Overview of Food Grade Xanthan Gum (Ⅰ)

Xanthan gum, commonly known as corn gum and Hansen gum, is a complex polysaccharide produced by fermentation of sugars (glucose, sucrose, lactose) by Xanthomonas campestris.

Xanthan gum, usually made from corn starch, is an acidic extracellular heteropolysaccharide composed of a 1,6-glycosidic bond, a branched chain, and a 1,4-bond, synthesized by Xanthomonas campestris with carbohydrates as the main raw material through aerobic fermentation bioengineering technology.

Xanthan gum is a white or light yellow powder with excellent thickening, suspending, emulsifying and water solubility, and has good thermal and acid-base stability, so it is widely used in various foods.

Xanthan gum can dissolve quickly in water and has good water solubility. Especially in cold water can also be dissolved, can save the complicated processing process, easy to use.

However, because it has a strong hydrophilic, if added directly to the water small and insufficient mixing, the outer layer of water absorption and expansion into a gum mass, will prevent water from entering the inner layer, thus affecting the role of the play, so we must pay attention to the correct use.

Xanthan gum dry powder or mixed with salt, sugar and other dry powder excipients and slowly added to the water being stirred to make a solution for use.

Xanthan gum solution has the property of low concentration and high viscosity (the viscosity of 1% aqueous solution is equivalent to 100 times of gelatin), which is an efficient thickening agent.

Xanthan gum aqueous solution has high viscosity under static or low shear, and shows a sharp decrease in viscosity under high shear, but the molecular structure remains unchanged.

The viscosity of xanthan gum solution does not change greatly with the change of temperature, the viscosity of the aqueous solution of xanthan gum in 10-80 ℃ between almost no change, even if the low concentration of aqueous solution in a wide range of temperatures still shows a stable high viscosity. 1% xanthan gum solution (containing 1% potassium chloride) out of 25 ℃ heated to 120 ℃. Its viscosity only decreases by 3%.

Xanthan gum solution is very stable to acid and alkali, its viscosity is not affected between PH 5-10, there is a slight change in viscosity when PH is less than 4 and more than 11. In the PH3-11 range, the maximum viscosity makes and minimum value difference of 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 solution at room temperature is quite stable, placed for several months, its performance still will not change.

Xanthan gum is also soluble in sodium hydroxide solution, and has thickening properties. The solution formed is very stable at room temperature. Xanthan gum can be degraded by strong oxidizing agents, such as perchloric acid, persulfuric acid, and the degradation is accelerated with the increase of temperature.

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

Many enzymes such as protease, amylase, cellulase and hemicellulase are unable to degrade xanthan gum.

But xanthan gum in the dissolution process, due to the rapid dissolution of the granule surface to form a viscous gel layer, easy to lead to agglomeration, reducing the overall dissolution rate, in some applications are somewhat limited. At present, xanthan gum is mostly used for dry heat treatment with starch to improve the viscosity, paste inhibition, thermal stability and other physical and chemical properties of starch, including tapioca starch, corn starch, potato starch, etc. Dry heat treatment with xanthan gum, the hydroxyl group of starch molecules and the carboxyl group of xanthan gum molecules cross-linked to cause changes in physical and chemical properties.