LA Gellan Gum Applications

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Gellan gum is a hydrocolloid produced by the microorganism Sphingmonas elodea. Gellan gum is manufactured by fermentation from a carbohydrate source(glucose). Deacylation is carried out by treating the product with alkali.

Gellan gum is based on a linear structure of repeating, glucose, rhamnose and glucuronic acid units. In high acyl Gellan gum two acyl side chains, acetate and glycerate are present. Both substituents are present on the same glucose molecule and on average there is one glycerate per repeating unit and one acetate every two repeating units. After deacylation procedure, in low acyl Gellan gum the acyl groups are removed. The properties of the two forms are considerably different. High acyl products form soft elastics gels while low acyl Gellan gum produces firm, non elastic, brittle gels.

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The solution or gels made by low acyl gellan gum is clear with quite high transparency while high acyl is not transparent. The gels formed by low acyl gellan gum is brittle with high gel strength. Low acyl Gellan gum is only partially soluable in cold water. The divalent ions present in materials or water will inhibit the dissolution of low acyl gellan gum into the water.Gellan gum can be completely desolved when the temperature of solution is above75 Celcius Degree. While this can be imporoved by the use of sequesterants.

High acyl Gellan gum swells in deionised water to a starch like consistency. The presence of sodium ions can reduce this swelling behaviour and is useful to aid the dispersion of the product and reducing the viscosity of the solution. Heat is required to fully hydrate high acyl Gellan gum and it fully hydrates between 70 to 80 degrees C. Both forms of Gellan gum can be dispersed in milk and hydrated on heating. The products will only hydrate successfully at a ph above 4.0.

The dissolution of the product depends on the medium and the process: it is improved by heat treatment(time, temperature), shear stress(stirrer, homogenizer). A complete dissolution can be rapidly obtained by boiling for 5-10min or at around 85-90℃ for 20-30min with sequestrants.

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Compared with other hydrocolloids,Gellan Gum has many peculiar advantages:

1.Low dosage: The dosage of gellan gum is of 1/3-1/2 of K-Carrageenan or 1/5 of Agar Agar. For instance, for gels, dosage of gellan gum is 0.05%-0.4%. By controling the dosage of gellan gum in a lower lever, for example 0.01%-0.04%, it may help to form very weak gels, also called pre-gels. So the very low dosage gellan gum solution can be of good stabalizing and suspending agent. Especially for large grains in solution, the ONLY suspension agent is gellan gum.

2.Excellent acid stability:Gellan gum can help to form gels under pH from 3.5-7.5 and the gels are very stable.This is better than Carrageenan which can only be used in neutral solution, while pectins can only be used under acid solution.What's more, by controling the types of added ions, heat reversable and heat irreversable gels can be formed to meet different kinds of requirements.

3.Adjustable gel elasticity and rigidity:By using gellan gum only, various kinds of gels can be formed(for example, elastic gels and brittle gels) to meet the requirements of different products. This is different from carrageenan , agar or pectins who can form only one kind of gel.

4.High transparency:Low Acyl Gellan Gum can form high transparency gels;When dissolved in water, the solution made by low acyl gellan gum is also very clear and transparent.

5.Better taste-releasing ability;

6.Good compatibility with other ingredients and hydrocollids.

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