Gellan gum gels can be made at very low concentrations of even 0.05%; however, firm gels require concentrations of about 0.2%.
At concentrations less than about 0.05%, thickening occurs (this is true of all hydrocolloids, i.e., at concentrations below that required to form gels, they thicken aqueous systems).
Unlike other gums like agar, gellan gum can’t form a gel simply by dissolving it under heat and then cooling the solution. Addition of a cation is necessary for the gellan gum gelation.
Particularly to obtain a heat-resistant gel, the addition of the divalent calcium cation is effective.
Dispersions of gellans must be heated to 75–85°C (depending on the hardness of the water) to dissolve the gellan gum, which is required before gel formation can take place.
Ions increase the dissolution temperature. Sugars reduce gel strength.
-native gellan (high-acyl types)
-low-acyl (partially deacylated)
Types that can be blended to form intermediate types.
Native (high-acyl) types form thermally irreversible (non-melting) gels with potassium and calcium ions and thermally reversible (meltable) gels with sodium ions. The gels are soft, very elastic, and non-brittle.
While Gels made from low-acyl types are hard, non-elastic, brittle, and always thermally reversible.
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