## 3 Results and Discussion
### Physicochemical and Chemical Characterization of Juices
**} \\ \cline{2-11}  & **Prult** & **NT Justice** & **TT juice** & **HPP juice** & **Prult** & **NT juice** & **TT juice** & **HPP juice** & **Prult** & **NT juice** & **TT juice** & **HPP juice** \\ \hline \hline \multicolumn{11}{c}{Hermal} \\ \multicolumn{11}{c}{Guminal} \\ \multicolumn{11}{c}{2-Hermal} \\ \multicolumn{11}{c}{2-Hermal} \\ \multicolumn{11}{c}{2-Hermal} \\ \multicolumn{11}{c}{Normal} \\ \multicolumn{11}{c}{2-Hermal} \\ \multicolumn{11}{c}{Nonmal} \\ \multicolumn{11}{cThe head space of the juices obtained from the three cultivars separately presented, to a significant degree, the same volatiles of the starting matrices. Among all the 51 detected volatiles, several of them (36) had primary flavor compounds, as they were already present in the aromatic fraction of the fruits, while other molecules mainly derived from the process (Table 3). Some volatiles present in the aromatic fraction of fresh fruits were lost during the pressing phase, as were some esters, such as isoamylclaproate and hexylcaproate. Other aromatic compounds are generated by the extraction process, as by the stabilization treatments, especially aldehydes, such as furfural, benzaldehyde, and 2,4-decadienal, and alcohols, such as butanol. This latter was present in the starting juices of all the three cultivars, but it was lost after treatments in PIN and RD. The loss of alcohols could be ascribed to heating and to high pressure, applied for the stabilization of the products [49]. In addition, some volatiles resulted characteristic of the single cultivars, as heptanal detected in GD fruit and juice aromatic fractions (Table 3). Statistical analysis showed that, in juices, there was a significant interaction between the considered factors--cultivar and treatment. Specifically, for the NT juices, the total volatile amount resulted almost three times higher in PIN and RD cultivars compared with GD (Figure 3); in the thermal-treated juices, RD showed a total volatile content two folds higher than GD. Finally, among the HPP-treated juices, GD products were those with the highest total volatile amount. Considering the different cultivars, the TT did not seem to affect the aromatic molecule content, especially in PIN and RD cultivars, while HPP treatment determined an increase in the total volatile content in GD (Figure 3). This trend may depend both on the starting fruit variety and on the initial juice characteristics. It was indeed observed that in juices rich in aromatic components, such as those obtained squeezing Pink Lady and Jonagold apples, thermal pasteurization lead to an increase in volatiles compared with HPP treatment [12]. In our case, the volatile content in PIN and RD was not affected by either TT or HPP, while in GD juice, both treatments augmented the volatile quantity. Among the chemical classes detected, aldehydes were mainly represented by hexanal and 2-hexenal, with typical herbal and apple notes and characteristic of apple juice flavor. Statistical analysis did not evidence any difference among these volatile contents in fruits, while in juices, a significant interaction between factors was noted. In fresh juices (NT), aldehyde concentration resulted lower in GD juice (1.80 \(\pm\) 0.0 ppm) than in PIN and RD juices (5.6 \(\pm\) 1.2 and 6.0 \(\pm\) 1.4 ppm, respectively); this trend could be due to a more pronounced oxidation of fatty acids in PIN and RD. No differences were observed among the cultivars within TT and HPP-treated juices. Moreover, in GD juices submitted to HPP processing, a significant increase in total aldehyde content (6.6 \(\pm\) 0.5 ppm) was  
Figure 2: Volatile composition and amount of fruits pertaining to three apple cultivars. The means with different letters are significantly different (\(p<0.05\)). observed compared with NT and TT (1.80 \(\pm\) 0.0 ppm and 1.7 \(\pm\) 0.9 ppm, respectively). This phenomenon could be mainly ascribed to a rise in hexanal and 2-hexenal concentration.