## 3 Results
### Phenolic Compounds
This trend was correlated to the flavonol astilbin (R.t. 49.8 min) and to a tentatively assigned hexoside derivative of gallic acid (R.t. 12.4 min, \(\lambda_{\text{MAX}}\) = 267 nm; mass = m/z 331, ESI -). As with musts (T0-T4, Figure 1A,B), the separation along PC1 in Figure 1C (vinvilation factor) was strongly correlated with _trans_-caftaric acid. In bottled wines (Figure 1E), both the trends were clearly visible; they were perfectly aligned with PC1 and PC2. However, the temporal trend (PC2) did affect in this case more the samples V2 than V1. Figure 1: PCA of HPLC-DAD peaks. (**A**) PC1 vs. PC2 score plot for must samples; (**B**) PC1 vs. PC2 loading plot for must samples; (**C**) PC1 vs. PC2 score plot for fermentation and stabilization samples; (**D**) PC1 vs. PC2 loading plot for fermentation and stabilization samples; (**E**) PC1 vs. PC2 score plot for bottled samples; (**F**) PC1 vs. PC2 loading plot for bottled samples. Loadings are indicated with their HPLC retention times as labels. Blue font indicates V1 samples; red font indicates V2 samples. (**A–C**) into the PCA plot indicates the three replicates. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **Assignment** & **R.L.** & **Full MS** & **MS/MS** & **UV-Vis \(\lambda_{\text{max}}\)** & **Identification** \\  & & **(_min_)** & **(_min/2_)** & **(_min/2_)** & **(_mm_)** & **(_mm_)** & **Identification** \\ \hline
**1** & gallic acid, hexoside (\({}^{\text{a}}\)) & 12.4 & 331 (ESI -) & 153 \(\leftarrow\) 331 & 267 & Assigned by DAD (\(\lambda_{\text{MAX}}\)) and MS\({}^{2}\) analysis. \\
**2** & gallic acid & 17.1 & 169 (ESI -) & _na_ & 267 & Standard injection. \\
**3** & (c)-galloacethen & 24.0 & 305 (ESI -) & 125, 219 \(\rightarrow\) 305 & 279 & Fluorescence analysis. Standard injection, assigned by DAD (\(\lambda_{\text{MAX}}\)) and MS\({}^{2}\) analysis. \\  & & & & & (\(\lambda_{\text{MAX}}\)) and MS\({}^{2}\) analysis. \\  & & & & & & (\(\lambda_{\text{MAX}}\)) and MS\({}^{2}\) analysis. \\
**4** & & & & & & \\  & & & & & & \\
**5** & & & & & & \\
**6** & (-) epigallocatechin & 31.4 & 305 (ESI -) & 125, 219 \(\rightarrow\) 305 & 279 & Fluorescence analysis. Standard injection, assigned by DAD (\(\lambda_{\text{MAX}}\)) and MS\({}^{2}\) analysis. \\
**7** & (+)-catechin & 33.1 & 289 (ESI -) & _na_ & 279 & Fluorescence analysis. Standard injection. \\  & & & & & & \\
**8** & & & & & & \\  & & & & & & \\
**9** & _trans_-caffe acid & 37.0 & 179 (ESI -) & _na_ & 297, 327 & Standard injection. \\
**10** & (-)-epictemic & 38.5 & 289 (ESI -) & _na_ & 279 & Fluorescence analysis. Standard injection. \\
**11** & \(p\)-cumaric acid & 45.5 & 163 (ESI -) & _na_ & 295, 308 & Standard injection. \\
**12** & astilbin & 49.8 & 449 (ESI -) & 449 & 290, -340 & Standard injection; assigned by DAD (\(\lambda_{\text{MAX}}\)) and MS\({}^{2}\) analysis. \\
**13** & taxifolin (\({}^{\text{\gamma}}\)) & 50.8 & 303 (ESI -) & 125, 285 \(\leftarrow\) 303 & 290, -340 & Standard injection; assigned by DAD (\(\lambda_{\text{MAX}}\)) and MS\({}^{2}\) analysis. \\ \hline \hline \end{tabular}  
\({}^{1}\)_cis_ isomer, \({}^{2}\)_trans_ isomer, _na_ = not acquired, R.L. error = \(\pm\) 0.5 min, mass error = \(\pm\) 0.3 n/z \(\lambda_{\text{MAX}}\) error = \(\pm\) 2 nm. (\(\cdot\)) Tentative assignment.  
\end{table} 
Table 2: Compounds identified by HPLC-DAD and HPLC-MS analysis. This trend proceeded from lower to higher values of PC2 and it was strongly correlated to GRP (Figure 1F), which decreased from W0 to W9. The complete trends for astilbin, taxifolin, _trans_-caftaric acid and _S_-glutathionylcaftaric acid (grape reaction product or GRP) from T0 to W9 (T16) were displayed in Figure S2. The concentration of GRP in the samples appeared gradually to increase up to W3 and then sharply decreased (see Figure S2), whereas its precursor (_trans_-caftaric acid, R.t. 28.0 min) displayed overall increasing trend with a temporary decrease between T3 and T5 for V2 (start of the fermentation).