## 3 Results and Discussion
### Sensory Analysis  
In order to determine some differences related to the use of oxygen during the crushing phase and define the overall sensory profile of virgin olive oil samples from the cultivars under study, these samples were subjected to sensory analysis by 9 panelists. The evaluation was conducted using a special quantitative descriptive analysis form in which expert tasters reported the intensity of the various descriptors on unstructured scales. In addition, different attributes were evaluated, concerning four aspects of visual evaluation (\"deep green\", \"moss green\", \"yellow-green\", and \"yellow\"), eight related to the olfactory characteristics (\"fruity\", \"herbaceous\", \"artichoke\", \"hay\", \"green apple\", \"floral\", \"tomato\", and \"almond\"), and four related to the gustatory-retro-olfactory attributes (\"fatty\", \"sweet\", \"bitter\", and \"pungent\"). Moreover, off-flavors (\"earthy\", \"winey-vinegary\", \"rancl\", and \"fusty\") were also included in the evaluation sheet. The sensory analyses carried out on the virgin olive oil samples confirmed the sensory impact of the chemical changes described above. Thus, the addition of oxygen during the crushing phase modified the sensory profile of the oils in accordance with the observed changes in phenols and volatile compounds. Furthermore, from the sensory profiles of the virgin olive oils shown in Figures 1 and 2, the attributes \"fruity\", \"pungent\", and \"bitter\" were clearly detected by the panelists (median > 4 in all the samples). None of the oils produced in this experiment presented sensory defects. Figure 1: Sensory profile of Ogliarola olive oil obtained by adding three different concentrations of oxygen (0.2 L/min for OG2, 0.4 L/min for OG3, and 0.8 L/min for OG4) during crushing phase in comparison with control test (no oxygen added for OG1)  
The availability of oxygen concentrations at increasing levels during crushing had an impact on sensory descriptors in all the samples tested compared to the virgin olive oils obtained by traditional processing (the control sample), although this effect was strongly influenced by the cultivar. In particular, the profiles of Ogliarola oils showed significant differences (\(p<0.05\)) for the attribute \"pungent\", while those of Coratina oils showed significant differences for the \"artichoke\", \"bitter\", and \"pungent\" attributes. The explanation of the sensory notes by the volatile composition also depended on the cultivar. Thus, for example, the herbaceous sensory note reported in the Ogliarola samples seems to be influenced by the concentration of (E)-2-hexenal (Table 3), and the sample presenting a higher intensity of this sensory note also showed a higher concentration of this aldehyde. In the case of Coratina oils, however, the influence of (E)-2-hexenal on the herbaceous perception seems to be less evident. In order to identify changes in the sensory profile from a multivariate perspective, principal component analysis (PCA) was carried out with the scores provided by the panelists. PCA plots, shown in Figures 3 and 4, underline that the oils obtained with oxygenation treatment are characterized by a higher intensity of some \"green\" sensory notes, such as \"fruity\", \"herbaceous\", \"artichoke\", and \"green apple\", compared to control samples [4,74,81]. This effect is more pronounced in oils extracted under oxygen flow at 0.2 L/min, which presented a higher content of volatile compounds derived from the lipoxygenase pathway (C5 and C6 aldehydes, either saturated or unsaturated), contributing to \"green\" attributes [84] in both cultivars (Table 3). Figure 2: Sensory profile of cv.