## 2 Extraction and Purification Methods of Ginger Polysaccharides
### Purification Methods of Ginger Polysaccharides  
Ginger crude polysaccharideoften contains a variety of impurities, and it usually includes pigments, proteins, and inorganic salts. So, it needs to be purified further (Figure 2). Pigments can be removed by adsorption of macroporous resin and activated carbon. The commonly used deproteinization methods are the Sevag method, the trichloroacetic acid (TCA) method, and the enzymatic method [50; 51]. Inorganic salts, monosaccharides, and other small molecular substances can be removed by dialysis and ultrafiltration. Next, the crude ginger polysaccharide solution needs to be further purified by column chromatography, and a suitable buffer solution is used as the mobile phase. Column chromatography is the most widely used method in the classification and purification of polysaccharides [52]. It can be divided into anion exchange chromatography and gel filtration chromatography. In the preparation of ginger polysaccharide GP1 and GP2, the crude ginger polysaccharide (GPS) was treated with S-8 macroporous resin column and  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Polysaccharide Fraction** & **Extraction Methods** & **Time (min)** & **Temperature (\({}^{\circ}\)C)** & **Solid–Liquid Ratio (g/mL)** & **Total Yield (\%)** & **Ref.** \\ \hline A water extracted & & & & & & \\ polysaccharides (WEP) & & & & & & \\ containing fraction from & & & & & & \\ ginger rhizome & & & & & \\ \hline Crude ginger & & & & & & \\ polysaccharides were & & & & & \\ extracted by hot water & & & & & & \\ extraction (HCGP) & & & & & \\ \hline Crude ginger & & & & & & \\ polysaccharides were & & & & & \\ extracted by enzyme & & & & & \\ assisted extraction (ECGP) & & & & & & \\ \hline Crude ginger & & & & & \\ polysaccharides were & & & & & \\ extracted by ultrasonic cell & & & & & \\ grinder extraction (UCGP) & & & & & \\ \hline Polysaccharides from & & & & & \\ ginger (_Zingiber officinal_ & & & & & \\ Roscoe.) stems and leaves & & & & & & \\ (GSLP) & & & & & \\ \hline Polysaccharides from & & & & & \\ ginger (_Zingiber officinal_ & & & & & \\ Roscoe.) stems and leaves & & & & & \\ ginger (_Zingiber officinal_ & & & & & \\ Roscoe.) stems and leaves & & & & & \\ (GSLP) & & & & & \\ \hline Polysaccharides from & & & & & \\ ginger (_Zingiber officinal_ & & & & & \\ Roscoe.) stems and leaves & & & & & \\ (GSLP) & & & & & \\ Roscoe.) stems and leaves & & & & & \\ (GSLP) & & & & & \\ \hline A novel polysaccharide & & & & & \\ (ZOP) was extracted from & & & & & \\ _Zingiber officinal_ & & & & & \\ (GSP) & & & & & \\ \hline Ginger polysaccharide (GP) & & & & & \\ \hline \end{tabular}
\end{table}
Table 1: _Cont._the Sevag method to remove impurities, such as proteins, fragments, and nuclear acids, which can improve the purity and quality of GPS. Next, 0.1-1.0 mol/L NaCl solution was used as mobile phase, and DEAE-52 cellulose column was used for linear gradient elution. Subsequently, GP1 eluted with distilled water and GP2 eluted with 0.1 M NaCl buffer were further purified on Sephadex G-200 column. Finally, it was freeze dried [42]. In the preparation of neutral ginger polysaccharide (NGP), the crude ginger polysaccharide (CGP) was initially purified by DEAE-52 cellulose column, then further purified by Sephadex G-100 column, and finally freeze-dried to obtain purified NGP [47].