## 3 Results and Discussion
### VC Profile of Mushrooms  
The whole VC profile of the untreated and treated mushrooms is given in Supplementary Materials (Table S1. Volatile compound profile). The VC in fresh mushrooms (% of total VC for those accounting for >1% of the whole profile) is shown in Table 2. The main VC in all the tested fresh mushrooms was 1-octen-3-ol, which was the highest in the _B. edulis_ VC profile (61.9%). The other most abundant VCs were 3-octanol and 1-octanol in _B. edulis_, oct-(2E)-enal and (E)-2-octen-1-ol in _C. cibarius_, and benzaldehyde in _R. caperata_. Mushroom flavour is mainly formed by the aliphatic components, such as 1-octen-3-ol, 2-octen1-ol, 3-octanol, 1-octanol, and 3-octanone [39]. Compounds, such as fatty acid degradation products, terpenoids, 3-(methylthio)propanal, and \(N\)-heterocyclic compounds \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**RT, Min** & **VC** & **BE—Non-Treated** & **Ca—Non-Treated** & **Ro—Non-Treated** \\ \hline
5.763 & Hexanal & nd & 1.89 \(\pm\) 0.17 b & 0.445 \(\pm\) 0.025 a \\
9.949 & Benzaldehyde & 0.538 \(\pm\) 0.027 a & 1.27 \(\pm\) 0.13 b & 35.6 \(\pm\) 2.5 c \\
10.493 & 1-Octen-3-ol & 61.9 \(\pm\) 2.5 b & 55.2 \(\pm\) 0.51 a & 50.4 \(\pm\) 3.8 a \\
10.669 & 3-Octanone & 5.62 \(\pm\) 0.34 b & nd & 1.81 \(\pm\) 1.6 a \\
10.885 & 3-Octanol & 8.81 \(\pm\) 0.72 c & 0.525 \(\pm\) 0.049 a & 3.71 \(\pm\) 2.7 b \\
11.091 & Octanal & 5.47 \(\pm\) 0.61 c & 0.367 \(\pm\) 0.028 a & 1.34 \(\pm\) 0.21 b \\
11.844 & 3-ethyl-2-methyl-1,3-hexadiene & nd & 1.82 \(\pm\) 0.26 & nd \\
12.476 & Oct-(2E)-enal & 4.55 \(\pm\) 0.39 b & 16.3 \(\pm\) 0.58 c & 2.25 \(\pm\) 0.23 a \\
12.728 & (E)-2-octen-1-ol & nd & 16.9 \(\pm\) 0.18 b & 1.13 \(\pm\) 0.11 a \\
12.788 & 1-Octanol & 8.01 \(\pm\) 0.78 & nd & nd \\ \hline \hline \end{tabular}  
* RT—retention time; BE—_Boleus edulis_; Ca—_Canthallus charius_; Ro—_Razites operate_; VC—volatile compound; nd—not detected. Data are represented as means (n = 3, replicates of analysis) \(\pm\) SD; \({}^{\rm a\times}\) for the same analytical parameters between mushrooms; means with different letters are significantly different (\(p\leq 0.05\)).  
\end{table} 
Table 2: Volatile compounds (in whole profile >1%) of non-treated mushrooms (% from the total volatile compounds). cause individual odours between different mushroom species [40]. The unsaturated alcohol, 1-octen-3-ol, is very common in most mushroom species and is characterised as a \"mushroom-like flavour\" and \"raw mushroom\". The odour of 3-octanol is described as earthly, mushroom, dairy, creamy dairy, musty, creamy, waxy with a slight fermented green minty nuance, herbaceous, somewhat nutty, and fatty, and the taste is musty, mushroom, and earthy; 1-octanol possesses a medium-strength waxy, green, citrus, aldehyde, and floral odour with a sweet, fatty, coconut nuance, and a waxy, green, citrus, orange, and aldehyde taste with a fruity nuance; the odour of oct-(2E)-enal is described as fresh, cucumber, fatty, green, herbal, banana, waxy, green, and leafy, and the taste is described as sweet, green, citrus, peel, spicy, cucumber, oily, fatty, and broth; the odour of (E)-2-octen-1-ol is green and vegetable-like, lending a pleasant, fatty note to fruity complexes, and its taste is strong, fatty, oily, and sweet, with fruity and citrus notes [41]. [PERSON] et al. [42] found that the main VC in four boletus varieties were aldehydes, esters, alcohols, acids, pyrazines, ketones, and phenols; 1-octen-3-ol and 2,5-dimethylpyrazine were the predominant VC among samples, while 3-(methylthio)propionaldehyde and 2,6-dimethylpyrazine were the main compounds in _B. edulis_. Comparing the VC profile of fresh mushrooms with thermally treated and ultrasonicated ones, a greater variety of VC was identified in treated mushrooms (Table 3). Comparing the changes of VC in thermally treated and ultrasonicated mushroom samples of the same species, in thermally treated _B.