Application of Xanthan gum

Xanthan gum is a high-molecular polysaccharide material made by the polymerization of 5 molecules of sugar as a unit. Each unit consists of 2 molecules of glucose, 2 molecules of mannose, and 1 molecule of glucuronic acid. Its main chain is composed of β-glucose connected by 1,4-glycosidic bonds to form 2 molecules of glucose as a unit. Its structure is the same as that of cellulose. There are 2 molecules of mannose and 1 molecule of glucuronic acid on the C3 of glucose. Form a side chain. There are pyruvate and carboxylic acid side groups on the side chain. Because its side chain contains acidic groups, it is a polyanion in an aqueous solution, which constitutes the tertiary three-dimensional structure of xanthan gum: the side chain with anion wraps around the main chain to form a helical structure, and hydrogen bonds between molecules form a double-stranded helix. The double-stranded helical structure is maintained by weak non-covalent bonds to form a regular "super-joined ribbon-shaped helical polymer." Its unique properties are related to the pyruvic acid contained. Under normal circumstances, the content of pyruvic acid in xanthan gum can be used to measure its performance. Xanthan gum is similar to white or light yellow powder, soluble in water but insoluble in most organic solvents. The aqueous solution is not sensitive to changes in temperature, pH, and electrolyte concentration, so it is stable to cold, heat, oxidants, acids, alkalis, and various enzymes. At low shear rates, it has high viscosity even at low concentrations. For example, the viscosity of a 1% xanthan gum aqueous solution is equivalent to 100 times that of gelatin at the same concentration.

Xanthan gum properties

1. With the increase of shear rate, the typical rheological properties will reduce the viscosity and thin the glue due to the destruction of the colloidal network. However, once the shear force disappears, the viscosity can be restored, which makes it a good pump. Delivery and processing performance. Using this feature to add xanthan gum to the liquid that needs a thickening agent, not only the liquid is easy to flow during the transportation process, but also can be restored to the required viscosity after being stationary, so it is widely used in the beverage industry.
2. High viscosity liquid containing 2%～3% xanthan gum at low concentration, its viscosity is as high as 3～7Pa·s. Its high viscosity makes it have broad application prospects, but at the same time it brings troubles to post-processing in production. Monovalent salts such as 0.1% NaCl and divalent salts such as Ca and Mg can slightly reduce the viscosity of low glue solutions below 0.3% but can increase the viscosity of higher concentration glue solutions.
3. Heat resistance xanthan gum has almost no change in viscosity in a wide temperature range (-98～90℃). Even if it is kept at a high temperature of 130°C for 30 minutes and then cooled, the viscosity of the solution does not change significantly. After many freeze-thaw cycles, the viscosity of the glue does not change. In the presence of salt, the solution has good thermal stability. If a small amount of electrolyte such as 0.5% NaCl is added under high-temperature conditions, the viscosity of the glue can be stabilized.
4. The viscosity of acid and alkaline xanthan gum aqueous solution is almost independent of pH. This unique property is not possessed by other thickeners such as carboxymethyl cellulose (CMC). If the concentration of inorganic acid in the glue solution is too high, the glue will be unstable; acid hydrolysis of polysaccharides will occur at high temperatures, which will cause the glue to decrease in viscosity. The content of NaOH greater than 12% can cause xanthan gum to gel or even precipitate. If the sodium carbonate concentration exceeds 5%, it can also cause gelation.
5. Anti-enzymatically hydrolyzed xanthan gum skeleton has a peculiar ability not to be hydrolyzed by enzymes due to the shielding effect of the side chains.
6. Compatibility: Xanthan gum can be miscible with most common food thickener solutions, especially when it is miscible with alginates, starch, carrageenan, carob bean gum, the viscosity of the solution is in a superimposed form Increase. The presence of various salts in aqueous solutions shows good compatibility. However, high-valent metal ions and high pH will make it unstable, and the incompatibility can be prevented by adding complexing agents.
7. Solubility Xanthan gum is easily soluble in water but insoluble in polar solvents such as alcohols and ketones. In a very wide range of temperature, pH, and salt concentration, it is easily dissolved in water, and its aqueous solution can be prepared at room temperature, and air mixing should be minimized when stirring. If the xanthan gum is mixed with some dry substances such as salt, sugar, monosodium glutamate, etc. in advance, then moistened with a small amount of water, and finally stirred with water, the performance of the prepared glue will be better. It can be dissolved in many organic acid solutions and has stable performance.
8. Xanthan gum solution with 1% dispersibility has a bearing capacity of 5N/m2, which is an excellent suspending agent and emulsion stabilizer in food additives.
9. Water-retaining xanthan gum has good water-retaining and fresh-keeping effects on food.

Xanthan Gum Application

1. In petroleum industry drilling, the 0.5% xanthan gum aqueous solution can maintain the viscosity of the water-based drilling fluid and control its rheological properties, so that the viscosity of the high-speed rotating drill bit is extremely small, which greatly saves power consumption. However, the drilling position of the hole maintains high viscosity, which prevents the collapse of the good wall and facilitates the removal of the cutting debris from the well.
2. In the food industry, it is better than current food additives such as gelatin, CMC, seaweed gum, and pectin. Adding 0.2% to 1% in the juice can make the juice have good adhesion, good taste, and control penetration and flow. ; As an additive to bread, it can make bread have good stability, smooth texture, save time and reduce costs; use 0.25% in bread filling, food filling, and icing to increase taste and flavor, smooth product organization, and extend shelf life. Improve the stability of the product to heating and freezing; in dairy products, adding 0.1% to 0.25% in ice cream can play an excellent stabilizing effect; provide good viscosity control in canned foods, which can replace part of the starch and one part of pathogen Gum can replace 3 to 5 parts of starch. At the same time, xanthan gum has also been widely used in candies, condiments, frozen foods, and liquid foods.