## 3 Results and Discussion
### Analysis of Volatile Compounds by HS-SPME/GC-Ms
\begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Time (h)** & **Aldehydes** & **Alcohals** & **Alkanes** & **Alkanes** & **Ketones** & **Esters** & **Others** \\ \hline
0 (Control) & 496.35 \(\pm\) 44.56 \({}^{\rm\,\rm\AA}\) & 311.02 \(\pm\) 61.60 \({}^{\rm\,\rm AB}\) & 13.34 \(\pm\) 1.40 \({}^{\rm\,\rm AD}\) & 133.48 \(\pm\) 7.25 \({}^{\rm\,\rm C}\) & 22.84 \(\pm\) 3.65 \({}^{\rm\,\rm AD}\) & 49.98 \(\pm\) 4.35 \({}^{\rm\,\rm AD}\) & 3.75 \(\pm\) 1.21 \({}^{\rm\,\rm AD}\) \\
0 & 499.00 \(\pm\) 26.34 \({}^{\rm\,\rm A}\) & 296.54 \(\pm\) 108.77 \({}^{\rm\,\rm AB}\) & 12.59 \(\pm\) 1.49 \({}^{\rm\,\rm AD}\) & 133.39 \(\pm\) 15.50 \({}^{\rm\,\rm C}\) & 23.39 \(\pm\) 3.18 \({}^{\rm\,\rm AD}\) & 50.95 \(\pm\) 14.33 \({}^{\rm\,\rm AD}\) & 3.18 \(\pm\) 0.51 \({}^{\rm\,\rm AD}\) \\
8 & 348.02 \(\pm\) 24.26 \({}^{\rm\,\rm AB}\) & 282.95 \(\pm\) 15.66 \({}^{\rm\,\rm AB}\) & 19.35 \(\pm\) 0.80 \({}^{\rm\,\rm AD}\) & 146.06 \(\pm\) 28.37 \({}^{\rm\,\rm AD}\) & 19.32 \(\pm\) 5.43 \({}^{\rm\,\rm AD}\) & 42.00 \(\pm\) 8.12 \({}^{\rm\,\rm AD}\) & 1.68 \(\pm\) 0.38 \({}^{\rm\,\rm AD}\) \\
16 & 514.80 \(\pm\) 120.50 \({}^{\rm\,\rm AD}\) & 335.73 \(\pm\) 9.34 \({}^{\rm\,\rm AD}\) & 82.85 \(\pm\) 18.66 \({}^{\rm\,\rm AD}\) & 522.37 \(\pm\) 100 \({}^{\rm\,\rm AD}\) & 28.35 \(\pm\) 8.50 \({}^{\rm\,\rm AD}\) & 58.34 \(\pm\) 6.86 \({}^{\rm\,\rm AD}\) & 6.50 \(\pm\) 1.59 \({}^{\rm\,\rm AD}\) \\
24 & 411.93 \(\pm\) 79.23 \({}^{\rm\,\rm AD}\) & 305.17 \(\pm\) 11.34 \({}^{\rm\,\rm AD}\) & 28.90 \(\pm\) 0.82 \({}^{\rm\,\rm AD}\) & 142.50 \(\pm\) 32.01 \({}^{\rm\,\rm AD}\) & 22.05 \(\pm\) 5.81 \({}^{\rm\,\rm AD}\) & 47.67 \(\pm\) 7.87 \({}^{\rm\,\rm AD}\) & 40.07 \(\pm\) 0.84 \({}^{\rm\,\rm AD}\) \\
32 & 742.72 \(\pm\) 50.90 \({}^{\rm\,\rm AD}\) & 372.05 \(\pm\) 17.51 \({}^{\rm\,\rm AD}\) & 39.60 \(\pm\) 6.09 \({}^{\rm\,\rm AD}\) & 678.77 \(\pm\) 31.66 \({}^{\rm\,\rm AD}\) & 100.69 \(\pm\) 39.44 \({}^{\rm\,\rm AD}\) & 77.71 \(\pm\) 6.97 \({}^{\rm\Ipomeamarone in ketones is a kind of mycotoxin that belongs to the class of furan terpenoids produced by _C. fimbriata_-infected sweetpotatoes. It can be seen from Figure 5A that ipomeamarone was not detected at 0 h of inoculation. During the early period of infection from 0 to 32 h, the growth of _C. fimbriata_ in sweetpotatoes was in the lag phase, resulting in low levels of ipomeamarone, from 0 to 12.93 ng g\({}^{-1}\) FW. The release of trace amounts may have been due to the stress response generated by mechanical damage at the inoculation holes [46]. From 48 h on, the content of ipomeamarone increased rapidly and reached 14,203.80 ng g\({}^{-1}\) FW at 72 h, accounting for 81.88%, which was the main component of ketones. Dehydroipomeamarone is a direct precursor for the synthesis of ipomeamarone [47], which is also toxic [48]. Trans-farnesol has been confirmed to be the initial precursor for the synthesis of ipomeamarone, and 6-oxodendrolasin is an intermediate in the synthesis from trans-farnesol to ipomeamarone. Therefore, it can be speculated that dendrolasin may also be one of the intermediates for the synthesis of ipomeamarone according to the structural formula. The trends of trans-farnesol, dendrolasin, and dehydropropomeamarone content from 0 to 72 h are shown in Figure 5B-D. The content of these four substances increased with the prolongation of infection time. Table 2 shows the correlation coefficients between the total colony count of _C. fimbriata_ and trans-farnesol, dendrolasin, dehydropropameamarone, and ipomeamarone. The correlation coefficients were all higher than 0.9, indicating a high connection among the four substances mentioned above in the synthetic pathway. To sum up, even when there are no obvious lesion symptoms on the surface of sweetpotatoes, large amounts of ipomeamarone may have accumulated in the internal infected parts, greatly increasing the risk of toxicity and compromising food safety. Therefore, it is of great significance to explore early discrimination and prediction technology for _C. fimbriata_-infected sweetpotatoes.