# Effect of Different Drying Methods on the Quality of _Oudemansiella raphanipes_
## 3 Results and Analysis
### Effects of Different Drying Methods on the Appearance Quality of O. raphanipes
Therefore, the dried product has a porous structure, which helps to absorb water. Therefore, this drying method has a high rehydration rate. Both HD and ID are dried by heating, and the prolonged high temperature deforms the cells of the fruiting body, damages the tissue structure, and hardens the surface crusts, which is not conducive to rehydration. As shown in Table 4, the \(L^{\star}\) values of hot air drying, infrared radiation drying, and vacuum freeze drying are 66.68, 65.17, and 79.26, respectively. The \(L^{\star}\) value of _O. raphanipes_ before drying is 93.11. This indicates that all three drying techniques resulted in a decrease in the brightness of _O. raphanipes_. The increase in \(a^{\star}\) and \(b^{\star}\) values is due to the formation of brown polymers in the relevant components of _O. raphanipes_ during the drying process, resulting in the darkening of their color, referred to as browning. According to the comprehensive score of color difference in the table, it can be seen that various drying treatment methods have certain differences (\(p<0.05\)). In terms of color, the \(L^{\star}\) of VD was significantly higher than that of HD and ID, and the values of \(a^{\star}\) and \(b^{\star}\) were lower than those of HD and ID. It allows the sample to be in a vacuum, non-high-temperature conditions, which can reduce the possibility of enzymatic as well as non-enzymatic browning of _O. raphanipes_, and, therefore, can maximally maintain its original color. On the contrary, ID was dried at high temperature, and the samples underwent severe browning, hence the darker color of the gill. The effect of HD coloration was close to that of ID, which was affected by \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Drying** & **Drying** & **Moisture** & **Rehydration** & \multicolumn{3}{c}{**Color**} \\
**Method** & **Time (h)** & **Content (\%)** & **Rate (\%)** & **\(L^{\star}\)** & \(a^{\star}\)** & \(b^{\star}\)** & \(\Delta\)E \\ \hline Fresh & - & - & - & 93.11 \(\pm\) 0.08 \({}^{\rm a}\) & 0.65 \(\pm\) 0.03 \({}^{\rm d}\) & 6.46 \(\pm\) 0.68 \({}^{\rm c}\) & - \\ HD & 10 & 6.5 \(\pm\) 0.1 & 3.96 \(\pm\) 0.15 \({}^{\rm b}\) & 66.68 \(\pm\) 0.20 \({}^{\rm c}\) & 2.45 \(\pm\) 0.05 \({}^{\rm b}\) & 11.69 \(\pm\) 0.08 \({}^{\rm a}\) & 27.13 \(\pm\) 0.04 \({}^{\rm b}\) \\ ID & 10 & 6.5 \(\pm\) 0.1 & 4.11 \(\pm\) 0.21 \({}^{\rm b}\) & 65.17 \(\pm\) 0.08 \({}^{\rm d}\) & 2.66 \(\pm\) 0.02 \({}^{\rm a}\) & 12.30 \(\pm\) 0.13 \({}^{\rm a}\) & 28.74 \(\pm\) 0.20 \({}^{\rm a}\) \\ VD & 24 & 6.5 \(\pm\) 0.1 & 6.70 \(\pm\) 0.17 \({}^{\rm a}\) & 79.26 \(\pm\) 0.04 \({}^{\rm b}\) & 0.60 \(\pm\) 0.04 \({}^{\rm c}\) & 7.96 \(\pm\) 0.12 \({}^{\rm b}\) & 14.00 \(\pm\) 0.05 \({}^{\rm c}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Effect of different drying methods on moisture content, rehydration ratio, and surface color. temperature so that it also underwent severe browning internally, which is the same as that reported by [PERSON] et al. (2018). The microstructure of _O. raphanipes_ samples after different drying treatments was observed by scanning electron microscopy. As shown in Figure 1, each sample exhibits different degrees of looseness. As can be seen at 1500 and 4000 magnification, the HD exhibits a porous, honeycomb ultrastructure with a large degree of surface crumpling and collapse. This may be related to the characteristics of hot air drying. During the heating process, the water molecules in the surface layer of _O. raphanipes_ evaporate at a faster rate, while the thermal movement of water molecules in its interior is slower, so the water evaporation of _O. raphanipes_ is not uniform. The organization of the HD samples corroborates with the low rehydration they exhibit. The ID samples showed a dense structure, which may help to increase the density of the ID samples; however, the collapse of the spatial structure may reduce the ability of the tissue to absorb water during rehydration. [PERSON] et al. 's study [PERSON] et al.