# Effect of Different Drying Methods on the Quality of _Oudemansiella raphanipes_
## 3 Results and Analysis
### Effects of Different Drying Methods on the Volatile Substances of O. raphanipes
As can be seen in Table 5, the effect of different drying techniques on the C\({}_{8}\) alcohol content was significant (\(p<0.05\)). The response intensity of 1-octen-3-ol was significantly different among the three samples, which is in agreement with the results reported by [PERSON] et al. [44]. Among them, the highest response intensity of 1-octen-3-ol was found in VD, followed by ID and HD. These results suggest that C\({}_{8}\) alcohols are less stable in mushrooms due to oxidization, degradation, and enzymatic reactions and are susceptible to drying temperatures and techniques, and their degradation can easily take place during heat treatments [45; 46]. 1-octen-3-ol can be produced by the conversion of 13-HPOD and 10-HPOD, while 1-octen-3-ol can in turn be oxidized to 3-octanol and 3-octanone [47]. C\({}_{8}\) compounds such as 1-octen-3-ol can be produced by the auto-oxidation of polyunsaturated fatty acids, enzyme-catalyzed oxidation, and cleavage of polyunsaturated fatty acids, with enzyme-catalyzed being the predominant pathway. Enzymes, being products of living cells, can interact with substrates to produce different molecular substances. Mushrooms are rich in unsaturated fatty acids (such as linoleic acid) that are oxidized by enzymes to produce eight-carbon molecules [48]. However, HD drying makes the cell integrity disrupted, which in turn affects the enzyme-substrate interaction. The response intensity of other alcohols, such as isobutanol, n-hexanol, 2,3-butanediol, 2-ethylhexanol, and nonanol, shown in Table 5, were significantly different in VD, probably due to high decarboxylase activity during ketoacid conversion [49]. Aldehydes and ketones are carbonyl compounds, of which aldehydes are a relatively abundant volatile compound in edible mushrooms, with a low odor threshold and a strong overlapping effect with other compounds. Aldehydes from C\({}_{5}\) to C\({}_{9}\) are usually derived from fat oxidation and degradation, and they have a fat-scented odor. From the table, it can be seen that the content of aldehydes in HD and ID was significantly higher than that in VD and concentrated in the C\({}_{5}\) to C\({}_{9}\) group of compounds. Among them, 3-methylbutyratealdehyde and 2-methylbutyraldehyde have a cocoa flavor, and benzaldehyde has a sweet taste and a special almond flavor, which can give the product a fatty flavor. And both hexanal and benzaldehyde dimethyl acetal have a grassy odor. Ketones are used as flavor substances to provide floral and fruity aromas, with excellent and long-lasting flavor characteristics, which are mainly generated by heating through lipid oxidation [50]. The major 8c ketone in mushrooms is 3-octanone, which possesses mushroom and herbaceous flavors. As shown in Table 5, the response intensity of 3-octanone was higher after drying by hot air and infrared radiation, which may be due to the enzymatic oxidation of 3-octanol to produce 3-octanone [51]. After hot air drying and infrared radiation drying, aldehydes constitute the main aroma of _O. raphanipes_ flavor characteristics, and ketones 3,5-octaiden-2-one also play a certain role in contributing to providing a fruity aroma, which may be the result of heating and drying, conducive to the formation of aldehydes and ketones carbonyl compounds, whereas vacuum freeze drying cannot easily generate carbonyl flavor substances due to the low-temperature and anaerobic conditions. Esters not only have strong volatility at room temperature and low threshold but also impart a sweet and slightly oily odor to food. As can be seen from Table 5, compared with vacuum freeze drying, the content loss of esters after hot air drying and infrared radiation drying is higher, which may be due to the reaction of ester compounds with a large amount of moisture in the drying process under heating conditions and hydrolyzed to alcohols or phenols as well as carboxyl compounds [52]. Vacuum freeze drying preserves the esters better due to the lower temperature and vacuum environment.