## 2 Results and Discussion
### Effect of Wine Fining Treatments in the Profile of Volatile Organic Compounds
For Viosinho (Figure 8), the first and second PCs explained more than 86% of the system variance. The samples treated with bentonite were separated from the samples treated with DCMC through the second PC. In fact, peaks **1** (ethyl acetate), **13** (isoamyl acetate), **20** (ethyl hexanoate), **50** (ethyl decanoate), **57** (2,4-di-tert-butylphenol), **61** (ethyl dodecanoate), **67** (heptadecane), **70** (nonadecane), and **71** (eicosane) separate this monovarietal wine treated with bentonite from the DCMC-treated wine samples, which were characterized by peaks **29** (4-methyl benzaldehyde), **31** (2-butoxyethyl acetate), **37** (diethyl succinate), and **44** (2-phenethyl acetate). The control was separated through peak **38** (ethyl octanoate) from all other Viosinho samples along PC1. \begin{table}
\begin{tabular}{c c c c c} \hline
**Peak \#** & **Chemical Family** & **Compound Name** & **LRI\({}_{\text{Calc}}\)****a** & **LRI\({}_{\text{Lit}}\)****a** & **\(\Delta\) (LRI\({}_{\text{Calc}}\)-LRI\({}_{\text{Lit}}\))** \\ \hline
17 & Miscellaneous & 3-(Methylthio)-1-propanol & 977 & 981 & \(-\)4 \\  & (methionine) & & & \\
18 & Miscellaneous & 3(2H)-Thiophene, & 984 & 996 & \(-\)12 \\  & & dihydro-2-methylthio)-propanoate & 1100 & 1098 & 2 \\
32 & Miscellaneous & Vijispirane & 1275 & 1281 & \(-\)6 \\
45 & Miscellaneous & Isobutyl-2,2,4-trimethyl-3- & 1348 & & NC \\  & & hydroxy-pentanoate & & \\
57 & Miscellaneous & 2,4-Di-tert-butylphenol & 1511 & 1513 & \(-\)2 \\
59 & Miscellaneous & Dehydro-a-thinachalene & 1537 & 1514 & 23 \\
23 & Terpenoid & Limonene & 1026 & 1028 & \(-\)2 \\
26 & Terpenoid & \(\beta\)-Ocimene & 1038 & 1049 & \(-\)11 \\
30 & Terpenoid & Terpenolene & 1086 & 1088 & \(-\)2 \\
34 & Terpenoid & Nerol oxide & 1153 & 1153 & 0 \\
36 & Terpenoid & Linalool & 1171 & 1099 & 72 \\
40 & Terpenoid & Nerol & 1226 & 1228 & \(-\)2 \\
46 & Terpenoid & Geraniol & 1285 & 1267 & 18 \\
60 & Terpenoid & \(\alpha\)-Calacorene & 1540 & 1542 & \(-\)2 \\
63 & Terpenoid & \(\alpha\)-Corocalene & 1617 & 1623 & \(-\)6 \\
16 & Unknown & Unknown & 971 & & \\
35 & Unknown & Unknown & 1167 & & \\
41 & Unknown & Unknown & 1231 & & \\
42 & Unknown & Unknown & 1236 & & \\
51 & Unknown & Unknown & 1415 & & \\
58 & Unknown & Unknown & 1519 & & \\
64 & Unknown & Unknown & 1639 & & \\
65 & Unknown & Unknown & 1658 & & \\
66 & Unknown & Unknown & 1663 & & \\ \hline \end{tabular}  
* \(\text{LRI}_{\text{calc}}\)–retention indices calculated from CS—C20 \(n\)–linear alkanes, LRI\({}_{\text{Lit}}\)—linear retention indices reported in the literature for DB5 capillary column [17; 30; 31; 52; 53], NC—not calculated.  
\end{table} 
Table 2: \(Cont.\)Figure 8: PCA illustrating the simultaneous projection of the wine samples (objects)—by a mark, and VOC (variables) loadings—by a number, for the Viosinho varietal wine. The different concentrations of bentonite (B) or DCMC (D) in g/L are indicated. Figure 7: PCA illustrating the simultaneous projection of the wine samples (objects)—by a mark, and VOCs (variables) loadings—by a number, for the Encruzado varietal wine. The different concentrations of bentonite (B) or DCMC (D) in g/L are indicated. For Moscatel de Setubal (Figure 9), PC1 and PC2 were responsible for more than 84% of the system variance. Samples treated with DCMC were characterized by peaks **22** (hexyl acetate), **31** (2-butoxyethyl acetate), **37** (diethyl succinate), **44** (2-phenethyl acetate), **50** (ethyl decanoate), and **57** (2,4-di-tert-butylphenol) along PC2, whereas samples treated with bentonite were characterized by peaks **1** (ethyl acetate), **13** (isoamyl acetate), **29** (4-methyl benzaldehyde), and **32** (ethyl 3-(methylthio)-propanoate), also mainly along the PC2. Once again, the control was separated through peaks **20** (ethyl hexanoate) and **38** (ethyl octanoate) from all other Moscatel de Setubal-treated samples along PC2.