## 3 Results and Discussion
### Evolution of the Concentrations of Cu and SO\({}_{2}\) during Wine Production
For Chardonnay, the bentonite treatment led to elevated concentrations of hexanal at PB, but this effect only remained significant (\(p\leq 0.05\)) for the high SO\({}_{2}\) treatment (HSO2) after 15 months of bottle aging. This concentration increase was possibly due to the higher Fe concentrations (Table S2) in the bentonite-treated wines [35], inducing a higher oxidative production of hexanal. For 3-methylbutanal and phenylacetaldehyde, the impacts of Cu and SO\({}_{2}\) treatments were significant (\(p\leq 0.05\)) in both Chardonnay and Shiraz (Figure 2C-F). In all cases, the SO\({}_{2}\) treatment led to increased concentrations of both aldehydes immediately after fermentation (PAF). In the Chardonnay, a further increase in the concentrations of the two aldehydes occurred after PAF as for hexanal, and the treatment effects remained significant (\(p\leq 0.05\)) until after 15 months of bottle aging (15 Mo, Figure 2C,E). This indicated that the Chardonnay juice SO\({}_{2}\) concentration influenced the 3-methylbutanal and phenylacetaldehyde concentrations in wine until at least 15 months after bottling, regardless of the multiple wine production steps and the standard SO\({}_{2}\) additions after fermentation. This in turn indicated that upon free SO\({}_{2}\) depletion in the wine during aging (i.e., oxidatively or thermally), the wines with more SO\({}_{2}\) addition to the juice had a larger reservoir of oxidative-aroma compounds to release. With Cu treatment, phenylacetaldehyde concentrations decreased after fermentation (PAF) and remained reduced until PB. However, the differences were less evident after bottle aging (15 Mo, Figure 2E). Bentonite treatment increased the concentrations of 3-methylbutanal in most Chardonnay samples at PB and/or 15 Mo (Figure 2C,E). In the Shiraz, both SO\({}_{2}\) and Cu treatments increased the concentrations of 3-methylbutanal and phenylacetaldehyde at PAF, which then decreased significantly (\(p\leq 0.05\)) until PB, when no difference amongst treatments was found (Figure 2D,F). The increase in phenylacetaldehyde concentration during red wine aging, as observed in Figure 2F, has also been reported by [PERSON] et al. [56], who indicated that this compound was less reactive to flavonoids than other Strecker aldehydes. Methional only showed a marginal difference in the Chardonnay wines after cold stabilization (PCold for Chardonnay, Figure 2G-H). Benzaldehyde, the least electrophilic compound of all the aldehydes studied, was the only aldehyde that showed no decrease in concentration during the Shiraz production (Figure S1). This is consistent with benzaldehyde having a particularly slow reaction rate with red wine flavonoid compounds [12]. The lack of an SO\({}_{2}\)-induced (SO\({}_{2}\) treatment) effect on benzaldehyde is also consistent with it being a particularly weak binder to hydrogen sulfite [12]. Impacts of Cu or SO\({}_{2}\) Addition to Juice/Must on Wine Color Parameters, Protein Concentration (Chardonnay Only), and Esters and Terepenes Concentrations in Wine  
Results of the color parameters, esters and terpenes for both Chardonnay and Shiraz, and the protein concentration of the Chardonnay, are summarized in Tables S3 and S4. No significant (\(p\leq 5\)) of the 3-methylbutanal and 3-methylbutanal are shown in Table 1. The 3-methylbutanal is shown in Figure 2. The 3-methylbutanal is shown in Figure 3.  
0.05) influences from the Cu or SO\({}_{2}\) additions to the grape juice/must were observed for most of these features in either of the wine matrices. Another interesting observation was that the Cu addition to the grape juice/must resulted in an increased concentration of certain esters after fermentation (PAF). Three higher alcohol acetates (HAAs), two ethyl esters of fatty acid (EEFAs), two ethyl esters of cinnamic acids (EECAs), and ethyl propanoate showed increased concentrations in Shiraz with Cu additions to the must. Alternatively, the Cu and SO\({}_{2}\) addition to Shiraz must resulted in decreased ethyl phenylacetate concentrations after fermentation (PAF).