| Abstract
| - Olive stoning during the virgin olive oil (VOO) mechanical extraction process was studied to showthe effect on the phenolic and volatile composition of the oil. To study the impact of the constitutiveparts of the fruit in the composition of olive pastes during processing, the phenolic compounds andseveral enzymatic activities such as polyphenoloxidase (PPO), peroxidase (POD), and lipoxygenase(LPO) of the olive pulp, stone, and seed were also studied. The olive pulp showed large amounts ofoleuropein, demethyloleuropein, and lignans, while the contribution of the stone and the seed in theoverall phenolic composition of the fruit was very low. The occurrence of crushed stone in the pastes,during malaxation, increased the peroxidase activity in the pastes, reducing the phenolic concentrationin VOO and, at the same time, modifying the composition of volatile compounds produced by thelipoxygenase pathway. The oil obtained from stoned olive pastes contained higher amounts ofsecoiridoid derivatives such as the dialdehydic forms of elenolic acid linked to (3,4-dihydroxyphenyl)ethanol and (p-hydroxyphenyl)ethanol (3,4-DHPEA-EDA and p-HPEA-EDA, respectively) and theisomer of the oleuropein aglycon (3,4-DHPEA-EA) and, at the same time, did not show significantvariations of lignans. The stoning process modified the volatile profile of VOO by increasing the C6unsaturated aldehydes that are strictly related to the cut-grass sensory notes of the oil. Keywords: Olive stone; oil mechanical extraction process; phenols; secoiridoids; volatile compounds;polyphenoloxidase; peroxidase; lipoxygenase
|
