
  • L. E. Whittaker
    • 1
  1. 1.Silsoe College SilsoeCranfield UniversityBedfordUK

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