Xanthan Gum

Xanthan gum, also known as xanthan gum, is a widely used microbial extracellular polysaccharide produced by fermentation engineering of Xanthomnas campestris with carbohydrates as the main raw material (such as corn starch). It has unique rheological properties, good water solubility, heat and acid-base stability, and good compatibility with a variety of salts. As a thickener, suspending agent, emulsifier, and stabilizer, it can be widely used in more than 20 industries such as food, petroleum, and medicine.

Xanthan gum is a light yellow to white flowable powder with a slight odor. It is easily soluble in cold and hot water, the solution is neutral, resistant to freezing and thawing, and insoluble in ethanol. It disperses and emulsifies in water to become a stable hydrophilic viscous colloid.

1. Suspension and emulsification

Xanthan gum has a good suspension effect on insoluble solids and oil droplets. Xanthan gum sol molecules can form super-bonded ribbon-shaped spiral copolymers, forming a fragile glue-like network structure, so they can support the morphology of solid particles, droplets and bubbles, showing strong emulsification stabilization and high suspension ability.

2. Good water solubility

Xanthan gum can dissolve quickly in water and has good water solubility. It can also dissolve in cold water, which can save complicated processing and is easy to use. However, due to its strong hydrophilicity, if it is directly added to water and not stirred sufficiently, the outer layer absorbs water and expands into micelles, which will prevent water from entering the inner layer, thereby affecting the effect, so it must be used correctly. Mix the xanthan gum powder or dry powder auxiliary materials such as salt and sugar, then slowly add it to the stirring water to make a solution.

3. Thickening property

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

4. Pseudoplasticity

Xanthan gum aqueous solution has high viscosity under static or low shear, and shows a sharp drop in viscosity under high shear, but the molecular structure remains unchanged. When the shear force is eliminated, the original viscosity is immediately restored. The relationship between shear force and viscosity is completely plastic. Xanthan gum pseudoplasticity is very prominent, and this pseudoplasticity is extremely effective in stabilizing suspensions and emulsions.

5. Stability to heat

The viscosity of xanthan gum solution will not change greatly with the change of temperature. The viscosity of general polysaccharides will change due to heating, but the viscosity of xanthan gum aqueous solution has almost no change between 10-80℃. Even low-concentration aqueous solution still shows stable high viscosity in a wide temperature range. 1% xanthan gum solution (containing 1% potassium chloride) is heated from 25℃ to 120℃. Its viscosity only decreases by 3%.

6. Stability to acid and alkali

The xanthan gum solution is very stable to acid and alkali. Its viscosity is not affected when the pH is between 5-10. The viscosity changes slightly when the pH is less than 4 and greater than 11. In the pH range of 3-11, the difference between the maximum and minimum viscosity is less than 10%. Xanthan gum can be dissolved in a variety of 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 the quality will not change for several months. Xanthan gum can also be dissolved in sodium hydroxide solution and has thickening properties. The resulting solution is very stable at room temperature. Xanthan gum can be degraded by strong oxidants such as perchloric acid and persulfate, and the degradation accelerates with increasing temperature.

7. Stability to salt

Xanthan gum solution can be miscible with many salt solutions (potassium salt, sodium salt, calcium salt, magnesium salt, etc.), and the viscosity is not affected. Under high salt concentration conditions, even in saturated salt solutions, it still maintains its solubility without precipitation and flocculation, and its viscosity is almost unaffected.

8. Stability to enzymatic hydrolysis

The stable double helix structure of xanthan gum makes it extremely antioxidant and anti-enzymatic. Many enzymes such as protease, amylase, cellulase and hemicellulase cannot degrade xanthan gum.

Due to its unique properties, xanthan gum has extremely wide applications in more than a dozen fields such as food, petroleum, medicine, and daily chemicals. Its high degree of commercialization and wide range of applications are far beyond the reach of any other microbial polysaccharide.

1. Food: Many foods are added with xanthan gum as a stabilizer, emulsifier, suspending agent, thickener and processing aid. Xanthan gum can control the rheology, structure, flavor and appearance of the product, and its pseudoplasticity can ensure a good taste. Therefore, it is widely used in salad dressings, bread, dairy products, frozen foods, beverages, condiments, brewing, candy, cakes, soups and canned foods. In recent years, people in more developed countries often worry that the calorific value of food is too high and makes them fat. Xanthan gum can dispel people's concerns because it cannot be directly degraded by the human body. In addition, according to a report from Japan in 1985, xanthan gum was the most effective anticancer agent among eleven food additives tested comparatively.

2. Daily chemical industry: xanthan gum molecules contain a large number of hydrophilic groups, which is a good surfactant and has antioxidant and anti-aging effects. Therefore, almost all high-end cosmetics use xanthan gum as their main functional ingredient. In addition, xanthan gum can also be used as a component of toothpaste to thicken and shape, and reduce tooth surface wear.

3. Medical: xanthan gum is a functional component of microcapsule drug capsules that are currently in great demand internationally, and plays an important role in controlling drug sustained release; due to its strong hydrophilicity and water retention, it also has many specific medical applications, such as forming a dense water film to avoid skin infection; alleviating thirst after radiotherapy, etc. In addition, Li Xin and Xu Lei wrote that xanthan gum itself has a significant enhancing effect on the humoral immune function of mice.

4. Application in industry and agriculture: In the petroleum industry, due to its strong pseudoplasticity, a low concentration of xanthan gum (0.5%) aqueous solution can maintain the viscosity of the drilling fluid and control its rheological properties. Therefore, the viscosity is extremely low at the high-speed rotating drill bit, saving power; while the relatively static drilling part maintains high viscosity, thereby preventing the well wall from collapsing. And because of its excellent salt resistance and heat resistance, it is widely used in drilling in special environments such as the ocean and high-salt layer areas, and can be used as an oil recovery and displacement agent to reduce dead oil areas and increase oil recovery rates.