Molecular characterization of Dalmatian cultivars and the influence of the olive fruit harvest period on chemical profile, sensory characteristics and oil oxidative stability

Four Dalmatian autochthonous olive cultivars (Buhavica, Drobnica, Lastovka and Oblica) were molecularly characterized by analyzing length variability of genomic DNA sequences encompassing 15 microsatellite repeats. Furthermore, several important parameters of olive oils were analyzed in relation to the harvest period. An analysis of major phenolics secoiridoids was done by qNMR, while the fatty acid profile of oils and squalene content was determined by GC–FID. Oxidative stability was evaluated by the Rancimat method and sensory evaluation was carried out by a trained professional panel. The results indicate that the effect of the harvest period on the phenolic profile of oils depends on the olive cultivar and is related to its genetic profile. Drobnica oil from the late harvest contained an extremely high concentration of oleocanthal + oleacein (966 mg/kg). The longest oxidative stability was achieved by Drobnica and Lastovka oils from the early harvest period (20.95 and 18.65 h). Squalene had no effect on the oil oxidative stability. This study shows that the content of phenolic secoiridoids depends mainly on the cultivar. In addition, some cultivars, such as Drobnica did not show significant change of phenolic secoiridoids content in relation to the harvest period. © 2017, Springer-Verlag GmbH Germany

Removal of pomace residues is critical in quantification of element concentrations in extra virgin olive oil

Analysis of elements in Extra Virgin Olive Oil (EVOO) is challenging due to the complex oil matrix as well as very low element concentrations in oil. We postulate that inadequate sample preparation (in particular, the presence of pomace residue in oil) may significantly contribute to variations in EVOO element concentrations. In order to confirm this hypothesis, EVOO and pomace samples were analysed for content of 29 elements by ultrasonic acid extraction and ICP-MS detection. Comparative analyses of non-centrifuged and centrifuged EVOO samples confirmed significant influence of pomace residues on element concentrations. Ranges of macronutrients (25–286 ng g−1), micronutrients (0.3–1.1 ng g−1) and trace elements (0.001–0.2 ng g−1) in centrifuged EVOO samples were up to 1000 times lower than in non-centrifuged oils. We have shown that pomace residue, even when present in very small quantity (1 g of pomace in 1 kg of oil), significantly altered concentrations and relative proportions of many elements in EVOO. Therefore, adequate sample pre-treatment (removal of pomace residue via centrifugation) is essential for determining real multi-element composition of olive oil. This is critical in application of EVOO multi-element composition in traceability studies and determination of geographic origin of olive oi