## 2 Results  
### Effect of Oral Components on Wine Aroma Volatility  
In this work, the relative effect of different oral components on the volatility of typical and chemically different wine odorants was assessed in synthetic wines spiked with human saliva (HS), artificial saliva (AS), and buccal epithelial cells (BC). These wine-oral systems were intended to better represent the physiological environment in the mouth during drinking, in which odorants might differently interact with oral physiological components. Static headspace analysis, which is the best suited to reveal these interactions [20], was used for this purpose. In addition, SPME using short sampling times was selected once it its appropriateness for this type of studies was previously proven [32]. First, the relative effect of the different oral component on the headspace amount (absolute peak area) of each studied aroma compounds (guaiacol, \(\beta\)-phenyl ethanol, ethyl hexanoate, and \(\beta\)-ionone) was explored by one-way ANOVA. Results showed a significant effect of oral components on aroma volatility for all tested compounds. On the basis of the F-ratios and probability (\(p\)) values, the highest effect of oral components was on guaiacol (F = 19.362, \(p\) = 0.004), followed by \(\beta\)-ionone (F = 16.637, \(p\) = 0.012), ethyl hexanoate (F = 16.282, \(p\) = 0.012), and \(\beta\)-phenyl ethanol (F = 14.675, \(p\) = 0.008). In order to determine the extent of the effect of each oral component on aroma volatility, a means comparison test (Tukey test) was also performed. Figure 1 shows these results. As it can be seen, oral components modified the volatility of the tested aroma compounds in a different way, depending on the oral component added to the wine, but also depending on the type of aroma compound. This makes it difficult to extract straightforward conclusions. However, some interesting findings can be highlighted from these results. Firstly, and as it can be seen in Figure 1, in general, wines with BC exhibited higher headspace aroma amounts compared with the other types of wine systems. The effect of BC seemed to be higher in the case of \(\beta\)-phenyl ethanol. This polar compound could be salted out by the addition of BC, which  
Figure 1: Effect of oral components (HS: human saliva, AS: artificial saliva, BC: buccal cells) added to synthetic wine on aroma volatility, (**a**) Guaiacol, (**b**) \(\beta\)-Phenyllethano, (**c**) Ethyl hexanoate and (**d**) \(\beta\)-Ionone. Different letters on the top of the bars for each aroma compound denote significant differences among wine systems (\(p\) < 0.05) from Tukey test. could modify its solubility in the wine. Actually, using a model of oral epithelial cells, it has been shown that the surface of the oral cells present both highly hydrophobic and hydrophilic domains due to the different expression of MUC1/Y-LSO mucin [33]. The expression of MUC1 results in the presence of more hydrophobic and more charged areas at the cell surface [33]. This might explain the change in wine polarity, making it more hydrophobic and provoking the salting out of more polar molecules. This could also explain the higher headspace amounts of guaiacol. However, this explanation might not be valid in the case of more hydrophobic compounds, such as \(\beta\)-ionone, which exhibited similar headspace amounts in the presence of BC. For this compound aroma volatility was similar in the wines with BC and HS, but significantly lower in the case of AS only containing mucin. The retention of this hydrophobic compound by mucin, as it has been described for other hydrophobic aroma compounds [21], might be the reason for these differences. Other effects of epithelial cells that have been previously described are related to their ability to metabolize different types of volatile organic compounds from different chemical families [25; 34; 35]. However, under our experimental conditions, we could not prove this hypothesis.