Phenolic enrichment of foods curated in olive oil: Kinetics and chemical evaluation.

Since ancient times food has been preserved in vegetable oils for curation. Nevertheless, the transfer of bioactive compounds from these oils to curated foods has not been studied. This research has evaluated the phenolic enrichment of foods curated in olive oil. For this purpose, six foods (fish, vegetables, and cheese) were immersed in olive oil for 30 days and analyzed to determine these antioxidant phenols by LC-MS/MS. Oleuropein aglycone, hydroxytyrosol and tyrosol were the main phenols quantitatively enriched in the foods (up to 42.1, 26.2 and 53.0 mg/kg, respectively). The total phenolic content ranged from 5.8 to 12.1 mg in the evaluated foods taking as reference the recommended daily intake (150 g for fish, 200 g for vegetables, and 50 g for cheese). This research proves the phenolic enrichment of foods curated in olive oil, which can hypothetically increase their antioxidant and bioactive properties.

The secoiridoid profile of virgin olive oil conditions phenolic metabolism.

The European Food Safety Authority highlights the beneficial effects of olive oil phenols, mainly, secoiridoids. Nevertheless, the metabolism of secoiridoids in humans has not been fully elucidated. This research evaluated the metabolism of secoiridoids in humans after intake of olive oils with diverse phenolic profiles. For this purpose, three extra virgin olive oils (EVOOs) were ingested by six volunteers at scheduled meals, and urine samples were collected the following morning for subsequent LC-MS/MS analysis. Using untargeted analysis, urinary metabolites revealed representative patterns associated with the various olive oil phenolic contents in absolute and relative terms. We were able to identify metabolites obtained through phase I, phase II, and microbial metabolism with discrimination between tyrosol and hydroxytyrosol derivatives. Metabolism of phenols is differentially activated as a function of the olive oil secoiridoids content, and this proof-of-concept study shows how urinary metabolites represent olive oil phenolic content.

The decrease in the health benefits of extra virgin olive oil during storage is conditioned by the initial phenolic profile.

Phenols are responsible for the only health claim of virgin olive oil (VOO) recognized by the European Commission EU 432/2012 and the European Food Safety Authority. In this research, we studied the decrease in the phenolic content of 160 extra VOOs (EVOOs) after 12 months storage in darkness at 20 °C. Phenolic concentration was decreased 42.0 ± 24.3% after this period and this reduction strongly depended on the initial phenolic profile. Hence, EVOOs with predominance in oleacein and oleocanthal experienced a larger decrease in phenolic content than oils enriched in other phenols. Complementarily, hydroxytyrosol and oleocanthalic acid increased significantly in aged EVOOs, which allowed their discrimination from recently produced EVOOs. These changes are explained by degradation of main secoiridoids during storage due to their antioxidant properties. Hydroxytyrosol and oleocanthalic acid can be considered markers of olive oil ageing, although they can also provide information about quality or stability.