## 2 Results and Discussion
### Effect of Wine Fining Treatments in the Profile of Volatile Organic Compounds
The above PCA results for each monovarietal wine seem to indicate that significant differences are possible to identify between bentonite- and DCMC-treated samples and the respective controls, mainly by peaks **20** (ethyl hexanoate) and **38** (ethyl octanoate). Actually, both these compounds decreased in quantity when the two fining agents (i.e., bentonite or DCMCO) were used, as also observed by [PERSON] el al. [PERSON] et al. (2017) for the Siria and Arinto wines when the addition of bentonite was under study. It has been proposed that removal of these long chain esters by negatively charged bentonite results from a synergetic effect of the adsorption of the esters to the clay and proteins. The same should happen in the presence of DCMC. Nevertheless, it is not clear from the individual PCAs (Figures 7-9) whether the VOC profiles exert a differential effect in the aroma of the wines when bentonite or DMMC are used. Thus, in Figure 10, all monovarietal wines and controls are represented (only mean values were considered for the sake of clarity). PC1 and PC2 explained almost 79% of the system variance. Controls of the three varietal wines were completely separated from the varietal wines treated with DCMC and bentonite through the first PC, by peaks **20** (ethyl hexanoate) and **38** (ethyl octanoate). The first PC also separated Viosinho from Encruzado, mainly by peaks **29** (4-methyl benzaldehyde) and **37** (diethyl succinate), which characterized Viosinho, and peak **50** (ethyl decanoate) characterizing Encruzado. Moscatel de Setubal-treated samples were considered as a reference for the case of the **50** (ethyl decanoate), and the **50** (ethyl decanoate), respectively. The second PCAs (Figure 10) was used to estimate the effect of the **50** (ethyl decanoate), and the **50** (ethyl decanoate), respectively. The **50** (ethyl decanoate), and the **50** (ethyl decanoate), respectively. de Setibal varietal wine was separated from the other varietal wines through the second PC, by peaks **13** (isoamyl acetate), **32** (ethyl 3-(methylthio)-propanoate), and **44** (2-phenethyl acetate) and within the same varietal wine between the bentonite and DCMC treatments. The second PC also separated Viosinho from Encruzado, regardless of using bentonite or polymer. It may appear that the separation obtained was more impacted by the varietal wine than by the bentonite or DCMC treatments. Within each varietal wine, the use of bentonite or polymer does not indicate a significant change in the VOC profiles obtained. It is worth noting that for each varietal wine, the VOC profiles and treatments were concentration-dependent, but less dependent on the fining agent used (i.e., bentonite or DCMC). Indeed, in Figure 10, this is clear for Viosinho and Encruzado, though less evident for Moscatel de Setibal. The capacity to promote protein removal, the phenolic content and pH preservation, the slight calcium depletion and predictable changes in the wine aromatic fraction allowed us to propose DCMC as a sustainable alternative to bentonite firing in white wine protein stabilization.