Besides, the LOX gene showed an increased accumulation DAPT secretase 208255-80-5 of transcripts in the olive fruit during ripening (Figure 3), which coincides with a decrease in the synthesis of volatile compounds as detected in olive paste and olive oil aroma. This result indicates that the LOX gene was expressed at late developmental stages of the olive ripening, suggesting that it is probablly linked with the senescence process. Although its contribution to the biosynthesis of the olive oil aroma cannot be ruled out, it exhibits LOX activity in a 2:1 ratio with LA as substrate, as suggested also by Palmieri-Thiers et al. [7].The concentration levels of (E)-2-hexenal are greater in olive oil than in the equivalent olive paste obtained with or without malaxation, regardless of the zone of olive cultivation.

In fact, the volatile compounds formed during crushing and malaxation steps are accumulated into oil generating the characteristic aroma. Besides, using these characteristic metabolic profiles (hexanal, E-2-hexenal, and other aldehydes) in combination with genetic and spectroscopic analyses allows us to set up a strategy for a cultivar and/or geographical origin discrimination of the extra virgin olive oils [35].The olive oil samples collected in each area of olive plants cultivation considered showed the maximum levels of (E)-2-hexenal in 200DAF fruits. An elevated concentration of (E)-2-hexenal was found in all samples obtained from Rende areas, with respect to samples obtained from Mirto-Crosia area (Table 2). These results indicated that LnA was clearly the preferred substrate of LOX enzyme for both environments.

All olive paste samples of Mirto-Crosia area showed a higher content of hexanal+1-hexanol than paste samples obtained from Rende area (Table 1), and this behaviour was even more pronounced for the olive oil sample (Table 2). The (E)-2-hexen-1-ol was present only in olive oils at 170 and 230DAF fruits obtained from Mirto-Crosia area (Table 2). This aspect might be due to an over-activity of the dehydrogenase (ADH) enzymes in these samples. Finally in all samples, the (Z)-3-hexen-1-yl acetate was not detected.3.3. Effects of Malaxation on the Volatile Composition?Tables Tables11 and and22 show the data obtained monitoring the selected volatile compounds in samples of olive pastes kneaded with and without malaxation (t = 0 and t = 30min) (Table 1) and in olive Dacomitinib oils obtained after 30min of malaxation (Table 2). It is important to point out that the amount of the volatile compounds changes with the prolonging of malaxation step, and with the olive ripening stage.