## 3 Results
### Pca  
To evaluate the associations between the effect of UV-C, storage time, and the studied variables, the dataset was subjected to a principal component analysis (PCA), and only the components with eigenvalues \(\geq\) 1.0 were considered as having a major contribution to the total variation [35]. Six principal components were chosen based on this criterion, and the relative percentage of variability explained, as well as the related eigenvectors, are shown in Supplementary Table S2. The first two components explain 30.1% and 19.6%, respectively, of the total variability, and Figure 4 shows the score plot (a) and the loading plot (b) of PC1 and PC2, while Supplementary Figure S1 shows the overview score plot of the six components. The traits of protein, hardness, chlorogenic acid, trans-cinnamic acid, and quercetin were positively correlated with PC1, while rutin and caffeic acid were negatively correlated with PC1 (Table S2). The a* Tips, TFC, and DPPH were positively correlated with the PC2, while b* Tips and ABTS were negatively correlated with PC2, respectively (Table S2). The difference between UV-C treatment and storage time was evident at times T0 and T1, which were separated from T2 and T3 along the PC1 component, while the UV-C1 and UV-C2 were separated from UV-C3 and UV-C4 along PC2. Independent of the storage time, the control was grouped with UV-C3 and UV-C4 (Figure 4a). UV-C1 and UV-C2 treatments were more closely related to the main antioxidant compounds over the storage period. Similarly, hardness and proteins were associated with milder UV-C treatments, although their effects were more evident during the last storage times (T2 and T3). The separation of the samples treated with the highest UV-C doses is more influenced by ferulic acid and the L* Middle, but only at T0 and T1. As highlighted by PCA in our study, the control was grouped with UV-C3 and UV-C4, indicating that high intensity has overall fewer effects than low intensity, especially evident for hardness and antioxidants.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{4}{c}{\(\Delta\)E} \\ \hline  & & **T0** & **T1** & **T2** & **T3** \\ \hline \multirow{4}{*}{Tips} & UV-C1 & 4.11 \(\pm\) 0.16 & 6.50 \(\pm\) 0.33 & 1.65 \(\pm\) 0.52 & 5.25 \(\pm\) 0.22 \\  & UV-C2 & 4.53 \(\pm\) 0.28 & 2.1 \(\pm\) 0.14 & 1.86 \(\pm\) 0.07 & 4.38 \(\pm\) 0.03 \\  & UV-C3 & 1.87 \(\pm\) 0.07 & 0.85 \(\pm\) 0.08 & 2.28 \(\pm\) 0.11 & 1.33 \(\pm\) 0.25 \\  & UV-C4 & 1.74 \(\pm\)0.35 & 0.92 \(\pm\) 0.11 & 2.18 \(\pm\) 0.04 & 5.14 \(\pm\) 0.20 \\ \hline \multirow{4}{*}{Middle} & UV-C1 & 15.64 \(\pm\) 0.06 & 1.74 \(\pm\) 0.06 & 5.09 \(\pm\) 0.01 & 5.76 \(\pm\) 0.07 \\  & UV-C2 & 8.44 \(\pm\) 0.06 & 4.46 \(\pm\) 0.08 & 1.38 \(\pm\) 0.10 & 6.00 \(\pm\) 0.11 \\ \cline{1-1}  & UV-C3 & 2.21 \(\pm\) 0.13 & 1.77 \(\pm\) 0.11 & 2.44 \(\pm\) 0.06 & 6.85 \(\pm\) 0.21 \\ \cline{1-1}  & UV-C4 & 3.95 \(\pm\) 0.08 & 4.68 \(\pm\) 0.28 & 6.15 \(\pm\) 0.07 & 4.76 \(\pm\) 0.08 \\ \hline \hline \end{tabular}  
* \(\mathrm{T0}\) = the first day of each UV-C treatment; T1 = 7 th day of storage; T2 = 14 th day of storage; T3 = 21 st day of storage.  
\end{table}
Table 5: Difference between the color of the control and the color of the UV-C samples (\(\Delta\)E) in the Tips and the Middle of the asparagus years during storage.