Gellan gum is a water-soluble anionic polysaccharide produced by the bacterium Sphingomonas elodea. It is commonly used as a gelling, thickening, and stabilizing agent in various food, pharmaceutical, and industrial applications.
Gellan gum is highly soluble in water and forms a viscous, clear solution at low concentrations. It is also soluble in other polar solvents such as alcohols and glycols. The solubility of gellan gum in water is influenced by factors such as temperature, pH, and the presence of other solutes.
At higher concentrations, gellan gum can form gels or viscous solutions depending on the conditions. The type of gel formed can vary from a soft, elastic gel to a brittle gel depending on the concentration and the presence of cations such as calcium and magnesium.
The solubility of gellan gum in water is affected by temperature. Generally, gellan gum is more soluble in hot water than in cold water. At higher temperatures, the viscosity and solubility of gellan gum increase, while at lower temperatures, the viscosity and solubility decrease. However, even in cold water, gellan gum can be easily dispersed with stirring and forms a clear, viscous solution at low concentrations. The solubility of gellan gum in cold water can be improved by using mechanical agitation, such as high-speed mixing or homogenization.
There is a significant difference between high acyl and low acyl gellan gum in terms of their solubility in water and their gelling properties. High acyl gellan gum has a higher degree of substitution and is more soluble in water, while low acyl gellan gum has a lower degree of substitution and is less soluble in water. The gelling properties of the two types of gellan gum differ due to their degree of substitution. High acyl gellan gum forms a soft, elastic gel when combined with cations such as calcium and magnesium, while low acyl gellan gum forms a firmer, more brittle gel. The gels formed by high acyl gellan gum are thermally reversible, meaning that they can be melted and re-gelled without losing their gelling properties. The gels formed by low acyl gellan gum are thermally irreversible, meaning that they cannot be melted and re-gelled without losing their gelling properties.
