After the tremella polysaccharide is extracted, it is mixed with various impurities such as inorganic salts and proteins. These impurities need to be removed through a series of processes, and finally the components of the tremella polysaccharide are separated to obtain a pure tremella polysaccharide single component. At present, the separation and purification of tremella polysaccharides mostly adopt the following process: low molecular weight organic solvent precipitation, deproteinization, decolorization, separation and purification of tremella polysaccharide components.
Low molecular weight organic solvent precipitation
Using the principle that polysaccharides are almost insoluble in high-concentration organic solutions, soluble impurities and most polysaccharides are separated. Methanol, ethanol and acetone are the most commonly used organic solvents, and polysaccharides with relatively high purity can be obtained through repeated water dissolution and alcohol precipitation.
Protein is the main impurity in the extraction process of Tremella polysaccharide. In the purification process of tremella polysaccharide, the organic solvent method is often used to deproteinize, so that the polysaccharide activity will not change much. Commonly used organic solvents include trichloroacetic acid, tannic acid, and sevage reagent. In addition, enzymatic combined sevage reagent deproteinization has also been reported.
Part of the pigment will be entrained during the extraction process of tremella polysaccharide. The presence of pigments can affect the structure of polysaccharides and also affect the biological activity of polysaccharides studied. Decolorization methods include hydrogen peroxide method, adsorption method, ion exchange resin method, etc. Hydrogen peroxide decolorization method is easy to inactivate polysaccharides, while adsorption method is easy to introduce small particles of impurities, which will affect the quality of the final product. The decolorization process of the ion exchange resin method only uses water as the solvent, and it has a strong decolorization ability without affecting the activity and yield of polysaccharides. Compared with the hydrogen peroxide method and adsorption method, it has large adsorption capacity, fast adsorption speed, It has the advantages of stable physical and chemical properties, and is a commonly used decolorization method for tremella polysaccharides.
Separation and purification of each component
Tremella polysaccharide is a mixture mainly including five kinds of polysaccharides. In order to better study the biological activity of each component, it is necessary to separate and purify the components of tremella polysaccharide to obtain a homogeneous polysaccharide. Common polysaccharide separation and purification methods include: organic solvent fractional precipitation method, metal complex method, salting out method, quaternary ammonium salt precipitation method, organic salt precipitation method, ion exchange column chromatography, and ultrafiltration method. Among them, the widely used separation method is ion exchange column chromatography. Ion exchange column chromatography often uses cellulose or dextran gel as the stationary phase, and uses acid groups as cationic adsorbents or amino groups as anionic adsorbents. It can not only separate and purify polysaccharides, but also concentrate and desalt polysaccharides. This separation method can not only ensure the activity of polysaccharides, but also save energy and has no pollution, so it is widely used.