# Characterization of Freisa Wines from Piedmont (Italy) by Aroma and Element Profile
## 3 Results and Discussion
### Major, Minor and Trace Elements  
Table S1--S3 show the mean, standard deviation, and minimum and maximum concentrations for each element determined in FA, FC, CTF, LF, and MF wines. For comparison, Table S4 shows the distribution of major, minor and trace elements in Freisa wines analyzed in this study and in other red wines obtained from vineyards in Italy. Overall ANOVA showed that there were significant differences in the content of AI (\(p<0.1\)), Fe, P and Rb (\(p<0.05\)), and Cr and Zn (\(p<0.05\)) in Freisa wines collected in different geographical areas of Piedmont. Amongst major and minor elements, only the phosphorus content showed a highly significant difference by sites, whereas no significant differences among the Ba, Ca, Cu, Mg, Mn, Na, Ni, and Ti content of wines by sites were noted. This can be considered a confirmation of the similar composition of Piedmont Freisa wines: for 53% of the elements considered, there were no significant differences. Above all, a highly significant difference was highlighted for only one element. This finding allows us to hypothesize that Freisa wine can likely be well differentiated from other red wines. With regard to major and minor elements (Table S1), the most abundant ones were Ca, Mg, and P. The concentrations of all the major elements, with the exception of Na, show lower standard deviations than those found for minor and trace element concentrations in all the areas investigated. The CTF wine samples are characterized by the highest mean concentration and standard deviation for Fe and Na and by the lowest mean concentration for P and Rb. Figure 3a reports the box plots of the major elements in wine samples collected in the five different Piedmont areas. It is possible to notice that CTF samples showed a greater variability for most major elements investigated. Moreover, it is evident that the element characterized by the highest variability was phosphorus. This behavior is likely due to the great importance of this element for the growth of plants which assimilate it in large quantities according to its availability in the soil. In fact, the available fraction of phosphorus strongly depends on the pH and Ca concentration in the soil as well as on the possible addition of fertilizers. All these factors can influence the P content in the wines, and hence, a greater variability for this element is not surprising. Among the trace elements, the most abundant were Cu and Mn, followed by Al, Sr, Zn, Cr, Ni, Ba, and Ti. In particular, Ti concentrations in Freisa wines showed a great variability as it was present in some wine samples in very high concentration. The assimilation mechanisms of this element by plants are not well understood and, therefore, it is difficult to find an explanation for this behavior. However, contamination of this element can be excluded given that it is not considered a typical pollutant and its source is usually geogenic. Cr and Ni were characterized by a low variability (relative standard deviation percentages were 7.1 and 9.8, respectively). Finally, the overall low concentrations of Al, Cu, Fe, and Zn permit the exclusion of possible contamination by the winemaking process, which could lead to an increase in these elements. Indeed, it is known that these elements can be introduced into the wine due to long contact of the same with materials (aluminum, brass, glass, stainless steel, and wood) from which wine-making machinery, pipes, casks, and barrels used for handling and storing wine are made [35; 36]. This is a confirmation that, as the maturation times necessary for Freisa wine are reduced if compared with those of other more mature wines, contamination during the winemaking process is less likely. The FC samples showed lower mean concentrations for Cr, Sr, and Ti than the other Freisa wine samples. Instead, CTF samples were characterized by the highest mean concentrations for Cr, Sr, Ti, and Zn.