## 3 Results and Discussion
### Aroma Concentration and Composition Analysis of B. roseflavus Samples
\(\alpha\)-pinene, styrene, octanal, 1,3,5-trithiane, and 2,4-undecadien had rOAV values > 10, presenting floral, fragrant oil, grassy, sulfurous, and buttery aromas, respectively, indicating that these are the major contributors to the aroma of _B. roseflavus_. Notably, 13 out of the 17 key aroma substances had higher rOAV values in the CN group than in the DBG group, suggesting that _B. roseflavus_ from CN has a more intense aroma. The Pearson correlation coefficient method was used to calculate the relationship between key aroma compounds and environmental factors (Figure S3B). The results showed that, except for ethyl acetate, 3-mercapto-2-pentanone, (+)-\(\alpha\)-pinene, and octanal, key aroma compounds were significantly positively correlated with daily average air temperature, daily average air humidity, daily average soil temperature, daily average soil humidity, and daily light intensity. Research has demonstrated that the synthesis and accumulation of aromatic compounds in crops, including grains, tea leaves, flowers, and fruits, are affected by environmental factors such as temperature, humidity, and light conditions during their development. For instance, high temperatures and low rainfall before grape ripening lead to higher levels of phenolic compounds, contributing to weight variations in grape fruits, while cooler conditions favor an increase in terpene content in grapes [42]. Dry air or insufficient vapor pressure leads to the loss of aromatic compounds in grains, while humid air allows grains to accumulate stronger and more complex aromatic compounds [43]. This is likely due to abiotic stress enhancing the expression of aroma-synthesizing genes, leading to the accumulation of characteristic aroma compounds [44; 45]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multirow{2}{*}{**Compounds**} & \multicolumn{2}{c}{**Threshold**} & \multicolumn{2}{c}{**OAVs**} \\ \cline{3-5}  & & \(\mu\)**g/g** & **DBG** & **CN** \\ \hline
1 & Propyl sulfide & 0.003 & 1.302 \(\pm\) 0.063 b & 0.349 \(\pm\) 0.031 a \\
2 & Naphthalene, 2,7-dimethyl- & 0.042 & 1.369 \(\pm\) 0.088 b & 0.128 \(\pm\) 0.003 a \\
3 & Naphthalene, 1,3-dimethyl- & 0.042 & 1.369 \(\pm\) 0.088 b & 0.128 \(\pm\) 0.003 a \\
4 & Pentanoic acid, 4-methyl, ethyl ester & 0.006 & 1.517 \(\pm\) 0.043 b & 0.279 \(\pm\) 0.001 a \\
5 & 3-Hexen-1-ol acetate, (Z)- & 0.031 & 3.198 \(\pm\) 0.538 b & 6.925 \(\pm\) 0.336 a \\
6 & Phenol, 2-methoxy-4-propyl- & 0.0044 & 3.561 \(\pm\) 0.041 b & 0.375 \(\pm\) 0.039 a \\
7 & Butane, 1-(ethylthio)- & 0.001 & 3.906 \(\pm\) 0.19 b & 1.047 \(\pm\) 0.092 a \\
8 & 3-mercapto-2-pentanone & 0.0007 & 4.412 \(\pm\) 0.492 b & 9.761 \(\pm\) 0.23 a \\
9 & 5,9-Undecadien-2-one, 6,10-dimethyl-, (E)- & 0.01 & 4.422 \(\pm\) 0.435 b & 2.016 \(\pm\) 0.119 a \\
10 & 2,2,4-Trimethyl-1,3-pentanediol disobutyrate & 0.014 & 5.269 \(\pm\) 0.324 b & 1.465 \(\pm\) 0.465 a \\
11 & (1R)-2,6,6-Trimethylbicyclo [3.1.1]-lept-2-ene & 0.0053 & 5.664 \(\pm\) 0.331 b & 11.086 \(\pm\) 0.675 a \\
12 & Naphthalene, 2,6-dimethyl- & 0.01 & 5.752 \(\pm\) 0.37 b & 0.536 \(\pm\) 0.014 a \\
13 & 2,4-Undecadien, (E,E)- & 0.001 & 6.493 \(\pm\) 0.165 b & 0.684 \(\pm\) 0.002 a \\
14 & Styrene & 0.0036 & 40.645 \(\pm\) 0.737 b & 11.353 \(\pm\) 0.405 a \\
15 & Octanal & 0.0007 & 41.244 \(\pm\) 4.394 b & 120.834 \(\pm\) 6.005 a \\
16 & 1,3,5-Trithiane & 0.00004 & 359.051 \(\pm\) 37.124 b & 14.2 \(\pm\) 8.097 a \\
17 & 2,4-Undecadienal & 0.00001 & 649.305 \(\pm\) 16.517 b & 68.398 \(\pm\) 0.17 a \\ \hline \hline \end{tabular} Note: different lowercase letters in the same row represent significant differences between samples (_p_ < 0.05).  
\end{table} 
Table 3: Odor activity values (OAVs) of key volatile substances (N = 3, average \(\pm\) SEM).