Xanthan gum can be widely used in more than 20 industries such as food, petroleum, ceramics, textile, printing and dyeing, medicine, paper making, geology and mining, fire extinguishing, paint, toothpaste, cosmetics and so on.
In recent years, the production capacity of xanthan gum in the world has been greatly improved through continuous technological transformation. Xanthan gum has a broad market and good prospects. It is the largest and most widely used microbial polysaccharide in the world.
1. Production of Xanthan Gum
1.1 Culture medium
Xanthan gum is produced by Xanthomonas campestris in the following culture medium. Glucose, sucrose, starch, etc. Are used as carbon sources. Protein, fish meal, soybean meal or nitrate is used as the nitrogen source. Then inorganic salts such as KH2PO4, MgSO4, CaCO3 and the like and trace elements such as Fe2 , Mn2+, Zn2+ and the like are added. As well as glutamic acid, citric acid, and that like, which are production accelerator.
1.2 Production process
The production of xanthan gum includes two parts: fermentation and extraction. The fermentation process includes continuous process and batch process. But it is the batch process that is really industrialized. The actual process is: seed culture, seed expansion, and fermentation. Xanthomonas absorbs oxygen and emits carbon dioxide during its growth. The growth temperature is 2 to 35 deg C. At 40 degrees, the Xanthomonas stops growing. The extraction process of the xanthan gum comprises the following steps.
(1) treatment of fermentation broth. Centrifugation, filtration, enzyme treatment, hypochlorite oxidation, filtration and ultrafiltration concentration were used for pretreatment. Removing thallus cells and various insoluble impurities. O that the xanthan gum does not contain active bacterial cells, insoluble impurities and pigments which affect the quality of the product and the like. And concentrate that fermentation liquid.
(2) precipitation reaction. Calcium salt, aluminum salt, quaternary ammonium salt or acid precipitation method is used. And prepare an industrial-grade refined product. The organic solvent precipitation method is used for preparing the food-grade refined product.
(3) that precipitate is filter and washed.
(4) drying, crushing, sieving and packaging the finished product.
1.3 Production of industry grade xanthan gum
The extraction method of industrial grade xanthan gum is generally to sterilize the fermentation broth first. Kill viable bacterial cells. Is prepared by directly carrying out spray drying or roller drying. However, this method consumes a lot of energy because of the high water content of the fermentation broth. The purity of the product is low. And that color of the finis product is dark. And that cost is high. Another method is to precipitate xanthan gum with calcium salt, ammonium salt, etc. Because of the low added value of its products, the market is limited. Therefore, food grade xanthan gum is generally developed in China.
1.2.2 Production of food-grade xanthan gum
The extraction method of food-grade xanthan gum generally uses alcohol as precipitant, such as methanol, isopropanol, ethanol and other lower alcohols. Because ethanol is used for post-extraction, the cost is high, and the production and application are limited.
Xanthan gum produced by non-alcohol method can effectively solve this problem. The process flow is as follows: the strain is inoculated into a fermentation tank after graded culture in a seed tank, the fermentation is carried out for 48 to 60 hours by aeration and stirring under the condition of 30 deg C, the pH value is adjusted to 2 by dilute hydrochloric acid after the tank is put, and the xanthan gum is precipitated, and a light yellow finished product is obtained after dehydration and drying.
However, this method puts forward harsh requirements for extraction equipment and pipelines, and at the same time, hydrochloric acid-containing wastewater needs to be treated. Therefore, the choice of precipitant is still a problem to be solved in the production of food-grade xanthan gum in China.
Application of Xanthan Gum
Xanthan gum has unique properties. It is widely used in more than ten fields such as food, petroleum, medicine, daily chemical industry and so on. Its advantages are high commercialization and wide application range. These advantages are second to none in any other microbial polysaccharide.
2.1 Food.
Xanthan gum is added to many foods as a stabilizer, emulsifier, suspending agent, thickener, and processing aid. Xanthan gum can control the rheology, structure, flavor and appearance of the product. Its pseudoplasticity can also ensure good taste. Therefore, it is widely used in salad dressing, bread, dairy products, frozen food, beverage, condiment, brewing, candy, pastry, soup and canned food.
In recent years, people in more developed countries have tended to worry that the calorific value of food is too high to make them fat. Xanthan gum dispels this concern because it is not directly degraded by the human body. In addition, according to Japanese reports in 1985, 11 kinds of food additives were compared and tested, and xanthan gum was the most effective anti-cancer agent.
2.2 Domestic chemical industry.
Xanthan gum molecules contain a large number of hydrophilic groups. It is a good surface active substance, and has the effect of anti-oxidation and preventing skin aging. Therefore, xanthan gum is used as the main functional ingredient in almost all high-end cosmetics. In addition, xanthan gum can also be used as an ingredient of toothpaste to thicken and shape, and reduce tooth surface wear.
2.3 Medicine.
Xanthan gum molecules contain a large number of hydrophilic groups. It is a good surface active substance, and has the effect of anti-oxidation and preventing skin aging. Therefore, xanthan gum is used as the main functional ingredient in almost all high-end cosmetics. In addition, xanthan gum can also be used as an ingredient of toothpaste to thicken and shape, and reduce tooth surface wear.
2.4 Industry and agriculture.
In the petroleum industry, due to its strong pseudoplasticity, a low concentration of xanthan gum (0.5%) in aqueous solution can maintain the viscosity of drilling fluids and control their rheological properties. Therefore, the viscosity is very low at the part of the drill rotating at high speed.
And that pow is saved. While maintaining a high viscosity at the relatively static borehole location. Thereby preventing collapse of the borehole wall. And because of its excellent salt resistance and heat resistance.
Therefore, it is widely used in drilling in special environments such as ocean and high salinity area. And can be use as an oil displacement agent for oil extraction to reduce dead oil areas and improve oil recovery.