# Impact of Chitosan-Genipin Films on Volatile Profile of Wine along Storage
## 3 Results and Discussion
### Impact of Chitosan-Genipin Films on Wine Volatile Composition
Figure 6: GC \(\times\) GC—ToFMS peak area of the same volatile compounds identified (uindicated in Table S1) in white wine (WW) and red wine (RW) in contact with chitosan-genipin films during 2 (2 M) and 8 (8 M) months. Log P is the logarithm of the octanol/water partition coefficient of the compounds in this biphasic system. The hydrophobicity effect resulting in the retention of volatile compounds by Ch-Ge films was reflected in both wines volatile composition, namely in ethyl esters family. This group of compounds showed a significant decrease (\(p<0.05\)) after 8 months in contact with Ch-Ge films, especially for the long chain esters, such as ethyl nonanoate (in WW and RW), ethyl decanoate (in RW), and ethyl dodecanoate (in WW and RW), as shown in Figures 4 and 5. These results are in accordance with the wine model solutions behaviour for ethyl hexanoate when compared with ethyl acetate (Figure 3). The same behaviour was observed for alcohols, where a significant decrease (\(p<0.05\)) of their amount was also observed, with statistically significant differences for decan-1-ol (in RW), undecan-2-ol (in WW and RW), and dodecan-1-ol (in RW), in accordance with the non-retention of hexanol in wine model solutions. The inhibition by chitosan [39] of lipoxygenase and other enzymatic activities still present in wine [40] may explain the lower content of (Z)-hex-3-en-1-ol and 3-methyl-pentan-1-ol in the Ch-Ge wines. As observed for model solutions containing hexanoic acid (Figure 3), a significant decrease (\(p<0.05\)) of the amount of acids after 8 months in both wines in contact with Ch-Ge films was also observed, statistically significant for butanoic (in WW), decanoic (in RW), hexadecanoic (in RW), and 2-methylbutanoic acids (in WW and RW), as shown in Figures 4 and 5. The principal component analysis performed to the GC \(\times\) GC peak areas of the volatile compounds of the wines in contact with Ch-Ge films (Figure 7) placed in PC2 negative the wines with longer contact with films due to the furfural, 3-methylbutanal, and phenylacetaldehyde, which increase their content in these wines (Figures 4 and 5, and Table S1). These results are in accordance with the data obtained for the wine model solutions containing pentoses or amino acids in the presence of Ch-Ge films, which formed furfural (Figure 1A) or Strecker aldehydes (Figure 1B,C), respectively. The content of furfural had an increase in the wines in contact with Ch-Ge film during 8 months when compared with wines in contact with the films during 2 months: from 1.7 \(\times\) 10\({}^{6}\) to 8.9 \(\times\) 10\({}^{6}\), \(p<0.05\) for white wines (Table S1 and Figure 4) and from below the limit of detection (6.0 \(\times\) 10\({}^{3}\)) to 4.8 \(\times\) 10\({}^{6}\), \(p<0.05\) for red wines (Table S1 and Figure 5). The occurrence of furfural in wines is usually valorised due to its association with toasted sweet foods [41], giving particular notes to aged white wines in toasted wood barrels [42; 43]. Phenylacetaldehyde, benzaldehyde, and 3-methylbutanal, Strecker degradation derived products, known to confer positive distinctive notes to wine aroma, should provide fruity [44], almond [45], and malty [46] aroma scents to wines in contact with Ch-Ge films. Touriga Nacional wines are characterised by their content on monoterpenic compounds, such as linalool, \(\alpha\)-terpineol, and geraniol [47; 48]. The amount of these compounds did not show significant differences in the presence of Ch-Ge films. For Encruzado, no data are available concerning its varietal aroma characteristics [27; 49]. Nevertheless, the chemical families responsible for the varietal aroma in white wines are monoterpenic, sesquiterpene, and norisoprenic compounds. It is possible to observe that Ch-Ge films had low impact on these classes in white and red wines (Figures 4 and 5), allowing to explain why the white wines were highly appreciated by the panel test of experts [21].