A single phenolic group and even a compound play different roles in the sensory properties and stability of virgin olive oil (VOO), which in turn are strongly influenced by several factors. Understanding the causes of differences in phenolic compound composition and oxidative stability (OS) in VOOs is essential for targeted and timely harvest and processing while maintaining desired oil quality. The phenolic profile and OS of two monocultivar VOOs (Oblica and Leccino) grown in two geographical sites of different altitudes (coastal plain and hilly hinterland) were analyzed throughout the ripening period over two years. Concentration of secoiridoids was 30% higher in the Oblica than in the Leccino VOOs, which in turn had significantly higher values of OS. Both cultivars had more than twice as high concentrations of the two most abundant phenolic compounds, the dialdehyde form of decarboxymethyl oleuropein aglycone and the dialdehyde form of decarboxymethyl ligstroside aglycone, and OS values in a colder growing site of higher altitude. Among the studied monocultivar VOOs, the secoiridoid group did not behave equally during ripening. The hierarchy of different influencing factors was investigated using multivariate statistics and revealed: cultivar > geographical site > harvest period > growing season. In addition, the possibility of traceability of VOO using molecular markers was investigated by establishing SSR profiles of oils of the studied cultivars and comparing them with SSR profiles of leaves.
Keywords: DNA; Olea europaea L.; cv. Leccino; cv. Oblica; environmental conditions; molecular identification; phenolic profile; principal component analysis; secoiridoids; traceability.