What Is the Difference Between Gellan Gum Viscosity and Gel Strength?

Content:

A customer asks for "high viscosity gellan gum."

Another asks for "high gel strength."

Are they asking for the same thing?

Not necessarily.

This is a common source of confusion when discussing gellan gum specifications.

Viscosity and gel strength are related to the structure of the system, but they are measuring different things.

What Is Viscosity?

Viscosity describes how strongly a liquid resists flow.

In simple terms:

Higher viscosity = harder to flow.

Honey has a higher viscosity than water.

A typical thickening gum is often selected mainly because it can increase viscosity.

What Is Gel Strength?

Gel strength describes how much force is required to deform or break a gel under defined test conditions.

A firm jelly has a higher resistance to deformation than a very soft gel.

So:

Viscosity is mainly about flow.

Gel strength is mainly about gel structure.

They are not interchangeable.

Can Gellan Gum Have Low Viscosity but Strong Gelation?

Yes.

This is one of the reasons gellan gum is interesting.

A hot gellan gum solution can have relatively low apparent viscosity.

After cooling, the system can develop a much stronger structure.

So looking only at the viscosity of the hot solution doesn't necessarily tell you how strong the final gel will be.

Why Is This Important in Beverages?

Suppose you want to keep particles suspended.

You don't necessarily want a thick drink.

If you use a conventional thickener, you may increase viscosity enough to slow down sedimentation.

But the consumer may notice the thicker mouthfeel.

Gellan gum can provide another option.

A small amount can create a weak internal structure that helps support suspended particles without making the beverage feel excessively thick.

Can Two Samples Have Similar Viscosity but Different Gel Strength?

Yes.

Two gellan gum samples can show similar flow behavior under one test condition but produce different gel structures after cooling.

This is why a single viscosity number should not be used to predict all aspects of performance.

What About High Acyl and Low Acyl?

The difference becomes particularly obvious when comparing HA and LA gellan gum.

High acyl gellan gum generally produces softer, more elastic gels.

Low acyl gellan gum generally produces firmer, more brittle gels.

So the final texture can be very different even if the processing conditions are similar.

Why Does Temperature Matter?

Viscosity is strongly affected by temperature.

A liquid generally flows differently at 20°C than at 80°C.

Gel strength is also temperature-dependent.

Therefore, when comparing results, always specify the test temperature.

Otherwise, the numbers can be misleading.

What About Shear Rate?

Viscosity isn't always a single fixed number for hydrocolloid systems.

Some systems are shear-thinning.

That means the apparent viscosity decreases as shear increases.

So a viscosity measurement should ideally include information about:

• Temperature

• Shear rate

• Concentration

• Measurement method

Without these conditions, saying "the viscosity is 100" doesn't tell you very much.

Why Do Customers Sometimes Ask for Viscosity?

Sometimes "viscosity" is simply being used as a convenient way to describe expected performance.

A customer may really mean:

"I need a gellan gum that gives stronger structure."

Before selecting a product, it is worth asking what they actually want to achieve.

Do they need:

• More suspension?

• Stronger gel?

• Higher viscosity?

• Better texture?

• Better stability?

These are different requirements.

How Should You Test Them?

If you are developing a new formulation, test viscosity and gel strength separately.

For viscosity, keep:

• Concentration

• Temperature

• Shear conditions

• Measurement method

constant.

For gel strength, also control:

• Hydration

• Cooling

• Setting time

• Sample geometry

• Test temperature

• Instrument conditions

Then the results become much more meaningful.

What About a Beverage That Is Too Thick?

If the beverage is too thick, simply reducing gellan gum may not always be the best solution.

First ask what the gellan gum is doing.

If it is being used mainly for suspension, you may be able to reduce the concentration and optimize the formulation around the minimum effective level.

If it is being used for gel structure, you may need a different gellan gum type or processing condition.

What About a Gel That Is Too Weak?

The opposite problem also requires investigation.

Don't immediately assume that you need more gellan gum.

Check:

• Hydration

• Concentration

• Gellan gum type

• pH

• Calcium and other ions

• Heating

• Cooling

• Storage time

A weak gel can result from processing rather than insufficient dosage.

A Useful Way to Think About It

Think of viscosity as asking:

"How difficult is it for this material to flow?"

Gel strength asks:

"How difficult is it to deform this gel?"

Those are two different questions.

And with gellan gum, both can be important.

The Bottom Line

If you're buying or developing gellan gum, don't use "viscosity" and "gel strength" as if they mean the same thing.

They don't.

A good technical specification should make clear what property is being measured and under what conditions.

And when choosing gellan gum, start with the actual application requirement.

Do you need flow control, suspension, gel strength, or a particular texture?

Once you answer that question, choosing the right gellan gum becomes much easier.