Gellan Gum and Shear

Gellan gum can behave very differently depending on how much shear the product experiences during processing.

This is especially important when using gellan gum for suspension.

A formulation may look relatively thick when it is sitting still but become much more fluid when it is pumped, mixed, or poured.

This is not necessarily a problem. In many applications, it is exactly what the manufacturer wants.

What Does Shear Do to Gellan Gum?

When a gellan gum system is subjected to shear, its internal structure can be disrupted or rearranged.

As a result, the apparent viscosity can decrease while the product is moving.

Once the shear is removed, part of the structure can recover depending on the formulation and processing conditions.

This behavior is particularly useful for fluid gels.

Why Is This Useful in Food Production?

A good suspension system needs two seemingly opposite properties.

When the product is sitting on the shelf, it needs enough structure to keep particles from settling.

When the product is being pumped or poured, it needs to flow easily.

Gellan gum can provide this combination.

The product can have relatively low apparent viscosity under shear while maintaining enough structure at rest to suspend particles.

What Is a Fluid Gel?

A fluid gel is not simply a thick liquid.

It contains a weak gel structure that provides a certain yield stress.

Below that stress, the structure can support suspended particles.

Once enough shear is applied, the structure breaks down and the product flows more easily.

This is one reason gellan gum is useful in beverages containing fruit pulp or other particles.

Does More Shear Always Mean Better Flow?

Not necessarily.

The effect depends on the formulation and the amount of structure that has developed.

Very aggressive processing may change the final texture or particle distribution.

The important question is not simply how much shear the product can tolerate.

It is whether the processing creates the desired balance between suspension at rest and flow during processing.

What Happens During Pumping?

A product may behave differently inside the tank and inside the pipeline.

In the tank, the product may have relatively high apparent viscosity.

Once it enters the pump and pipe, shear increases and the product may flow more easily.

This can be useful because a product that is stable in the package does not necessarily need to remain equally viscous during pumping.

However, pump selection and filling conditions still need to be considered.

Can Shear Affect Particle Suspension?

Yes.

Shear can temporarily redistribute particles throughout the product.

This is useful during mixing and filling.

But once the product stops moving, the suspension must depend on the structure of the formulation itself.

If the particles remain suspended only because the agitator is running, the formulation is not providing enough static structure.

Why Does a Beverage Become Thin After Mixing?

This can be completely normal in a shear-sensitive system.

The product may appear thicker when undisturbed and become much more fluid during shaking or pumping.

This behavior is often desirable because consumers want a beverage that pours easily.

The important question is whether the product returns to the required structure after the shear is removed.

Does Mixing Speed Matter?

Yes.

Different mixing speeds produce different shear conditions.

A laboratory trial using a small high-speed mixer may not reproduce the same structure as a factory batch mixed with a large low-speed agitator.

This is one reason why scale-up can produce unexpected viscosity differences.

The mixer type, impeller design, speed, batch volume, and mixing time can all matter.

Can Excessive Shear Damage the System?

It depends on the formulation and process.

Not every gellan gum application is equally sensitive to shear.

A short period of controlled mixing is very different from continuous high-shear processing for an extended period.

If the final product depends on a delicate fluid-gel structure, excessive processing may change its behavior.

The actual production process should therefore be tested rather than assuming that laboratory mixing conditions can simply be copied.

How Should Shear Be Tested?

A useful development test is to compare the product at different stages.

Measure the system:

• Before mixing

• After controlled mixing

• After pumping

• After filling

• After resting

Observe both viscosity and suspension.

This can reveal whether the product is simply shear-thinning or whether the processing is permanently changing the structure.

What About High Acyl and Low Acyl?

The two types can behave differently because they form different gel structures.

Low acyl gellan gum generally forms a firmer and more brittle gel.

High acyl gellan gum forms a softer and more elastic gel.

For fluid-gel applications, the choice should be based on the required combination of suspension, flow, and texture.

It is not enough to compare the two types only by viscosity in a beaker.

Can Shear Be Used Deliberately?

Yes.

In some production processes, shear is part of the formulation strategy.

A weak gellan gum gel can be formed first and then gently agitated to create a smooth, pourable fluid gel.

This can provide good suspension without producing a product that feels excessively thick when consumed.

The processing equipment therefore becomes part of the functionality of the hydrocolloid system.

Final Thoughts

Shear is not simply something that a gellan gum formulation has to survive.

It can also be used to control how the product behaves.

A properly designed gellan gum fluid gel can remain structured enough to suspend particles at rest while becoming much easier to flow during pumping, filling, and consumption.

For development work, always evaluate the product both under shear and after the shear has stopped.

That is often much more informative than measuring viscosity at a single mixing speed.