# Effect of Different Drying Methods on the Quality of _Oudemansiella raphanipes_
## 3 Results and Analysis
### Chemical Composition of PS-V, PS-H, and PS-I  
From Table 6, it can be seen that compared with the other two drying methods, the highest polysaccharide yield was obtained from vacuum freeze drying _O. raphanipes_ because _O. raphanipes_ had a higher rehydration rate after vacuum freeze drying, and the cellular tissues of the vacuum freeze-dried samples showed a porous three-dimensional structure, which was conducive to the penetration of the extraction solvents during the extraction process. Therefore, vacuum freeze drying has a good effect in the process of extracting polysaccharides. In Table 6, the content of polysaccharides (66.77%) and glucuronic acid (20.22%) obtained after infrared radiation drying of _O. raphanipes_ was higher than that obtained after vacuum freeze drying (61.50%, 16.40%) and hot air drying (60.44%, 13.20%). Infrared radiation drying disrupts the metabolic equilibrium of carbohydrates and produces macromolecules, such as polysaccharides, which increase the production of polysaccharides and glyoxalates. The ultrasonic cavitation effect and acoustic flow effect of vacuum freeze drying can cause damage to the sample, breaking down macromolecules such as polysaccharides into monosaccharides or oligosaccharides, resulting in a reduction in polysaccharide content and glyoxalate. The high temperature and long drying time of hot air drying can cause material color deterioration and nutrient degradation, and the thermal efficiency is low, so the polysaccharide content and uronic acid are relatively low. As shown in Table 6, the protein content of PS-V was 1.29%, which was slightly higher than that of PS-H and PS-I. Vacuum freeze drying has the lowest loss of protein, and the non-high-temperature vacuum environment reduces the rate of biochemical reaction in the fruiting body, which can maintain its original structure and shape and reduces the loss of nutrients. The lower protein content under hot air drying and infrared radiation drying may be due to the higher drying temperature, which promotes the decomposition reaction of proteins; in addition, the high-temperature conditions may also destroy the spatial structure of proteins and denaturation of proteins, so the degree of protein destruction is directly proportional to the drying temperature and processing time.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Samples** & **PS-V** & **PS-I** & **PS-H** \\ \hline Yield (\%) & 1.92 & 1.74 & 1.67 \\ polysaccharide content (wt\%) & 61.50 \(\pm\) 1.45 b & 66.77 \(\pm\) 1.77 a & 60.44 \(\pm\) 1.79 b \\ protein (wt\%) & 1.29 \(\pm\) 0.05 a & 1.09 \(\pm\) 0.08 b & 1.06 \(\pm\) 0.13 b \\ Uronic acid (wt\%) & 16.04 \(\pm\) 0.46 b & 20.22 \(\pm\) 0.99 a & 13.20 \(\pm\) 0.53 c \\ Polyphenols (wt\%) & 5.30 \(\pm\) 0.34 a & 4.56 \(\pm\) 0.24 b & 3.29 \(\pm\) 0.19 c \\ \hline \hline \end{tabular}  
* Data are expressed as the mean \(\pm\) standard deviation (\(\mu\) = 3), and different letters within a row are significantly different (\(p\) < 0.05).
* \end{table}
Table 6: Effect of different drying methods on general physicochemical properties.  
Figure 4: (A) Infrared spectrum of PS-V, PS-H and PS-I; (B) ultraviolet spectrum of PS-V, PS-H, and PS-I.