Phenolic content of commercial olive oils

The phenolic composition of commercial virgin olive oils (Picual, Hojiblanca, Arbequina and Cornicabra varieties) was studied by high performance liquid chromatography, sampling oils over 1 year. Oils sold in March displayed the lowest polyphenol concentration, particularly in secoiridoid aglycons. In contrast, lignans and tocopherols concentrations were not affected by sampling date. Among varieties, Picual and Cornicabra oils had slightly higher concentrations of polyphenols than Hojiblanca and Arbequina. Overall, the concentration of polyphenols in commercial Spanish virgin olive oils ranged from 330 to 500 mg/kg oil, which is higher than data reported previously. In contrast, olive oil and pomace-olive oil (mixtures of refined and virgin olive oils) had much lower concentrations in polyphenols than virgin olive oil, although higher than other edible vegetable oils. Thus, olive oil can be considered a good source of natural antioxidants. Moreover, the polyphenol and tocopherol contents of virgin olive oils were also found useful for the classification of the different commercial monovarietal oils when analysing the data by chemometric methods.