VIRGIN OLIVE OIL OF OUSLATI AND CHEMLALI TUNISIAN CULTIVARS: QUALITY PARAMETERS AND AROMA BIOSYNTHESIS DURING THE OIL EXTRACTION PROCESS

?The accumulation of aroma compounds starts at the moment of cell disruption during the crushing of the olive fruits (pulps and stones) through the lipoxygenase (LOX) pathway. In order to understand the part of pulp and stone in the biogenesis of virgin olive oil (VOO) aroma, the constitutive parts of olive fruits of two Tunisia cultivars (Ouslati and Chemlali) were separately analyzed. According to the obtained results, significant differences on the LOX volatiles composition were observed between olive pulps and stones (P < 0.05). These differences can be attributed to the difference in the distribution and the activity of LOX enzymes in pulp and stone. Our results showed that the LOX volatile compounds have mainly their bio-accumulation in pulp (about 90% for Ouslati and Chemlali cvs) than in stone (10%). (E)-2-hexenal was the dominant aldehydic compound in both crushed pulp and stone. However, 3-pentanone, (E)-2-pentenal, pentanal, 1-penten-3-ol and 1-pentanol were present in lower amount in olive pulps than in stones. Moreover, quality parameter results (free acidity, peroxide value and fatty acids composition) obtained from VOO of Ouslati and Chemlali cultivars were within the limits established by the International Olive Oil Council.