Functional Properties of Gellan

As mentioned before, gellan gum has a number of functional properties that can be readily modified. These include:

• Versatile texture, which is one of its most important features. This is usually defined in terms of hardness (measure of rupture strength), modulus (measure of gel firmness) , brittleness (strain required to break the gel), and elasticity (measure of rubberiness).

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Isolation and Purification of Gellan Gum

Isolation and Purification of Gellan Gum

Optimization of fermentation parameters alone is not enough to ensure high yield of gellan gum. The next crucial step after the completion of successful fermentation is the recovery and purification of gellan.

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Rheology of the Fermentation Broth

Rheology of the Fermentation Broth 

The rheology of the fermentation fluid during gellan gum production exhibits strongly pseudoplastic behaviour, even at 0.1 % (by mass per volume). 

The initial broth viscosity is that of Newtonian fluid with a viscosity close to that of water, but the broth rapidly becomes non-Newtonian with strong shear thinning properties.
This pseudoplastic behaviour during the exopolysaccharide accumulation phase is also common in the production of other microbial polymers and described by power law model:

· h = t/g = kg n–1 

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