# Chemical Characterization and Volatile Profile of Trebbiano di Lugana Wine: A Case Study
## 3 Results
### Chemical Parameters
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{1}{c}{**Parameter**} & **LS \#** & \multicolumn{4}{c}{**Users of Storage**} \\ \cline{3-10}  & **(2005)** & **(2009)** & **(2011)** & **(2013)** & **(2015)** & **(2016)** & **(2017)** \\ \hline \multicolumn{1}{c}{Total Phenols (TP; mg/L)} & \({}^{**}\) & \(201\) \(\pm\) 6\({}^{a}\) & \(208\) \(\pm\) 6\({}^{a}\) & \(197\) \(\pm\) 6\({}^{a}\) & \(216\) \(\pm\) 5\({}^{b}\) & \(165\) \(\pm\) 5\({}^{c}\) & \(183\) \(\pm\) 6\({}^{d}\) & \(204\) \(\pm\) 6\({}^{d}\) \\ \multicolumn{1}{c}{Polymeric Phenols (TP; mg/L)} & \({}^{**}\) & \(5.1\) \(\pm\) 0.1\({}^{a}\) & \(7.5\) \(\pm\) 0.1\({}^{a}\) & \(4.4\) \(\pm\) 0.1 \({}^{c}\) & \(15.7\) \(\pm\) 0.4\({}^{d}\) & \(4.6\) \(\pm\) 0.1\({}^{c}\) & \(3.3\) \(\pm\) 0.0 \({}^{c}\) & 6.7 \(\pm\) 0.1 \({}^{f}\) \\ \multicolumn{1}{c}{Ratio \(TP/P\)/P} & \({}^{**}\) & \(39.41\) \({}^{a}\) & \(27.73\) \({}^{b}\) & \(44.7\) \({}^{c}\) & 13.76 \({}^{d}\) & 35.87 \({}^{e}\) & 55.46 \({}^{f}\) & 30.45 \(\pm\) 5 \\ \multicolumn{1}{c}{} & OD 280 nm (AU) & \({}^{**}\) & \(8.90\) \(\pm\) 0.29 \({}^{a}\) & \(9.49\) \(\pm\) 0.31 \({}^{b}\) & \(8.41\) \(\pm\) 0.29 \({}^{c}\) & 9.58 \(\pm\) 0.27 \({}^{b}\) & 7.14 \(\pm\) 0.25 \({}^{d}\) & 7.35 \(\pm\) 0.24 \({}^{d}\) & 8.14 \(\pm\) 0.24 \({}^{c}\) \\ \multicolumn{1}{c}{} & OD 320 nm (AU) & \({}^{**}\) & \(4.85\) \(\pm\) 0.15 \({}^{a}\) & \(5.81\) \(\pm\) 0.17 \({}^{b}\) & \(5.36\) \(\pm\) 0.16 \({}^{c}\) & \(6.52\) \(\pm\) 0.16 \({}^{d}\) & \(6.23\) \(\pm\) 0.19 \({}^{d}\) & 5.35 \(\pm\) 0.15 \({}^{c}\) & 4.69 \(\pm\) 0.16 \({}^{d}\) \\ \hline \multicolumn{1}{c}{Glutathione (mg/L)} & \({}^{**}\) & \(4\) \(\pm\) 0.2 \({}^{a}\) & \(11\) \(\pm\) 0.4 \({}^{b}\) & \(7\) \(\pm\) 0.1 \({}^{c}\) & \(9\) \(\pm\) 0.2 \({}^{d}\) & \(6\) \(\pm\) 0.1 \({}^{c}\) & \(11\) \(\pm\) 0.2 \({}^{b}\) & \(14\) \(\pm\) 0.4 \({}^{b}\) \\ \multicolumn{1}{c}{} & \({}^{**}\) & \(0.96\) \(\pm\) 0.05 \({}^{a}\) & \(0.84\) \(\pm\) 0.02 \({}^{b}\) & \(0.22\) \(\pm\) 0.03 \({}^{c}\) & \(0.30\) \(\pm\) 0.02 \(Transition metals, such as iron and copper, are usually found in wine and their presence is due to soil, vineyard treatments and winemaking tools [25]. The levels of transition metals ranged between 0-0.5 mg/L for iron [25] and 0.1-0.3 mg/L for copper [22]. Iron and copper are catalysts for oxidation reactions and can participate in oxidative phenomena, such as oxidative browning, even at low concentrations [25; 26], as well as causing iron and copper case. In order to limit these alterations, their contents should be less than 5 mg/L for iron and 0.3-0.5 mg/L for copper [25; 27]. Iron and copper contents in the wines analyzed were lower than the values considered responsible for wine instability (Table 2). However, for the wines with longer storage, the content of iron was slightly higher suggesting an influence time-dependent as showed by its positive correlation with the storage time (0.74) (Table S1). A further confirmation was obtained by the principal component analysis (PCA) (Figure 1). Two components explained 64% of the total variance, 40% and 24% for P1 and P2, respectively. The values of b*, chroma, absorbance at 420 nm and the content of iron were the chemical parameters affecting Trebbiano di Lugana wine produced in 2005. On the opposite side, the values of L*, hue and absorbance percentage at 420 nm were more related to the younger wines. PCA showed the distribution of wine samples related to storage time (p1), with the chemical parameters that were majorly affected by the storage time being L*, b*, chroma, hue, absorbance values at 380 nm and 420 nm and iron. The phenol indexes were more influenced by the year of production instead of storage time.