Monitoring of Bioactive Compounds from Hojiblanca Extra Virgin Olive Oil Variety and Olive Oil Byproducts During Storage Time

Extra Virgin Olive Oil (EVOO), the juice derived from the first cold pressing of the olives without any further refining process, naturally contains high levels of phenolic compounds associated with the health benefits. Indeed, these compounds exert strong antiproliferative effects on many pathological processes, which have stimulated chemical characterization of the large quantities of wastes generated during olive oil production. In the Mediterranean area, EVOO is produced from September to February, and oil is generally stored in the mill plant until commercialization. During this storage time suspended solids and others materials are deposited by precipitation in the bottom of the tank generating a solid waste. Phenolic fraction has been previously assessed in these byproducts which can be considered an important natural source of phenolic compounds, mainly hydroxytyrosol, tyrosol and decarboxymethyl oleuropein aglycone. In this investigation, phenolic profile on EVOO and solid waste generated during storage has been monitored using solid phase and solid–liquid extraction processes followed by high performance liquid chromatography (HPLC) coupled to electrospray time-of-flight mass spectrometry (TOF-MS). EVOO from Hojiblanca variety was obtained and stored in ten tanks without headspace at room temperature in darkness. In order to monitoring phenolic profile in both, EVOO and solid waste, sample collection and phenolic compound extraction were carried out every thirty days during a period of ten months. Half-life (t1/2) of the individual compounds was calculated as ln 2/ Kel, where Kel (elimination rate constant) was established from the slope of the elimination phase in the concentration vs. time plot. A variable trend was observed for phenolic content in both, EVOO and byproducts, during the storage. Qualitative results of phenolic and derived compounds in EVOO and storage byproduct suggested degradation pathways which were confirmed taking into account half-life and Kel for the complex phenols and their oxidized and hydrolyzed derivatives. Indeed, when the correlation for the pair oleuropein aglycone or decarboxymethyl oleuropein aglycon and their hydrolyzed derivatives was evaluated, the determination coefficients (r2) were higher than 0.970. These results showed the trend of the phenolic compounds in EVOO as well as byproduct during storage time, which are of great value in establishing of the EVOO quality and solid waste. These phenolic molecules, after suitable purification, can be used as food antioxidants or as ingredients in nutraceutical products due to their interesting technological and pharmaceutical properties.