What Are the Performance Characteristics of Xanthan Gum?

Xanthan gum is currently the best-performing biological adhesive that combines thickening, suspension, emulsification, and stability in one. The number of acetic acid groups at the end of the molecular side chain of xanthan gum has a significant impact on its performance. Xanthan gum has the general properties of long-chain polymers, but it has more functional groups than general polymers and can exhibit unique properties under specific conditions. Its conformation in aqueous solution is diverse and has different characteristics under different conditions.

Xanthan gum's suspension and emulsification

Xanthan gum has good suspension of insoluble solids and oil droplets. Xanthan gum sol molecules can form a fragile jelly-like network structure by forming super-band spiral copolymers, which can support the shape of solid particles, droplets, and bubbles, showing strong emulsification and suspension capabilities.

Good water solubility of xanthan gum

Xanthan gum can quickly dissolve in water and has good water solubility. It can even dissolve in cold water, which saves complicated processing and is easy to use. However, due to its strong hydrophilicity, if it is directly added to water without sufficient stirring, the outer layer will absorb water and swell into lumps, which will prevent water from entering the inner layer and affect the function, so it must be used correctly. Xanthan gum powder or powdered auxiliary materials such as salt and sugar are mixed well and slowly added to the water being stirred to make a solution for use.

Thickening ability of xanthan gum

Xanthan gum solution has the characteristics of low concentration and high viscosity (the viscosity of a 1% aqueous solution is equivalent to 100 times that of gelatin) and is an efficient thickener.

Xanthan gum's pseudoplasticity

Xanthan gum aqueous solution has high viscosity under static or low shear, and viscosity drops sharply under high shear, but the molecular structure remains unchanged. When the shear force is eliminated, the original viscosity will immediately recover. The relationship between shear force and viscosity is completely plastic. Xanthan gum's pseudoplasticity is very prominent, and it is extremely effective in stabilizing suspended and emulsified liquids.

Thermal stability of xanthan gum

The viscosity of xanthan gum solution does not change significantly with temperature. General polysaccharides will change viscosity when heated, but xanthan gum solution shows stable high viscosity at low concentrations over a wide temperature range, even a 1% xanthan gum solution (with 1% potassium chloride) heated from 25 °C to 120 °C, and its viscosity only decreases by 3%.

Acid-alkaline stability of xanthan gum

Xanthan gum solution is very stable to acid and alkali. Its viscosity is not affected when pH is between 5-10, and there is slight variation when pH is less than 4 and greater than 11. Within the range of pH 3-11, the difference between the maximum and minimum viscosity is less than 10%. Xanthan gum can dissolve in various acid solutions, such as 5% sulfuric acid, 5% nitric acid, 5% acetic acid, 10% hydrochloric acid, and 25% phosphoric acid, and these xanthan gum acid solutions are quite stable at room temperature and will not change for months. Xanthan gum can also dissolve in sodium hydroxide solution and has thickening properties. The formed solution is very stable at room temperature. Xanthan gum can be degraded by strong oxidants such as perchloric acid and persulfate, and its degradation will accelerate as the temperature rises.

Salt stability of xanthan gum

Xanthan gum solution can be mixed with many salt solutions (potassium salt, sodium salt, calcium salt, magnesium salt, etc.), and viscosity is not affected. Even under higher salt concentration conditions, xanthan gum solution can maintain its solubility without precipitation or coagulation, and its viscosity is almost not affected.

Stability of xanthan gum to enzymatic reactions

The stable double helix structure of xanthan thickener gives it strong antioxidative and anti-enzymatic ability, and many enzymes, such as protease, amylase, cellulase, and hemicellulase, cannot degrade xanthan gum.