Characteristics of Xanthan Gum
Jul 02, 2020
Xanthan gum is currently internationally integrated with thickening, suspension, emulsification and stabilization. The most superior biological glue. The number of pyruvate groups in the molecular side chain ends of xanthan gum has a great influence on its performance. Xanthan gum has the general properties of long-chain polymers, but it contains more functional groups than general polymers, and will show unique properties under certain conditions. Its conformation in aqueous solution is diverse and exhibits different characteristics under different conditions.
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-like spiral copolymers, forming a fragile glue-like network structure, so it can support the shape of solid particles, droplets and bubbles, showing strong emulsification stabilization and high suspension ability.
2. Good water solubility
Xanthan gum can quickly dissolve in water and has good water solubility. Especially it can dissolve in cold water, which saves complicated processing and is convenient to use. But because it has strong hydrophilicity, if the water is added directly and the stirring is not sufficient, the outer layer will absorb water and expand into a micelle, which will prevent the water from entering the inner layer, thereby affecting its function. Therefore, it must be used correctly. Dry xanthan gum powder or mix it with salt, sugar and other dry powder auxiliary materials and slowly add it to the stirring water to make a solution for use.
3. Thickening
Xanthan gum solution has the characteristics of low concentration and high viscosity (the viscosity of 1% aqueous solution is equivalent to 100 times that of gelatin), and it is an efficient thickener.
4. Pseudoplasticity
The xanthan gum aqueous solution has a high viscosity under static or low shear action. Under high shear action, the viscosity drops sharply, but the molecular structure does not change. When the shearing force is eliminated, the original viscosity will be restored immediately. The relationship between shear force and viscosity is completely plastic. The pseudoplasticity of xanthan gum is very prominent, and this pseudoplasticity is extremely effective in stabilizing suspensions and emulsions.
5. Stability to heat
The viscosity of the 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 the xanthan gum solution will hardly change between 10-80℃, even at low concentrations. The aqueous solution still shows a stable high viscosity in a wide temperature range. Heat 1% xanthan gum solution (containing 1% potassium chloride) at 25°C to 120°C. Its viscosity is only reduced by 3%.
6. Stability to acid and alkali
Xanthan gum solution is very stable to acid and alkali, and its viscosity is not affected when the pH is 5-10. When the pH is less than 4 and greater than 11, the viscosity changes slightly. In the range of PH3-11, 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. After a few months, the quality will not change. Xanthan gum is also soluble 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 persulfuric acid, and the degradation accelerates as the temperature rises.
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 the condition of higher salt concentration, it maintains its solubility even in saturated salt solution without precipitation and flocculation, and its viscosity is almost unaffected.
8. Stability to enzymatic hydrolysis
The stable double helix structure of xanthan gum has strong anti-oxidation and anti-enzymatic ability. Many enzymes such as protease, amylase, cellulase and hemicellulase cannot degrade xanthan gum.
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